Dyson Slim DC18 Undercarriage Repair

dyson slim dc18

Introduction

This post gives a detailed description, with photos and reference to a Parts Diagram, of how to replace a Dyson Slim DC18 Undercarriage. The Undercarriage would require changing if part of it broke since parts cannot be obtained individually. I changed mine when the  Air Input Changeover Valve Actuator broke.

“Since I first published this article, in February 2013, I have had plenty of feedback from readers and I have gleaned information from statistical data which has encouraged me to improve it. So if you came here soon after I published it you should find better information now.” — Helpful Colin

Diagrammatic Breakdown of a Dyson Slim DC18

Here is a very clear diagrammatic breakdown of: The Parts of a DC18. This site, Vac Parts Warehouse, may also be a place where readers in the USA find it convenient to buy replacement parts.

NOTE: As a consequence of finding the parts diagram above,  I have renamed parts in my description to conform with it.

My Dyson Slim DC18 Undercarriage Problem

I wrote this article after I had a problem with my Dyson Slim DC18 where the rotating Air Input Changeover Valve in the Undercarriage didn’t work. Its purpose is to change the airflow from the Cleaner Head Assembly to the Hose Assembly when the DC18 body is lifted and locked into the upright position. A piece of plastic on a moving part of the undercarriage which should engage and operate the Changeover Valve mechanism had broken off. On investigation I found it necessary to replace the entire undercarriage, to fix it, because I could not buy an individual part.

I obtained the new undercarriage for my Dyson Slim DC18 from espares_logo(espares) a UK online parts store. They asked me for a review. You can find it here under Reviews of Dyson Undercarriage Assembly for DC18 dated 10 February 2013.

“Across the pond you can get parts from ereplacementparts.com. They have a nice site with exploded parts views for many products.” — Andrew Pardoe (25/08/2016)

Dyson Slim DC18 Undercarriage

For those who don’t know what part is the undercarriage this is it:

The Dyson Slim DC18 Undercarriage
The Dyson Slim DC18 Undercarriage

The Dyson Slim DC18 undercarriage is separate from the body and does not include the Barrel Wheel and Yoke Assemblies. The one above is taken from my Dyson Slim DC18 and has a broken Changeover Valve Actuator which would otherwise operate the Changeover Valve when the Dyson Slim DC18 is raised or lowered.

Removing The Old Dyson Slim DC18 Undercarriage

The main components of a Dyson Slim DC18 are:

  • Main Body (Duct Assembly and its parts).
  • Rotating Brush Head or Cleaner Head Assembly.
  • Undercarriage.
  • Barrel Wheel and Yoke Assemblies.
  • Cyclone and Bin Assemblies.

The tools required to work on a Dyson Slim DC18 undercarriage are:

In the list above I have provided links to Maplin online store in the UK where these tools can be obtained.

Most DIY and hardware stores sell similar tools too. e.g.:

The component parts of a dismantled Dyson Slim DC18 with the tools for working on it:

Dyson Slim DC18 Parts with tools used for dismantling it.
Dyson Slim DC18 Parts with tools used for dismantling it. Select the image to enlarge it.

NOTE: A new undercarriage doesn’t include the Barrel Wheel and Yoke Assemblies.

The Barrel Wheel and Yoke Assemblies include:

  • Barrel Wheel.
  • Axle.
  • 2 x e-clips.
  • Cleaner Head Assembly mounting point with Pipe Seal.
  • 2 x Outer Wheel Hubs.

Before remove the Undercarriage the Barrel Wheel and Yoke Assemblies have to be uncoupled from the Undercarriage by withdrawing the Axle that passes through the centre of the Barrel Wheel. The Axle passes through the Yoke Assembly, the Undercarriage and the Barrel Wheel and holds the three components together. Once the Barrel Wheel and Yoke Assemblies are detached it becomes easy to access the four screws which hold the Undercarriage to the Main Body Duct Assembly at the front. There are two other screws which are accessed from the back.

Dyson Slim DC18 Undercarriage Replacement Process

1.  Start by removing the Cleaner Head Assembly and disconnecting the flexible hose at the back as per user instructions.

Then pull off the Outer Wheel Hubs that cover and protect the end of the Barrel Wheel Axle by curling the tips of your finger around the edge and pulling them off. Some force is required but the plastic seems to be strong enough.

Alternatively release the cleaner from the upright position, using the foot peddle, and lay it down on the floor as in the picture below to expose the lugs on the Outer Wheel Hubs (as described in the comment submitted by Rachel Hall). You can then use a long screwdriver to assist in pushing the lugs through the hole in which they are located.

Dyson Slim DC18 showing the lugs of the Outer Wheel Hub
Lugs of the Outer Wheel Hub

Once removed you will see how four spring plastic lugs in the centre of each Outer Wheel Hub holds them on when they are clicked into a central hole. The Outer Wheel Hubs can rotate but only come into contact with the floor when the cleaner is leaned over to the side.

2.  Undo the T15 screw and remove the Swivel Cover.

The cover holds the Female Connector Housing Assembly (electric socket for the Cleaner Head Assembly) in place. Winkle out the socket and split the black plastic of the socket into two pieces (they are not glued but clip together). Only the cable and pins in the socket will pass through the holes in the undercarriage, so take the electrical pins out of the black plastic cover and observe carefully how this socket is assembled.

“Take a picture to show the wire colours so you can put it together again and maintain electrical safety.” — Andrew Pardoe (25/08/2016)

You may need a 6mm flat screwdriver to prise the clips open on the socket cover. Be careful. Excess strain on these clips may snap them off.

Dyson Slim DC18 Cleaner Head Swivel and Socket Housing with cover in place.
Cleaner Head Swivel and Socket Housing with cover in place.
Dyson Slim DC18 Cleaner Head Swivel and Socket Housing with cover removed.
Cleaner Head Swivel and Socket Housing with cover removed.
3.  Remove the Cleaning Head Assembly Pipe Seal which prevents the pipe dropping back through the socket.

Pull the Pipe Seal out of the socket it sits in and stretch the seal so that it can be pulled over the ridges on the end of the flexible pipe. There are two ridges on the pipe and two matching grooves in the seal into which they engage. The seal sits in the socket and is prevented from rotating in the socket by teeth similar to those on a gear wheel. There are teeth on the seal and teeth on the edge of the socket which engage with each other. See the picture below to understand how these parts fit together.

Four pictures of the Dyson Slim DC18 Rotary Brush Assembly Pipe and Seal.
Four pictures of the Rotary Brush Assembly Pipe and Seal.

4.  On one side of the undercarriage there is a Micro-switch which senses when the cleaner is locked in the upright position.

NOTE: Before removing the Micro-switch you may wish to go to Step 7 and remove the Barrel Wheel and Yoke Assemblies to gain better access to this switch.

Remove the cover by unscrewing the screw with the T8 bit and then pull the switch out of the housing together with its wires.

A rotating black plastic cam (part of the Micro-switch Cam Assembly) moves under the lever of the switch to operate it when the DC18 is stood in the upright position. Examine this closely. The cam is spring-loaded and in my new undercarriage the spring was not inserted correctly and so was not applying a force to rotate the cam and push it up under the micro-switch lever.

Consequently after reassembly the upright position wasn’t correctly detected. I had to dismantle part of the Undercarriage to fix the problem. The spring should rotate the cam to push on the switch lever. So the cam should not be floppy. Check it with the switch removed. The cam should want to move into the visible position under the action of the spring which is out of site.

Dyson Slim DC18 Upright Position Detection Micro-switch.
Upright Position Detection Micro-switch.
5.  Remove the four screws holding the Undercarriage to the bottom of the DC18 body (Duct Assembly) at the front using the T15 bit.
Screws Holding the Dyson Slim DC18 Undercarriage to the Body.
Screws Holding the Undercarriage to the Body.
6. Then remove two similar screws that hold the undercarriage bracket to the rear of the DC18 body (Duct Assembly) near the flexible hose connection port.
Undercarriage Fixing Bracket and Hand Tool Hose Connection Port at the back of the Dyson Slim DC18.
Undercarriage Fixing Bracket and Hand Tool Hose Connection Port at the back of the DC18.

7.  Remove the Barrel Wheel

Do this by prising off the e-clip on one end of the Axle. Do it by inserting a small (3mm) flat screwdriver in the gap between the e-clip and Axle and twisting. This stretches the e-clip, against its springiness, to a larger diameter so it will come off the Axle. Note how the e-clip sits in a groove on the Axle.

The Axle can be pulled out from the far side, the Barrel Wheel will drop free and the Yoke Assembly will come away from the undercarriage.

The flexible connecting pipe is part of the Undercarriage so they are replaced together. Effectively the Undercarriage is in two parts the Undercarriage and the Yoke but only the Undercarriage with the small wheels and red foot pedal attached is replaced here.

Ease the wires and Micro-switch out of the holes in the undercarriage taking careful note of how to re thread them.

Return to Step 4 if you were at that step.

Dyson Slim DC18 e-clip Removal.
e-clip Removal
8.  Commence reassembly using the new Undercarriage

Carefully thread the Micro-switch and wires back through orifices in the plastic. During reassembly it’s difficult to thread the cable back through the small orifice in the undercarriage shown below:

Location of the Small Cable Orifice on the Dyson Slim DC18.
Location of the Small Cable Orifice.

My advice is to temporarily attach a drawstring, using a clove hitch, behind the cable retainer’s flange and bind the drawstring and wires with electrical tape. Be sure to keep the drawstring straight. Don’t wrap it around the wires or it will cut into them when you pull hard. Bend the longest wire back on itself so that the two connectors are not side by side (to keep the bundle slim) and tighten the tape around the soft flexible plastic flange of the cable restraint so that the whole form is as thin as possible. Then thread the drawstring through the small orifice and use it to pull the cable form through. Don’t tie the drawstring to the small hole in the cable retainer’s flange – it may rip open. See below:

Binding the wires and drawstring with tape.
Binding the wires and drawstring with tape.
The cable form and drawstring totally bound with tape.
The cable form and drawstring totally bound with tape.

“Alternatively get a pair of locking forceps to thread through the hole. Just make sure to grab onto the rubber mount assembly instead of the pressed-on brass connectors.” — Andrew Pardoe (25/08/2016)

9. Take the barrel wheel axle with an e-clip on one end and thread it through the hole in the outer piece of the Yoke.

Then engage it with the Undercarriage, the Barrel Wheel, the other side of the Undercarriage and the outer piece of the Yoke on the other side. Then fit the second e-clip by squeezing it onto the groove in the spindle with pliers.

10.  Ensure that the grey peg on the undercarriage lever engages with the slot in the transparent disk.

Else it can’t rotate the Air Input Valve when the DC18 is moved between the upright and lowered positions. It was this peg that had snapped off which was the cause of my problem.

Dyson Slim DC18 Air Valve Operation
Air Valve Operation
11.  Refit the upright position detection Micro-switch ensuring that the cam functions correctly.

See Step 4 above. Hold the cover in place with the T8 screw.

“Fitting the Micro-switch cover can be awkward. It can get covered up when the undercarriage is in certain positions.”

12.  Reassemble the connectors in the Cleaner Head Assembly socket and place it in its housing.

Then fit the Swivel Cover over it and hold it in place with the T15 screw.

13.  Now check that the Undercarriage mechanism functions.

Don’t force anything to work. Dismantle parts and refit them if they don’t operate correctly. Check again that the Actuator for the Input Port Valve engages the slot in its transparent disc and rotates it, when the DC18 is moved between the up and down positions, before attaching the Hose Assembly that attaches to the Wand.

14.  When the mechanism is OK refit the Cleaner Head Assembly.

That’s so you can pick the DC18 up and stand it in an upright position.

With the DC18 upright:

  • Reconnect the Hose Assembly that attaches to the Wand.
  • Connect power and carry out a Suction test at the end of the hose.

Check the air valve changes the air input from the Hose to the Cleaner Head Assembly when the DC18 is lowered. Do this by Checking there is suction through the Wand/Hose when the DC18 body is locked in the upright position but not when it is lowered.

Check that air is being sucked in through the Cleaner Head Assembly when the DC18 body is lowered:

  • switch OFF,
  • remove the Cleaner Head Assembly,
  • switch ON and check for suction at the Cleaner Head Assembly connecting port.

If there is suction:

  • switch OFF and continue with Step 15 below,
  • else investigate the problem.
15.  Finally replace the Outer Wheel Hubs.

Just align the fixing lugs on each Outer Wheel Hub with the central hole on either side of the Yoke Assembly and push evenly on the outer surface at the centre of the Outer Wheel Hubs until their lugs click into place. If not already attached, connect the Cleaner Head Assembly and wand. Perform a functional test..

Author: Helpful Colin

I have a background in telecommunications and a fascination with all things scientific and technical - from physics to electronics, and computing to DIY.

112 thoughts on “Dyson Slim DC18 Undercarriage Repair”

  1. Thank you for this Colin. Your instructions worked perfectly and i now have a fully functional dc18 again. The only downside being that I’ll be probably made to use it again.

    Saved me a new vacuum cleaner though so thanks again!

  2. Thanks Colin for the comprehensive instructions. When I spoke to the helpdesk at Dyson regarding the problem (small broken plastic bit – same as yours), although they were helpful, they suggested it was a near impossible task that they would have no idea of how to do it and they certainly wouldnt try to replace the undercarriage themselves, so good on ya!

    Its replaced and has even more suck than it did before & the roller ball moves more freely too. Im almost excited about being able to vacuum again! (OK so that bits a lie).

    PS: as an additional instruction, if you have trouble removing the roller ball end caps, you can raise the undercarriage to gain access to the back of the lugs with a long screwdriver to ease removal (I had trouble just trying to pull em off as you suggested)

  3. Top instructions, as with the others, saved me a new vacuum. Repair, reuse. Love it. Thanks so much.

  4. I was able to do a simple tab repair. Using a piece of metal, a 1/4″dia x 1/4″ long threaded spacer. I cut the metal into roughly the shape of the plastic the tab is broken off from. I drilled a hole for the screw and attached the spacer to the metal tab.
    I drilled a couple small holes in the plastic (for bonding grip) and using epoxy, I bonded the new tab piece to the plastic, positioning the spacer where the tab belongs.

    Parts; 1 steel nailing plate from hardware store fo the metal,
    1 screw to attach the spacer
    1 spacer obtained fro eBay
    1 tube of epoxy.

    Total cost; $1.50

    Pictures are available ifyou want them

      1. Hello, the metal I used is 0.04″ or a little over 1mm. It slips into the slot and is shaped like the plastic. I would attach picture but unable.
        Any way it is working great.
        Chuck

    1. Chuck
      Can you send me pictures of your repair. I am not sure about the clearances when in the upright position. Has the metal on plastic situation been ok? No apparent wear? Would love to save $60.00
      Thanks

    2. Chuck – Can you send pictures of the repair? My tab is broken off as well – never saw the piece – so its a challenge to fabricate a new one.

      Thanks,!

    3. Would find pics very helpful. Were you able to do the repair without taking the vacuum apart?

    4. Mr. Jensen, please send me your pictures. I have the exact same issue with a broken tab and would like to save $60.

    5. Hi Chuck,

      I can see there has been a long line of people who would like to see your pictures of the repair you made. If you can send them to helpful.colin@btinternet.com, as attachments, I will happily add them to my blog and give you full credit for them in my text. If you have any specific text relating to your pictures or design that you would like me to include then please let me know that too.

    6. I made a card template then made a steel plate with a brass dowel to locate in the slot. I then fixed it into place with epoxy. Made from scrap so no cost and works perfectly.

    7. Do you still have the pictures? I would like to fix it instead of replacing the undercarriage. Thanks.

  5. Thanks Colin. You’ve just saved me the cost of a new vacuum and my wife things I’m a genius! I am hopeless when it comes to doing this kind of thing and even with your instructions I struggled a little. Probably took me nearer an hour. The most difficult bit was opening up the electrical socket as I was afraid of shattering the plastic, but I managed it in the end. It all went back together a lot quicker than it came apart. Thanks again.

  6. Thanks so much for publishing this. I just fixed my wife’s DC18 and she’s happy again. And I didn’t have to fork over for a new unit. Just the under carriage. I did find it difficult to get to the four screws in step 4 before removing the roller ball and the assembly that holds the rollerball end caps. Once that assembly was out of the way, they were easy to remove. I reassembled in this manner and had little trouble.

    Thanks again. And yes, very helpful, Colin!

  7. Hey Colin – just wanted to say thanks for posting this. I had the exact same problem as you – the little tab that engages the clear disc was broken, and I had to rotate it by hand to switch from the floor brush to the wand! I Googled the issue, found your listing and wow! It’s the same problem! I ordered a replacement undercarriage from http://www.vacpartswarehouse.com (very quick and well priced!) and just replaced it tonight after printing your directions. Great of you to post this to help people out – I’ve got a new machine now for about $60!

    I agree with Jonathan G. – be careful when you open that little socket to hold the wires in place – it’s delicate!

    Thanks again Colin!

  8. All I can say is ditto to what Brad said and his problem. Thanks Colin, for the very helpful post and a working Dyson.

  9. THANKS from California !! Colin, you’ve taken something appearing prohibitively complex and reduced it to a straight forward repair process saving a number of us much money. I purchased the under-carriage assembly on line, $56, and was able to replace it. Now running like new. Thanks for taking the time to photo-doc the process, incredibly good job.

    1. I’m pleased I helped you. I’m glad I took the time to photo all the parts. Sometimes I do jobs which I would like to add to my blog but I just have to get on with them and can’t spare the time to take photos all the way through, which is a shame.

  10. Colin, thanks very much for publishing this tutorial. I had the same part break, and my wife and I decided to order the undercarriage for $56 and do the repair ourselves. After 30 minutes of tinkering ourselves, we decided to see if there was a manual online. We stumbled onto your tutorial, and it took us through the disassembly and reassembly without any further hassle. We are very grateful! The photo-diagrams are a fantastic aid. Thanks again.

  11. Many thanks Colin easy and very helpful,timed myself from start to finish 69.37 mins.part cost £45.53 including delivery charge good saving on new Dyson.

    1. Well done Steve. I see you got yours cheaper than mine. It’s a pity DC18s have this weak point. Previously I had a DC03 which had several weak points. My DC31 Animal acquired from the Gadget Show at the NEC in April 2011 hasn’t developed any problems yet. It gets used several times per day – we have a dog. Dyson’s are getting better.

      1. Many thanks Colin easy and very helpful, timed myself from start to finish 69.37 mins.part cost £45.53 including delivery charge good saving on new Dyson.
        As a post script Amazon UK was the cheapest place I found for the undercarriage.

  12. On reassembly, is there a helpful hint to returning the cable and pins in the socket through that first entry in the undercarriage? Mine seems to get stuck at the end and will not go all the way through that tunnel in the undercarriage. I don’t want to damage the pin or wiring by using too much force. Maybe I’m doing something wrong?

    1. When I did it I didn’t have too much trouble. I suspect the retaining flange near the end of the curly cable is a bit too fat for the hole. I have dismantled part of mine to demonstrate how the wires and flange can be tightly bound with electrical tape to make them as thin as possible and how a piece of string can be tied to the cable to pull it through the hole with a bit of brute force but hopefully without any damage. Tie the string behind the cable flange – not to the end of the wires. See Dyson Slim DC18 Undercarriage Replacement Process section 8 which I have edited and included three more photos. Good luck.

      1. Thanks so much for the update. Although I’m a do-it-yourself kind of girl, when I received my undercarriage part I felt a bit overwhelmed, until I found your blog that is. I was able to thread the wires through, but I feel like an idiot because my problem was that I could not figure out how to take apart the black connector from the wires. I was afraid of breaking the part and having to wait another week for a replacement. Anyway, I was able to complete the undercarriage replacement by following your very thorough instructions. Vacuum works great again. Thanks for taking the time to post the helpful information.

  13. Colin, thank you, this was very helpful. In my case I needed to replace the Cleaner Head Coiled Cable Loom Assembly “DY-911049-02” on the DC18. The procedure is the same but there are a lot more steps once you have the base removed. The replacement is possible but it requires a ton of patience and additional tools.

  14. Colin – Superb instructions, easy to follow. Fairly simple removal and replacement and no issues with threading the electrical wires and connector. – Just one suggestion – as you begin step 4, I removed the spindle and rollerball. It gave me more room to work in getting out the mircroswitch and was easy to see the wiring flow to be ready for reassembly. Think that others may find it helpful as well. Overall great photos and instructions. Dyson is repaired for around $65 and my wife is thrilled to have her machine back operational.
    Thanks Again!!

  15. Wow Colin!!!
    Thank you for your super-thorough instructions. Just done the replacement followed your instructions and it was totally straightforward.
    Delighted!
    Saved us buying a new dyson!!
    Thank you!!
    Clare

    1. Clare, I’m glad you’ve been successful. I’ve recently updated this post to improve it after receiving other comments. I included more pictures so that people can see extra detail before they proceed. I hope they helped you.

  16. Colin: Just like everyone else, I wanted to say thank you thank you thank you! Your instructions made it easy for me — usually I’m inept at such stuff. I got the part for about 65 bucks delivered. Installed in about an hour. Much easier than I thought… And so, you’ve saved us the cost of a new vacuum. I hope to attempt over fixes in the future. Much better than just rebuying everything in life!

    On a technical note: In my case the wire assembly (not the microswitch one) slid back through with great ease. I don’t know if newer versions of the part have been modified, but the whole I needed to get it through was more than generous. MUCH more…

    Thanks for making the internet useful today.
    M.

    1. Mart, I’m glad I helped you. Well done for having a go yourself. I’m interested in the design of your DC18. My image with the caption “Location of Small Cable Orifice” in section 8 shows where my curly cable exits through the small hole in my machine. I would welcome any photo you have that shows how it is done on your machine. If its suitable I might edit my description accordingly.

  17. We’ll done Colin. Got a new undercarriage from amazon uk £47 free delivery. Fitted it in 20 mins. Very good instructions. Like a new Hoover !!

    1. Hi Don,
      Thanks for the good comment. As you can see I’ve received many on this article. It’s the most popular one I’ve written. After I changed my undercarriage the whole foot pedal system worked easier than it ever had, but I don’t know why.

  18. Did anyone run into trouble getting the rear wheels to deploy when raising the vacuum to the upright position? The motor on my vac went bad and when it came back from Dyson they missed a step somewhere and I have to lower the wheels again with my foot. Not a big deal and absolutely not worth sending it in for, I’m just wondering if it might be easy to fix myself. There’s clearly a button on the front of the undercarriage assembly that gets compressed in the upright position and *should* be causing the wheels to snap down but nothing happens for mine. The spring labelled 13 in the parts list (attached either to the pedal or the lock arm assembly) is clearly in place but that’s all I can say. I haven’t been able to deduce anything else by external observation.

    Great to see this post and the number of people who found it! I wouldn’t have expected it for a vacuum that had kind of a short run (at least, here in the US).

  19. Thanks for such a helpful guide, and saving me purchasing a new vacuum cleaner, took about 30 minutes altogether. Thanks for documenting as made the replacement straightforward, bought directly from Dyson for £41.60 although bloke on the phone said I wouldn’t be able to do it myself, what an idiot.

  20. A really helpful guide, it made replacing the undercarriage on our Dyson a relatively simply job. Thank you for providing this useful information.

  21. Another one fitted here… thanks for the great guide, all went like clockwork, no issue with putting the cable back through neither.

      1. Yep, was straightforward following your guide. The cable went through without issue, just fed it in from behind and the two wires came out the other side enough to grab and pull the curls through.

  22. Dear Colin, thank you for the helpful guide. Unfortunately, I had to dismantle most of the unit in order to replace the damaged coil cable that powers the head. Your post helped me most of the way back, however, and I seem to have an extra spring that I cannot place. More concerning, though, is the spring which connects the wheel part of the undercarriage to the rest of the undercarriage. I had to guess that it connects to the screw underneath the micro switch housing (the top screw), but I think the spring is on wrong because it sticks up and out of the undercarriage alongside the duct assembly. Do you know what I am describing? I can send a photo.
    Thanks, for any assistance you can provide.

  23. colin, I replaced the undercarriage with your helpful instructions. now a new problem. overheats. not much suction coming out of the wand tube or the brush area, but tons of suction coming out of the tube that goes into the bin. I know I did everything right and everything works beautifully but the loss of suction and overheating. any clues? the only thing that didn’t seem right was the micro switch spring seemed a little weak like you described in item 4.

    1. Hi Ray,

      Sorry to hear you still have a problem. Overheating will occur if air cannot flow through the motor to cool it. So that will be fixed when you get the air flowing again.

      If the air changeover valve is working OK when you move from upright position to the lowered position you will have to look for a blocked pipe. Look at my post at http://helpfulcolin.com/2014/07/dyson-slim-dc18-filter-cleaning/ (or you can search on my site for ‘Dyson filter’). Fig.1 shows a ‘Block Diagram of Dyson Slim DC18 Air Flow’. The Interconnecting Pipe on the right, in Fig. 1, is the one with a circular orifice that you can see when the bin is removed. I presume that is where you have tested for suction OK. The Interconnecting Pipe on the left, in Fig. 1, is the one with the rectangular orifice.

      To test if the Cyclone and Pre-filter are OK: Undo the bin catch and allow a small gap to appear at the rectangular orifice so that air can just get in while the circular orifice is still sealed to the bin. You may need more hands to squeeze that side closed without closing the catch. Turn on the DC18 and test for suction at the rectangular orifice by inserting a sheet of paper and check if it appears to be sucked into the bin with a decent amount of pressure. If that looks OK you will need to check if the Interconnecting Pipe on the left or any other items to the left of that in Fig. 1 are blocked. Sorry to say you may have to dismantle some parts again if it gets to that stage. Tip: use long, stiff but flexible wire (e.g. as used for house wiring) to poke through pipes to check if they are blocked. You may be able to poke through the valve. Warning: Don’t move the DC18 from upright to lowered position with anything inside the valve or you may break the mechanism for rotating the valve.

      Good luck.

  24. Most useful. thanks. A bit of detective work on the old unit showed that a screw had jammed the rotating air valve and this is what probably caused the failure. Pressing the pedal would cause the peg to try & turn the plastic disc, but snap when the disc wouldn’t, because the screw had jammed it.. Lesson, don’t force it in the future.

    Jeremy

  25. Colin thanks for taking the time to post this. Replaced the Undercarriage in an hour at a cost of $63.00.

  26. Hi Colin, Yours must be one the best tutorials for what is quite a complicated repair to a Dc18. What a pity the DC18 ( which I think is the best in the range ) has this inherant fault liability, it must cause the demise of the majority of scrapped machines and could have been designed not to break so easily.
    Wish you well and keep it up.
    Bill

  27. Thanks Colin…..your instructions worked like a champ. Replaced my undercarriage in less than 30 minutes & unit is like new! Appreciate your efforts in making the article. Saved me about $300 🙂

  28. Colin,

    Thanks very much. I couldn’t have done it without you. You saved me a bunch of money.

    Good job!

  29. Thank you for this Colin:
    Your instructions helped ease my fear of tackling the job, Your photos are a huge help. I called Dyson first they said the repair was “Repair Center only” and they could not sell me the part, The repair center is an hour and half away in Paramus NJ . They informed me minimum “bench charge” was $150.00 plus parts plus and an hourly rate. I asked for the part # they gave me the part # for the yoke (DY-912365-01) instead of the undercarriage part (DY-912376-01) , I was glad I already looked it up myself. They offered to sell me a new Dyson at a discount $599.00, I declined their gracious offer. I found the part on-line $54.00 with free shipping , the entire repair took 1/2 at most. a hint for others when re-installing the rubber cleaner head pipe seal I was having difficulty getting the seal back on the hose as it was dry. I put some plumbers lube on it and it went together with ease, Vaseline would work just as well. As everyone once else has said my DC 18 works better than ever! it never stood up without manually engaging the the red lever, now it works as it should Thank you again.
    Regards, Terry

    1. Hi Terry,

      I’m pleased it went well in the end. Nobody wants you to be able to fix anything these days in case you save a buck or two, or (in the EU/UK) hurt yourself in the process.

  30. Colin,
    The info you provided was excellent and was a great help! Thank you for your assistance as the vac is up and running again!!!!!

  31. My wife never runs the vac but decided to clean up after the holidays. Caught her stomping on the assembly to get it to stand upright. Quoted her the part and figured two hours labor. Your article saved me. Took a little less than half an hour and it works perfectly. Saved my wife a lot in labor costs. (Of course I’ll never see that cash)
    Many, many thanks.

  32. Thanks very much Colin.
    I had the exact same problem with my DC18,
    ordered the undercarriage and followed your online instructions. I found then clear and precise and now have a fully operational vacuum once more.
    Richard (Bristol).

  33. I just wanted to say a quick thank you. These instructions helped me repair a broken undercarriage that had a similar problem to yours. I spent $55 instead of $500 for a new vacuum.

  34. Hi Colin,

    This was really helpful as it enable me fix my Dyson but unlike you I elected to restore the functionality by repairing the existing undercarriage. After all it was only missing a very small piece of plastic with a spigot on it to operated the air valve…

    I pulled off the left hand wheel in order to get better access for drilling a couple of holes later on but that was the only dismantling I needed to do. I cut a piece of thin steel plate (about 1mm thick) to be about 2 inches long by half an inch wide. Drilled a hole at one end and attached my replacement spigot. I used a cut down standoff of the type used to mount the motherboard in a PC (I had a some round ones rather than the usual hexagonal ones). But you could just use a nut, bolt and a few washers. With the handle upright and the air valve in the corresponding position I insert the new spigot into the top of the slot in the clear plastic disk that rotates the air valve. The piece of steel was then just slid in the gap “in-board” of the broken plastic arm (that used to have the spigot on it) with the top edges of the steel and the plastic lined up. The two were then drilled and joined together with two small nuts and bolts. I used countersunk small headed bolts throughout to reduced risk of fouling during operation as space is a little tight. It’s also important to cut the bolts to exactly the right length after a trial fit.

    In summary I simply replaced the missing piece of plastic with a piece of steel which is much stronger then the original and should last indefinitely. The wheel was popped back on and everything works like new. Took about an hour and cost nothing as I used stuff I had lying about.

    But I couldn’t have done it without the inspiration given by you article though.

    Thanks again.

    PS The downside was that “Senior Management” was a tad disappointed she couldn’t have that new vacuum cleaner after all!

  35. Hi Colin can you tell me the best place to order the rotary brush pipe for the slim ball dc18 or the lower duct pipe

    1. Hi Mark,
      Dyson sell parts direct. Look at: http://www.dyson.co.uk/spares/select-variant.aspx?category=Uprights
      Here you have to choose between DC18 All floors and DC18 Allergy. Similar parts ar shown on both pages. There is a “Hose U bend assembly” for example. You may be wanting that or you may be after the parts it connects to inside the DC18. Unfortunately most manufacturers don’t expect you to be doing anything with a screwdriver so they are not inclined to sell some parts. However I noticed these words on the left of this page: Can’t find the right spare part? “If you can’t find the spare part you are looking for please call 0800 298 0298 as more spare parts are available to order by phone.”
      Check out the parts of a DC18 at: http://www.partswarehouse.com/Dyson-DC18-Upright-s/3889.htm
      You may find the hose parts you want are built into the undercarriage. I can assure you some hose parts are, and so you will have to buy a new undercarriage to get them; OR you could find someone who has changed their undercarriage for a different reason and get their broken one from them with a good pipe in it which you may be able to use.
      Apart from the dyson site undercarriages can be obtained from espares, and other places e.g. http://www.4yourdyson.co.uk/dyson/wand-and-hoses/range:dc18, as mentioned in my blog.
      Good luck Mark.

    1. Hi Richard,
      Well I only had to replace my undercarriage once. The machine is still in use at my Mother-in-law’s house.
      I have upgraded to a DC75 Dyson Cinetic Big Ball Animal. The benefits are:
      No bags to buy,
      No filters to maintain,
      No loss of suction,
      Designed for homes with pets. (We now have a dog.)
      There are no filters because it is capable of putting the finest particles into the bin with all the other dirt.
      I was lucky to see it nearly new on ebay being sold by a couple who had inherited it from a relative but already had that model themselves.

  36. Thank you Colin for providing a very clear photo of the DC18 Slim undercarriage so that I could see how to fit a replacement ‘Pedal Plunger’ and spring which broke recently. Such a simple part, but without it the machine will not stand upright. Cheers.

  37. Colin, thank you! A couple of suggestions:

    1. For the cleaner head power socket, snap a photo so you can match the colors when you reinsert them in the plastic plug. My DC18 has black and white wires, not brown and blue. Either the cleaner head is not polarized or I guessed correctly 🙂

    2. In step 8, rather than tying a clove hitch, get a pair of locking forceps to thread through the hole. I have a pair and they are fantastic for such jobs. Just make sure to grab onto the rubber mount assembly instead of the pressed-on brass connectors.

    3. Across the pond you can get parts from ereplacementparts.com. They have a nice site with exploded parts views for many products. (http://www.ereplacementparts.com/dyson-dc18-upright-vacuum-parts-c-179635_179636_508034.html) I bought the undercarriage without having seen your blog by referencing these parts views. I’ve also got a 14 year-old battery operated lawn mower that I’ve been keeping running with parts from them.

  38. Thank you Colin, I would not have been able to remember all of the subtle details of how to field repair a Dyson Vacuum. My wife did need to help with a flashlight and locating the right tools were a bit trying but the end result was well worth the effort.

    1. Colin, Thanks so very much for your excellent instructions. I had the entire undercarriage removed, except for the Cleaner Head Power Socket, which, as you know, will not fit through the narrow sleeve in the undercarriage. Your helpful diagram and accompanying text assisted me in the last step in disassembling this socket. You saved me an expensive repair or the cost of a new vacuum.

      Again, much appreciated.

      Best Regards,
      Mike

  39. Thank you Colin! My old Dyson stopped switching just after its warranty expired, so for a while I’ve been switching it manually, later bought a new model and the old one was sitting in the storage. Somehow I bumped onto your article, ordered new piece from amazon, paid $55 and now I have functioning Dyson.
    Thank you a lot!

  40. Is there a video on this repair? I was told by a servicer that its not worth repairing and to by a new Hoover.

    1. Sorry Robin, I don’t know of any such video. I haven’t made one and don’t have the easy access to this particular vacuum cleaner any longer so I can’t consider making one.
      One way forward might be to ask someone you know to be very good at dismantling and rebuilding technical items that they aren’t already familiar with to do it. If they will just buy them the part and leave them to it. Try and get them to commit to a time period when they will get it done as it is common for people to put things off into the future.
      Regards, HC.

  41. Thanks for this detailed guide. Hope you can start doing YouTube video guides too if you haven’t already begun.

Please Comment Below (or Select An Existing Comment's "REPLY" Button First) - See HELP for Details.