[Dommyem]

I decided this needed it's own thread:


THIS IS COMPLETE. PLEASE READ THIS COMPLETELY BEFORE YOU START AS THERE ARE STEPS THAT DIDN'T WORK AND I HAD TO UPDATE PARTS. - Good luck

I have the same rattle as everyone else so went looking for a new turbo. I managed to buy a replacement 2nd hand rear turbo form Lithuania..... and it turns out that it had the same issue as the one on my car even though I told the guy to check that the wastegate would only pivot and not rock back and forth (must have smashed into the language barrier nicely!).

Ok, so I am a mechanical design engineer by trade and I will try my best to offer you a permanent fix to this issue.

Since I have this new faulty turbo at hand I will try to repair it.

The plan is:

1. I am going to attempt to remove the wastergate from the turbo by disconnecting the actuator with the small E-Clip, and grinding off the weld that holds the linkage arm to open/close the wastegate.

2. Try to remove the worn bush (which I hear looks elliptical from the wear).

3. Make a new bush out of Stainless Steel 304 (I have access to a lathe).

4. Fit the new bush.

5. Re-fit the wastegate by carefully welding the linkage back on so that the thing still rotates, and the wastegate seals against the port in the turbo.

6. Re-connect the linkage to the actuator.

7. Finally, take my car and the fixed turbo to the garage to have the turbo swapped with my other faulty one on the car.

Now, I did some googling and someone in america did this with a stainless bush, I do not work in a turbo repair industry so I am copying his idea. There wasn't many pics which is a pain. but this is what he had uploaded:



Wish me luck! I will try to upload some pics and a detailed engineering drawing of the new bush when it's done - SolidWorks FTW .

*UPDATE 1* 13/11/2015 11:20ish

First mark some lines where everything sat as it came off the car. I used a black pen to highlight and area and then a scribe to leave a shiny line. I marked the angle of the wastegate lever on the turbo itself, the nut position on the actuator rod, and also the angle between the actuator rod and the wastegate lever.

Plug any inlets and outlets of the turbo to avoid getting swarf anywhere! I used tissue.

Phase 1 - Removing the wastegate.
It went well. I managed to get the actuator disconnected very easily by removing the small E-Clip (careful not to lose it). Now, removing the lever that connects the wastegate to the actuator - from the wastegate pin/body, was a pain. I had to grind off the weld (which was rock hard) to leave a nice flat surface. Then I had to work out where the centre of the pin was so I could drill out any of the penetrated weld which holds the lever to the pin. Once the centre was marked and punched (10mm in from each 3 edges of the curve) I drilled it out (starting at 1.5-2mm drill, then stepping up to a 4mm, then 6mm, then 8mm, and finally an 10mm) I made sure to not do drill too deep. I must have only gone down 1.5mm - 2mm with the first drill. Eventually you will weaken the mounting between the lever and the wastegate pin to the point where you can shear the joint with a flat head screw driver with minimal force (if it feels stiff or begins to bend anything STOP and drill some more). Boom ,it popped off the top and the wastegate pin fell into the turbo. Check the wastegate pin for wear. I used a vernier to check the rod wasn't out of round. It measured at 11.37mm all around.

Phase 2 - Removing the Bush from the turbo.
This was hard. I am thoroughly trying to complete this repair using pretty basic machinery. I do have access to Mills, presses, lathes, and I'm trying to use them as minimally as possible - as I would like people to take my drawing of the new bush to a local machine shop and get it made so they can fix their turbos themselves. So to do this you ened to assemble a very basic extractor. I used a M10x50 Cap head screw, M10 Nut, M10 Washer, M16 Nut, 19mm Spanner, 20mm Spanner, 8mm Hex Allen Key, and a 17mm Spanner. You need to thread the bolt through the bush in the turbo so that the head is inside the turbo. Then place your 19mm spanner over the bush head on the outside of the turbo. Now put the M16 nut over the shaft of the screw. Now put the M10 Washer on the M16 nut, and then the M10 Nut on the washer. You are building a strange contraption so bare with me. Now put the 8mm Hex allen key inside the turbo and locate the end in the M10 Cap Head Screw. Using the 17mm spanner tighten the M10 nut. This will start to get tight. Then continue until you feel a slight pop, that is the bush freeing itself from the turbo housing. Keep tightening the M10 nut until you have pulled about 7mm of thread through the contraption. Now undo the nut, and add in the 20mm spanner on top of the 19mm spanner and repeat this process. This will free the bush completely. I noticed upon extraction that there is a small pin holding the bush in (bit late). This is near impossible to remove without drilling a hole in the turbo. I didn't fancy that. So not bothered about that. The pin barely engaged with the bush so it was no biggie. When I come to refit the new bush I may try to push the pin into the bush to help hold it.

Photo's here:

View post on imgur.com

(The sketch in the photos of the bush is not the final drawing btw)

*UPDATE 2* 13/11/2015 14:00

Phase 3 - The new Bush.
I know that not many of you will have access to a lathe, but if you do then great - go get some 20mm stainless 304 or 316 rod. I dont know why I am sharing the images of the CAD side of things, but hey-ho I made the effort to do this thing, may as well share. At the bottom of the images is the new drawing. Manufacture away!
If you do not have access to a lathe, then I would suggest walking into your local precision engineers with a bag of doughnuts and a thirst for knowledge and they might just do you one of these for free. Otherwise I would guess you will be charged maybe 1-3 hours labor. The material cost will be about £1 ($1.50) realistically.

Photo's here:

View post on imgur.com

*UPDATE 3* 05/03/2016

Ok so this got a little messy and more complicated. I managed to make a new bush, fit it into the turbo, weld on the wastegate bracket which connects it to the vacuum actuator, and do a high-temp trial using a blowtorch to simulate the exhaust gasses heating and expanding everything. The trial was to see if the wastegate would rotate open and close smoothly. I noticed that when cold the wastegate seemed fine - it would open and close pretty smoothly, but after applying some heat (dull red glow) the shaft of the wastegate was sticking in the bush. So this lead to a complete removal of the wastegate and bush for a rethink.

I had a re-measure of the wastegate shaft and noticed it was also worn elliptically in the middle (it was perfectly round at the top and the bottom - where I had measured previously (measure twice cut once, obviously wasnt enough). So this meant that the wastegate pin needed to come off completely. I used a grinder to remove the remaining shaft leaving just the trap door part of the wastegate. This was then milled flat. I then drilled a hole to 8mm+0.1/-0.00 diameter through the middle of where the shaft was. (I will upload more pics - I think I captured this stage).

Now a new shaft needs to be made. (NOTE: DO NOT SCRATCH OR MARK OR DENT THE SHAFT - IT HAS TO BE PERFECT, NO SAND PAPER, NO VICE MARKS, NO DROPPING IT).
I bought some DIA12mm x 60mm length dowel pins from ebay for £5.00 (I only needed one but got 5). The reason for these is that they are Stainless steel so will have the same expansion properties as the bush, and dowel pins are slightly hardened and have a super silky smooth ground finish. I then took my dowel pin, and turned down one end to DIA8.00mm +0.00/-0.05 over about 15mm so that it would fit all the way through my wastegate trap door part. I then used a TIG welder to melt the exposed dowel pin end to the waste gate trap door - creating a new wastegate with shaft assy. The shaft of the wastegate needs to be cut so that once fitted in the turbo about 5-10mm is poking through the bush.

The new-new bush. So we now have a 12mm shaft on our wastegate. We need to mod our bush so the two can fit together. I bought a cheap adjustable reamer (think it does from 10mm to 13mm or something) from ebay, and drilled the bush out to just under 12mm. I then reamed it to 12.15mm very accurately - this is sooooooo damn important. Took some trial and error with a deal of research into thermal expansion bla bla bla so anyways thats the key number. 12.15mm - SUPER IMPORTANT. Once this is done, re-fit the bush using a fly press and make sure it goes in nice and flat/square/tangential to the turbo.

Now the hard work is over (mostly) re-insert the wastegate into the bush (this is the point where you say - fuck me that fit is smooth) thats what youre after, if your fit isnt lovely and smooth then youve got to polish the bush with some super fine grit wet and dry or scotch bright. Now you must assemble your turbo. This takes a bit of fiddling around. You need to make sure that the wastegate is in the correct position to the bracket that was brainsed/welded to the top before we started. OH yes the bracket, make sure the bracket is smooth top and bottom, it has a DIA12mm +0.2/+0.05 hole in the top which is concentric to the outside of the larger curved end - so it pivots about the same centre point as before. Ok now you need to play about with how far the actuator can pull, and make sure that it has the correct range to fully open/close the wastegate once its all welded together. Once youre happy, weld it up using a TIG welder, do a small weld, then leave to cool, then do one opposite (see pics). Now it should look structurally sound and pivot like a dream. Do a heat up trial once again and try to pivot, if all is good then connect up the actuator again. congrats - she's ready to go.

Photo's here:

View post on imgur.com

PM me if you get stuck.

[mankytron]

Nice work. I love it when people "fix" things instead of throw out and buy new. I am going to have to get a lathe some day....seems awful handy!