[Mk2] [Turbo] Issue Gen 2 3sgte medium boost destroying turbos

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gips
Posts: 25
Joined: Tue May 04, 2010 12:09 pm

[Mk2] [Turbo] Issue Gen 2 3sgte medium boost destroying turbos

Post by gips »

Hello all,
im having trouble with recently increased boost on my car. Was using a Ct26 in perfect condition for around 2 years, boost was regulated by wastegate, so it was going around 0.8bar. After a while due to maf issues , when cold(leaning out in low rpm even after adjusting the idle screw) i decided to go with aftermarket ECU and increased boost. Problem was that as soon as i upped the boost to ~1bar and drove for like 30KM the turbo blew totally by bending the shaft and destroying the impellers. It was not possible to rebuild, so i went a CT20B. Everywhere i read they say you can boost this one safely at 19PSI. So there i went 19PSI. Problem is after like 2000km the turbo axial play increased a lot, it started smoking and it ended up also having a lot of radial play leading to a rebuild with replacing the compressor wheel as the old one was touching the housing and was damaged. After disassembly the rebuild company found a very small particle of silicone like 0.5mmx0.5mm on the nozzle of the axial bearing, so we decided that was the actual issue not the boost. There i go new rebuilt turbo, boosting again 19 psi and after 1000KM problem, it started smoking again. I checked it and there is a lot of axial play , no radial play at all, but it seems the axial is big enough for the turbo to smoke. Im for a rebuild again, but the question is, what is going wrong, are the CT20B incapable of producing safely 1.25bar ? Im not using a highly modified engine. Gen2 head, cams are stock from N/A and a 3inch freeflow exhaust. That is pretty much it. Any suggestions are appreciated.
jimGTS
Posts: 14024
Joined: Tue Dec 14, 2004 1:40 pm
Location: North Kent

Re: [Mk2] [Turbo] Issue Gen 2 3sgte medium boost destroying turbos

Post by jimGTS »

too much heat?? timing advanced too much?

i had a 20b up to close to 19psi (17/18) for a good 5-10k miles, no play what so ever and no smoke. this one was a standard untouched who knows how many miles turbo.

what quality of rebuilt parts are being used?
how is the oil feed? perhaps not enough oil getting to parts, so creating heat and damaging parts.

just a few ideas
androo007
Posts: 2363
Joined: Mon Mar 03, 2014 1:43 pm

Re: [Mk2] [Turbo] Issue Gen 2 3sgte medium boost destroying turbos

Post by androo007 »

So you're running an ecu for a rev 2 specifically but with rev 3 running gear? I'd check afrs
gips
Posts: 25
Joined: Tue May 04, 2010 12:09 pm

Re: [Mk2] [Turbo] Issue Gen 2 3sgte medium boost destroying turbos

Post by gips »

Build parts, i have no idea, but i will take a look , when its apart. Verified the oil feed, it seems more than enough oil is reaching the turbo. The turbo is now off the car and look serviceable, so i will probably try once more with another rebuild.
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