Question on Intercooler O-rings

kilodawg · kilodawg's Garage

I have been dealing with a rich running condition at the onset of boost which results in stumbling and black smoke. It usually occurs around 2600 to 3000 RPM's and then goes away as the RPM's increase.

I thought a disconnected vacuum line might be the problem but no joy there. Since I'm new to all this I have asked questions and gotten a good game plan to at least start learning and troubleshooting (baby steps). I will get into it over the holiday's but this evening as I was looking at parts diagrams and trying to get the lay of the land I noticed something that might be part of the problem.

In looking carefully at the pipe that goes from the intercooler to the turbo, I noticed that on the turbo end of the pipe at the sealing ring/O-ring joint there is oil around the joint. Not much but it is damp and noticeable when looking at it from both in the engine compartment and from underneath. Is that normal or is it indicative of a leaking ring.

Thanks!

David · David's Garage

There shouldn't be any oil past the compressor so you may have a turbo problem.

rsrmike · 11-23-2008, 07:14 AM

It sounds like you do have a boost leak. If you do, the turbo will spin much faster than it should, as it takes much more air volume to pressurize the intake enough to open the wastegate through the signal hose. Sometimes, the wastgate won't open at all until the exhaust back pressure pushes it open. This is very bad for the turbo. They wil blow oil into the compressor housing under these conditions, but it doesn't mean the turbo is toast. It's probably shortened it's life somewhat, but you may find if you fix all the boost leaks, and quite overevving the turbo, the oil leaking into the compressor will slow down considerably. Look for any other signs of oil leakage in the intact tract. There are multiple places for leaks to develop, All the O-rings are subject(especially after being subjected to super-heated oil spewn from a turbo operating well out of it's efficiency range) Also the plastic injector blocks and gaskets between the intake manifold and the heads, and the bypass valve (BOV) assembly has two round clear seals that are prone to leak. These can make a strong click or knock noise when blipping the throttle, as part of their function is to dampen the piston noise in the bypass valve, the click is usually the first sign of seal failure but doesn't mean they are leaking boost...yet

kilodawg · kilodawg's Garage

I don't hear anything unusual, no clicking so I assume the BOV valve isn't at the root of the problem. I also haven't driven the car that much and while in this state I have avoided boost when I do drive it. Maybe I've taken it up for a spirited acceleration a total of 6-10 times since I've been having the stumbling. It does clear up over 3000 RPM's or so but I'm not sure if that's good or bad under the circumstances...

Miguel Antonett · 11-24-2008, 08:48 AM

It is not clear to me what you car's problem is , but I can tell you that 930's need to be opened up frequently. Lots of WOT is necesary to keep the engine & turbo blades clean and balanced; if not, they become dull (like an old ladiess car - no punt here), oily and smokey with every acceleration. I have seen even oil emulssion (milky color deposits around the oil cap... due to the lack of proper oil temps...). I'm not saying that's your case but something to consider. M2c.

sand_man · 11-24-2008, 08:58 AM

Quote:

Originally Posted by Miguel Antonett

...if not, they become dull (like an old ladiess car - no punt here)...

LOL! Old ladies sweat...young girls glisten! Did I just say that out loud...

rsrmike · 11-24-2008, 09:15 AM

LMAO at you 2...

Sounds like a boost leak to me, order you up some intercooler O-rings and give it a shot! If you are not pouring out white smoke yet, give the turbo a chance to redeem itself.

You may also consider doing a complete intake leak pressure test, there are several threads here about the various ways to do so. the best ways require a good source of compressed air and some specialized, yet easily attainable/fabricated equipment so keep that in mind...

Like Miguel said, when all is fixed and it's not stumbling, go out and blow that sucker out, you should have tons of carbon in the muffler by now, should make for a good smoke show, if you see some glistening young ladies while you're at it, even better!!!