I've been chasing an oil leak on my stock twins (130,000 miles) for sometime. The car will leave a few small spots of oil from city driving but will leave a spot larger than the palm of your hand after even a short run at the track. Oil is leaking from the turbos and blowing by the underside of the car when pushed hard apparently. Oil smoke can be observed from the primary turbo area when the hood is up after a hard run. I have replaced the entire oil feed line and banjos and am certain this is not the culprit. I have also replaced the gaskets on the oil drains from the turbos. The leak appeared to be in the vicinity of the primary turbo's underside when I was under there replacing the drains but I cannot pinpoint it. The car will idle all day long without a single drip but when driven it will certainly leak. The harder it's driven the more it leaks. I am not blowing oil through the intake tract or white smoke out the exhaust. Boost is completely normal. Replacing the oil feed and the drain gaskets did not seem to make any difference in the leak at all; I'm pretty certain these are not the culprits. Everything I have tried has not effected the problem.

It seems I have a plain old oil leak but I have not been able to fix it. Is it possible that the turbo housing(s) themselves have failed and are leaking oil from the center section? Even though I don't see signs of oil in the intake or exhaust? I honestly have no other ideas what it could be and have no recourse but to pull the turbos.

 

You may need to tighten the bolts a bit more. Stress cracks around the bolt(s) opening may have developed causing the leak. But I doubt you have hair-line cracks on the Chamber(??) Check your main feed line that connects on top (dual nut line). It may be leaking and dripping down below the Turbo housing.

 

So higher oil pressure causes a larger leak. If it isn't the turbos, it must be a bad line. Have you checked all of the lines that are immediately pressurized when you push the car? Do you get the same leakage just revving the car while it is stopped?

I know that you have probably already done all this. Just trying to offer something that you may have forgotten.

Adam

 

My turbos (original, 112k) also boost fine, have minimal shaft play, and average oil in the intake tract, but they leak externally like a bitch. Seems at least one, and more likely both compressor housings are leaking oil (between compressor and center section). No one has every really explained to me why this would happen or what the cause would be, I suppose there is an o-ring present that has rotted over time. You'd have to tear them down to fix it regardless, and you might as well get a full rebuild while you're in there if that is the case.

I'm currently struggling with this issue now...the oil leakage doesnt bother me per se, but I'd rather it not be there. I know they will continue to get worse soon, especially now that I went nonsequential and am actually producing respectable top end boost. I don't want to put much real money back into twins, even though I know you can make decent power from them. I'm not sure I want to take the step up to large single, either.

 

I am as confident as I can be that the feed lines and/or returns are not leaking because I have replaced all of them. I have even entirely replaced the stock feed line with an SS line that now connects to the stock banjos with an AN fitting. The feed is not leaking and best I can tell neither is the drains. The center sections of the turbos are wet with oil but it is not originating from the feed or the drains.

 

If your absolutely sure you don't have a top feed line/bolt leak,..then I would suspect a hair-line crack on the Housing. I would also concur with RotaryResurrection that it may be an O-Ring failure. Either way,.. a more in-depth investigation should be initiated.

 

I know you don't want to do it (I wouldn't), but it sounds like the turbos are due for at least an inspection.

 

At 130,000 miles on the original turbos, you must be entitled to some type of an award. I would say you got every mile out of those babies. I would guess you are due for at least a rebuild but the bigger concern is the housings and whether the cracks (and there will be cracks) in the housings will allow for a rebuild.

 

Sorry to bring this thread up again. Been searching for a while, and I came across your post. Damon, you mentioned the banjo bolt, beside that is another nut which is attached to the housing maybe (not sure). I have a small leak near that nut. When I start the car it smokes a little from that area (under the hood) for maybe 1-2 mins and then its back to normal no more smoke. I believe my turbos are on there way out.

I think that area is also sealed by a copper washer and am failing to understand how that seal might miss. Any idea? Any possible repairs? Has anyone faced such a leak from that area before? Any suggestions.

Am in Bangladesh, so that sucks big time. Maybe the only option I have is to get a USED set of turbo from Japan or the US, thats the conclusion I have come to after reading all the posts. Bryan BNR made things easy for me to understand why the stock twins shouldn't be rebuilt.

 

IF you see oil coming out of the TURBINE HOUSING or the bolts/clamps that hold the CHRA to the turbine housing, then the turbos are leaking oil via the turbine piston seal and require rebuild or replacement. They will rapidly get worse and you'll start seeing a LOT of smoke both from inside the exhaust pipe and from the turbos themsevles as the oil runs down onto the manifold/turbine housing and burns off.

IF the oil is limited to the CHRA and the lines going into/out of it, then you simply have a loose bolt, bad or missing crush washer (top supply line), or bad or missing gasket (drain line).

 

I cannot yet confirm whether its from the bolts or clamps thats hold the Center Housing Rotating Assembly. Am planning to take off the air filter pipes and taking a closer look. I don't have a lift at my place, as a result taking a look from the bottom of the car is not possible right now.

RR, I know that my turbos are very weak, and from your explanation I'm quite sure now since there is oil (kindly see the attached picture which i took quite sometime ago), however any idea how long i can drive around like this? Am going to order USED turbos but that'll take some time to arrive. Right now the leak is not even in the drop form, it just wets the nut area a little. Is it SAFE to drive around like this, without boosting maybe?

 

You can take apart all of the oil lines, and look for any grit that got sandwiched under a copper washer or gasket. Also look for scratches in the metal faces - a scratch going from the inside to the outside will leak oil regardless of the gasket.

Dave

 

Hate to be reminded about this thread!

The leak in my case turned out to be the front cover gasket. A portion of the stock paper gasket had pushed out and oil was blowing down the side of the engine and onto the turbos. It was very tough to see in there but finally one day I removed a bunch of stuff and poked around. It pissed me off that I had been chasing the wrong problem the entire time because the way the oil collected I was convinced the turbos were the culprit.

New front cover gasket and the motor has been 100% leak free for years now.

 

Thanks Dave for the info. Am planning to take a look at it this weekend as per your advice. Dave, the more I think of it, my turbo I believe is the culprit here. The lower IC pipe has quite a bit of oil. (see the attached pic) Am going to order some turbos this way or that, will keep a spare if needed. Would you believe my car has only 54000kms NOT miles. The previous owner never did take care of it. Anyways, a good friend of mine with the same name as yours is helping me get a good set of twins. Do you think with such mileage my old set my be rebuild? That way i can keep a spare for the future, and not just throw away my current turbos.


LOL. Sorry about that Damon. But hey, thanks.....its because of your thread that I got replies from people like RR, Dave and yourself.

 

So how many miles are on those twins now, big D?

 

^ Around the time of the front cover gasket replacement I installed a used set of twins that were fresher than mine. If the mileage claim on them at time of my purchase was true they now have about 60,000 miles on them. No issues with them whatsoever at present. These are the turbos that dynoed 240 to the wheels at 11 psi. Car builds boost quicker from low revs compared to my other turbos but once past transition they feel the same to me.

 

Damon,

How long did it take you to replace the front cover gasket? I think I have a leak there

Thanks

 

Just long enough to write the check I had Rotary Performance take care of it for me at the time as I was too busy. I would expect a full weekend for most people.

RP pulled the motor which is what I would have done. Much easier to work on the front cover (and the pan) with the motor removed. If anyone has pulled the motor before I bet they could do it that way just as quickly as doing it in the car, but pulling the motor will not test your patience as much. The front cover gasket is a big job.

 

Thanks Damon.