Docmartin

I'm hoping someone can give me some insight that will help explain what I experienced today. The car has a STS TT kit on it. Today I missed a shift from 2nd to 3rd at the red line and when I got it into 3rd the car went up in oil smoke. Smoke from under the hood and the back of the car. The rear bumper was covered in oil speckles.

I took it home, after pulling over and waiting for the smoke to go away. It was running fine and I even went into boost in 2nd on the way home. All normal and no more smoke. Parked on a level surface, waited 10 min and checked the oil. It was a little low, but not drastically. I checked underneath the car and I found oil on the undercarriage in front of the turbos. I found oil underneath the engine and all around the oil filter. It looked like a little oil dripped after I parked. The oil spot was about the size of a quarter. Inside the engine compartment there is no oil splattered anywhere or on the side of the engine. Only underneath.

I've dropped it off at my local shop and had my gf follow me when dropping it off. No smoke or drips or anything unusual spotted. On the way there I went into boost in 2nd again and nothing out of the ordinary. I was keeping an eye of my oil pressure gauge when boosting and it was only up to around 50 psi for that brief little stint.

Oil pressure at idle hasn't changed, ~20 psi with oil temps at ~220-230 degF. Boost gauge reads 13-15 mmHg while idling when warmed up. Coolant reservoir still colored pink and at the same level. Oil has no change in color. No audible changes when idling or driving, but the car is loud as **** to begin with.

I've been searching the forums and whilst there are tons of threads on the STS kit and smoking oil, none describe the experience I had. My shop doesn't open until Monday and I'd like to have some idea of what is going on before I chat with them. Where did the oil leak and why? What would cause these symptoms?

Thankfully all of this happened within 2 miles of my place before the gf and I headed ~40 miles to Saxapahaw for lunch. Kicking myself because I know I fucked up missing that shift. The beginning of the highway was wide open and a new NSX wanted to play. I know I shouldn't take the bait in those situations, but what's the point in having a turbo corvette if you can't rise to the occasion and have some fun with a 160k super car? Any thoughts would be much appreciated. I'll update when I know more. It sucks to stumble on an old thread where the solution was never posted.

sonnysucks

What weight oil do you use? Honestly, (i'm a new owner, so maybe i'm wrong) but 20lbs at idle at 230 seems low? i'm more like 32-38 but I run a 10w40... are you maybe running too light of an oil? Also, what is your breather setup look like, is it possible you just vaporized some oil and blew it out? I know seems unlikely, but I've seen it on my other turbo cars without proper catch can setups and / or open breather elements off the head.

Docmartin

Thanks for the reply Sonny.

5W-30 I believe. 20 psi fully warm is what it's made since I've had the car. Maybe its low but at least it didnt change after the incident. I have a 97 C5 also and that LS1 makes 20 psi when warm at idle too. Also uses 5W-30.

Spoke with the shop yesterday and they didnt have time to investigate yesterday but initial theory is that it blew out of the rear main seal. Thinking it may have over boosted when I missed the shift and got back into gear.

I think they are investigating today and hoping to hear back later on after they drive it on the street, put it on the dyno, and compression test it. I'm hoping this is what happened because I don't like the other theory...

Ventilation system is stock STS setup. There was a pressure issue a while back and the pcv was fixed. I dont know enough about the ventilation system but it's on my list of things to chat to them about when I see them in person. I've been reading up on modifications to the stock STS ventilation setup but ultimately I'll do what the shop recommends.

sonnysucks

I'll be curious to hear what they find.

I checked yesterday on the drive home and definitely at 230 degrees I still see 36-38PSI of oil pressure at idle... not sure if it's 10w40 or if I have a really active oil pump??? I grabbed a picture just to make sure I'm not crazy.

Docmartin

Here's a quote from an old thread about oil pressures

No word on my car yet. Hopefully today.

sonnysucks

Humm... i still see 35+ at temp, i'm running 10w40 mobil.

Docmartin

10W-40 is more viscous than 5W-30 so oil pressures will be higher.

Finally got my car back today. Turns out the shitty STS crankcase ventilation system wasn't doing it's job. Plenty of threads on that issue. So when I missed my shift and got back into gear it blasted my rear main seal. Had a leak down and compression test done while it was there and all came back well. Got the rear main seal replaced and deleted the STS PCV system. Added in two 2 breather filters for crankcase ventilation. Back on the dyno it made the same power and it checked out on the road.

Couple months ago we had three pistons replaced and car tuned at 10 psi. The system uses a MBC and after I got the car back I was seeing boost creep up to 14 psi in 4th gear and the only time I've ever been in boost in 5th I saw 17 psi. We were planning on replacing the controller, but after getting this fixed the car is rock steady at 9-10 psi during 4th gear pulls. I asked if they had another go at messing with the MBC and it was mentioned that the boost creep might have been a symptom of the faulty PCV system.

Happy to have my car back after a few weeks. Even happier that I'm not seeing boost creep. Now it's time to get it on E85.