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Discussion Starter · #1 ·
I finished a full build on my car about 2 months ago. Tuning was done about a month ago and I've been enjoying the power for about a month, doing 2-3 WOT pulls to about 130mph per week.

Last night at WOT, 7000rpm in 3rd, the car let out a ton of blue smoke. Pulled over, looked under the car and the whole undercarriage of the car was covered in oil. The car did not lose oil pressure, and was still running well with no issues other than the oil.

Checked the oil and it was 3/4 on the dipstick. I'm guessing the car dumped about 1/2qt in about 15s.

Started the car back up and no oil was leaking. Kept it under vacuum and limped it home, stopping regularly to check for more oil leaking under car and the oil level. It was fine. No blue smoke on cruise or decel. I didn't try putting the engine under load.

I have to start pulling stuff to really see where it is coming from. Around the valve covers is dry. The front top half of the engine is dry. There is significant oil on the front bottom of engine, about 1/2 up the side of the the engine towards the back, the transmission is coated, headers/xpipe, and rear end all have a decent amount of oil on them.

Without starting to tear into it, it looks like the front crank seal. Would this much oil come out under boost? The fact that it didn't continue to pour oil when driving it home under vacuum, it is not leaking at idle and has good oil pressure leads me to believe the leak isn't from a pressurize oil source like an oil cooler line.

Car is making 15.5psi on ported MMS260 heads and 2.5 cam. I was debating running a mighty mouse wild setup, but currently only have the Moroso catch can on the car, which maybe allowed too much crank pressure? Next step is to pull the damper and check the seal, but thought I'd ask if anyone has had something similar happen and if the font seal makes sense. Anything else I should be looking at?
I'll also be doing a compression test.

Finally, is there enough room in there to pull the damper without removing the rad shroud/fans?

Thanks!
 

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Looks like some got burnt up on the headers, ergo the blue smoke.

Good thing it didn't hit the flash point.
 

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How is your moroso routed?

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If you had enough oil in the pan to reach the seal, and the crankcase was under pressure, I guess I could see it pushing oil out past the front seal. But there's no way you should have that much oil in the pan. If you did, the crank would whip it in to a froth and you'd have long since had pressure problems. Especially under load, all the oil in the pan is going to go to the back of the pan, not the front... can't really tell from the picture, but it looks like there's oil well forward of the front of the engine block. Something was spraying oil and a lot of it. It's not in the induction path, but that's about all you can say. You're going to have to take it apart to see. Start at the front and work your way back and maybe you'll find the culprit before you get to the front seal.
 

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Discussion Starter · #5 ·

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You said full build, including motor?

If a leak path doesn't become apparent when you start pulling stuff apart, compression test?

Let us know what you start finding

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Yes, you can push the front seal out with too much crank case pressure. Yes it can puke out a lot of oil. My friends C6 Grand Sport (dry sump) motor did it. It pushed so much oil out we were sure it kicked a rod out of the block. Turns out it was just a front seal.

If you are up in the rpms and there is a lot of oil draining back from the heads, yes it can make its way to the front of the motor to the front seal area.

On my V, I was pushing a fair amount of oil out of the rear main with just an air oil separator like your moroso catch can. I switched to a mighty mouse wild catch can/breather and it went away. The moroso is not venting any pressure to atmosphere and probably isn't passing enough air back into the intake to keep crank case pressure in check.
 

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This is how my disaster started first started with rear main seal then oil pan leak then front seal leaking after chasing all those leaks I blew apart 3 or 4 pistons and now rebuild process hopefully this won’t be you but check now before too late
 

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Discussion Starter · #9 ·
Leakdown was OK on all cylinders. Definitely the leak was the front main seal. Really surprised that much oil could come out of there. Oil was not over filled.

Will be replacing the seal in a couple weeks and adding the wild catch can. I wasn't even on E85 yet. All part of the fun I guess!

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Discussion Starter · #10 ·
This is the follow up. Blew the front crank seal right out! So, yes, a crazy amount of oil can be released when this happens!



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Check your crankcase ventilation. Under boost, blowby will pressurize the crankcase. Pressurized crankcase is the only way I can see that happening. The PCV is supposed to vent that pressure... there's usually a checkvalve and at least on cars I've owned in the past, the valve can get sticky. I put a Vortech on my 02Z06 (a couple of decades ago) and after a few 10Ks of happy driving it, I wailed on it one day and it blew the dipstick and a bunch of oil right out of the motor. PCV valve had gotten sticky.
 

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Discussion Starter · #13 ·
Replaced with mighty mouse wild now.

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