LT1 Leaking onto exhaust

[Beef supreme]

It's not too bad of a leak, I'm losing a quarter of a quart every 2,000. I didn't notice it when I first bought the car, but after switching to synthetic and a few thousand miles later; lo and behold. I wouldn't mind it if it just wasnt that it stinks The simple solution is obivous, but which conventional oil is truly the best for an lt1?

The other solution is to fix the seal.

The leak is coming down the tranny bell, and with some speed and revs enough drips out then flies onto the pipes. It's not dripping down the oil pan or coming from the front, does anyone have any idea as to where the leak is and will this be a hard job to fix? It only leaks when the oil is hot, it'll put a couple drips wherever I park.

I have a 1995 firebird with a 4l60e; sitting at 150k miles.

Thanks for the help guys.

[cocobolo95]

Rear of intake manifold is a common leak on these cars. I wish my cars only lost a quart of oil every 8,000 miles. Valve cover gaskets, cylinder heads, oil pressure sender, are all leakage candidates.

[Locruid]

Before I lost my heads on my car, I drove 40 miles a day and my oil level was still full in between Oil Changes. I'm hoping it stays that way LOL

[Beef supreme]

Originally Posted by cocobolo95

Rear of intake manifold is a common leak on these cars. I wish my cars only lost a quart of oil every 8,000 miles. Valve cover gaskets, cylinder heads, oil pressure sender, are all leakage candidates.

It's not burning oil, and the cover gaskets are new and sealed well; I replaced the gaskets while doing a valve adjustment.

I'll try and clean it up and take it for a ride to see where its leaking down at tomorrow and report back. I'm hoping it's the intake manifold, if it's the rear seal then **** it haha.

[dereklukosus]

I recently switched to synthetic also and have had my main start leaking bad and sounds like I spun a rod. It isnt a terrible ticking yet but i want to drop the pan and inspect before i put natural oil back in a try it. I got 140 thousand on my 97 z28. dont switch to synthetic on a high mile motor is what i learned even though it was a "high mileage" synthetic blend. Id put the natural oil back in it. its got a way better viscosity and it wont leak so much that way saving you some miles if nothing else. synthetic just doesnt protect as well. I literally put 2000 miles on my synthetic oil change only and now im pretty sure I screwed myself and now the motor is too far gone.

[Beef supreme]

Originally Posted by dereklukosus

I recently switched to synthetic also and have had my main start leaking bad and sounds like I spun a rod. It isnt a terrible ticking yet but i want to drop the pan and inspect before i put natural oil back in a try it. I got 140 thousand on my 97 z28. dont switch to synthetic on a high mile motor is what i learned even though it was a "high mileage" synthetic blend. Id put the natural oil back in it. its got a way better viscosity and it wont leak so much that way saving you some miles if nothing else. synthetic just doesnt protect as well. I literally put 2000 miles on my synthetic oil change only and now im pretty sure I screwed myself and now the motor is too far gone.

I had the opposite effect as far as noise goes. I don't know if the car has been on synthetic or conventional but aside from a small leak its been a good change. It's made the car run better in general, throttle response, valvetrain noise, and it keeps a real nice oil pressure.

I felt behind my manifold and above the egr hose there's a 2-3 inch line that's covered in wet oilly sludge. That size of leak seems about right for the amount of oil I'm losing. It leaks only under load so far. Guess I'm gonna be doing a intake seal job.

Does anyone know a successful guide or method? I hear people say they've had to redo the job multiple times before they got it right.

[95 Firehawk]

It's pretty straight forward. The only thing I did special was allow for the RTV to set up for a while prior to reinstalling the intake, then allow it to cure for
24 hours before starting the engine.

The other precaution to prevent future occurrences is to try to move the EGR pipe as far away from the intake/block mating area and some suggest wrapping it to further protect from heat expansion.

Try googling it and read a few of the different write-ups to get familiarized with the similarities and differences between them. Good luck!


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[E&A's T/A]

Maybe a little known fact is synthetic oil is actually a better cleaning oil so a lot of the time what happens to an engine that has been run on conventional oil all it's life is that the seal collect some of the gunk the conventional oil leaves behind and after running synthetic oil for a while that gunk gets cleaned out of the seal and causes the seal to leak.

[Beef supreme]

Originally Posted by E&A's T/A

Maybe a little known fact is synthetic oil is actually a better cleaning oil so a lot of the time what happens to an engine that has been run on conventional oil all it's life is that the seal collect some of the gunk the conventional oil leaves behind and after running synthetic oil for a while that gunk gets cleaned out of the seal and causes the seal to leak.

Bingo boingo, I hoped for no leak but I expected one after the change. I'm currently about halfway through. I got the manifold off. Just need to clean it, seal it, and throw it all back together; also I'm replacing the lifters with brand new ones. I got a brand new set of oems for $90; I figured why not, get some more life outta her.

[Beef supreme]

Update: I just finished putting it all back together and that did the trick! The rtv on both sides was looking sad, blown out pretty much; there was probably a vacuum leak caused by all that. There's no drips when I put her up and no smoke after a good blast. The lifters being changed also helped as well, the car idles as if brand new and valve train noise has decreased noticeably. It also no longer ticks on a cold start. The whole thing took me three days of work, about 4 hours each day. I would have gotten it done much faster had I not A: Broke the oil pressure sensor B: Dropped shit behind the engine.

I bet my neighbors hate me though, their kids will be out playing and in my mechanic work I always curse like a sailor with a sea urchin in his booty. "Mommy what does @#$% #$%!@!@# mean?"