LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Oil leaking from where????

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Old Sep 7, 2009 | 03:13 PM
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Default Oil leaking from where????

i have a bad oil leak that happened after i went to the track friday, the entire underside of the car is covered in oil because i drove 150 miles home with a oil leak

the problem is i dont know where it is coming from,
can the oil pressure sensor cause oil to cover the entire underside of the car without any oil up top in the engine bay???

most of the oil is from the back of the motor back

any ideas
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Old Sep 7, 2009 | 03:16 PM
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A. Intake manifold gasket
B. Valve cover gaskets
C. Oil pan gasket
D. All of the Above

I'm going with D

seriously though, i did have an oil leak from the intake gasket and the oil pan at the same time and got the valve cover gaskets done just because it was already torn down that far.

there are 3 kinds of LT1's. Those that leak oil, those that have leaked oil in the past, and those that will leak oil in the future
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Old Sep 7, 2009 | 03:19 PM
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i felt behind the intake and i felt a little oil and grease but seemed old, so i was thinking oil sending unit

the thing is i lost enough oil that it wont read on the dip stick anymore
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Old Sep 7, 2009 | 03:23 PM
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hmm. i didn't think the OSU could leak that bad. its just one small screw. i wouldn't think that would leak that bad unless it was not installed at all with the hole exposed.

if you felt oil behind the intake, then the intake gasket is probably leaking. i'd guess that is the number 1 leak area on these cars. there is no "gasket" back there. it's just RTV and after several years it will break down and oil will leak out of there. do you see smoke coming from your engine after you shut the car off? when my intake gasket was leaking bad i'd see smoke coming out from the back of the motor on the drivers side where the oil from the intake would drip down onto the exhaust after i shut the car off and it would burn off. the oil pan gasket is another commin leaking point but if your seeing oil on the back of the motor it probably isn't coming from the oil pan unless you're running the car upside down
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Old Sep 7, 2009 | 03:25 PM
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would the OSU blow out all of a sudden, or leak enough oil to spray everything
how bout the rear main can it start to leak bad all of a sudden or over time
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Old Sep 7, 2009 | 03:29 PM
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Originally Posted by Smoke Em
would the OSU blow out all of a sudden, or leak enough oil to spray everything
how bout the rear main can it start to leak bad all of a sudden or over time
not sure on either of those. i would think if your OSU was leaking that bad you'd see it on the gauge like maybe it would show no oil pressure or something,. as for the rear main i think you can look under the car and see if there is oil sitting in the little metal catch thing that is under the torque converter (on an A4, not sure about the M6 whether it has one under the clutch area) i had my RMS changed as preventative maintenance when my trans was rebuilt in the fall of 07.
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Old Sep 7, 2009 | 04:17 PM
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just check the metal pan under the converter and if there is oil in it then bad news
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Old Sep 7, 2009 | 07:37 PM
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Originally Posted by Smoke Em
would the OSU blow out all of a sudden, or leak enough oil to spray everything
how bout the rear main can it start to leak bad all of a sudden or over time
OSU - yes to both

Rear mains usually start out slow, and build over time....but not always.
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Old Sep 7, 2009 | 07:43 PM
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Originally Posted by Smoke Em
just check the metal pan under the converter and if there is oil in it then bad news

not necessarly. The oil pan at the back could be leaking enough to leave oil in the dust shield. so it wont always be the RMS. I guess dropping the oil pan isnt the greatest news either, better then dropping a trans. lol
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Old Sep 7, 2009 | 09:14 PM
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Originally Posted by Badazz 97 TA
not necessarly. The oil pan at the back could be leaking enough to leave oil in the dust shield. so it wont always be the RMS. I guess dropping the oil pan isnt the greatest news either, better then dropping a trans. lol
haha, joe knows about dropping oil pans on LT1's



that's actually jpack under my car but joe was there too.
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Old Sep 7, 2009 | 09:53 PM
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just replaced the passenger side valve cover gasket on my car today. after seeing others had had this problem, i found a pin hole leak in the oil dipstick too where the bracket is to mount it to the block. it has leaked all over my #6 and 8 plug boots and primaries, starter, torque convertor inspection cover, trans pan and pretty much everything else below and behind the general area. definately something to look into.

Last edited by itSSlowZ28; Sep 7, 2009 at 10:06 PM.
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Old Sep 7, 2009 | 10:21 PM
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I think the OP should first hose everything down with brake cleaner because we know a small leak can be blown everywhere due to turbulence. Then drive a few miles and inspect. Having a leak after hard driving (race night) could be cause by poor pcv. Just another thought.

GL
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Old Sep 10, 2009 | 06:05 PM
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good news and bad news, its not the rear main, its something from above the trans
im thinking intake gasket, or oil pressure regulator, i dont think its a head gasket because there is oil on both sides of the block,
but as lt1 owners know its a pain in the *** to see anything so i think the next thing to do is take in intake off
unless some has another idea please let me know
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Old Sep 10, 2009 | 06:46 PM
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reseal the intake. can't hurt. clean up everything real good and see what you get
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Old Sep 10, 2009 | 06:55 PM
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does the intake have a gasket all the way around or does it just have rtv on the back and gaskets on the side or ??
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Old Sep 10, 2009 | 08:31 PM
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It has RTV on the front and the back, and gaskets on the sides.
You will need to pick up the gaskets (they come in a set of two, of course) and a tube of RTV (I use Ultra Copper). Seal it well (there are writeups on this, such as http://www.bfranker.badz28.com/fbody/intakefix.htm) and most recommend to let it set for 24 hours to let the RTV set before starting the engine.
Give it a good washing, and look to see if there are any other leaks present.
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Old Sep 11, 2009 | 08:56 PM
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Originally Posted by Smoke Em
would the OSU blow out all of a sudden, or leak enough oil to spray everything
how bout the rear main can it start to leak bad all of a sudden or over time
Just to put this out there a few years ago on a 94 camaro I had I left a trail of oil about 4 miles long all the way form base to my house and by trial I mean you could follow it back to the exact spot I was parked and it was the oil sending unit so it can leak a good amount of oil. Not saying this is or isn't your problem just replying to your question.
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Old Sep 12, 2009 | 07:15 AM
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Originally Posted by Badazz 97 TA
not necessarly. The oil pan at the back could be leaking enough to leave oil in the dust shield. so it wont always be the RMS. I guess dropping the oil pan isnt the greatest news either, better then dropping a trans. lol
I agree!!


Earlier this spring, I spent several evenings under my '96 Z-28, changing out the rear main seal, front cover seals, and oil pan gasket, because I found oil dripping from the torque converter inspection cover. Well, instead of looking more carefully FIRST, I jumped to the conclusion that the rear main MUST be leaking, so let's get it done.....Bad move.

AFTER going through the hassle of pulling the tranny, and I was able to get a much better look at the rear of the engine, I could then see that the rear main was not leaking. But, since I bought the "all inclusive" FelPro gasket kit, I changed everything.

Problem is, after ALL that work, the engine was dry for about a week or so, and started seeping oil from somewhere again!! After all that hassle, I don't have the ambition to get under there again, and time has been a little tight these days anyway. I just dumped a bottle of the "UV dye" in the oil, now I'm searching for my blacklight....last time I saw it, I was using it to light up my flourescent rock posters in the late 60s-early 70s. I'm sure I packed it away in one of my boxes of old stuff.....
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