I have had a slight oil leak at the back of my motor for some time now. It is getting worse and worse with time so i plan on fixing it this week so i can head to the track. is there anyway to be sure its the intake manifold? From what i have heard they tend not to leak that bad. When i park the car after driving there is a noticable spot of oil on the ground. Just want to make sure its the manifold before i go through all the work to take it apart/put it back together.

 

Wipe your hand along the back of the intake manifold. If you hands comes out oily, you know where the leak is.

 

If it is allot of oil, chances are it is the rear seal.

 

Steve, like OB1 said, reach with your hand on the back side of the block above the bellhousing and see if its wet with oil. That will tell you.

 

The other thing to check while u are in there is the oil-pressure sender at the back of the block behind the intake....

Guess where my nutorious oil leak was comming from??? The one that didn't go away when I replaced my intake manifold gaskets 3 times, and my rear main once, and ate 2 clutch disks... and I didn't find until I removed the motor for a rebuild.... :GRRRRR:

 

As you are running an M6, I would also make sure that you are not experiencing a leak from the input shaft seal of the T56 tranny.

I also took out 2 clutches.

Initially, I did the intake manifold fix (probably wasn't leaking much if at all, but still a good preventative measure), replaced rear main seal, pan gasket and gasket between rear main housing and block.

After that I ruined the second clutch within about 4000 miles. Much cussin'.

I finally got slightly smarter (or less dumb) and did the flourescent dye and black light trick in the engine oil (Snap-On product) and determined absolutely what was leaking, and ultimatley determined that the engine wasn't leaking oil at all - at least not in any amount that would drip or ruin a clutch.

I had to let the engine run for 6 to 7 hours before I saw a drip and it was ATF - and it was not glowing fluorescent.

Short story long, I just replaced the clutch disk again and the input shaft seal on the T56 (I actually used 2 seals, since there is room for 2 and somebody on this board said that they had done that with success) and am switching to Honda Z1 ATF. Though others will probably disagree with me, my problems almost certainly started when I switched to Mobil 1 synthetic ATF (too watery?).

Hope this helps in your diagnosis.

 

On both LT1 cars I have had they both developed the infamous intake oil leak. On the first car I had it happened three times (the second time was my fault, the third I am not sure what happened) On the second car I had the leak fixed and it hasn't came back in 45,000 miles. Generally it was just a small leak but it did leak bad on my first car.