I recently replaced all the gaskets in my 1975 350. Like the head gaskets, oil pan gasket (was a giant *****), intake manifold gaskets, carburetor gaskets, and valve cover gaskets. Now there is a massive oil leak on the passenger side rear of the engine, and i cannot for the life of me find it. Ive re-tightened all the oil pan bolts, all the intake manifold bolts, and re-torqued all the head bolts, and it still leaks.

When i start the engine, it runs fine, but after about 30 seconds there is a big puddle of oil under it, and it smokes like crazy from dripping onto the header.

Has anybody ever had this problem? Or have any advice on how to fix it?

 

take the valve cover off and see if the gasket has slipped off. check the fitting at the oil pressure sensor. if you have mechanical oil pressure gage check the tubing to make sure it has not been damaged. if you have a small mirror clean it up back there and run it and then look as best you can to see if you can track it.

 

And if those things check out, take a look at the back of the intake manifold, at the lifter valley wall. Did you use the supplied rubber end gaskets that like to squish out? (Oops) If you did, and that's where the leak is coming from, you'll want to remove the intake manifold and put it back on using only RTV on the ends, and toss the rubber gaskets.

 

I tossed those stupid little rubber gaskets right out of the package because i was told that they slip. I replaced the valve cover gaskets after i discovered this problem, hoping that it would fix it, but i wasn't that lucky. Where is the mechanical oil pressure sensor located? That is going to be my next step.

 

that would be in back of the intake. if its mechanical there will be a small plastic hose coming out of it for the oil to go threw to the gage. if not then there will be a wire or two.

 

The mechanical outlet is more towards the driver's side, to the right of the distributor as you look at the engine from the front. It could be leaking and running down, but I would expect that towards the driver's side, not pass. side.
If it's leaking on the headers, is it on the end of the headers near the collector, or higher near the exhaust ports? If it's lower then you may need to see if the pan gasket is OK, and didn't shift at the corners.

 

Well i pulled the head on that side of the motor to check the head gasket, it was fine. Looked at the back of the intake manifold at the mating surface, it was soaked in oil so I cleaned it off and put a nice big ol' bead of RTV across it, and a little bit around the oil pressure sensor tube. Put the engine back together, fired it up, and son of a ***** if it doesn't still smoke.It leaks onto the header from that cross member from the on the frame that goes under the motor, but there is oil all over the top of the bell housing for the transmission. So now, i think i have to take the oil pan off again (oh joy) and re do that gasket as well. As I recall it is a cork gasket and I used RTV on it, because I didn't know better at the time. But now I know that RTV and cork is a no-no.