Been chasing an oil leak at the back of a 272 Y-block in my 55 Ford. I thought it was the rear main, but I changed the oil yesterday, today came home ,didn't start the engine, just rolled it out onto the driveway. Got back a few hours later and found a good size oil puddle under the car. Will the rear main leak with the car just sitting????? Or should I be looking at something else. I've had it running after changing the oil and filter to check for leaks and didn't see anything......
Y blocks can leak oil from many places, seemingly at will. Check pan bolts, oil pump bolts and oil pump suction tube seals. Also check the area around the oil filter. If you still have the canister type filter it is possible to have multiple gaskets wedged in there that will leak. If you have a spin on filter the sheet metal sealing plate has been known to warp and not seal against the filter. Then there is always the possibility that the valve covers or even the valley cover leak oil. These areas should get you started; I am sure others will chime in.
Spot on Brodie. My steel sealing plate on the canister was warped and, that along with two or three old gaskets, caused a decent leak. Also had the oil pressure sending unit leaking, the valve cover leaking, the pan gasket leaking.. All fixed now but altogheter they didnt sufice for a puddle tough...
years ago chased a leak on a datsun buddy's shop used an oil additive that helped find it. left a color trace where it was leaking. unfortunately it found several. not sure what it was called.
There are several products out there. I like to use the flourescent dye for A/C leak detection. Just put an ounce or so in the crankcase, run the engine, then inspect with a black light. Any oil leaking shows up under the black light. If it doesn't show up right away drive the car for a few days and recheck.
I had a leak because of a missing bolt next to the distributor. It was a threaded hole use to bolt on a wire guide and would squirt oil at higher rpms. At first I thought it was a rear seal because it was draining down the back of the engine.
There is the same hole on the other side - check that one too. If open, use a very short bolt as a long one can hit a pushrod.
Check the oil pump pickup tube nuts on both ends,the 2 rear pan bolts should be removed and coated with sealer,we used to use aviation permatex for that but on my last 2 Y engines I used the permatex product called "the right stuff".Those rear pan bolts very commonly leak and look JUST like a rear main seal leak.You didn't mention if this is a fresh engine or not? If not it may well be the rear main seal.You can change that seal w/o pulling the engine.Also many of these engines have had the oil pickup tube damaged on the oil pump side by overtightening the nut.If this is it you need a new tube although I have had some success with sealers,just be real careful not to get any IN the oil pump!
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