i need some help on a 327. i have read all the posts on leaking rear seals. i still cant get it to stop. i have been involved with engine building for a lot of years and this problem has me baffled. i have used double lip and offset seals on this engine. the seal is installed with the large lip pointed in. the cam plug is in and not leaking. the three screw in plugs are in and not leaking. the oil sending unit is not leaking. the back of the block is dry.the valve covers have been cheched and are ok. i used both one piece and four piece oil pan gaskets in my attempts to solve the leak if it was not the seal. a dab of sealer was used on the cap and seal ends. the block is a 66 the crank is a 62-66 small journel with a smooth seal area. seals were tried offset and aligned with the cap with no success. this block and crank have never been together before. crank is std/std seal area is smooth. what am i missing here. im not talking about a drip every 1000 miles here. i start it up and when its warm and driving after 5 miles oil is coming out at a very fast pace forming a puddle in no time. idling on initial start up both times there was no leak. also drove with the oil cap off to eliminate a over pressure situation.
Just to clarify, the oil is not coming from the pan itself or where the oil filter screws in? I had a leak issue once with an aftermarket oil pan.
first off thanks for the replys. the pan is a morosso 8-quart. i checked the dimensions to the morosso catalog to make sure i was not over filling it. the engine has a spin on oil filter adaptor using a ph-8 filter and does not apear to be leaking. the filter is dry and the leak is centered in the engine. when i put it together i was able to get a good look at how the pan was sealing and it looked good both times. i have a lift in the shop and with the flywheel off inspection is easy. when i took it apart after the first attempt i looked very carefully at the pan gasket for signs of a leak. the pan gasket was dry.when i put it together the second time i used sealer around the pan area after the pan was installed for extra protection. now that it is all together its hard to see up there for a 100 percent diagnossis on the pan gasket or seal. i thought about smoking the engine to help determine the source. even with a source it wont provide a cure. with the crank seal area being smooth i have also ruled out a reverse rotation boat crank with reverse knurling. im about ready to pull the engine and mic the crank and cap. also put a dab of goo in the corners prior to installing the pan. has anyone seen a screwed up cap or a block in the seal area. i would think most of the oil would return to the pan due to the cap having a area for the oil to return. i also have a high volume oil pump on the engine.
Now you got me curious if the main journal is out of round. If that was the case, wouldn't the most of the crank be out of round and the engine running rough? For fear of sounding redundant, the rear seal is good right?
I've had oil leaks that I couldn't find at first. You gotta get under there while it's running and start wiping with a rag and following the flow upstream 'til you can trace it to its source. I understand that even if you do that, you still might not be able to determine whether it's the seal or at the rear of the pan. But at least you could narrow it down pretty close.
yes i have a gasket on the dist. i was by myself so i wasnt that exited about putting a running car on the lift and standing under it. i have a friend coming over this weekend and maybe i will try it. i will most likely shut it off for the inspection with the flywheel right there spinning. ive grown to like all my fingers. its only a matter of time that i solve this leak. i even had a guy who works in a speed shop in town stop by and has put together more sbc than anyone around and he said i was doing everything right and nothing looked amiss. I'm a hemi guy so I'm not that familiar with the abc.
I have built and been around a lot of motors, especially Chevys What do you have for breathers on the engine? I wonder if it is not breathing enough and intermittently causing gasket leaks...I have seen this happen before, in fact it happened on my Camaro and it was the only time I saw it, although I had valve covers breathers, they did not breath well, it leaked at the valve covers and pan. Are you seeing oil on the motor? any idea of pinpointing where the oil is coming from or only on the ground? Do you have a bolt in the front of the block near the fuel pump?? there is a p***age there, that must be plugged....
this is a NON hamb friendly photo of my 69 Corvette...see the stainless steel bolt and washer in the top right of photo on the front of the block, opposite the fuel pump.....? that bolt is there, with teflon liquid thread sealer Another example
I've read that some motors have a rear seal problem after being line-bored, and they would have to shim the seal. Don't think that was a sbc, though.
Racer, I've had the exact same problem before, back in the 70's I had a automotive machine shop and rebuilt a 350 motor that did the same thing. I know I put in at least 80 hours on that motor in and out 4 times. I found that the crank diameter was out of round only on the oil seal area, why?, who knows and for how long who knows, so I had to install a new crank re-balance and everything for the guy to stop the leak. I don't know if the hi volume pump has to do anything with it, I've never used a hi volume or hi press in a SBC, they just dont need that much oil to live. Good luck.
the last sbc i put together leaked bad at the seal. i put a few dabs of black silicone at the seal ends and no more leaks. and a hv oil pump wiont make on leak.they dont put out that much more volume.
When rod or main journals are welded to restore one or more journals there is a very real chance that the crank will distort and curl. Grinding the mains true does not ensure that the diameters and shoulders of the crank's snout, timing sprocket seat, rear seal surface, pilot bearing bore or flywheel flange run true. The main m***es of the crank will also be offset many thousandths of an inch, so the balance can be pretty bad too. With the pan and pan and rear main cap off I'd use a dial indicator to judge how much runout the seal surface has.
Have you tried a Fel -Pro Grey rear main seal?I do not know the part # ,but a good parts man/ store will know about it. I have used these on problamatic leaks and they solved the problem.Twice the price of a black seal ................but they work.
all great ideas i will check them this weekend if i can. i never knew about the front bolt thats a easy thing to check. i dont think it is leaking though because the oil is pouring out the back. the crank was rebalanced with evidence of welding. i went with a six inch rod at the shops recommendation. so i will check the run out. the engine shop did say at times they have used a shim in the seal area. i think he said something about a zip tie for a shim. i was going to bring him the cap to look at. the shop is wisconsins largest speed shop and do alot of sbc engines. the crank was a used original that was std/std. thanks all
i have heard that milodon makes a softer pan gasket compared to the felpro blue one piece pan gasket. i run the stock 327 chrome valve covers. they have no breathers originally. the engines had a vent just to the left of the distributor and a hose or line ran down. its unplugged i was able to blow through it. and just to be safe i ran it with out the filler cap off. the speed shop in kenosha wi said he has seen out of round cranks in the seal area. he said smoke it and rotate the crank.
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