304 rear main oil leak

[mrhc]

I have a 304 V8 that has been completely rebuilt. All new gaskets, seals, piston rings- the whole thing. I have an oil leak dripping from the bell housing. It has leaked since it has been running again. There was a leak in the valve covers and I got that one stopped with new gaskets. I have changed the RMS twice. I'm tired of doing this job, so many bolts!! Anyway, I have been reading up on these leaks and I came across a thread that suggests getting a double lipped seal, made by Mopar. I think I have used Fel-Pro before. I nicked the upper seal before this last time I changed it so, not surprised it leaked. But this time, I know it didn't nick the upper seal. It is leaking worse without the nicked seal than with it. Shouldn't be that way. It should have sealed. Would the double lipped seal do the trick or is there a problem with the crankshaft? Is there something that I am missing? I am going to tighten the oil pan in the rear to make sure this is not the problem, but I'm not optimistic.

 

[carnuck]

Are you sure it's not the cam plug leaking? Rear of intake leaking? Even the slightest scoring of the rear main surface will chew up a seal in seconds. Having the breathers on the valve cover or intake or oil filler plugged will build up internal pressure and force the seal so tight that it burns out in minutes too. (crank needs lube to keep the seal from burning up too)

 

[flatie46]

I've been going through the same deal except at the front of the pan. It's all a crappy design. 2 piece main, pan gaskett in 4 pieces. This will be my second time on mine. I've had much better luck keeping old Harleys from leaking than I have this 304. Maybe it's AMF instead of AMC.

 

[carnuck]

Are you sure it's not the oil sender dripping back or the end plate gasket on the oil pump? Aftermarket oil pump gaskets except for what Full-Size Jeep Parts (Wagoneer, Grand Wagoneer, Full-Size Cherokee and J-truck) or Bulltear.com - Home sell suck.

 

[flatie46]

Are you sure it's not the oil sender dripping back or the end plate gasket on the oil pump? Aftermarket oil pump gaskets except for what Full-Size Jeep Parts (Wagoneer, Grand Wagoneer, Full-Size Cherokee and J-truck) or Bulltear.com - Home sell suck.

I dont think so, too much oil blown on the other side of the engine. I am pulling the oil send unit out to re-seal the threads just for the heck of it and since its so easy to get to at this point.

 

[mrhc]

Are you sure it's not the oil sender dripping back or the end plate gasket on the oil pump? Aftermarket oil pump gaskets except for what Full-Size Jeep Parts (Wagoneer, Grand Wagoneer, Full-Size Cherokee and J-truck) or Bulltear.com - Home sell suck.

I pulled the oil sender out and taped all the threads. It was dripping oil there but not enough to cause the leak I'm getting on the back of the engine. My oil sender unit in toward the front of the engine on the passenger's side, not close to the bell housing. I tightened the oil pan up a bit today and going to crank her up tomorrow and see if the leak is still as bad as before. I'm hoping giving an extra turn on the oil pan bolts might help.

 

[mrhc]

Are you sure it's not the cam plug leaking? Rear of intake leaking? Even the slightest scoring of the rear main surface will chew up a seal in seconds. Having the breathers on the valve cover or intake or oil filler plugged will build up internal pressure and force the seal so tight that it burns out in minutes too. (crank needs lube to keep the seal from burning up too)

Nothing on the back of the engine is wet. I had a leak on a valve cover but I fixed that a while ago. Everything on the engine as far as gaskets and seals are new. I had the short block rebuilt- new rings, new bearings, new seals and I rebuilt the heads and intake with all new gaskets. All the hoses for emissions and exhaust are new, including the PCV - I even thought I had put this in backwards, but I checked it and it is correct. I followed the instructions in Chilton's to the letter on how to replace the rear main seal. It still leaks. :???: I'm just wondering if the two lipped seal would help?

 

[69jeepcj]

I was going to say the seal lip has to face a certain way when you install it, but you have already checked that. I think I would try the two lipped seal,,, what else can you do but try..

 

[Turbogus]

Perhaps Chilton's have cleaned up their act but on other vehicles I've noticed over the years that sometimes they have incomplete data or even get the order of operations goofed up. Food for thought. I'm going to use the follow as a guide when I get around to doing mine;
MoC's Build Thread - Page 9 - JeepForum.com

 

[hoobness]

Bad crank? Had that prob with a 258 and 2 PC RMS. That job is a total pita, I feel for ya man lol

 

[carnuck]

If you scratch the crank while taking the old seal out, you may as well take your motor apart and have the crank polished.