Rear main seal ?

*1bad66* · Post by ***1bad66*** » April 28, 2007, 7:03 pm

Ok I got the rocker arm problem taken care of and the cam broke in but now I might have an even bigger problem. While I was breaking the cam in I heard a weird grinding noise that would start and stop. It kinda sounded like gears grinding? Then I looked under neath to check for leaks when I was done and I am about 99.9% sure the rear main is gone. My only ? about the rear main is, can you change that while the motor is in the truck and how hard is it. Any feedback is greatly appreciated. thanks

mikecarson · Post by **mikecarson** » April 28, 2007, 7:33 pm

I've done it before, and it's a pain in the behind.

Drop the pan, loosen the mains, remove the rear cap, and work the upper seal out. Getting the new one in is kinda tricky, but it is possible.

jakdad · Post by **jakdad** » April 28, 2007, 8:03 pm

They used to sell a tool at the parts houses called "Sneaky Pete". It is a rear main removal and install tool. Like Mike said, I've done it too but a PIA. I was a young buck then and thought pulling the engine was a lot of trouble. Today, I'd pull the engine.

*1bad66* · Post by ***1bad66*** » April 29, 2007, 1:52 pm

You guys have got to be tired of hearing stupid questions from me but I really do appreciate the help. Today I started the 351 up and it runs great and the grinding noise I heard yesterday is gone, but once it ran for 10 min or so and got warmed up good I started hearing a thump thump sound that got louder and my oil pressure went from 45-50 psi to 5 psi. When my oil pressure went I shut it off immediately. It has a new oil pump, the engine was rebuilt 20 yrs ago and had maybe 5000 miles on it before sitting until now. I dont now what to do with it but lately it seems like im taking one step forward and 10 backwards. Thanks again for the help.

jakdad · Post by **jakdad** » April 29, 2007, 9:16 pm

Might have a broken pump shaft. All you have to do is pull the distributor to see. Just a thought.

*1bad66* · Post by ***1bad66*** » April 30, 2007, 2:27 pm

I dont think it is that because it has a brand new oil pump and shaft. but you never now.My dad said he thouught it might be a rod bearing because of the thump thump noise it is making. He said he had a 302 a long time ago that made that noise and thats what it was, But I dont know. I am going to have to take the oil pan off anyways when I change the rear seal. thanks

Fanatic · Post by **Fanatic** » April 30, 2007, 7:01 pm

I am going out on a limb here but I've seen it done.
You heard grinding noise--I don't know how a rear seal will do this. But I have seen flywheel bolts that were too long rub on the main cap (or possibly not having the spacer in that acts as a washer for all of the flywheel bolts.)
If this happened could some metal shavings been sucked up by the oil pump?
Or possibly the starter bendix gear hitting the flywheel. Remember---manual and automatic starters ARE different !

I would say find the cause of the grinding first---pull the starter - look at bendix-look at flywheel gear-drop pan-look for telltale signs.

Uncle Skip · Post by **Uncle Skip** » April 30, 2007, 7:22 pm

Which motor. If its an FE, forget it and pull the motor. You can't get the side seals in properly on an engine stand let alone trying to put it in under the damn truck.
Do it right, do it once.
U@ss

*1bad66* · Post by ***1bad66*** » April 30, 2007, 8:32 pm

The motor is a 71 351w and it has a C6. The grinding noise I heard before came and went but now it is gone. Now it is making a new noise that sounds like it is coming from the 5th or 6th cylinder and it makes a Thump, Thump sound and I have from 5-10 psi of oil pressure at idle and when I rev it up to around 3000 it only goes to about 20 psi, before I had between 40-50 psi. Thanks for all the help but it sounds like Im going to just tear it back apart until I find my problem.