Hi,

I am planning on removing the 351M from my 79 truck this weekend to fix a rusted-out oil pan(leaks bad). At the same time, I was planning to replace the oil pump. Anything else that I should do to "freshen" up the motor while it is out and semi-apart? Should I replace the rear "main" seal, I have heard that they leak too?

Is it possible to change the crank bearings to help with the low oil pressure, or does the crank/block need to be machined before the bearings can be replaced?

Any advice is appreciated,
-Brents

 

Hi Brents, yes I would replace that rear main seal at this time. The crank bearing replacement is not a bad idea, but if you have no knocks, I wouldn't worry too much about that, unless you have a lot of miles on the mill.
my 2.5 cents

Wayne
e-mail
http://home.pacbell.net/whomrig

 

It's pretty easy to check the main bearings to see if they need replaced. I'm having a brain fart at the moment, but auto parts stores sell this stuff that looks like white plastic thread for measuring the gap between the crank journal and bearing. The idea is to take the cap off and put a piece of the thread stuff on the bearing, then replace the cap and torque it back down to factory specs. You take the cap back off and measure the thickness of the now smashed thread (the wrapping paper doubles as a guage) to determine the clearance. If it's within specs, don't change them. If it's off, change them BUT!! make sure you get the size of the bearing (should be stamped on the back) to make sure you don't get replacements that are too small. As cranks get worn out, people grind the journals down and get bearings with smaller inside diameters to bring everything back into spec. Very bad things will happen if you get the wrong size journal bearing.

Don't know if you knew all this stuff or not.

 

Yank the 351 Modified out and put in a 351 Windsor (all problems solved)
steve,

 

Only problem with that plan, steve, is that you'll have to swap trannies also.

 

I thought it was the 352 that had the bad rear main seal. I'd never heard of it with the 351/400 family. Anyone else had this experience?