Here's the situation. I have an 85 3/4 ton 4x4 with a 351W. I currntly have the normal oil leaks and am getting ready to pull the engine and rebuild it. However, I don't know why it does what it does. Whenever I fill the oil and drive the truck slowly it's fine. Whenever I have to really get into the gas, it blows oil out of the valve cover breather and the dipstick tube. And I don't mean just a little bit, it's a lot. Anyody got any ideas as to why and how I can verify the problem or fix it? Any help at this point is greatly appreciated.

 

Sounds like you have too much crankcase pressure. Maybe your PCV valve is clogged? Have you checked it or changed it regularly and recently? Easy and cheap to fix.

Did this start all of a sudden or has it been going on for a long time and gradually got worse? I assume the first since you probably wouldn't write if you were used to it. Assuming the first, it is possible that if it isn't the PCV, it might be a ring broke in one of your cylinders. Check your compression for each and take note of any that is way different from the rest, say 10-20% or more difference. Not easy and cheap to fix.

It could be something else causing too much pressure in the crankcase, but my brain isn't firing all cylinders this morning.

Hope this helps,

Jim Henderson

 

>I currntly have the normal oil leaks and am getting ready to
>pull the engine and rebuild it.

It's ready to be pulled and rebuilt.Sounds like excessive blowby caused by worn rings and cylinders.

 

That's what I thought. Time to rebuild. Thanks for the help guys.

 

>It's ready to be pulled and rebuilt.Sounds like excessive
>blowby caused by worn rings and cylinders.

The problem is not blow by. It is excessive pressure. Time to rebuild any way!!!!

 

I'm really curious on this subject. If not blowby, then where does the excess pressure come from?

 

It could come from either too much oil or a heavy duty oil pumps that creates too much pressure!!