Hey guys, I got a question for you. One of my friends has bought a 68 F100 with a 351W (I think). Well unfortunately for him, after he bought it, the guy that he bought it from said that one of the cylinders doesn't have as much compression as it should have.
So, my question for you, cuz I'm not as much of a truck guy as I wish I was, and my friend knows nothing about cars.

How does a cylinder lose compression, and what can you do to solve the problem?

Any help would be wonderful.


Thanks, Frankie.

 

Several things can cause low compression.

old/bad piston rings

valves that don't close all the way or seal poorly.


Whe you get a chance, run a compression check on all cylinders and let us know what you get.

 

gtex is right, but it *could* be a head gasket leaking into a coolant or oil passage- and if it has a 351W in it, i doubt that it is original- count the valve cover bolts- 3 on the bottom and 2 into the intake is an FE - probably a 360 or 390...

 

If it has low compression on two adjacent cylinders it's probably a blown head gasket between those two cylinders.

 

Flyboy is right....What about burned valves?? that could cause it. turn it over to TDC on the leaking cylender, and listen through a hose. If you hear a hiss from the carb, it is getting by the intake valve, if through the tailpipe, its going through the exhaust valve. If you pull the PCV valve and hear it, its the rings. You *might* see bubbles in the antifreeze if its leaking through the head gasket into the cooling system, not sure...