I have a 1999 Ford F250 with 5.4 V8 SOHC work truck, which I use to pull 4 ton trailers. The truck has 214,000 miles and the timing chains ate the front of the engine. So i pulled a running engine from the junk yard with 134,000 miles on it and am going to replace the timing chains, oil pump, and all the gaskets. Since i am already so far in I was going to replace the bearings and piston rings, but I have had a couple people tell me not to replace the rings or I will develop too much pressure and blow the top of the engine. Is this true? If so should I just leave it alone or should I redue the heads. I am just trying to do a budget rebuild that will last.
When I rebuild engines, I run a bottle brush hone to clean up the cylinders.
Then using one of the pistons, I push the new rings into the cleaned up bores and measure the ring end gap.
And file the rings to obtain the correct end gap.
Then when I install the new rings on the pistons, I make sure the ring end gaps are staggered to make sure there’s no oil burning.
Never had a problem.
Whoever told you that replacing the rings will blow the top off of the motor due to increased pressure is totally, and I mean TOTALLY, full of crap.
By that misguided logic this should mean that every new engine from the factory should be blowing up…
I have had a couple people tell me this. Their theory is that doing only the lower or upper half of the engine could destroy the other half.
We can see both posts with the identical wording to 2 different people. One post is fine.
I’ll second this thought. These people are telling you “old mechanics tales” and they are not true.
But while the heads are off, valve side down, squirt some brake-clean into each intake port and look at the combustion chambers to see if any are leaking. Then do the same on the exhaust. If the valves don’t leak, put the heads on the refreshed block and go. If one or 2 leak, pull those valves and if the seats are OK, lap the valves by hand with valve grinding compound to seal them up. Put new valve stem seals on those valves when you re-assemble.
Sorry about the double post, not sure how that happened.
I thought that this was a case of old tales like not replacing trans fluid on old cars because it will clean the dirt in the bad gaskets and o-rings and ruin yours trans.
Thanks for the info about the valves, I will try this weekend.