i just did a compression test on my 94 ford f150 with a 5.0.
I got 180psi across the board. the motor has 210,000 miles on it. what do you guys think about that compression??? sounds good to me but i don't know for sure.

If it is good i think i might just install a new timing chain this weekend(water pump is shot so i halfway there). right now the timing is all over the place.

and hopefully i can just run the motor tell it dies of old age.

jake

 

180 is good. The actual compression numbers will go down (or sometimes even up) with age. The most important thing is that you don't have a difference of more than 20psi between cylinders. If your results are the same all the way across thats perfect.

-Jon

 

on a scale of 1-10 how good is 180??

 

That's very good, but cranking compression is affected by many things. If the engine is warmed up, and the throttle is wide open, you should get good numbers. Next add a couple squirts of oil from an oil can into each cylinder, one at a time, and test them again. That will tell you the condition of your rings.

 

when i got those readings it was a cold motor, throttle was closed. the motor had been run a hour and a half or so before hand.

i pulled all the plugs and used a jumper wire across the starter relay. i was not in the cab so i didn't have the throttle open

i guess i will just throw in a timing chain.

 

The timing chain starts to stretch the minute it is first used. It's never a bad idea to change it, IMO.

 

All I can say is don't break those pump bolts! I just started my '88 F-150 today for the first time in nearly two weeks. I just put on a new water pump, timing cover (busted), thermostat, timing chain, and all hoses. It was a huge pain. My chain had about 1/4" of play. When I fired it up with the new one, it spit and sputtered and ran very rough at idle. I nearly blew a gasket in my brain, thinking I messed up the timing. It began to smooth out and now purrs like a kitten. I guess it adjusted to the new chain?
I'll take it for a test drive tomorrow. My only fear now is having a leaky gasket.

My 5.0 has 190,000 miles.

 

i changed the timing chain yesterday. took me 3 hours from start to finish.
it had around 3/8th of play, it was trashed. all of my bolts came out easy no real problem. i don't know if it runs any better, but now i know that it is not going to leave me stranded on the freeway.

 

You should have the throttle held wide open with the airbox totally disconnected from the throttle body for a good compression test. You also need to have a battery charger on the battery, and remember to let the engine crank until you get 3 compression strokes on the cylinder your testing.

-Jon

 

My motor at 130k cranked over 155 on every cylinder but I did not disconnect the air box? HOw much difference does that make and is 155 a good number. According to my chiltans it is??