ok I was able to get the compression test done tonight on my 98 f150 with a 4.6 romeo and here are the results...

cylinder 1= 150psi
cylinder 2= 50psi
cylinder 3= 150psi
cylinder 4= 150psi
cylinder 5= 150psi
cylinder 6= 0psi
cylinder 7= 150psi
cylinder 8 =150psi


I rounded to 150psi even though they ranged from 145 to 155...

Im not very experienced when it comes to the major internal parts of an engine...can someone school me real quick on why the 2 cylinders are not getting compression? <!--IBF.ATTACHMENT_197262--><!-- THE POST -->

 

bad rings.... my guess. could be wrong thought

 

Was there a problem before that would indicate to you that there was a problem? 0 psi is not a positive indicator and I would test it again to make sure something is wrong.

 

I just replaced my old motor with this 4.6...it has 90k on it and I never heard it run before i bought it...the guy told me it ran great before his car was totalled but it sat for over a year...

 

Sounds like stuck piston rings to me. You could try putting penetrating oil in the #2 and 6 cylinders through the spark plug holes and letting it sit for a day. Then turn it over with the plugs out to blow out any remaining pen oil. See if that helps your compression any.

 

I will try that tomorrow...I can tell the number 2 cylinder is getting a little but number 6 does nothing at all when i turn it over...

 

Bent or stuck open valve?

 

I can understand not getting any compression with a bad or open valve but what about my #2 cyl that gets a little compression? maybe its just not as far open or i guess it coulld be just bent...I am going to pull off the valve covers either tonight or tomorrow...I will keep ya posted..

 

let us know, curious the hear. hopefully it is not rings.

 

well i have a little good news....I left my mechanic a message this morning as to the results of the compression test...Im sure someone on this forum may have gave me this advice already but he instructed me to put a couple shots of oil in the cylinders that werent firing and then re-test...I did so and my #2 cylinder fired right up to 150psi...thats better than the previous reading of 50psi...I unhooked gauge and turned it over to push out the oil and retested again to get the 150psi reading...Im assuming either a valve or the piston/ring was froze up....now as for my #6 cylinder...it still reads 0psi after the oil...which my mechanic tells me that should rule out a ring and tells him its probably a stuck valve or fallen rocker....

 

my compression tester adapter came off in the #6 plug hole...anyone know of any tricks to get it out? its not very tight at all but of course the female end is facing up...

 

I got the adapter out(dont ask how)...I retested the #2 cylinder and its not keeping compression without oil in it...valve covers are coming off this weekend..

 

drivers side valve cover is off and guess what I found laying in the bottom of the #6 cyl valve body??? you guessed it...a rocker arm!!!! now to figure out how that little sucker goes back on.....

 

that is a lot better than messing with rings. what about the other cylinder losing compression?

 

I havent taken that valve cover off yet...I wonder since this cylinder is directly across from the other one if they are connected?