low compression

[itmmik]

i have a 1989 f350 flat bed low compression 100 on some 200 on others can hed gaskets be blown on both sides at the same time
i bought the truck not running he bought an injector pump just had the trans rebuild 122 miles on it. clean truck no rust no damage
it just shut off he got a lot of bad info on fixing the truck found compression problem after reassembling any thoughts on this

 

[Austin86250]

do you have the individual cylinder numbers? if its neighboring cylinders it may be the head gasket

 

[DrCharles]

Definitely post all the numbers - but the heads are going to have to come off (as a minimum) with numbers in the 100's and only 200's on the good ones... Hopefully it's not time for a complete rebuild!

I wonder if it was badly overheated - that can certainly blow head gaskets on both banks...

 

[itmmik]

thanks i will write down numbers tonight what is the best place to by rebuild kit for it
only have 1200 in it he payed 1800.00 for the trans work

 

[IDIBRONCO]

Before you go about pricing/buying rebuild kits, I suggest that you tear the heads off of the engine and see what's wrong. If the cylinders and pistons look fine, then I don't see any point to rebuilding the entire engine.

 

[itmmik]

compression numbers
1- 100 2- 100 3- 275 4 - 75
5- 75 6- 50 7- 250 8- 175 yea boy them some good numbers
pulling heads

 

[Reggie f250]

Do a leak down test first. At least put air in each cylinder to find out where it comes out. Rings valves or head gaskets so you know which way to go.

 

[quickster]

Run it and take off the oil fill cap. If you're getting blowby like a steam train I'd say it's time for rings.

 

[itmmik]

thanks for all replies i think i will just pull the engine and rebuild

 

[itmmik]

cylinder pressures
1 100
2 100
3 275
4 75
5 75
6 50
7 250
8 175
do not look good what do think

 

[backyard_mechanic]

Mind posting a picture of your compression tester? I wouldn't mind having a good one for these trucks in my tool box.

 

[Big Bart]

Did you say he just put the engine back together? If so what work did he do?

Ditto on -

1) Leak down test via glow plug holes. Take off oil and radiator caps so you can hear leaks or bubbles. You are in a sense testing for piston ring seal leaks. Little to no leak rebuild heads and re-install heads. Lots of air past the rings, a rebuild or minimum Hone, pistons, and rings.
2) Pull the heads and see what you find. Send pics and we can weigh in on next steps.
3) If he just re-ringed it could be he did not hone it or did not lube the rings. So you are getting low compression as the rings have not seated but let us know what you referred to above about “after resemble”.

 

[IDIoit]

whats the condition of the engine?
has it been sitting long?
was the engine cold?
compression test dont tell you much, just if it builds compression,
DO A LEAK DOWN TEST!
ALSO, squirt some oil down the cylinders and rotate it a few times.
stuck rings can give you false readings