results of my compression test readings, please interpet

[jbuller]

OK i just got finished doing my compression test. my tester only goes up to 250 psi so its not completely accurate on the readings that were higher than 250 psi. ok first i pulled all 8 of the glow plugs. then started on the first cyclinder. heres what i got

front of engine

300psi 300psi
300psi 75 psi
100psi 300psi
150psi 300psi

when i squirt oil in glow plug hole the onse that are low i get about another 25 to 30 psi. does this sound like rings to you guys? also what is a normal compression reading on a healthy 7.3? i cant find it anywhere. thanks

 

[JRJ04]

how did you do this yourself? buy the tool or rent it? what made you do the test? I just had 3 injectors replaced and ive got it running a little rough on idle and am worried that might be the case.

 

[jbuller]

i bought the adapter that screws into to glowplug hole

i had another guy crank the truck over while i read the guage.

 

[95_stroker]

also what is a normal compression reading on a healthy 7.3? i cant find it anywhere. thanks

You should be +400 psi on all 8 holes.

Dieselmann

 

[RoyBoy]

You need a gauge that goes higher to get accurate readings. You're just shooting in the dark otherwise. You actually could have damaged your gauge if you pegged it out
Also, adding oil to the cylinder should bring compression back up to the level of the other cylinders or higher, if its rings/ cylinder walls.

 

[Zookie400]

lso, adding oil to the cylinder should bring compression back up to the level of the other cylinders or higher, if its rings/ cylinder walls.

+1

are there bigger injectors in this truck?

 

[jbuller]

no

just stock injectors, they are brandnew ones thoug i just replaced them about 4 or 500 miles ago. I borrowed a freinds gauge that goes up to a thousand psi, stil the same readings on the lower compression cylinders and the ones that i was guessing 300 are realy anywhere from 275 to 350psi only one cylinder was 350 the rest were closer to 300.

 

[Dogman]

This is the same test you would do on a gasser but it works with diesel too. There’s only one other way I know you can test the rings. Use the compression tester hose and put compress air to it and see if you can hear the air blowing out the oil ports that will be rings or the air coming out the turbo intake, intake valves not closing or the tail pipe exhausted valves not closing. You’ll need to block the glow plug ports to do the test. This is old school testing.

What’s your mileage? With reading like that sounds like a motor rebuild is just over the hill

 

[jbuller]

well the mileage is only 210000

I just decided to pull the motor out and tear into it and see whats wrong with it. well i got the radiator out the intercooler out, the turbo off the fan off most every thing off or loose but i am wandering if it is gonna fit comming out of the engine bay if i leave the waterpump on it it looks like its gonna be tight. any sugjestions on pullin this thing out? do i need to disasemble the radiator suport to get it out?

 

[jbuller]

ok

got it out i just had to take loose the uper radiator support and it cleard just fine. can wait to open it up and start measurin stuff. I think im gonna find some good stuff in that thing, i can beleive it actually ran with compression thaat low in 3 cylinders. i will let you all know what was causing the smole ans what parts are worn out or broken on the inside next week when i start the rebuild. i still need to get an engine stand for it. any ideas where i should look to get one at?