Compression Numbers?

[Powerstroked]

Did a comp test on my wag, all were dry tested. Lowest was 95, highest was 103. The gauge is very old, so these numbers may be low. The motor runs great, but burns oil when idleing. I'm hoping valve seals may be the answer. What do all you expert's think? Thanks :eek:

[Powerstroked]

BTTT Come on, anybody have any input? :confused:

[Cecil14]

Those number sound ok. I think average is suppose to be around 125 or so, may be wet test though. I know as long as all cylinders are within 10# of each other you should be ok.

Might be time for a valve job.

Anybody else?

Anthony

[Nobby]

Compression should be anywhere from 120-150.
Your variation looks fine.
Figures are slightly low, but you suspect the gauge so perhaps treat yourself to a new gauge. Not much to go wrong with the gauge tho other than weakening in the mechanism or manufacturer inaccuracy.

Forgetting the numbers for a sec how did they pump up? Did it come up very quickly or was it still low 1st maybe 2nd stroke. Slow to come up would be indictative of rings yep do a wet test to substantiate that.
Quick to come up and the culprit is valves or head gasket.
You say she's burning oil at idle by this you mean she's smoking at idle. This would lead me to suspect the rings which would show up in those slightly lower compression figures.
Really need to know how it pumps up and then how it behaves wet.

Just to check your PCV system is working OK, i.e. your air filter is not wet with oil?

Whats your mileage on this engine?

[Powerstroked]

Mileage is 103,000. PVC is new. Will do another comp test with new gauge soon. I'll let you all know. Thanks

[Stuka]

I have 167k, and my lowest was 147.5, highest was 153. This test was done dry, with a good working guage.

[Powerstroked]

Did another comp test with a new comp gauge. All cylinder's where between 90-100 dry. Wet test all cylinder's 100-105. Pressure came up in two stroke's. Still burning oil on start up, guess it's time to pull valve cover and see if there are any seals there. Thanks

[243]

I don't know if it matters to you or not, but the 75 FSM listed 140 psi minimum for a 360 with 20 psi difference max.

[mechanic58]

I have to agree...they should be higher, but it IS good that they're all close together. Means your motor is evenly worn out. LOL.

[mdill]

Pull your oil cap, take a look at the filter, is it all plugged up with goo ?
One easy sign of worn out rings is the PVC system can't handle the blowby
and the extra goes out the oil-cap breather pluging it up.

Mike D.

[Smooshy]

Thats a good point mdill, you need to have a vac. in crank case for good pressure. Also when you crank the engine over does it have that reading at first or take a second to build up? If it takes a few seconds that may be a sign of not so good compression.