Compression Test - high? (1 Viewer)

[RenegadeQ]

I did a compression test yesterday with all the plugs out and the engine hot.

Results were

155 psi
160 psi
150 psi
150 psi
145 psi
150 psi

Then I checked my manual and found 149 psi should be the top pressure. Any idea what would cause higher readings? I'm assuming my 150 readings should really be 149 psi.

 

[NocalFJ60]

The guage's accuracy could be a little off which would cause it. Also in New Orleans if you are below sea level in theory it would be higher.

If it was ever rebuilt, it could be higher compression than stock. I would test 5 again and see if it come up some. Other than that I would say the engine is in good shape.

 

[agent orange]

I wouldnt worry about having too much compression, you can run up to 200 on pump gas with aluminum heads and attention to quench. Consider yourself lucky.

 

[2mbb]

Those numbers look similar to mine (mine may be a little higher). I've got the original 2F with close to 200K miles. I wouldn't worry about it. 149 psig may be the lower limit to what is considered acceptable.

 

[brian]

i've heard that carbon build up can raise it.

std 149 psi
limit 114 psi

 

[RenegadeQ]

Good. Then I'll assume my oil buring problem is coming from the valve guide seals. Thanks for the feedback.

 

[Sherpa 60]

"All plugs out, engine hot "...and throttle held wide open???

 

[grant5127]

i've heard that carbon build up can raise it.

std 149 psi
limit 114 psi

true... and your #s are correct........

 

[grant5127]

I did a compression test yesterday with all the plugs out and the engine hot.

Results were

155 psi
160 psi
150 psi
150 psi
145 psi
150 psi

Then I checked my manual and found 149 psi should be the top pressure. Any idea what would cause higher readings? I'm assuming my 150 readings should really be 149 psi.

because heated gas expands.... every stroke of the cyl. over the guideline limit of the test procedure raises the pressure.........

 

[grant5127]

Good. Then I'll assume my oil buring problem is coming from the valve guide seals. Thanks for the feedback.

a leak down test is a useful tool in oil consumption diagnoses.....

 

[FJ40Jim]

The 81-later high compression engines will gauge at 165. The service manual specs are not updated to reflect this.