100psi compression difference

[wrenchmaster]

is a spread of 400 - 500psi too far between cylinders?
Cylinder
1 400
2 400
3 500
4 400
5 410
6 500

 

[Topzide]

Looking through a Haynes manual I have which covers '94 - '01. Doesn't list a difference on the diesels but on the gas specs, says no mare than a 40 psi difference. Not sure if that can be transferred or not. It does say that for compression test, the gauge should be capable of 500 psi. To me it seems to far a spread. Hopefully others can chime in.

 

[Ozymandias]

I came up with around 50psi (3bar) for Gas and around 80psi (5bar) for Diesels.

The difference originates out of the compression ratio.

 

[wrenchmaster]

I came up with around 50psi (3bar) for Gas and around 80psi (5bar) for Diesels.

The difference originates out of the compression ratio.

So these are the acceptable differences between cylinders?

 

[Topzide]

What @Ozymandias, has found is that the difference needs to be within those specs. Anything over those numbers needs to be repaired. If you were at 80 psi, that would be the maximum you could be at between cylinders. So with 100 psi difference, some serious checking needs to be done to find the issue. If you can get below 80 psi between them, that would be acceptable.

 

[SnoKing]

is a spread of 400 - 500psi too far between cylinders?
Cylinder
1 400
2 400
3 500
4 400
5 410
6 500

What is the issue you are working on?

https://www.4btengines.com/compression-testing-a-cummins-engine/

https://www.google.com/search?q=200...ome..69i57.33783j0j7&sourceid=chrome&ie=UTF-8

 

[SAndreasen]

is a spread of 400 - 500psi too far between cylinders?
Cylinder
1 400
2 400
3 500
4 400
5 410
6 500

If it runs and starts ok I wouldn’t even worry about it . What’s the story and why are you checking it ?