Compression test results help

[ausdrift]

So ive done a test at home and got some interesting results. I have some ideas but wanted to get some analysis from everyone as to why my results are like this and causes.

 

I got, front to back

 

167

160

150

140

157

145

 

Thoughts?

 

Thanks1524024723762

[GTSBoy]

It seems like most of your cylinders are OK and a couple are little softer.  There's a million things that could cause those differences.

[Roger Overson]

Do another test, like this wet test

https://www.freeasestudyguides.com/compression-test-injecting-oil.html

[NEO25T]

I tested my motor a month or 2 back and got readings from 100 - 115psi, leakdown showed an average of 20% all cylinders within a couple of %.

Light oil film in pipework and cooler but still starts and runs good with no smoke 

[admS15]

Id be happy with that result.

[ausdrift]

I was wondering why some individual cylinders were different to others in the way my 6 are, for example, and why i can have such a wide spread of pressure over the engine...

[admS15]

Up to 10% variation is quite normal. Yours is a little bit over that but still pretty good for a +20 year old engine.

 

Heaps of things can cause the variation. From ring, bore, valve guide, valve wear to name a few.

 

I would honestly be happy with that and not be investigating any further. If you had 1 down to 110-120, that would be more concerning.

 

 

[ausdrift]

Ok good to know things all seem fine. So there is nothing specifically causing cyl 4 and 6 to be lower than the rest then? I know if two joining cyl are low it can be head gasket related, but wasnt sure if there is a typical reason for this.

[tridentt150v]

Probably just the ring gaps lined up, they will rotate with use.  Its just coincidence.