Compression test on my 89 Comanche

[dkmcgowan]

I did a compression test on my 89 Comanche I just purchased today.  It has 126k original miles on the motor.

 

The results are below.  They seem fine.  The manual says between 120 - 150 and nothing with more than a 30 psi difference.

 

1 - 130 psi

2 - 135 psi

3 - 135 psi

4 - 140 psi

5 - 125 psi

6 - 125 psi

 

I kinda wish that cylinders 5 and 6 had either the 130 or 135 instead of the 125.

 

These numbers seem normal for 126k miles?

[Megadan]

all 6 cylinders are within 15% of each other, so that's good. If I remember correctly, a Renix 4.0L should be around 150psi +/- 10 in good shape, so again, you aren't too far off.  The lower compression on one or two cylinders can sometimes be caused by buildup allowing a bit of compression loss, or other common problems with old age.  The real question is, did you perform a leak down test?  That would be more telling if your rings themselves are worn.

[ggcnash]

You're in good shape