compression test

[Walker2]

Chrysler 115. Third cylinder down had spark but no fuel. Performed compression test. From top down 105-65-10-105...Rebuild?

 

[Nordin]

Rebuilding is necessary. Compression should be 140-150PSI (factory spec.).
Number 1 and 4 (105) PSI is also low.

I am restoring an 70Hp Chrysler 1970 right now.
It has 130-140 PSI as spec. from factory.
Number 1 has 130 PSI, number 2 has 115 PSI and number 3 135 PSI.

Pulled the head and cylinder 2 has scored walls and all three rings are stuck in the piston.
Honed the cylinder but I still have score. Put a used std. piston in and now I have 125 PSI.

Will try to run it next summer and I think it will work but not with all power it should produce if all cylinder had 140 PSI.

 

[Walker2]

Thanks Nordin. That was helpful

 

[jerryjerry05]

The results, optimum results are what Nordin gave you.
Then you get into the area of cheap tools, test done wrong?

The 2 center holes? being as the results for those 2 is off?? maybe the head gasket's gone bad and giving bad results.

Good tools, make a lot of difference.

3 weeks ago I sold my 225.
The guy hooks up a brand new tester from Harbor Freight.
The first hole was 85#
I said NOPE!! WRONG!!
I had tested with a set from MAC tools and got 150 on all 6

Changed gauges(used mine) and the results were spot on

The tester you use, on a known good motor.
The results all need to be close, within 5# of each other.
If they all read 110 then it's the gauge.

Try removing the head and check the gasket.

 

[Walker2]

I had not thought of the head gasket Jerry. I bought the tester for $35. thought it'd be good enough. Man if t's just a head gasket, I will be so glad. I don't have a known good motor but I will either buy or borrow a good gauge. Thank you so much!

 

[catfishcarl99]

im re ringing and honing a 75 hp Chrysler as we speak. bottom had 40 middle had 152 top 125. the guy I bought it from tested and wrote it on the block. I re tested same results. bottom piston scored the middle had the rear ring free front froze. top both stuck. your results are bad either way your gonna need to remove head to inspect. I took mine off. walls looked good in cylinders.. it wasn't until I removed pistons that I found the issue.

 

[catfishcarl99]

after replacing the rings cleaned pistons and honed mine is now 150--148-150. had to swap a good piston from a junk motor to replace scored one. I even re used the head gasket. it was not the problem in my case.

 

[Walker2]

Thanks Carl. Hope I just have a gasket problem ... we'll see this weekend

 

[jerryjerry05]

Yea, keep us posted.

 

[Walker2]

Ok so head gasket looked like it had just been replaced. I think the cylinder walls are done. here's photos... rebuild?

 

[Walker2]

Photos are two middle cylinders (4 cylinder engine)

 

[racerone]

I doubt that will buff out.-----Time to tear it down.------Inspect all the parts.-----Determine what caused it !!-----Then repair as needed.-------It will need rebore on one for sure.

 

[jerryjerry05]

The repairs not easy but with the right manual, it can be done.
Then again there's a bunch of Chrysler/Forces for sale??