First Compression Test
 

Just finished my first compression test. #1=58lb; #2=35lb; #3=58lb; #4=587lb. Any thoughts?

Re: First Compression Test
 

Number 2 is low. Sorry, thats all I can offer LOL.

Re: First Compression Test
 

One thing to try before a second compression test is to find a good straight stretch of quiet road,and run the car hard in second gear,then take your foot off the accelerator and let it pull down to idle in second gear,repeat four or five times..this forces the rings to work in both 'directions'..then take back to the shop and compression test while its still warm..

Re: First Compression Test
 

I would think that #4 may be a little high,


or may be this is a typo?


Anyway, I agree with Jack and then repeat the test.


If #2 is still low, put some oil in that cylinder and retest. If the compression comes up, the problem is rings, If there is no or just a little improvement, the problem usually is valves and probably the exhaust valve.


If the problem is rings, continue to run the car and it may get better.


A bad valve will not fix itself.


Chris W.

Re: First Compression Test
 

Valves

Re: First Compression Test
 

If your tests indicate valves, on the principle of check the easy things first, check the tappet clearances before you start tearing things apart.

Re: First Compression Test
 

Hello
Sounds like a valve problem , try putting some oil in the low cylinder and see if it comes up, if it does them maybe a ring problem . But most likely a valve seat .
Dennis

Re: First Compression Test
 

LOL ! Yup, #4 reading is a tad high. LOL.

How has the car been kept or driven before you got it or how have you been driving since you got it ? If it has been sitting for awhile then continue to drive it normally for awhile and retest. If it has been driven right along then check the valve clearance and do leak test. The leak test can be done simply, nothing fancy. Just enough to see if there is a problem somewhere.

Re: First Compression Test
 

#2 is low, now to find out why, you need to do a differential test and determine what's going on.

Re: First Compression Test
 

Thanks all. Good advice. (Yes #4 was a typo!)

Re: First Compression Test
 

I had very similar results on my compression test. I ended up also doing a vacuum test and a leak-down test, both of which also indicated valve problems. Here's my thread for the leak-down test if you want to take a look:
https://www.fordbarn.com/forum/showthread.php?t=278957
Vacuum test:
https://www.fordbarn.com/forum/showthread.php?t=273571