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Seeking experienced opinions on my compression test results

el__Guapo

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c3: 140 (quickly leaks down after test). c6: 138
c2: 148 c5: 150
c1: 150 c4: 150

im thinking i have the dreaded cylinder 3 head gasket issue (or possibly cracked head!)
i do have a good case of the disappearing coolant (no leaks or white smoke or gunk in oil dipstick that can be appreciated)

What is the collective opinion on this?

(this is a 1990 single cab. 5 spd 4x4 with 200+k mi on the clock)
symptoms are: (the disappearing coolant and a significant loss of power when climbing, as well as sluggish acceleration in neutral)
 


franklin2

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Compression tests are not very good sometimes for a small crack or small head gasket leak. One of those testers that hooks to the radiator cap and pumps the system up under pressure and holds is sometimes better. You can then get a bore scope and put in the cylinder and see if any fluid is coming in.

That is a lot of test equipment that can be expensive though. You can look for other clues. You can pull the sparkplugs. All the plugs will look a little dirty and used, but if you are leaking coolant in one of them, that plug will look a lot cleaner and shiny, and may have a little green residue on it from the coolant. The leaking coolant creates steam and really cleans up the cylinder and the plug as you run it.
 

Dantheman1540

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I’d definitely rather see a leak down test done, they give a little better look at what might be going on. Mostly because if you have low pressure in a cylinder you can physically listen to where the air is escaping too. For example, hissing in the oil fill neck, or bubbles in the radiator.
 

Uncle Gump

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10% is allowed highest to lowest on a compression test... you are within those limits.

Loss of coolant is concerning... but if it was getting into the cylinder it would certainly be blowing steam out the exhaust. Also... as franklin stated... that plug would be clean... steam cleaned.

search "glove test" here in the forums... it's a simple test and can confirm if you have a blown head gasket.
 

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