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Compression Test Numbers

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NoHndlbrsRqrd

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Discussion starter · #1 ·
Hey guys. So as you have probably noticed I am chasing down two problems at the moment. I must say that all in all it's going well, and damn I appreciate all the input. Anyway, so I did a compression test this evening to enlighten myself and to see if there was any evidence of headgasket issues. What I found surprised me.

#1-165 psi #2-189 psi #3-165 psi #4-165 psi

Spec is supposed to be 178 psi I read. So they are all the same and within 14 psi of 178 psi until cylinder #2 which is like 189 psi! What? I was under the impression that one was supposed to lose compression in cylinders not gain it.

So I ask you guys, whats the news?
 
Discussion starter · #3 ·
At least three times I got that high reading, and before that I got 180 psi in #2. At first I found I was not cranking the motor over enough but once I figured out I could watch the gauge through the window I tested each cylinder over and over with identical number of cranks until I got consistent readings across all four. Once I got a solid reading I did all four again and came up with the same numbers.
 
Discussion starter · #5 ·
Been reading. Could it be that there is an extra bunch of carbon build up on the pistons? I looked down through the spark plug holes and the piston tops have all sorts of black on them. I dont know if its from the past owner who ran it with 550s and no fuel management or from oil being burned.
I am still suspect of the head gasket though in general, but maybe it is fine.
 
Discussion starter · #9 ·
Which method would you suggest to target the carbon build up on the cylinders while minimizing the risks of causing more problems in the engine, which is high miles (158,xxx)? Perhaps soak a cap full through the spark plug holes and the rest in tank?
 
#10 ·
On my '95 with 143k I ran one can through the tank, half through the crank case, and half through the BOV > IM hose.
Then I switched it form dino oil to full synthetic.
It loved me for it. If I had to do it again I'm not sure I'd bother with the crank case, but the vacuum hose is a good idea.
 
#11 ·
for 158k I'd be happy with those compression numbers. :)

Oh and with Mopar Carbon Combustion Cleaner, I always suck some in the car while its idling through the throttle body ports. It will bog the engine, gotta be carefull. Then i pour some in the cylinders and let it sit overnight with no plugs in it. then let it shoot it out all over the place by turning the car over with the plugs out. You can have a friend hold a rag over the top of the plug hole(don't let it get sucked in) To catch most of the stuff.
 
Discussion starter · #12 ·
Right on. My biggest concern was the high compression reading. I am going to use one of these cleaners and retest compression and see how it goes. Are Mopar Carbon Combustion Cleaner and Seafoam interchangeable in results? Could I use either brand to run in tank, through throttle, and overnight on the cylinders? Thanks for all the help guys.
 
Discussion starter · #13 ·
Hey all. So I currently have some seafoam in the tank and am letting it run through.

Quick question though, when I ran some through the IM it threw a cyl 4 misfire code. I cleared the code and it has not come back but was wondering if this has happened to any of you before.
 
Discussion starter · #18 ·
So post seafoam with a brand new gauge I just did a compression test and got the numbers as follows: #4=180psi #3=180psi #2=190psi #1=175psi. All those numbers were double checked. What is every ones thoughts on these?
 
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NoHndlbrsRqrd
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