Help!! Compression test results. Bad rings/ valves/ I dont know. - Jeep Wrangler Forum

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Old 05-25-2011, 02:38 PM   #1
Join Date: Feb 2011
Posts: 25
Help!! Compression test results. Bad rings/ valves/ I dont know.

Hello everyone yet again. I have an issue on my hands here and could use some input.

Background: Bought the jeep a few months back 128,000 miles on it, it has an HEI and MC2100 on it. A few weeks ago I had a scare about engine detonation from the HEI so I re curved it to keep the curve on the conservative side so I wouldn't destroy my engine. after a lot of playing around I got that under control but the jeep wouldn't idle very smoothly it was up ad down by like 100-150RPMs. Then I got into the big ported vs. manifold debate to try and smooth out my idle/denotation. Didn't work basically just got me confused between ported and manifold vacuum.

ANYWAYS long story short I tried everything (in the way of timing and card adjusting)to get my jeep to idle the way it did when I bought it 3 months ago. I never did check the plugs, until a couple days ago.... My Dad tells me bad set of rings. (I believe him) But what is your take on my plugs? I asked a friend that know quite a bit about jeeps and he said could be stuck valves, a fowling plug. He didn't think anything major engine work was needed because in the 258 usually its either #6 or #1 that have the problems. (but he didn't see the results from my compression test) The plug in the picture is from cylinder #2. Here are the results from my compression test.

DRY 1-140 2-145 3-145 4-65 5-145 6-145

WET 1-150 2-155 3-145 4-95 5-155 6-155

As the test shows cylinder 4 seems to have bad rings. (thats my guess I could be wrong) But the compression test shows #2 is right in line with the others. So I'm going to look into why plug #2 is giving me grief.

What do you think of the pressure reading in cylinder #4. Is 65 psi grounds for an engine overhaul? I would rather not but I have a 2000 mile trip the YJs gotta make coming up the end of June.

Thanks for the help

rambo3489 is offline   Quote
Old 05-25-2011, 03:10 PM   #2
Join Date: Jan 2010
Location: Las Cruces, NM
Posts: 2,303
Have you done a leak down test? This will usually show a stick or bad valve pretty quickly.

(Sold)1994 Jeep Wrangler 2.5L, Bestop top
/w steel half door and slider windows
5 speed, 2.5" lift, 31" tires,rack lights
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Old 05-25-2011, 04:26 PM   #3
Join Date: Feb 2011
Posts: 25
Originally Posted by Garyk View Post
Have you done a leak down test? This will usually show a stick or bad valve pretty quickly.

No not yet, I will hopefully be running one within the next few days.
rambo3489 is offline   Quote

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