4.2 Inline 6 Low Compression After New Seals and Gaskets - JeepForum.com
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Unread 12-02-2012, 08:36 PM   #1
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4.2 Inline 6 Low Compression After New Seals and Gaskets

Engine ran well, leaking oil. I removed the engine. Tore down and replaced all seals and gaskets. Reassembled and ran. Tried to run engine two to three days later after installing into Jeep. Would not run. Had very low compression in 5 of the 6 cylinders.

Did a compression test tonight:
1- 83. 3- 37. 5- 40 (wet- water/coolant mix)
2- 35 4- 35. 6- 30. Now what do I look for? I torqued everything according to Chilton manual.

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Unread 12-03-2012, 06:26 AM   #2
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1990 MJ Comanche 
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Location: Prescott, Arizona
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Did you do anything with the timing chain?
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

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Unread 12-03-2012, 08:10 AM   #3
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2000 TJ Wrangler 
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All six are low, very low. What was the compression before you opened it up? What does "wet - water/coolant mix" mean. Did you put coolant into the cylinder? Why? A wet compression test is normally done by putting a bit of oil into the cylinder.

Did you remove the head?

Did the valve timing get changed? This is what cruiser is alluding to.
Keep in mind that free advice can frequently be worth less than you pay for it.
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