Compression Test

Wrenching and Technical Information

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Mr.WJ
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Posts: 865
Joined: Fri Aug 26, 2011 8:06 pm
Location: Blacksburg/Chesapeake, VA

Compression Test

Post by Mr.WJ »

Well, since my Jeep decided to burn oil at Potts all day I decided to do a compression test to see how the motor is doing.

Commonly on the 4.7's the valve stem seals will fail and smoke considerably when idling and under de-accelation. Which I'm thinking this is my issue but still good to check compression anyways.

Conditions were as follows, a hot motor with the fuel pump relay pulled. Injectors were still firing but that shouldn't make a difference. Pulled all the plugs at once to test as well. This was also a dry test expect for one cylinder that read a hair lower I added a few drops of oil and the compression numbers increased slightly. Here are my results below, honestly I think they looked good expect for one but it was cold at that point, had to walk away from it for 2 hours. But I'm not sure how much of a difference it'd make.

Also I may have a slight head gasket leak according to the last oil analysis but it isn't definitive. Will see what happens on the next oil change soon.
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- 04 WJ Overland 4.7 HO, Bilstein 4600s, Tuned, 242HD Swap, 31" A/T's for cool kids
- 04 WJ Laredo 4.0, 3" OME HD Lift, Bilstein 5100s, JKS TB, IRO LCA's UCA's
- 05 LJ Rubicon 4.0, 3" OME HD Lift, Bilstein 5100's, JKS TB, Bumpers, Warn 9500ix, on 33 MTRs :cool:
- Bronco Water Pump Specialist, now leaks, fixed again and leaks for the second time
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Lil Whitey
Posts: 358
Joined: Fri Dec 28, 2012 1:01 am

Re: Compression Test

Post by Lil Whitey »

Piece of shit. scrap it :dennis:
Jake--Lube specialist--Formerly 97JEEPTJ
Club President 2010-2011 VP 2009-2010

Representing SC4WDA from the land of Texas currently. Way too flat.... :rainbow:
User avatar
Mr.WJ
Website Admin
Posts: 865
Joined: Fri Aug 26, 2011 8:06 pm
Location: Blacksburg/Chesapeake, VA

Re: Compression Test

Post by Mr.WJ »

:thumby: Yeah that is plan mmm "E" or "F" right now lol. Plan "A" hasn't even happened yet.
- 04 WJ Overland 4.7 HO, Bilstein 4600s, Tuned, 242HD Swap, 31" A/T's for cool kids
- 04 WJ Laredo 4.0, 3" OME HD Lift, Bilstein 5100s, JKS TB, IRO LCA's UCA's
- 05 LJ Rubicon 4.0, 3" OME HD Lift, Bilstein 5100's, JKS TB, Bumpers, Warn 9500ix, on 33 MTRs :cool:
- Bronco Water Pump Specialist, now leaks, fixed again and leaks for the second time
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