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#1
02-28-2008, 05:58 PM
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4.o Knock after H/ G Repair
After replacing head gasket in 97' Jeep. Knock from lower end continues to alude me. Block had only 12,000 miles on it before gasket failure. Yes, there was evidence of h20 in piston # 3 & 4. I have checked the trans./ fly wheel. Seems o.k. I have also disconncted each fuel inj. at seperate times but, no change in knock. Is it time to drop the pan? Could it be a loose connecting rod/
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#2
02-28-2008, 08:22 PM
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Re: 4.o Knock after H/ G Repair
OK so 97 Cherokee with 4.0. Is this a new engine that you put in? What was done....was it remanufactured, new, junkyard, or what?
You said you have a knock. Is it a loud clunkclunkclunk that increases with increased rpm? Or is it more of a dieseling sound? Are you getting any white smoke from the tailpipe? How about an oil analysis...have you done one? All of the above can be helpful in diagnosing the problem. Let us know what you find.
__________________
Ours: 2020 Jeep Wrangler 2.0, 53k 2013 Toyota FJ Cruiser, 84k Kids: 2005 Honda CRV, 228k
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#3
02-28-2008, 10:38 PM
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Re: 4.o Knock after H/ G Repair
Also are you sure the knock is coming from the bottom end and not the top end IE rockers, push rods and just sounds like it's at the bottom? There's not alot that could be bad at the bottom end main thing is the sleeves on the connector rods and bearing caps if one of them is bad it could possibly cause the problem you've indicated. As far as the block only having 12k on it before needing the HG replaced was it a new/remanufactured/junkyard or what. If it was new it almost sounds like the surface wasn't machined right causing a gap if it was reman/jy then it's possible it was a cracked block and the crack only opens up with heat and when it cools it closes back off.
__________________
1993 4 door Jeep Comanche project in the works.
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#4
02-29-2008, 04:26 PM
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Re: 4.o Knock after H/ G Repair
The knock i consistant to a point and does speed up w/ RPMs, Its not dieseling. No white smoke . Oil pan is dropped at this time. Engine was reman. No oil analasist
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#5
03-01-2008, 08:03 AM
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Re: 4.o Knock after H/ G Repair
With the knock consistent to rpm's I'd pull the valve cover and check the rockers and valves as there isn't much on the bottom end that could cause it.
__________________
1993 4 door Jeep Comanche project in the works.
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#6
03-01-2008, 08:25 AM
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Re: 4.o Knock after H/ G Repair
A bit too late, but when you had the head off did you check to see if you had a bent rod. IE, turning the crank over and measuring the distance from the top of the piston to the deck. If there was water in a cylinder there is a chance that you have a bent rod.
Also how long have you had the engine run after the repair. You may need to let it run a while to work all the air out of the lifters, a good 5-10 minutes. If they machined the head I assume that they checked thehead for cracks?
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