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Discussion Starter #1 (Edited)
So as I alluded to in the Good Morning thread a few days ago I had a busy winter. One of my winter break projects was to replace the heads on the wife's Jeep Liberty.


The repair was fairly strait forward. The hardest parts was torquing the head bolts, aligning the cam chains and the camshaft on the passenger side.

Here are some pictures of the teardown.

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Here is putting it back together.

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I picked up few specialty tools that make the job easer.

The 3.7L Jeep engine has 3 timing chains, the crank is connected to a balancer shaft and then the cam shafts are attached balancer shaft. To get the chains on and timed correctly you need to have 5 hands or the special tool 522902 made by OTC.

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I picked mine up from Amazon. It was well worth the $35 price tag.

I also wanted to get a proper harmonic balancer installer. I first ordered was made by Jeg's. I felt it was a steal at $60.

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When I went to use it I noticed that the treaded shank that threads into the end of the crankshaft was way to short. The threads on the crankshaft are set quite deep and only the last inch or so of the harmonic balancer bolt are threaded.

I sent it back and orderer one made by Lisle, 53760. This kit was double the price of the Jeg's kit but it was much better made and the adapters are much longer so it actually hit the threads in the crank.

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I also need to pick up a torque angle gauge as the head bolts are torque to yield and a nice set of hose clamp pliers it was time to get a set.

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The only tool that I wish I had was the cam wrench, they sell for over $80. The cam on the driver's side naturally lays in the proper position to replace the cam gear back on but the passengers side is about a quarter turn off and must be turned against the valve spring to get it to line up. So I used a pair of vice gaps on a non-machined part of the camshaft to turn it to where it need to be to get the gear on.

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What a project! Looks like you did a top-notch job. :thumbup1gif:

What was the initial issue to warrant changing of the heads?
 

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What a project! Looks like you did a top-notch job. :thumbup1gif:

What was the initial issue to warrant changing of the heads?

She was on her way to see her dad in the hospital, which was about an hour and a half away. Cruised on the freeway for about 45 minutes and then got stuck in traffic. She says it never over heated but started to run rough and the check engine light came on. I told her to park and I would come look at it. When I got there I started it up and it ran like crap so I had it towed home.

I figured she cooked it and it was either cracked head or head gasket. When I got it back to the house I pulled the plugs and the 3 on the passenger's side were soaked with coolant. I took the heads to a shop to have them checked out. Before I could get the second head out of my truck and inside the guy found the cracks in the first. They ran from the coolant passages into the combustion chamber. The passenger's side was really bad but the driver's side was not far behind. From what I understand it is a common issue with this engine.


On a side note:
I forgot to mention earlier that I did have one issue after I got it back together. I took it to get a pizza and test drive. I jumped on it going up a hill and it lost power, started running rough, and the check engine light came back. I was thinking I just sent 4 day $1800 and I goofed up putting it back together. :banghead:

I pulled the trouble code and there was a miss on the driver's side. Im thinking bad coil, timing is a tooth off or something else drastic. Luckily I had a few days to think about it. It finally dawned on me that the wife wanted to help as I was finishing up and I gave her the task of gapping the spark plugs and putting them in. Well she dropped the last one and I told her to double check the gap she did then installed it. I didn't even think that she might have broken the ceramic insulator on it. Sure enough I pulled the last plug and it was cracked and arcing out. Replaced it and it was all good. Here is to another 150K miles.:yahoo:
 

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I had a friend do that to a spark plug. He spent all winter swapping a newer Jeep TJ 4.0L into his YJ to replace the original carbed engine. On start up it ran great but had an occasional miss. Couldn't figure it out for the life of him. Brought it out on it first off road run with the club to show it off. As we were standing around complimenting him on the great wiring job I mentioned the miss. He got a bit sheepish and admitted it was driving him nuts. I took a closer look and suddenly saw the rear most spark plug arc out on the block. I pointed it out to him and he immediately changed it with a spare he had. Miss all gone. He was sooo happy. He did mention that he did drop one plug when installing them and thats what probably what caused it.
 

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Mike ,good to hear it is back together and running OK. Good job:bigthumb:
 
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