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  1. #1
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    '88 Jeep Comanche bike transporter

    I've got an '88 Jeep Comanche 4.0 I6 which has been pretty reliable since I bought it in '96. I use it to carry my bike to the local trails. Now it overheated and the mechanic says it's a blown head gasket. He quoted $1300 but if the head is warped, needs water pump etc, it's extra cost. It has 140,000mi. Any local Jeep experts with thoughts on fixing the truck?

  2. #2
    rho
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    Check the block/head for cracks... Its really a rather easy truck to work on.

    A head gasket isn't that hard to replace on the renix era mj's. water pump is easy. t-stat and hoses and doing a through check out of the cooling system including checking and most likely replacing the fan clutch and making sure the electric fan works. Also worth checking and out and maybe adding while you're in there is a transmission cooler. the AW4 dosn't like to be hot.

    I've had two 89 xj's (cherokee's with the 4.0..) with 250k on them. Wheeled the piss out of them for 50k.

  3. #3
    fashion ho
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    Do you still have the stock closed cooling system? If so, check to see if there's any crack on the plastic tank before tearing the engine apart. The tank is pressurized, and any crack causes the coolant to boil over in hot weather.

  4. #4
    rho
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    Also.. naxja.org is a great resource for the xj/mj.

  5. #5
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    The 4.0L head is easy to change. Blown head gaskets are not unheard of on the 4.0L.
    Your engine is the older Renix engine, as referenced earlier. For a decent bump in power, you can replace that head with a 91 or later head. Post 90 the 4.0L used a Mopar injection system. The engine's were called the 4.0HO. The heads are nearly identical, but the later head flows air far better.
    I have found a few 4.0HO engines at Pick and Pulls in the Sacramento area. Pull a head off, have a machine shop refresh it with new guides, seals, and a valve job.
    Its all Shits and Giggles until somebody Giggles and Shits

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