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Help with 4runner head gasket replacement!

Discussion in '3rd Gen 4Runners (1996-2002)' started by billcollector, Aug 19, 2014.

  1. Aug 19, 2014 at 6:14 PM
    #1
    billcollector

    billcollector [OP] New Member

    Joined:
    Aug 19, 2014
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    Gender:
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    First Name:
    Byron
    Vehicle:
    1998 4runner Limited 4x4
    Stock
    I own a 98 4runner with 190k miles on the original engine. I took it to my mechanic to get a full tune up. He called me to his shop to show me a serious issue with the truck. A noticeable amount of coolant debris has built up between the head and the block. He also pointed out 2 of the pistons were leaking. He says he wouldn't expect the truck to last too much longer driving it the way it is. He recommends resurfacing the heads and rebuilding the engine. The engine doesn't leak and there's no noticeable signs of a cracked head, but he recommended having the head resurfaced while it's already pulled out to be on the safe side. However, I've read online numerous times that these cylinder heads are only expected to last between 200-300k miles before they fail. I've also read that the cylinder head bolts must be replaced. Can anyone chip in on this?

    (NOTE: The truck runs great. But recently it started to idle high on start ups. The engine never overheats, no rough driving or anything else out of the ordinary.)
     
  2. Aug 20, 2014 at 4:04 AM
    #2
    Utah

    Utah Misanthrope

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    First Name:
    Kevin
    Land of Fake Beer
    Vehicle:
    The Gray Bastard
    3RZ, OME, 5.29s, 4.7, locked/locked
    More info is necessary. What is "coolant debris", dried crusty coolant? And what is a "leaking piston", and what's leaking out of it?

    Depending on the answers to the above, you probably just need to watch your oil and coolant carefully and see what happens. Watch for levels in either to drop, watch for oil in the coolant and coolant in the oil, etc. If you're really worried, rent a block tester kit from your local auto parts store and check for a blown gasket yourself.
     
    Bob likes this.
  3. Aug 20, 2014 at 5:17 AM
    #3
    TheBFA

    TheBFA New Member

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    Don't take this as fact, but I would say generally heads only need to be resurfaced when they have been over heated and warped. You would normally have symptoms of oil and coolant mixing if they were warped. If the heads are already out, you would need to put fresh gaskets in there anyway and the bolts/studs would need to be changed because they stretch when torqued so you don't want to reuse them. Machining the heads would increase compression slightly which you probably don't want on a higher mileage engine. As far as cylinders leaking, is he referring to low compression on those cylinders or just a lot of oil blow-by from the rings? If the compression is low then you would most likely want a rebuild. If it's just oil blow-by you could probably get away with using a heavier oil designed for higher mileage engines.
     
    Bob likes this.
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