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Coolant loss - advice needed URGENT

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  • Coolant loss - advice needed URGENT

    OK, Here's the story so far.
    '96 3rd Gen. 1KZ-TE motor, 290k kms, always super reliable.
    Starts blowing coolant out of radiator cap. Hard to start, lots of smoke and steam on starting, once running radiator cap off and cap clearly smell exhaust gas = Cylinder head gone...
    Head off, clear crack in No.3 cylinder. Old gasket is perfect, no blow-by so block / head can't be warped
    New head from reputable local engineering shop, new gaskets throughout, new head bolts, new timing belt, radiator acid cleaned, new thermostat (76'c), new hose from rad to header tank (old one was blocked solid with combustion crud). Meticulously rebuilt, correct torque sequences etc. Cylinder head temp monitor fitted and set to alarm @ 95'c.
    Cooling system refilled with water and cooling system flush, drained down, refilled with 50% red coolant, bled and both heaters nice and hot. Sorted, me thinks.........
    You can guess what's coming......
    Rebuilt - GOT SAME PROBLEM!
    ~100 mile run, not overheating (max head metal temp ~90'c) but I get back, truck smells of coolant and there's coolant everywhere out of the header tank, radiator half empty and smelling of exhaust gas.
    ....Fill in favourite series of expletives here.......
    So head comes off again, gasket is perfect - no blow-by.
    Head looks immaculate, head dye-pen tested - no cracks
    Block and bores dye-pen tested - no cracks
    Water pump off - immaculate
    Turbo off (only other place that exhaust gasses get close to water) - bearings are shot - a good 2mm of lateral movement.
    Coolant runs in the turbo in what looks like a closed chamber so unless it's cracked or worn through, don't see how exhaust gas would get in (and at this point water pressure is probably greater than exhaust gas pressure anyway), but it's cream crackered so needs replacing....

    So here's the plan.........

    Flush with hose from water pump to check there's flow to & out of all cooling passages & make sure there isn't a blockage causing local boiling
    Head is going back to supplier for a pressure test - just to be sure
    New turbo on order
    Rebuild with genuine toyota head gasket and another set of new head bolts
    Super-meticulous rebuild - triple-check all torques
    New radiator cap

    I'm 1000 in (parts alone) and REALLY want it sorted this time.

    So here's the question..

    Is there ANYTHING ELSE that could cause this problem that I've overlooked?????????

  • #2
    The only thing you haven't mentioned is the viscous coupling. If it has never been done, it's time to do it now. Aisin one from RT or renew the silicon oil yourself.

    good luck!


    • #3

      Yes, fan clutch re-built with 60ml of 6000cst silicone oil.

      Any other leads???


      • #4
        Not really...other than follow your plan of carefycar putting it back together with an original gasket and see. Fingers crossed for you !


        • #5
          Carefully, I meant.


          • #6
            Have you done a sniff test to see if there are any exhaust gases in the cooling system? That might eliminate any trouble with the head,
            Have you checked the water pump is actually turning the impeller?