1UZ in Thai longtail boat

Discussion in 'General Discussion' started by melvinmelvin, Jul 8, 2017.

  1. melvinmelvin

    melvinmelvin Member

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    I guess the best I can hope for now, with the new cylinder head leaking oil into the exhaust pipes,
    is that I spot something wrong/faulty with the gasket when I take off the cylinder head again.

    Since I now have new valve oil seals from the last round with the cylinder heads,
    would it be opportune to use the occation to change them on the new cylinder head?
     
  2. American Locomotive

    American Locomotive New Member

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    It's always a good time to change valve stem seals if you have the cylinder head off.
     
  3. melvinmelvin

    melvinmelvin Member

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    Right, suspected that, will look at that now.



    Took the RH cylinder head off today (took its time, I have a smashed RH shoulder and need help from my neighbour for heavy screwing).

    Before removing the cylinder head, checked all sparkplugs, all 4 sparked on demand as they should, and they looked reasonably clean all of them - didn't like that.
    Off with the head.
    It was clearly a very bad gasket.
    Could easily see how water had leaked into the combustion chamber and caused white smoke.
    Could also easily see how engine oil had leaked into the chamber and further into the exhaust piping.
    Could, however, not see any reason for the mill running on 7 instead of 8 cylinders.

    SURPRISE: all 4 sparkplugs were reasonably clean, all valves were reasonably clean, as well as piston tops and combustion chambers.

    Anyway, will commence on the gasket making stuff tomorrow.

    Re running on 7 rather than 8:
    Have had similar problem before.
    I use a Merc Benz one speed external fuel pump (manufactured by Bosch).
    At least once, maybe twice, before I've had to change the pump 'cause it did not work with high enough pressure.
    (maybe the Benz pump does not fancy serving a Toyota mill)
    Have a spare pump in my box, will try that if 7 rather than 8 continues after gasket fix.
     
  4. cribbj

    cribbj "Supra" Moderator Staff Member

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    You can check for non-firing cylinders by putting an inductive timing light on each HT wire and seeing if it "fires" regularly.

    For non-firing injectors, there are devices called "noids" that clip between the injector and its electrical connection and they'll indicate firing pulses. If they indicate the injector is getting the pulse, you can then use a mechanic's stethoscope and hold it on each injector body to see if you can "hear" the injector actually firing.
     
  5. melvinmelvin

    melvinmelvin Member

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    right, thanks

    will also check that the plugs on the LH bank are working as they should,
    the non firing cylinder might be in any of the two banks

    have a new gasket now, the gasket workshop suspected that they maybe had made the faulty gasket too thick, so they made a thinner one
    will see if its OK
    the RH head is due to go in tomorrow

    (easier to work on this when the engine is hauled ashore - much more space around,
    and when the engine is running I can stand behind the exhaust pipes and feel the exhaust by hand and
    normally I quickly determine which pipe has a missing cylinder (only have 2 cylinders per pipe),
    then I'm down to two possible culprits - a better starting point for finding the none firing cylinder)
     
  6. melvinmelvin

    melvinmelvin Member

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    In thd process now, took the oppotunity to change the stem valve oil seals at the same time.
    With my nes toy from Amazon it went like a breeze, 16 valves in less than an hour.

    QUESTION RE CYLINDER HEAD GASKETS
    I noticed something that I find somewhat weird.
    Both the block and the cylinder heads have some holes for water, around both sides of the cylinder, the holes have a spherical shape, about an inch long.
    Generally two holes on each side of the cylinders.

    However, the gaskets do not have corresponding holes. Ie the water flow stops at the gasket.
    Is it supposed to be that way or do I have the wrong gaskets?

    In accordancde with advice from here I ordered gaskets for Toyota Celsior 1995.
    Received gasket numbers 11115-50021 and 11116-50011, original Toyota stuff.

    (have not experienced over heating problems)
     
  7. American Locomotive

    American Locomotive New Member

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    Remember both cylinder heads are identical castings, so the gasket is what controls water flow through the head for the correct side.
     
  8. melvinmelvin

    melvinmelvin Member

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    OK, thanks. I think I would need to see both heads and both block banks to fullly appreciate that.

    Testet the 4 plugs in the LH bank, good spark from all.
    Somewhat disappointing that all 8 plugs spark well. Will make it trickier to nail down the cylinder not firing.

    Anyway, the RH head went back in with the new (and thinner) gasket.
    Hooked up minimum of what is needed for a trial start, without coolant.
    The mill fired up immediately and responded to push on the "pedal".

    Cannot be sure - difficult to hear when running without manifolds/headers - but I got the impression that only 7 of the 8 fired.
    It was only running for a few seconds, just to test that the timing was OK - which it was.

    (am doing some rewiring of cable distribution to the instruments, so without seeing oil pressure or oil temperature I closed down within ten seconds)

    Before any further testing I must hook up the instruments to the new distribution panel and fix some wiring.
    And put on headers/exhaust pipes - radiator - fans - and various cooling related stash and fill up with anti freeze. Takes a day.
     

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