Overheating...

Discussion in 'Diesel Tech / 24 volts' started by PJHunter, Nov 5, 2005.

  1. PJHunter

    PJHunter

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    my 1KZT engine has begun to overheat. This is a new thing for it. My engine doesn't smoke. It's not leaking oil. My coolant reservoir is full but the radiator continually looks dry [so i keep topping it up].

    any ideas on what to look out for would be appreciated.

    the engine is bog std. and has done 125,000 miles and up until recently has run absolutely faultlessly. The first time we std to notice it overheating was in low gear up an extremely steep bank. But, we've also noticed the guage fluctuate hugely for no reason at all when driving on the flat?

    thanks all for your help

    Al
     
  2. wesintl

    wesintl

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    cracked head or possible head gasket if your continually topping the rad.

    I would do a test for combustable gasses in the coolant.
     
  3. crushers

    crushers post ho

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    that and a coolant pressure test...
     
  4. PJHunter

    PJHunter

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    thanks for your responses... i understand about testing the pressure in each cylinder but how/where does one test coolant pressure and how/where does one test for combustable gasses in the coolant?
     
  5. PJHunter

    PJHunter

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    oh... if it helps.... I've seen it before that the coolant is getting lost as it's running out the overflow pipe. Would this indicate that there is too much pressure in the coolant?

    Also whould would too much pressure in the coolant or combustable gasses in the coolant indicate?

    Sorry for 20 questions but it does concern me and i want to sound somewhat knowledgable when i go to a garage rather than paying £60 for unnecessary research as they fumble around.
     
  6. mallred

    mallred

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    Could be building pressure from a headgasket or cracked head, but I would check the rad cap first it might have failed and letting out coolant early, a pressure test on the cooling system will tell if it something serious or not.
     
  7. Stone

    Stone Moderator

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    You can buy a cooling system pressure tester in most parts stores. It looks like a radiator cap with an attached rubber hose and bulb, similar to the ones they use in hospitals/doctors' offices to test your blood pressure. You take off your rad cap, replace it with the pressure tester cap, pump up/pressurize the system, and sit back and watch for leaks or for the pressure to drop. If your system is good, then it should hold the pressure. Good luck.

    Or this is a fancier one:
    [​IMG]

    http://www.northerntool.com/webapp/wcs/stores/servlet/NTELargeImageView?rfno=200215424&storeId=6970
     
  8. crushers

    crushers post ho

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    agreed, start cheap and work up...
     
  9. roscoFJ73

    roscoFJ73

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    Yep, radiator cap would be a prime suspect
     
  10. PJHunter

    PJHunter

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    i am finding this all very helpful. So thank you. I will go and look at buying a pressure testing kit today...

    ...just out of interest what would your thoughts be if the pressure test was actually ok? Would that mean it would definitely be something more serious like a cracked head or head gasket??
     
  11. crushers

    crushers post ho

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    if there is no leak occuring outside the block or into the passenger compartment (ie the heater core leaking) then yes it has to be loosing the pressure inside the block somewhere..
     
  12. David*BJ70

    David*BJ70 Looking forward to reach the end of the world

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    Before, I have the same issu.

    No coolant in the oil, non smoke, everything look dry... but after severale minute at high speed, all the coolant get out by the overflow pipe.

    I first change : water pump, radiator, some hose, T-stat, some gasket ant the rad cap.

    I try compression test.. but that not give me the answer.

    My solution : new head gasket. The piston pressure seem to get out in the cooling system.

    HTH
     
  13. wesintl

    wesintl

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    On the cracked heads I've had I've found the pressure test to be worthless.
     
  14. PJHunter

    PJHunter

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    So you're saying the pressure test didn't achieve anything?

    also... is it likely that a head would 'just go'? Wouldn't it take some extreme lack of maintenence or neglect to stuff a head?

    And wouldn't a head gasket 'just go' as well? Or are there cases where just through sheer time and age a HG would just wear out like any other component?? Also I always thought that where a HG had failed the engine wouldn't maintain any form of stable temp at all. Is my thinking wrong?

    On another note... when to buy a pressure test kit today but Halfords didn't have any. So I'll have to find another local automotive store here in Bristol that stocks 'em.
     
  15. wesintl

    wesintl

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    Yep pressure was fine. I left it on there for a bit too and it held steady. That was on my fj60.

    Exhaust gas in the cooland test is the best option IMHO.
     
  16. PJHunter

    PJHunter

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    but what would cause a head to crack if it hadn't overheated before?
     
  17. crushers

    crushers post ho

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    did you do a cold test or a hot test? i have had good results doing this test...
    cheers
     
  18. wesintl

    wesintl

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    Yep. I think a cold one is worthless. It's gotta be hot for the crack to open up hoses get soft for pin holes etc.. FWIW we did it at a mechanics shop to so unless we were both seeing things It didn't work. Actually I should modify my statment as I didn't do it on the 3B. I only did the gas pressure test and I pretty much knew from driving and loss of coolant what the problem was. It doesn't take a rocket scientist to know what's going on although at the time I was trying hard not to believe it. :frown:

    JMH.02
     
    Last edited: Nov 6, 2005
  19. wesintl

    wesintl

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    stock gauges aren't always accurate. Not saying it is a head crack but your coolant is going some where, either through a crack or bad gasket. Pressure test at least can help with pin holes in hoses and bad connections where you loose coolant onto the engine and it burns off. :)
     
  20. crushers

    crushers post ho

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    yes, i have found a cold test is worthless but a hot test does help. i have never done a exhaust gas test, how is that done?
     
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