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Temp running high when under load

Bruce Cameron Jan 4, 2017

  1. chapel gate

    chapel gate Well-Known Member Supporter I am in england

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    I still find it hard to believe that a vehicle designed for some of the harshest environments on the planet has a inherent overheating problem..
     
  2. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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    I don't think they do CG.

    Mine is run at -20C in winter and up to +50C in the summer and it doesn't give me any bother...

    Clean rad, proper coolant, no leaks, fan clutch at the correct viscosity, get it right and it stays right.

    JMO
     
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  3. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    Surprised you are using a freezer. :icon-biggrin: Dropped to a chilly 10C here yesterday.:lol:

    regards

    Dave
     
  4. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    Looking at the system overall, I think it is fair to say that 'generally' there are no problems if the system is kept up to snuff. Then there is the optional electric fan that is fitted for models destined for hotter climates, an admission that the viscous unit is not up to the job, but only when subjected to particularly hot areas, and FWIW it also makes the AC more efficient.

    If we look at the OE fitment of sponge pieces packed around the radiator edges to direct as much air as possible through the matrix, my own testing has shown this is essential at speed, and the slots cut into the bumper again to allow more air to the radiator when on the move, is that an admission the rad is not big enough, but then Land Rover do the same with the TD5 using rubber flaps to direct air, and they have few problems with overheating.

    Something I have noticed from rebuilding engines over the years, is that the water jacket area furthest from the water pump is invariably blocked with rust sediment and other deposits from years of use, this leads to overheating. Then the owners start changing the radiator, then the fan clutch......and....and..

    IMO the stock cooling system is pitched about right to cover perhaps 90% of expected conditions, keep it clean and it should be fine.

    regards

    Dave
     
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  5. frank rabbets

    frank rabbets Well-Known Member Supporter

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    Dave when I restored 6 cylinder Aston engines you could remove the bores and get to the inside of the block. The rear of the block had lots of silt built up which you could chip out. Half way up the liner. I wonder if silt build up cracked BAT21's block? that was low down on N0 6 IIRC.

    Is it possible to clean the 80 block out? Jet washer?
     
  6. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    You can purchase caustic cleaners which are supposed to only attack the loose rust and calcium deposits, but if circulation is already impeded then they are IMO of little benefit.

    I think the block on it's side blasted with perhaps an industrial steam cleaner would be more effective.

    regards

    Dave
     
  7. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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    That's why I'm an avid user of Mr T coolant. I'm sure most of these circulation problems stem back to owners that have let it become very diluted with ordinary water. Same goes for water pump seals, the proper coolant has rust retardants, anti sediment properties and lubricants, whereas just water acts almost the opposite on all counts.
     
  8. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    Agreed Clive but does the Toyota coolant come ready mixed where you are? Here most outlets sell antifreeze ready mixed with distilled water, you choose the temp protection and colour to suit, job done.

    I did drain and flush mine when I got it at the same time as fitting the new rad, and it has been drained and refilled since, I use an organic green version with enough protection to suit, never had a problem. I think there has been issues of mixing antifreeze causing fouling/clogging but topping up with plain tap water has IME caused the most problems on all sorts of engines.

    EDIT: Meant to add the correct mix raises the boiling point so that helps as well.

    regards

    Dave
     
  9. Grimbo

    Grimbo Active Member I am in great_britain

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    Going back to the original post , having re read the post the problem seems to coincide with an engine rebuild AND fitting the alloy rad .... my 1HDFT engine runs at the same temp all year round even when I forgot to roll the radiator blind up after the winter one year and drove it all hot summer long even towing 3.5 tons regularly with no noticeable increase in temp .....the only time I've had a cooling issue on my 80's was when a thermostat stuck open....it never got warm
    The unknown in this vehicle is the alloy rad ....its not standard and could well be very poor flow or design despite it being sold as "4 Row"
    I would suggest fitting a "standard" type rad or even a S/H one from Karl and filling with a good premixed coolant to rule out the simple things
     
  10. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    The gauge will indicate the same temperature when running a little cool or a little hot, it is designed to sit more or less in the centre or 'dumbed down'.......until something is really out of kilter, IOW, as per your experience and this adds credence to my thoughts about the rad blind.

    I think the OP should get a gas check on the coolant, it may be a leaking head gasket, and I do not mean leaking water to the floor, but leaking combustion. I have seen engines run perfect until driven hard or pulling heavy loads. The additional workload heats the engine and a weak/damaged head gasket allows combustion gases to get past the fire ring and into the water jacket, the load is removed and the cooling system copes and the problem disappears.

    I agree with the thought the OP has a problem with the rebuild or rad, very possible, good idea to pull the rad and try another, I would swap the stat as well just to confirm he did not get a new dud, BDST.

    regards

    Dave
     
    Last edited: Jan 12, 2017
  11. Grimbo

    Grimbo Active Member I am in great_britain

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    "I think the OP should get a gas check on the coolant, it may be a leaking head gasket, and I do not mean leaking water to the floor, but leaking combustion. I have seen engines run perfect until driven hard or pulling heavy loads. The additional workload heats the engine and a weak/damaged head gasket allows combustion gases to get past the fire ring and into the water jacket, the load is removed and the cooling system copes and the problem disappears. "

    We saw an issue with JCB engines getting hot under load .....rad's were getting changed as were hose's and even head gaskets , none of this would cure the problem.....it was traced to a fault in the FIP causing the pump to remain in the cold start advance position.....this was enough to lift the head under load and cause heating issues, rebuild the pump and all was well.....strange... you never stop learning
     
  12. StarCruiser

    StarCruiser Well-Known Member Guru I am in uk

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    Interesting. Bet whoever found that one got a pat on the back.
     
  13. frank rabbets

    frank rabbets Well-Known Member Supporter

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    At least the timing advance is not at all critical for the 80 so no need to chase that as a problem.
     
  14. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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    On the coolant issue, I can't answer the question with any certainty because my service does most of the work on my truck, and he didn't answer the phone when I called him.

    AFAIK, mr T coolant comes straight from a bottle ready to use in the system, with no dilution, but I'll stand corrected.

    My guys are purists they flatly refuse to fit non Toyota parts, period.

    I had a major battle with them when I wanted to fit the OME lift springs and shocks and again when I went for fitting Chris Blakemore's dropper brackets, to do away with the caster correction bushes!

    You'd think I was asking them to fit Jeep or Landrover parts, the row we had!

    Needless to say, my rad replacement was OEM and € 500 odd to boot, but the cooling system has been faultless since.
     
  15. Grimbo

    Grimbo Active Member I am in great_britain

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    May be.....but injection timing will still be , if it's set too advanced it will still affect things.
    Worth a quick check with a DTI in the pump
     
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