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Temp running high when under load

Bruce Cameron Jan 4, 2017

  1. Bruce Cameron

    Bruce Cameron New Member I am in australia

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    Hi the temp in my 80 ser is getting high when I tow or when doing four wheel driving ,it seems it only happens when under load .
    I have rebuilt the motor and it has been bored out 100 thou and the injector pump has not been touched ,could this be the problem of it running to lean and getting hot . I thought maybe it needs more fuel .
    I have also replaced the thermostat ,checked my clutch fan and put in a new alloy radiator .
     
  2. StarCruiser

    StarCruiser Well-Known Member Guru I am in uk

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    Is the alloy rad of the same cooling capacity as the original copper cored one from Mr T? I'm pretty sure I've read somewhere that some rads are not as good as the original.

    I'm assuming you have no issues with coolant levels/leaks of course.
     
    Last edited: Jan 4, 2017
  3. Beau

    Beau Well-Known Member I am in guyana

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    Check in between your main radiator and AC Rad as crud builds up there over time. It's hard to tell without removing the actual rad, but I highly recommend it.

    hmm a lean burn does give a higher combustion temp but lower EGT's, so I doubt that's your problem, especially if it' only occurring under load. Get your general cooling system checked. Start with the basics, it might be something simple.
     
  4. Bruce Cameron

    Bruce Cameron New Member I am in australia

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    Cheers StarCruiser the capacity is bigger than the standard and I have checked for leaks etc
    Thank you Beau I have had the rad out and cleaned in between the two rads .
    Next I will be going to a mechanic to see what they say
     
  5. Grimbo

    Grimbo Active Member I am in great_britain

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    Is your Rad one of the alloy ones on %bay , seen several from china and also some from holland .
    was thinking of getting one but very dubious of quality from china
     
  6. chapel gate

    chapel gate Well-Known Member Supporter I am in england

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    Fit an egt gauge to get some idea of whats going on. Then go from there. As said make sure that rads up to the job. Does it feel its lacking in power?
     
  7. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    Check you fan clutch is working properly. I have an all electric system on mine, but have found when under load or at speeds circa 75 - 80 MPH the fan used to come on. I stopped this by blocking the gaps around the radiator, from the factory there is sponge but this rots away after a few years. And of course an OE thermostat with the bleed hole at the top, check rad cap is holding pressure, is water being blown into the expansion tank?

    Bottom hose if soft can be sucked in due to the action of the water pump, also the hose inner liner can also collapse when under vacuum (cheers @clivehorridge ), is your heater hot including the rear one if fitted, if not then that indicates air in the system.

    On diesels more fuel means more heat, the reverse to a petrol engine.

    Be aware that the standard gauge is electronically controlled to keep the needle more or less in the centre, the fact that it is moving past centre indicates the engine is getting very hot.

    regards

    Dave
     
    Last edited: Jan 10, 2017
  8. StarCruiser

    StarCruiser Well-Known Member Guru I am in uk

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    Good point on the foam Dave. Mine has all but gone and if often thought I should replace it. I guess with mine having the engine driven fan at those sort of speeds I'm not relying solely on ram air so it is less noticible. I'm surprised it makes that much difference but makes sense when you think about it.
     
  9. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    I have been running a thread on MUD for around 6 years now, one of the mods include an electric fan install. I have collected and posted up pretty extensive data gleaned from gauges, and using thermal sensor guns.

    Keeping in mind the ambient temps here in Spain, most of the testing was done during the severity of the summer months, this time of year though the fan rarely comes on unless the AC is in use, YMMV.

    The short version is that at idle the fan is needed after around 5 -6 miutes, over around 20 -30 mph the fan is not needed up to about 70....ish mph or if you are towing a heavy load, above that figure then the fan engages. I installed gauges on the top and bottom hoses to monitor temps so can offer pretty concise readings. Replacing the foam I increased speed by about 10 - 15 mph before the fan came on.

    Before fitting the foam the fan would come on and go off in cycles of around 5 -6 minutes when at speed. I am not suggesting for one moment the fan moved as much or more air as the car at 80 mph but, when it came on it lowered the pressure behind the radiator, this allowed air to flow more easily through the matrix as opposed going around the outside. Eventually I blocked the space between the front bumper and the rad/AC condenser, fan no longer comes on at any speed, the air being directed through the rad with little space to go anywhere else.

    regards

    Dave
     
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  10. StarCruiser

    StarCruiser Well-Known Member Guru I am in uk

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    Makes sense Dave. Great to have the theory confirmed in such a solid way.
     
  11. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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    I bow to your knowledge and research into this Dave. However, your comments on bottom hose collapse due to the action of the water pump sounds rather odd to me. The water system is under pressure as governed by the rad cap, so I when up to pressure, none of the hoses should be collapsing. The pump is only a circulating pump, it generates no significant positive or negative "pressure" in its own right.

    JMHO and my personal application of schoolboy physics...
     
  12. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    I see where you are with this Clive, and agree a better explanation and use of terminology would have made things clearer as to what I was trying to get over. When the hot engine is switched off the system is under pressure, as the cooling system cools it creates a negative signal, the valve in the radiator cap allows water to be drawn from the expansion tank. If any of the hoses are soft or delaminating then the hose or the hose liner gets sucked in enough to collapse the pipe, there is then insufficient vacuum to draw back the water from the expansion tank, as an aside this can add to the overheating problem.

    Over time the hose liner is soft enough for the pumps action to collapse it before the system gets up to pressure, I have seen hoses collapse a number of times but only once on an 80 and it was the top hose on my own car during cooling, IIRC I documented it in my thread on MUD a few months back?

    Sorry mate, hope that makes more sense?

    regards

    Dave
     
    Last edited: Jan 10, 2017
  13. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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    No sorry necessary Dave, it just sounded a bit off the mark. It's a good point though, now I see what you meant.
    The system will be less likely to draw coolant back from the expansion tank if a hose or hoses don't have the wall strength to resist the lowering pressure on cooling. Never thought of that.
    I see a lot of silicone hose kits on eBay with various colours incl black. Are they any sort of safeguard against this, I wonder, or are they soft and squidgy as I imagine silicone to be?
     
    Last edited: Jan 10, 2017
  14. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    Re the hose collapse Clive, I remember I fitted a bottom hose to a customer's American 'Day Van' sometime last year, this had a reinforcing spring wound into it to prevent hose collapse, the longer the hose the more of a problem it seems to be?

    I was looking at replacing all of mine with silicone but unsure if I will bother, I did ask a few questions but with mixed responses, the kits seem to be all coming from China so..........

    There is a Subaru WRX I have worked on that had all silicone hoses but the guy got them from a club contact, they did not seem 'squishy' (like that word), so perhaps it is all about quality?

    regards

    Dave
     
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  15. frank rabbets

    frank rabbets Well-Known Member Supporter

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    You can get stiff silicone ones. Demon Tweeks.
     
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  16. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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    There's no answer to that Frank :lol: :thumbup:
     
    Dave 2000 likes this.
  17. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    smut smut smut! :icon-biggrin:

    regards

    Dave
     
  18. Dave 2000

    Dave 2000 Well-Known Member Supporter I am in spain

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    I have their new catalogue here Clive however, I have left my extra strong binoculars in the garage somewhere I cannot read the index. :icon-redface:

    They may have them on their website, if not give me a shout and I will find my 'bins' tomorrow.

    regards

    Dave
     
  19. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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    Hey, no worries Dave, it was only a thought.

    My truck is just fine with the OEM hoses I've got, and it's -20C outside, unlikely for an overheating problem this end these days :lol:
     
    Dave 2000 likes this.
  20. Towpack

    Towpack Well-Known Member

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    :shock: I've just got some meat out of the freezer and the thermometer said -19C!!
    At least that's one big + for living in the UK:thumbup:
     
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