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Overheat and soldered radiator?

Discussion in 'Daihatsu Hi jet' started by Whosuregunner, Mar 4, 2021.

  1. Whosuregunner

    Whosuregunner New Member

    92 Hijet S83P. Overheating when driving at highway speeds but also some weird behavior. Super-sleuths unite and hopefully help me figure this out.

    Seems not to overheat just idling or driving around the property. On the highway, it very slowly creeps up in temp and when that happens, the heat goes cold. If I stop and let it idle, it will cool off after several minutes.

    So flushed out the radiator, heater core and engine. Was pretty cruddy so I did it twice. Used the bleeder to get the air out.

    once the engine cools off to around the middle of the gauge, the heat comes back
    Radiator fan turns on ok.

    Why cold only when temp goes up? Coolant does not seem to be low. Might have to do a negative pressure fill to be sure.
    Thoughts?
     
    Last edited: Mar 4, 2021
  2. Whosuregunner

    Whosuregunner New Member

    Oh forgot to mention. I think the place I bought it from soldered the radiator. Prob had a leak. Found solder splatter and a roll of solder. Seems like they didn’t want to tell me. Not too happy about that either but I don’t think that’s the problem.
     
  3. fmartin_gila

    fmartin_gila Well-Known Member

    What mix are you running in the radiator? Seems as if the radiator is freezing because of the faster airflow when at higher speeds, thusly not letting the water circulate. I would ensure a nice 50:50 mix and go from there.

    Fred
     
  4. Whosuregunner

    Whosuregunner New Member

    Yep brand new 50/50 straight from the bottle.
     
  5. fmartin_gila

    fmartin_gila Well-Known Member

    Get all the air out? Possible air pocket at some high point. Got to be something restricting flow. Is it possible the water impeller is slipping on the shaft at higher speeds? Once found that on a Ford I was working on. Could also be collapsing the rad hose at higher RPMs, restricting flow.

    Just trying to give you some food for thought.

    Fred
     
  6. Whosuregunner

    Whosuregunner New Member

    Appreciate it. I didn’t see the hose collapsing. Tried to check for that. Went out this evening to water animals and it idled for a long time and stayed cool. I’m going to try to bleed the air out again. Maybe park on a sloped surface. If that doesn’t work, I’ll fill it with a negative pressure tool. Would have done that to begin with but didn’t want to drive to go get it from my buddy.
     
  7. bobjonah

    bobjonah Active Member

    Have you checked the thermostat ? It has an extra valve to open and close the bypass for warmup. If the whole system was gucked up, there is probably guck in there as well. I don't think that they use anti-freeze much in japan, and most older trucks are pretty guckey inside the cooling system
     
  8. Whosuregunner

    Whosuregunner New Member

    I have not yet. But I certainly will. Started it this morning and it came up to temp and had warm air at first then back to cold with needle in the middle/left. I'm gonna open the bleeder again and then check the Tstat. Will let you know status.
     
  9. shogun

    shogun Active Member

    all japanese cars use anti-freeze coolant of course as in the north we have the border line to Siberia, the question is when they changed it last time. Coolant is not only for anti-freeze. Glycol prevents coolant liquid freezing within your radiator by lowering its freezing temperature, alongside lubricating the water pump and inhibiting corrosion. Engine coolant is a mixture of antifreeze and water, with a common ratio of 50:50. This is because antifreeze works best as a diluted liquid. Antifreeze does not expire, but the additives that prevent engine corrosion do. As such, it’s recommended you replace your antifreeze in line with the manufacturer’s expiry guidelines.

    Bleed it again and check the thermostat. I once had a broken thermostat stuck in closed position. You can test the thermostat by dropping it in a boiling water pot and see if it opens.
     
    Last edited: Mar 6, 2021
  10. Limestone

    Limestone Well-Known Member

    You can check the thermostat by dropping it in a pot of hot water. If it's working, you'll notice!
    Limestone
     
  11. JMM

    JMM Member

    @Whosuregunner, I confess that I do NOT know how the water pump is constructed (I haven't needed to dig into that part of my truck yet), but I had a eerily similar situation in a '99 Audi:

    The water pump's impeller was made (of course) of freaking plastic. Over time, the integrity of its bond with the pump shaft was lost (not sure if it was a keyway, pressed on, or what). So, at low RPM's the impeller would work fine--it had hardly any load on it, and the bond was strong enough for it to lazily circulate the coolant. But at higher RPM's, the impeller was just slipping on the shaft--meaning the pump was turning and the impeller was taking a smoke break. Back at idle, it would be fine again. Accelerate, or try to run above 2000 RPM, and it would immediately start to get hot.

    New water pump was all it took. I hope your situation is as easily resolved.
     
  12. shogun

    shogun Active Member

    not only the Audi had that problem, most car maker 1990-2000 that time. water pump shaft was rotating but the impeller not (much). At that time the makers changed from metal to "plastic" impellers as the load on the water pump bearing was less than with steel/cast iron and maybe also because of production cost reasons, all had the same problem. This is meanwhile solved by new composite material impeller (so it is much less prone to breaking like the old plastic impellers).
    But if the Hijet has such a plastic pump I do not know, but worth to check.
     
    Limestone and JMM like this.
  13. Koffer

    Koffer Active Member

    How’s the belt on it ? Tight not slipping or glazed and slipping at higher RPMs . If the cooling system was nasty and the OG waterpumps had a stamped steel impeller it maybe rotted to the point it’s now just a Swiss cheese looking blender blade . The Subaru sambars run the waterpump withe smooth side of the timing belt and as the belt stretches it doesn’t bite as well to the point it will slip to the point there’s no real water flow .
     
    Limestone likes this.
  14. JMM

    JMM Member

    Ah, I didnt even think about tbe belt. Always start simple!
     
    Limestone likes this.
  15. Koffer

    Koffer Active Member

    You’ll need a 15305 belt from autozone if it’s pooched that’s a gates number too I think . It’s a 30.5” belt
     
  16. Whosuregunner

    Whosuregunner New Member

    Hey guys. So I bled out the system and it hasn’t overheated for a while. I had forgotten to put some coolant in the overflow tank and I think it was sucking air from there. But I’ve only drive once to town. It started to get hot just before I got home.

    Will keep an eye on it and maybe change the thermostat if it happens again.
     

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