1UZ-FE vvti swap coolant issues

Discussion in 'Diagnostic & Repair Tech' started by 1UZ-S13, May 13, 2018.

  1. 1UZ-S13

    1UZ-S13 New Member

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    FF5F1D58-F981-4FCC-84E7-EA881B8AD665.jpeg Hi!
    To make a long story short:
    I have a Nissan 200SX S13 drift/track car, with an 1UZ-FE VVTi swap. Custom harness from PEM in England(stock ECU), double 12" electric fans and a 58mm aluminium radiator.

    Filled the radiator with red coolant, and let the car idle for about 10 minutes, and the temperatures kept rising. Oil temp stayed at around 80*c, but the water temp kept rising, to about 110*c before we turned it off.
    Have tried replacing the thermostat, and the water pump doesn’t make any bad noises. Have also tried to take off the return hose from the radiator and have filled coolant straight into the engine so it’s full, but it still doesn’t circulate. Any tips or help would be much appreciated!
     
  2. gloverman

    gloverman Well-Known Member

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    Maybe you could try connecting the radiator hoses the correct way around. Thermostat is the inlet to the engine so goes to the bottom of the radiator not the top.
     
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  3. gloverman

    gloverman Well-Known Member

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    Also looping the heater allows for a passage of water to flow without ever seeing any cooling. In a standard system the coolant going through the heater hoses passes through the heater core which is another radiator acting as a heat exchanger. I recommend blanking this passage.
     
  4. gloverman

    gloverman Well-Known Member

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    Also the air bleed for a vvti is the hex head blanking plug on the throttle body.
     
  5. 1UZ-S13

    1UZ-S13 New Member

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    @gloverman how is it possible that the hose to the thermostat is the inlet? Because it opens when the coolant in the engine is hot, doesn’t it?
    So do you mean I’m supposed to fill the holes, each by themselves? Like with two plugs?

    Thanks for replying!! Finally someone with good knowledge.
     
  6. gloverman

    gloverman Well-Known Member

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    Yes the thermostat opens when the engine is hot and allows water from the radiator into the engine while at the same time the thermostat closes the bypass circuit which allows the water to by-pass the radiator while the engine is warming up. Maybe you should find a standard lexus and have a look at the radiator hose arrangement. Bypass thermostats in the bottom hose have been common for the last 30ish years.

    Yes two plugs for the heater circuit.
     
  7. 1UZ-S13

    1UZ-S13 New Member

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    Switched back to the old radiator, turns out it had a hole in it, that most likely happened when I took it out last time. Need to find someone who can fix it first, before we can try to fill it with coolant and try again.
    Will write here when it’s fixed!
     
  8. 1UZ-S13

    1UZ-S13 New Member

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    So I have installed the radiator the right way now, and have plugged the heater hoses seperatly. It still overheats/gets to 100*, and it doesn't seem like the thermostat opens correctly.. tried to open the hex screw (not all the way) but it seems like coolant is the only thing coming out of it.. help?
     
  9. gloverman

    gloverman Well-Known Member

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    Is it a factory thermostat? Have you had it out and tested It? Can you see flow in the top tank? Have you tested temperature at the front and back of thermostat along with top and bottom of radiator? What cfm are the cooling fans and what temp do they come on at?
     
  10. 1UZ-S13

    1UZ-S13 New Member

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    Yes both thermostats I've tried are from stock 1UZ's, and they look stock aswell. Haven't tested it in hot water yet. What top tank? The top of the radiator is hot, and the bottom is cold. Not sure, but the fans are 80w each. They should come on at 80-90* in the top hose, but they never came on so I put the fans on a switch instead. It seems like coolant is the only thing coming through the hex screw, not any air..
     
  11. Mat Grant

    Mat Grant Member

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    Hi, I had a similar problem - I put a post on here so you may be able to find it by searching - the problem with mine turned out to be a big air bubble in one of the hoses, once refilled it flows and cools perfectly. Someone suggested squeezing the hose to fel the coolant flowing, I noticed hardly any and the hose was quite easy to squish - this was the return hose from the bottom of the radiator to the thermostat.

    When I refilled it, I filled the hose whilst holding it above the coolant height, then connected it up, this then filled the system fine.

    Mat.
     

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