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Thread: Coolant loss. Need some ideas.

  1. #1
    Junior Member Automotive Encyclopaedia
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    Default Coolant loss. Need some ideas.

    I recently got the celica back from the panel beater with some advice from them that my radiator was leaking. I could certainly see some coolant at the base of the radiator.

    So off to a local purveyor of radiators for repair/replacement. They came back to me to advise that my water pump had failed but the radiator was fine.

    So many dollars later, new pump is in. Problem is, I continued to lose coolant after moderately short runs around town (in traffic and hot days so temps were fairly high. Factory temp gauge so no real temp indicator, but not significantly different to before the water pump replacement. Yes, I'll install a proper temp gauge).

    Coolant seems to go into the overflow but not go back in to radiator.

    Passed coolant system pressure test.
    Passed tee kay test.
    oil is fine and no coolant contamination.
    Coolant is fine and no oil contamination.
    No deposits under oil cap.
    New radiator cap.
    Radiator is not pressurised after a drive and cooled down.
    I can't find a vacuum leak in the overflow hose.

    So today, I had a really long drive on a cooler day (320km round trip).

    Didn't lose any coolant and the car ran cooler than it ever has.

    The only things I can think of is that there was air in the system that had to be worked out, or maybe I need to improve low speed cooling, shroud etc.

    Any ideas on things to check or am I just in keep an eye on it territory?

  2. #2
    Junior Member Backyard Mechanic
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    Default Re: Coolant loss. Need some ideas.

    After the long drive did the coolant level drop to normal cold level as engine cooled? The other thing, is it a recovery type cap. Should have small spring loaded button under main o ring seal.

  3. #3
    Junior Member Automotive Encyclopaedia
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    Default Re: Coolant loss. Need some ideas.

    Quote Originally Posted by ToyTA22 View Post
    After the long drive did the coolant level drop to normal cold level as engine cooled? The other thing, is it a recovery type cap. Should have small spring loaded button under main o ring seal.
    After the long drive there was no change. No loss of coolant. The overflow tank showed no change. But given that the operating temp was apparently lower than it was around town, I can't say that the overflow tank took any coolant on during the drive.

    Or in another way of thinking, with a higher pressure rated radiator cap and the lower temp on the long drive, no coolant was expanded out of the radiator and into the overflow.
    Around town with higher temps, there is evidence of coolant moving into the overflow but not going back in when things cooled down. Logic says there must be some vacuum leak in the overflow tank line, but I can't find it. Perhaps the radiator connecting pipe is cracked, so not leaking per se, but preventing overflow return to the radiator when cooling down.

    Thanks for taking time to help.

  4. #4
    Junior Member Automotive Encyclopaedia
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    Default Re: Coolant loss. Need some ideas.

    I'm not sure if it is the problem I need to solve but after a lot of hunting around and heat cycling, I found that the hose on the water bypass pipe (in underneath the thermostat housing and assorted bracketry alongside the exhaust manifold) looks to be losing coolant. Once it is cooled down, I'll check that it is not perished and is seated properly. Looks like the part is easily available and cheap, so might replace it anyhow.

  5. #5
    Junior Member Backyard Mechanic
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    Default Re: Coolant loss. Need some ideas.

    I think its something to do with the bypass and thermostat cycle before it opens, if it has en external bypass pull it all apart and clean it, Ive seen some terrible ones.

  6. #6
    Junior Member Backyard Mechanic jondee86's Avatar
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    Default Re: Coolant loss. Need some ideas.

    Just going to throw this in because while it is unlikely, it has happened If you have the same kind of expansion tank as some 80's Toyotas, it has one hose leading to the cap from the radiator neck and a short overflow hose on the other side of the cap. If for some reason the connections of these hoses is reversed, coolant will flow from the radiator to the expansion tank, but it will not return.

    The cooling system will then work in the old school style. Instead of being filled to the neck, the coolant level will be down in the header tank. It will stabilise there once the engine has reached its maximum operating temperature and pushed out as much as it needs to push out due to expansion. Topping up is futile

    Cheers... jondee86

  7. #7
    Junior Member Automotive Encyclopaedia
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    Default Re: Coolant loss. Need some ideas.

    Thanks to both of you. I had no thought about the overflow. Will check.

    I've ordered a replacement rubber hose for the bypass and I'll check the hard line as well when I pull it all apart.

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