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REVTECHRACING.COM
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Discussion Starter · #1 · (Edited)
breaking the new built motor in and just noticed my radiator sprung a leak near the neck/cap. all parts are brand new. when car is running all temps are ok and no leaks. but soon as i shut the car off the car seems to build more water pressure and then springs a leak near the cap . i even think there is trapped air in it also. car has about 100 miles on it and i have the thermostat in and just water in it for now. ill put antifreeze and redline in it soon as i figure this out.

any ideas on what could increase water pressure when car turns off? the over flow tank fraises and lowers like normal til after the car has been off for a hour or so ,then it sucks it dry.? :rolleyes:
 

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From my experience your problem may be as simple as only having water in the system. When you shut off your car the fans stop and the temperature may rise enough to cause it to overflow. I would suggest putting coolant in the system and see if that cures the problem.
 

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REVTECHRACING.COM
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Discussion Starter · #4 ·
wouldnt it over flow in the over flow tank then? it just builds up and sprays a lil bit threw a crack near the neck. along with air. and im sure the coolant system is full. its like shaking up a soda bottle when i turn off the car. driving/idleing all is cool and ok,no leaks at all.
 

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If it's spraying through a crack near the neck, then you need a new radiator. I read that you said all parts were new, but by what you are describing it sounds like the radiator neck is broken.
 

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medford turbo addict
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your rad. cap new also im guessing? while running the water pump and fans r cooling the water when u turn it off the water is just sitting still in the block collecting heat from the engine with no where 2 go so it starts boiling in the block and rad.
 

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Espresso Connoisseur
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When the engine is off, the water has no movement. It'll soak up the heat from the engine and have no where to go. Higher heat = increased pressure. Increasing the water temperature also will lead to boiling (this is where the coolant comes in handy). Boiling water creates steam/pressure that wants to get out of your system any way it can...
 

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Is the crack that you are talking about, just coolant spraying out from under the cap? If that's the case then not having coolant in it is your problem. If it's coming from an actual crack then that must be fixed first and then coolant added.
 

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REVTECHRACING.COM
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Discussion Starter · #9 · (Edited)
so wouldnt the cap vent to the over flow tank instead of stress cracking the radiator to vent steam/water??

i was going to attempt to run idle the car with no cap on and have a temp probe in the radiator and see the real temps instead of the needle on the dash. dash needle makes it to half way sitting at light and goes down to 1/4 when driving.

maybe add some coolant/water wetter to the radiator and see what happens next? the crack near the cap on radiator is so small i cant see it unless it leaks. it is a pin hole stream when leaking. could it be patched with abs cement? or other strong high heat bonding epoxy/glue ,etc? it is real tiny.

new toyota cap says 1.1 bar on it
 

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If all the parts are new, take the radiator out and go get a new one for free. But if that isn't an option you may be able to patch it. If you go this route I would add coolant after patching it and then just take it easy and watch it for a while to make sure it doesn't spring another leak.
 

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makipsee said:
a leak is a leak it should be fixed or a new rad.
2nd.

On a hot day or after a good long run, who can say what that leak is going to look like. It'll also be a weak point for potential catastrophic failure. Replace the radiator.
 

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REVTECHRACING.COM
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Discussion Starter · #13 · (Edited)
is the stock radiator abs plastic? i tried the abs cement for home pipes since the hole was a pin hole i couldnt really see it is so small.and that last 5 minutes when car turned off. strange,car driving or idleing and no leaks. car turned off 2 minutes later small piss stream.. i do notice the dbb turbo has coolant lines flowing threw it and turbo keeps whineing down after car is off for up to a minute long.but most likely means nothing. though i just would toss it in there. if it helps i tapped the water neck where the 2 stock nipples were and ran a braided -6 an line from the neck to the side nearest valve cover on turbo and the other comes from the unused nipple on water pump to shock tower side of turbo.
iwa thinking the new cap was bad until i seen the over flow rise and lower to the low /high area without overflowing,just goes near empty after long time sitting.

thanks for some ideas on how to trouble shoot this. any more you want to add before i go at it in the morning? :bigthumb:
 

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I do not own a supra so I am having trouble trying to visualize the lines that you are running to the turbo, but yeah just try to fix that leak or replace the radiator.
 

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REVTECHRACING.COM
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Discussion Starter · #15 ·
nosman4 said:
I do not own a supra so I am having trouble trying to visualize the lines that you are running to the turbo, but yeah just try to fix that leak or replace the radiator.
and add some coolant/water wetter :bigthumb: thanks
 

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i think you may need to add some/or even just a lil bit of red coolant and watter wetter and fix the leak and then see whats up. if the leak is that small i wonder what exact glue type/epoxy would hold up? if its a small enough crack ive seen people use a soldering iron to melt it back together then use a dab of jb weld ment for plastics. think that would hold up to the temps/pressure?anybody know? ive seen it work on every day cars all day long on plastic radiators. on his issue maybe it would work out?
 

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As previously stated, a leak is a leak, and the longer you wait the more potential it has to get bigger and maybe even cause a catastrophic failure.

I'd definately replace the radiator.
 

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Damn Spaniards
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If it is a new rad and it is leaking, why don't you just take it back? They DO have limited warranties on them. I'm sure a new rad is not supposed to leak. :1poke:
 
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