Dumb Question

[TheBlueSupra]

Ok I have a minor problem that has been driving me nuts ever since I dropped the crate engine in my supra. My coolant overflow reservoir looses all of its fluid about every 2 weeks turning on the low coolant light. I have no leaks, no burning coolant, no white smoke and my radiator is always full regardless of the overflow level. Where is the coolant going??? If my radiator levels dropped I would suspect a leak in a line, but they never do. Please help solve this mystery:1zhelp: Thanks

 

[AJ'S 88NA]

Have you checked the reservoir for cracks? Noticed any drips?

 

[suprarx7nut]

Time to find a coolant system pressure tester. I bet you've got a hidden leak somewhere. I have a similar problem with my truck right now. I've got a leak somewhere, but I can't find anything.

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[hvyman]

Or it's leaking out the bottom where the sensor is.

 

[TheBlueSupra]

Unless it leaks only while driving, and stops leaking before i get back in my driveway, then I can't see how it's leaking. I check every time I drive for drips and have yet to find any (I don't just check for coolant I want to know if anything leaks ) I will see about the pressure testing though, it's probably a good idea anyway. Is there any place that would leak while running but not all the time? Thanks for the help!

 

[hvyman]

Pin holes. Clamps not on all the way. When engine off and cool there is no pressure. At op temp it's under 13 psi.

 

[suprarx7nut]

There are loads of reasons and circumstances where it will leak only while driving and never noticeably drip. If the leak is near the exhaust the slow leak may evaporate and stop before the motor cools. I've had multiple leaks which I could only find with a pressure tester. I've rented them a lot in the past, and I think it's about time I actually buy my own to keep on hand. Definitely a worthwhile diagnostic tool to have around.

 

[TheBlueSupra]

Good thoughts thanks! I will look into it. My only confusion is that it only seems to disappear from the overflow, I ran the overflow dry for awhile (not intentionally) with no drop in the radiator level. I will definitely pressure test when I can, Thanks for the help!

 

[AJ'S 88NA]

Don't want to do that too often, lets air in the system when it gets too low for one thing.

 

[DEFIANT 7M]

Check/change your radiator cap, it may be leaking and burning off before you see it.

 

[TheBlueSupra]

As far as I know the rad cap is original, so it may be good to replace it regardless

 

[SRZMK3]

Check/change your radiator cap, it may be leaking and burning off before you see it.

+1 happened to one of my supras didnt ever notice because the radiator was always full but the cap didnt seal enough pressure and it kept putting coolant into the reservoir and then letting it out, only way i could tell is when i drove it alot to optimal temp then pulled over and looked under the hood and saw the reservoir output straw was wet with coolant.

 

[TheBlueSupra]

I will definitely replace the rad Thanks!