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Lossing coolant no leak....

gtscode

gtscode

Active Member
So I know "a guy"... he is looking at a car that is loosing coolant but there are no signs of leaks.

It would seem the water is burning up in the engine? The car isn't overheating or running hot.

What kind of things could cause this? Worse case cracked head??? Head gasket? Manifold gasket?

What is the best way to diagnose something like this?
 
I wish I knew! I've had the same problem from the first fire of my engine. No drips, no leaks, not coming out of the pipes. Heads have been pressure checked...twice.

I'm still losing coolant every time I start it up and go somewhere. Not much, but it does disappear.
 
Use compressed air to pressurize the cooling system and start looking (listening) for leaks. If the system won't hold pressure (the radiator cap will limit the level of pressure) you know you've got a leak. Odds are it is a VERY small leak that in normal operation is something like a tea pot letting off a bit of steam. The small volume of fluid/vapor loss wouldn't leave too much of a trail to spot. If it is near the exhaust it would vaporize almost immediately.
Once you know you have a leak and can't find it externally, you have little choice but to start opening up the engine. Good news is the problem is typically with the intake rather than a head.
 
Use a coolant system pressure tester, not shop air. The cooling system is only designed to take ~18psi. If you feed 100-300psi shop air into it, you're going to explode the radiator.

A cooling system pressure tester will screw onto the top of the radiator and let you pressurize the system with a hand pump. If you see the pressure dropping, there's a leak.
 
Glad you posted the question...my Explorer seems to have the same issue and is low on coolant every time I change the oil and usually sooner than that. It never runs hot so I haven't worried about it too much and just check the overflow from time to time.

Never have figured out where it's going but every once in a while I smell coolant when I am getting out of the car.
 
"Starfury" said:
Use a coolant system pressure tester, not shop air. The cooling system is only designed to take ~18psi. If you feed 100-300psi shop air into it, you're going to explode the radiator.

A cooling system pressure tester will screw onto the top of the radiator and let you pressurize the system with a hand pump. If you see the pressure dropping, there's a leak.
Click to expand...
It is possible to adjust the pressure output of your air compressor you know. Just sayin... :) Maybe I should have been clearer.
 
test the cap. it not be holding at the pressures it is supposed to be holding to. they fail from time to time.... radiator pressure tester can also test caps. if it tests good, you've got a head gasket, or a crack somewhere....
 
My car has always like running a little low on coolant. It will push it out the overflow to the level it likes, always the same. "fill it up to 1" below the cap" doesn't work for me, it will just vent the extra coolant. Never had a problem with overheating, leaks, or coolant in the oil. It just doesn't like a lot of coolant.
 
Sam, mine is the same way. With my larger crossflow radiator, "normal" coolant level is about 2" or more below the filler neck. Refill it any more than that and it'll just puke it out.

On a similar note, my brother had an Toyota MR2 spyder that had the radiator in the front of the car and the engine in the back. He was loosing coolant pretty fast but couldn't find any leaks. Turns out there was just air in the lines that was gradually burping out. The coolant loss leveled out after a few months once the air pockets worked their way out.
 
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