Coolant level

[Newsduck]

I'm looking for a little confirmation on how the collant system works before I take my wife's 2000 Cherokee into the shop. She came home and temp gauge spiked on her as she pulled up. I gave the ar time to cool down, checked the coolant recovery bottle, and it was bone dry. I filled it up with coolant, drove the car myself thsi morning, the temp stayed at an even 200-degrees Faranheit....I let the car cool down, checked the coolant recovery bottle, and the level fell from above full, to well be low add, although there is coolant. There was no apparant sign of leakage ont he ground, or inside the engine compartment. Is this just the radiator taking what it needed...or is there an insidious leak somewhere in the the system.

Thanks

[fredjacksonsan]

What happens is that when it gets really hot, some coolant flows into the reservoir (aka the overflow bottle). Then, when it cools down, some coolant is pulled back into the radiator.

Over time, some of the coolant can evaporate, and will reduce the level. If the level hasn't been checked in many months, this could be the result.

There could also be a slow leak somewhere. Check after you park for any leaked coolant under the vehicle, and keep a close eye on the coolant level for awhile.

[Newsduck]

Thanks for the quick reply.....I was surprised to see so little coolant in the recovery tank, considering there wasn't any fluid on the ground. perhaps the level in the radiator had been so low, that it will take filling the recovery tank again to get the level back to normal.

[fredjacksonsan]

Exactly; I'd recommend removin the radiator cap (when it's cool) and see if the level is to the top. Fill it there, replace the cap, then make sure the reserve tank is full.

Welcome! And Welcome to AF. Lots of good information here.

[AlohaBra]

Hey News....that coolant is going somewhere..

Eventually it will be outside or inside....

Inside...the engine ...is not good...

Outside...well you can spot it and fix it..

[Newsduck]

had the Jeep dealer look at the car...they couldn't find anything wrong, took off the head, no cracks....no sign of coolant in there, thank god. So basically, no idea what happened...last couple of times the oil was changed by Jiffy Lube, so who knows, maybe they never bothered to check or top off the level...but no signs of leaks, pressure good, and no problems with the head. A mystery.

[AlohaBra]

Two possiblities:

• heater core
• slow leakage at the thermostat gasket

WOW...you took the head off? Isn't that expensive. We usually just run a smog sniffer at the radiator to see if exhaust is going into the cooling system.
They use to have a dye to check that also.

Back to coolant loss...did you use a radiator pressure tested and pressurize the system and let it sit for several hours. Keep pressurizing it until you see coolant loss.