Coolant Leak?!

Hey guys,
Anyone have any ideas about this?: The last two times I have driven my Jeep, it has spit out about a half gallon of anti-freeze out of the little overflow hose running down the side of the radiator. I topped it off after it did it the first time and when I took it out again, it came shooting out as soon as I parked it in the driveway. It has been ridiculously hot here in Salt Lake City this last week (over 100 every day). I just can't figure out why so much coolant would come out like that. It's almost like it was boiling in there. Thermostat?

Thanks guys,

Mike

 

Radiator cap. If you can't get yours tested, just put on a new one, perhaps with a little higher temp rating.

 

Mike, the first thing I would do is check your circulation. The easiest way to check is to start up your engine with the radiator cap removed. As your engine heats up, the thermostat should open and you'll immediately notice the flow of fluid through the radiator. If this is the case change the radiator cap as mentioned earlier. If your vehicle overheats and you have no fluid moving through the radiator, you definitely have a circulation problem. Check the thermostat by placing it in a pan of water and bring it to a boil to see if it opens, make sure the small hole on the thermostat isn’t plugged.

Is the water pump leaking or making noise? When was the last time you flushed the cooling system?

 

Mike when you stop your engine all cool of the coolant stops. The core temp of the egine holds for a while until the heet can pass into the air around the engine. If it is like you say over 100` that can take quite a while. So in the mean time the coolant is still getting heeted up but now with no radiator airflow to remove the heet. Once the coolant reaches a temp that creates pressure the only thing holding it in the system is the radiator cap and it's built in spring. If this spring is weak broken or of a to low of rating to hold the coolant it will puke it out through the over flow.

Before coolant recovery became the norm it did this on all cars if the cap couldn't hold it.

I would suggest in this order'

1. Have NAPA check your cap to see if it holds the stated PSI.

2. Make sure that stated PSI is what is recomended for your engine.

3. if either of these don't meet muster buy a new cap.

This should slove the problem you have described.

If the theromsat was faulty your engine would either run HOT9the thremosat is not opening properly) or not warm up (the thermosat is opening to soon). But the thermosats only effect on coolant after the engine stops is that it will remain open until the coolant temp is below it's rated temp. Once that happens it will close. And thenormal way for a thremosat to fail is to stop opening causing over heeting.

If I knew what engine etc. your Jeep had I could possibly recomend a cap PSI rating. BUT NAPA or another good autoparts dealer should be able to look it up in their book for you.

 

as mentioned above, the expansion of coolant is caused by heat after engine shutdown.
Install a recovery tank, or do what I do: leave the level in the radiator 1"-2" down.
This will leave room for the expansion of the coolant; once you find that happy medium, no more leaky.