Too much pressure!

[dawright_1988]

There is way too much pressure in my coolant system. It was seeping out around the radiator cap and pouring out onto the ground. So... like an idiot, I tried to carefully take the radiator cap off to relieve the pressure. With a towel under my hands with one hand on top of the other... BOOM! The cap hit me in the gut and I got a face-full of coolant. It burned like a mother for about a half-hour. What could cause this much pressure? Also, could it be related to my frequent stalling problem?

[leolkfrm]

bad cap or head gasket my first thoughts

[75K30]

Wow, gotta watch out there. Sounds like it could have been a real problem, I do hope you are alright.
It does not take too much pressure to create a problem. The higher the pressure, the more it changes the boiling point, and will allow the engine to run higher in a temp range for much better efficiency. Alright that is the theory, here is the reality.
In certain cases when exhaust pressures are permitted to enter the cooling system, excessive pressures can result.
How do we determine whether or not a head gasket is bad or not, well a couple of different ways. One is to perform a pressure test of the cooling system. This requires a small hand type pump with a gauge that will permit you to presurize the system and verify any leaks when the gauge indicates a loss of pressure.
The second is a test kit that tests the coolant for the presence of hydrocarbons, or any other contaminations created by the combustion chamber.
You could also look right into the filler neck of the radiator while the vehicle is running. Always do this with a cool engine, and allow the t-stat to open. Good idea to have a meat type, or candy type thermometer to verify how hot the coolant is during this test.
Bubbles in the coolant trying to escape to atmosphere (the filler neck) are a sure sign that you have a head gasket problem.

[dawright_1988]

Originally Posted by leolkfrm

bad cap or head gasket my first thoughts

Do you mean a bad RADIATOR cap? Or some other type of cap?

[dawright_1988]

Originally Posted by 75K30

Wow, gotta watch out there. Sounds like it could have been a real problem, I do hope you are alright.
It does not take too much pressure to create a problem. The higher the pressure, the more it changes the boiling point, and will allow the engine to run higher in a temp range for much better efficiency. Alright that is the theory, here is the reality.
In certain cases when exhaust pressures are permitted to enter the cooling system, excessive pressures can result.
How do we determine whether or not a head gasket is bad or not, well a couple of different ways. One is to perform a pressure test of the cooling system. This requires a small hand type pump with a gauge that will permit you to presurize the system and verify any leaks when the gauge indicates a loss of pressure.
The second is a test kit that tests the coolant for the presence of hydrocarbons, or any other contaminations created by the combustion chamber.
You could also look right into the filler neck of the radiator while the vehicle is running. Always do this with a cool engine, and allow the t-stat to open. Good idea to have a meat type, or candy type thermometer to verify how hot the coolant is during this test.
Bubbles in the coolant trying to escape to atmosphere (the filler neck) are a sure sign that you have a head gasket problem.

Thanks so much for the info. That will be my job for tomorrow I guess.

[mudseeker]

i only have a little to add to 75's post.

with the radiator cap off, let the truck idle and reach operating temp. if at any point you see bubbles or a geyser come out of the radiator, then you have a bad head gasket. ( I see 75 mentioned bubbles)

i was working on a PT cruiser with a bad misfire and checked for a coolant leak by removing the cap. no lie, within 5 minutes a geyser of coolant erupted from the radiator and soaked the underside of the hood. i felt sorry for the guy, as he had just bought it used from a friend.

[436'd skylark]

It will moby dick if there is a crack or a bad gasket, but normally it will hydralock first. it starts as a small leak or crack and only a small amount of exhaust will leak in, not enough to really cause a problem. then when the motor is off, the coolant will seep out and lock it up tight. my guess is it was way hot or the cap is bad. of course i could be wrong!

[leolkfrm]

Yes a radiator cap, you never mentioned what was showing on the temp guage? If its too hot it will boil out, however you never mentioned the year, does it have an over flow?

[dawright_1988]

Originally Posted by leolkfrm

Yes a radiator cap, you never mentioned what was showing on the temp guage? If its too hot it will boil out, however you never mentioned the year, does it have an over flow?

It's a 94... and it does not have a temp guage. It just has a light that's supposed to come on to tell you something is wrong. Nothing ever came on though. I got hit in the face with a pretty generous amount of coolant and I can tell you that it was not boiling. THANK GOD FOR THAT! It was probably about 160 I would guess.

ALSO, I FORGOT TO MENTION THAT IT'S A JEEP CHEROKEE. I PUT IT IN THE WRONG FORUM BY MISTAKE! SORRY GUYS!

[dawright_1988]

Originally Posted by 436'd skylark

It will moby dick if there is a crack or a bad gasket, but normally it will hydralock first. it starts as a small leak or crack and only a small amount of exhaust will leak in, not enough to really cause a problem. then when the motor is off, the coolant will seep out and lock it up tight. my guess is it was way hot or the cap is bad. of course i could be wrong!

Do you mean it will lock the engine up tight? Because I had some trouble starting the thing today. I honestly didn't think it was going to start at all. I had to hold the gas all the way to the floor while I turned the key until it sputtered a little. You should've been there, haha, it sounded pathetic.