cooling prob... everyone thinks im crazy..

[02yellow3.0edge]

ok... if i fill my system with coolant and drive it 2-3 miles it will run hot(in the red) i'll com home shut off the truck and the reserve tank cap will blow off... after the motor blow all of the coolant out i can drive it 20-30 miles+ and its fine... long story short... if it has coolant it runs hot and builds alot of pressure and if it is bone dry it is fine.... i replaced the pump and stat.. dont know what to do??

p.s. when it is running hot i can turn on the heat and the temp drops a lil bit....

 

[GoodysGotaCuda]

Something doesn't sound right. Your engine is in the red within only two to three miles on a cold engine? You can try the basics such as a thermostat and radiator cap, but something tells me that isn't quite it...

 

[LittleHorse]

oh boy...

it's not running fine bone dry. It's heating up even faster and even hotter. You just don't know it because your coolant temp sensor isn't in contact with the coolant flow so it can't report an accurate temperature.

Not to mention your water pump seal NEEDS fluid to help lubricate it against the shaft.

 

[02yellow3.0edge]

i changed pump cap stat.. i dont know what else to do

 

[Sasquatch_Ryda]

Cracked head causing combustion chamber pressure to get into the cooling system??

 

[02yellow3.0edge]

if i use a comp. tester on all 6 cylinders would that tell me anything or should i pressure test the system

 

[02yellow3.0edge]

10-4.... what is a leak down test?

 

[kawasakiman27]

leak down is pressure testing the cooling system. I would start there. pressure it up to 15-17 and wait to see if pressure drops than look for leak. If you see no leak make sure the tester isnt leaking with soapy water. the cap is blowing off brings me to assume the pressure in the system is building up substantially via combustion exhaust pressure and steam.

 

[Sasquatch_Ryda]

That is just a cooling system pressure test, it won't find internal engine leaks.

A leak down test is when you pressure each cylinder up individually via the spark plug hole with a leak down tester. You pressure it up and see if the gauge holds a constant pressure, and then you will go through each cylinder, you can pop the rad cap and see if there are air bubbles coming into the cooling system via one of the cylinders/ combustion chambers. If you got bubbles in the cooling system then you've got a cracked head/ blown head gasket.

 

[rurouni20xx]

correct sasquatch, i recommended testing the cooling system to kawasakiman b4 by pulling the plugs and listening in the cylinders for hissing to test for a leaking head gasket, i didnt specify the dif to him, thats partially my fault for the confusion. the leakdown test is the more definitive test but the equipment is pricy, and im not sure if autozoo would let you borrow it. thats why i specified the cooling leakdown test to kawyman since i know you can borrow a cooling system tester and watch the coolant there, plus since its a cooling system issue this can help diagnose other problems like bad hose connections etc. this thread seems related to another one, the problem that was possible per everyone else was a bubble in the line from not properly bleeding the system, anybody think that thats still possible?

 

[Sevensecondsuv]

Yeah your gauge is deceiving you. It's not reading the overheated condition because the temp sender has to be imersed in coolant to give an accurate reading. If the cooling system is dry, it's not imersed in coolant and not giving you an accurate reading.

The overpressurization is most likely due to a cracked head or blown head gasket. I'd tear the engine down to the point of taking the heads off and inspect. Usually the bottom end survives cracked heads or blown head gaskets just fine. But if you've been driving it 25 or 30 minutes after "blowing all the coolant out of it" you've probably warped the block and destroyed the internals as well. Nice Job!

 

[racinranger]

you may just need to properly bleed the air out of the cooling system. what it sounds like to me you got air in there, then you go boil the truck and get it smokin hot. it pops the cap. then you repeat the process and drive it without coolant at all. I like to use an air lift to vacuum the cooling system down and fill it. if not atleast run the truck at idle with the cap off and bleed the cooling system. Do that before you go chasing cracked heads and other such bullshit. Basics first!

 

[shadetree]

Two things. Are you "burping" the air out of the system? You may have too much coolant. Fill the system with water. With the radiator cap off start the engine and let it come up to operating temperature. It may push a little water out as it heats, but this is ok. When the thermostat opens, the water level will drop as air leves the system. Once it has dropped, refill the radiator, replace the cap and give it a test drive.

The other thing is the wrong/defective radiator cap. There is a small button like valve on the bottom center of the cap. This valve must be closed against the cap. If it is hanging down, wrong cap. I went thru this on one of my Merkurs with the same sypmtoms you have. Run ok when driving, but water would percolate out when stopped. It was a Stant cap, and was the wrong part number for my car.shady

 

[fordwheelinman]

did you install the thermostat in the correct orientation?