Coolant Reservoir Boiling, need help!

[Maverick0007]

I recently had a radiator get a hole in it and I broke down, so I changed the radiator myself. The temperature reads just fine and the vehicle seems to run fine, but when I raise the hood, the coolant reservoir is boiling coolant. Any ideas?

 

[jimbo74]

thermostat

 

[410Fortune]

yeah its getting too hot.

Did you replace the thermostat when you did the radiator?
Did you use a new radiator?
What about the cap?

also which truck is this? 4.0L OHV?

 

[jimbo74]

possibility of the water pump blowing up internally?

 

[Maverick0007]

The thermostat is a couple months old, I installed a used radiator that doesn't have any leaks. I used the same cap on the radiator

 

[Maniak]

a weak radiator cap can do that too. If is supposed to let pressure out at 13 (or 16, depending on the pressure of the cap) psi. If it lets it out too early it will drop the boiling point of the water which can make it boil and even if it isn't boiling it will be letter water into the overflow when it shouldn't be.

~Mark

 

[Maverick0007]

What psi cap is recommended?

 

[410Fortune]

I believe 17# is stock, check with Ford

 

[Maverick0007]

I have not replaced a cap before, is it easy?

 

[410Fortune]

Yeah its real simple, push down and turn
Your stock cap should say the # on top of it.

I suspect air in the system
Did you burp it properly with the new rad?

 

[Maverick0007]

I am new at the radiator installation, how do you burp it?

 

[Maniak]

I believe 16psi was factory.. but most books say use a 13.. In hotter climages I like the 16psi. It gives you more protection from boiling.

~Mark

 

[410Fortune]

Okay, with the thermo tested and installed properly (spring towards engine, weep hole up top) you fill the system with your 50/50 mix.
keep going till all air bubbles purge, squeeze the upper and lower hoses, this helps.

Now start the engine with the rad cap off
run it at idle for a few minutes.
You will see air bubbles being purged

once it starts getting really warm and rising put the cap on it, run it to operating temp.
Fill your overflow with 50/50 and you should be good to go.

If air is trapped behind the thermostat it will never open, truck will get hot quickly.
You can boil water and pour it down the upper radiator hose, this will open the thermo and release any trapped air.

 

[Maverick0007]

410, you are so smart. I will keep you updated with progress. Thank you all very much.

 

[Maverick0007]

When I had the radiator cap off and started the engine, fluid was coming out like a volcano eruption, is this normal?

 

[hermitrl]

Sounds like a possible blown head gasket to me. Pressure is escaping to the water jacket and boiling the coolant.

 

[410Fortune]

Which truck is this? 91-92? 02?

No it is not normal, if the truck is cool (has not been running) fluid should not gush from the radiator cap opening.

 

[BigDakota]

A question..did you fill your radiator to the very top of the cap opening and then did you start it ....Antifreeze will blow out like you said if you overfilled...the starting of the engines rotation on the water pump, combined with air in the system will make the radiator "burp" the excess out...it would be a couple of short and sweet gushes and then thats it!!!

 

[Maverick0007]

This is on the 92, I filled the radiator to the very top.

 

[Maverick0007]

Also note, that this is not leaking any coolant at all. Should I replace the thermostat?