Cooling issue

Falcon20x

Registered User
I replaced the head gaskets, the heads, the thermostat and the water pump.

The temperature ( i have a temperature gauge build in the radiator cap) goes to 260, coolant in the tanks goes up in level ( a lot). The system sits there for a 30 seconds or so the fan kicks in then temperature drops back to 180 as the coolant level in the expansion tank drops back down in level.

What is the issue?
 
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As a reference, what does the gauge on the dash have to say?

I think your cap/gauge should be returned and replaced with a quality straight 16# stock cap.

Did you bleed the air out when filling? Have you driven it for a few days to help that happen?
 
As a reference, what does the gauge on the dash have to say?

I think your cap/gauge should be returned and replaced with a quality straight 16# stock cap.

Did you bleed the air out when filling? Have you driven it for a few days to help that happen?

Dash guage shows about 2/3 study

No air in the system

I did not drive it this time since it is the second time it happened

Radiator temp cap gauge always worked well
 
I should have mentioned that the thermostat is a fail safe type. Just swap it again, sure enough it was open. The fail safe worked, that explains why it open at 260 degrees
I tried another thermostat, same thing happened again.
:confused: I really have no idea why the thermostat would not open at the given temp. Everything was chafed except for the radiator and the sensors. What I'm missing here?


Any help would be greatly appreciated
 
Twice?

Are you sure you had them pointed the right direction? What temp are they?

Did you try to peek into the radiator to see if it is clear or plugged?

Can you feel it to confirm it's flowing coolant?

Don't be so quick to think you've removed all the air yet...

What pressure(s) is that cap?
 
Twice?
Actually 3 times

Are you sure you had them pointed the right direction? What temp are they?
192 degrees. You can only instal them one way,but yes properly installed according to the manual.


Did you try to peek into the radiator to see if it is clear or plugged?
seems pretty clean. Flushed it before use. Water seemed to flow properly during the flush

Can you feel it to confirm it's flowing coolant? Did not try that, but it is flowing once the thermostat opens.

Don't be so quick to think you've removed all the air yet...

Still not sure what would keep the thermostat from opening causing the coolant to back up in the expansion tank?
I would like to think I some what good at this stuff. I completely rebuild the engine, the transmission and the brake system on this car but I plead ignorance on this one, I have no clue.:(
 
Get a new cap - straight 16#.

Describe what part of the stat you see when it's in the housing.

Which head gaskets did you use? Did you confirm their orientation when installed?

Does the fan come on & stay on or does it cycle? What speed?

Do you see flow inside the radiator with the cap off as the stat opens?

What process did you use to air bleed?
 
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I have a cap I will try that

Below is the picture of thermostat



I use the Fel Pro head gasket, properly installed with the arrow pointing to the front.

Yes the fan comes on around 250 degrees


Do you see flow inside the radiator with the cap off as the stat opens?


Did not wait until the temp to get that high before to put the cap back on.

What process did you use to air bleed?

Used the screw on top the Thermostat housing and left the cap open.
Still do not understand how any of this would keep the thermostat from opening.
 
From opening? You said they were stuck open.

If the fan comes in after just 30 seconds, you've got major/multiple issues.

Hard to tell in the photo, but it looks like a 180 stat, not 192....?
 
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May be I was not clear in my explanation, sorry. The thermostat will not open driving the temp up to 260 degrees and pushing the cool back in the expansion tank.

Since it is a fail safe thermostat it will end up opening and stay open( fail safe mode), but only after the temp reached 260 degrees. The fan comes on a little bit after reaching the 260 degrees then shuts off when the temp goes back down.
The thermostat has 192 degrees stamped on the back
 
Suggest putting that thermostat in a pot of water on the stove with a thermometer to see what temp it starts opening, is fully opened, and then turn off the heat and see what temp it starts closing and is fully closed.

David
 
Suggest putting that thermostat in a pot of water on the stove with a thermometer to see what temp it starts opening, is fully opened, and then turn off the heat and see what temp it starts closing and is fully closed.

David

He said they're failsafe and they (all three) popped, which means they've done their job, are now stuck open, and have to be discarded, I think?

Of course if #4 hasn't failed open yet... :)
 
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