Coolant pressure?

[Deplorable1]

I was looking at my radiator today and noticed a little coolant leaking at the petcock. I opened the hood and went to loosen the radiator cap and heard it start to hiss like it had pressure from just being driven. The truck hasn't been started in a couple weeks. Is it normal for the coolant system to still have pressure this long?

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[Deplorable1]

What you see on the bracket and belt is all it burped out

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[cattlerepairman]

Yes. Mine definitely does that. I was paranoid and put an exhaust gas probe on it at the local garage (sniff the "gas" coming out when you open the cap; if it is exhaust gas there is a head gasket leak). Nada. Just coolant pressure. Mine also has not read the TM and dislikes coolant being filled to the filler neck. Whenever I do, she will burp out a quart or so. That's where she likes her coolant to be. Never argue with a lady.

 

[Deplorable1]

Thanks cattlerepairman, I was concerned but I'll give it the sniff test just to be sure.

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[Big Tom]

Mine also did that ,I found that the Copper overflow line was clogged, clean it out and never had pressure again after sitting , it doesn’t make sense I know but give it a look and see if it’s clogged

Big Tom

 

[sandcobra164]

That's a good sign that the hoses and everything related to the cooling system is healthy and holding tight. You're truck doesn't have an overflow bottle and the cap holds around 7 to 14 psi of air pressure before it allows any overflow out of the radiator. If you fill a deuce radiator to the bottom gasket of the cap it will purge some coolant as it heats up and expands as cattlerepairman pointed out.

 

[Deplorable1]

Thanks everyone for your input. I drove it today after adjusting the mirrors I installed awhile back. When I get home tomorrow I will smell check the radiator. Thanks again.

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[Jeepsinker]

Pressure in a sealed system should always return to atmospheric when temperature reaches ambient. System has no pressure when you put the cap on, so unless volume ( either fluid or gas, i.e. combustion gas) enters the sealed system then it should return to the same pressure ( atmosphere) when it cools. The headgaskets on these engines suck. Some combustion leakage is common, even if it is slight.

 

[CMPPhil]

Mud wasps in the vent tube.

Mine also did that ,I found that the Copper overflow line was clogged, clean it out and never had pressure again after sitting , it doesn’t make sense I know but give it a look and see if it’s clogged

Big Tom

Hi

Big Tom

May have hit this one DEAD ON THE HEAD, check the vent tube, I've had mud wasps plug the vent on non-pressure systems to the point it blew a 2 inch top hose off. With a cab forward that fills the cab with steam, collateral everywhere.

Now my service list is running a wire up the vent tube.

Cheers Phil