Im having this problem. In the morning the up and lower radiator hoses are rock hard on cold start in till engine reaches 190℉ then they soften to normal and its cause my radiator to leak when cold.
And this is a 1991 pickup 3vze new all aluminum radiator new hoses new water pump fresh coolant. And Tstat that has 10,000 miles on it

 

What about your radiator cap?

 

Its Brandnew not more than 2 weeks old

 

What pressure cap should i have

 

I believe a standard is 13psi. What's strange is it's building pressure after it's cooled off

 

Because the cap that came with radiator say 15-18psi i dont understand either could the pump be creating to much pressure. While the tstat is closed

 

Try taking the cap off in the morning when it's cooled off. It sounds like the system is holding pressure.

 

How do you fix it if its holding pressure what causes it to do that.

 

Verify that's it's building pressure when you take the cap off the pressure should release. This is the first I've heard of a cooling system build pressure with the engine off. Pressure builds with heat.

 

It should, when warm, vent pressure and coolant to recovery tank, then suck the coolant back in as it cools off.


If it's building pressure up when cold starting, I'd suspect a head gasket issue that 'fixes' itself once warmed up and things 'expand'.

 

I let it cool while at work and before i pulled the cap i felt the hose and it was super soft and ran it till it warmed up with cap off and it did fine. Added the cap and it slowly built pressure to normal. I think it cool and pulls coolant in and doesnt let it exspand into exspansion tank when its hot causing a over full cooling system. Ill get some block tester tomaro. And test the coolant for exhaust gases and pickup a radiator cap

 

possible solutions: wrong psi rad cap (should be 13psi), thermostat is wrong temp (should be 180), head bolts need to be retorqued



disregard title due to post in wrong thread.