Coolant bottle overflow?

[sdeeter19555]

So remind me, as it's been a while...

This 2019 Laramie had a head gasket weep on the driver's rear head. That was "fixed" with some stop leak as the system would hold 18psi overnight. I know it's a bandaid, but that worked.

Fast forward, I drove the truck last night for the first time since 1/1/25. Got home, parked in the garage, come out to a puddle of coolant under the front passenger's headlight...everything was dry, assumed the coolant bottle overflowed.

So I started it in the garage just now. The coolant was at the same level I filled it to originally, I added nothing. Let truck warm up, and I can watch the overflow bottle start filling up. There are zero bubbles in the bottle, there is no exhaust odor, coolant appears normal. But what is puzzling is there is also zero pressure on the system based on squeezing the hoses, the coolant bottle is starting to fill and the truck is still cold.

By the time it got to operating temp, the overflow bottle was near to the point of overflowing. But again, ZERO pressure on the hoses even at operating temperature.

I am suspecting a bad radiator cap because there is no pressure on the system? Yes/no?

 

[HSKR R/T]

So remind me, as it's been a while...

This 2019 Laramie had a head gasket weep on the driver's rear head. That was "fixed" with some stop leak as the system would hold 18psi overnight. I know it's a bandaid, but that worked.

Fast forward, I drove the truck last night for the first time since 1/1/25. Got home, parked in the garage, come out to a puddle of coolant under the front passenger's headlight...everything was dry, assumed the coolant bottle overflowed.

So I started it in the garage just now. The coolant was at the same level I filled it to originally, I added nothing. Let truck warm up, and I can watch the overflow bottle start filling up. There are zero bubbles in the bottle, there is no exhaust odor, coolant appears normal. But what is puzzling is there is also zero pressure on the system based on squeezing the hoses, the coolant bottle is starting to fill and the truck is still cold.

By the time it got to operating temp, the overflow bottle was near to the point of overflowing. But again, ZERO pressure on the hoses even at operating temperature.

I am suspecting a bad radiator cap because there is no pressure on the system? Yes/no?

Your stop leak bandaid is probably causing more issues with you cooling system. Even if it was just a bad cap, not holding pressure, it shouldnt cause the reservoir to overflow.

 

[sdeeter19555]

Eally? That's one of the most common symptoms of a bad cap?