Upper radiator hose getting pressure when cold?

[454cid]

Will a stuck open thermostat allow the pump to pressurize the upper hose from startup? I think I may have something going on, but haven't explored much yet. I do see that my temp doesn't seem to be coming up as fast, but also bumped the gauge sending unit pretty good and maybe stressed the wire while doing valve cover gaskets and plugs.

 

[0xDEADBEEF]

I would guess it's about atmospheric when cold and thermostat open. You should be able to squeeze it I would think.

 

[454cid]

I would guess it's about atmospheric when cold and thermostat open. You should be able to squeeze it I would think.

Today I felt the hose before starting the truck and after and I do think it's getting pressure right away. It also took a bit before the truck came fully up to temp. I may change the thermostat....I think I have a new one in my stash.

 

[smdk2500]

In the 6.5TD world a hard upper hose while the engine is warming up is a sign of a blown head gasket. I don't know if the same would hold true on the gas engines. Are you loosing any coolant that isn't accounted for?

*Edit* I just reread what you had said and it could be possible that you could have a t-stat issue since you have a slow warm up issue. I would still look into a possible head gasket issue just to make sure especially since your pushing 300k and I'm assuming that they've never been done. They don't last forever.

 

[454cid]

In the 6.5TD world a hard upper hose while the engine is warming up is a sign of a blown head gasket. I don't know if the same would hold true on the gas engines. Are you loosing any coolant that isn't accounted for?

*Edit* I just reread what you had said and it could be possible that you could have a t-stat issue since you have a slow warm up issue. I would still look into a possible head gasket issue just to make sure especially since your pushing 300k and I'm assuming that they've never been done. They don't last forever.

Yes, a head gasket is actually the first thing that occurred to me....hoping that's not it.

I'm thinking I might do the chemical test for exhaust gases in the cooling system.

 

[wirlybird]

How about removing the radiator cap when cold, place your hand over the radiator fill opening start the truck and see if pressure builds.

 

[454cid]

How about removing the radiator cap when cold, place your hand over the radiator fill opening start the truck and see if pressure builds.

I could do even better..... I have a pressure gauge. Thank you for bringing that up. I don't use it very often.... I'm not even sure of it's exact location in my mess of a garage.

 

[Frank Enstein]

If the radiator is blocked it would build pressure right away. Normally the coolant heating up and expanding makes the pressure.

 

[454cid]

If the radiator is blocked it would build pressure right away. Normally the coolant heating up and expanding makes the pressure.

My thought was that normally the thermostat would be cold and closed, shielding the hose from the pump, but if it were stuck open the pump may put some pressure on the upper hose. It was just a thought.... I have no idea if it would actually happen like that.

I doubt the radiator is blocked. It's not that old, and it does cool the engine.

 

[Pinger]

My thought was that normally the thermostat would be cold and closed, shielding the hose from the pump, but if it were stuck open the pump may put some pressure on the upper hose. It was just a thought.... I have no idea if it would actually happen like that.

I doubt the radiator is blocked. It's not that old, and it does cool the engine.

The radiator is in communication with the block via the bottom hose so the pump sees an open path (assuming a clear radiator - which appears to be the case).

As mentioned earlier, pressure is from heat - or gasses escaping the engine.