3.0 Cooling System Issues

[Roger_Hughes]

Hey all! My 99 has me scratching my head. I replaced both head gaskets less than 200 miles ago and now my cooling system seems to be building pressure. I can’t trace it down. I have:
-replaced t-stat
-replaced radiator cap
-ran til hot w/cap off to bleed air (don’t have a vacuum filler)
-confirmed that coolant is making its way to reservoir upon reaching OT & pressure (level stabilizes after expansion)
-confirmed that the reservoir does not bubble with engine running or after turning off.

the catch here is that the upper radiator hose starts leaking coolant out of where it slides onto the radiator and the hose does feel quite stiff until bleeding all the pressure to the reservoir. I haven’t replaced the hose to confirm the hose is fine but I just feel like it’s building too much pressure. I don’t know how unless my new head gaskets are toast. It appears to be intermittent too. I bled the system Saturday, took it for a 10-15 minute drive afterwards and nothing leaked. Got in it to drive to work this morning and was leaking coolant out of the hose again about 7 minutes down the road. The heat is also hot (not great but definitely enough to keep cab warm). I’m getting frustrated with it! Anybody have any ideas? Maybe I’m overlooking something? Hoping to feel pretty stupid once I find it. Thanks in advance.

 

[franklin2]

It can't build more pressure than the radiator cap will hold. Not sure what lb cap you use, but if it has a 13lb cap, the system will not build over 13 psi. If it does, the cap opens and allows fluid into the reservoir. The reservoir should start out at about half full when the engine is cold. If the system builds pressure, starts filling the overflow reservoir, and keeps filling it till the reservoir overflows, then yes you might have a problem.

 

[Roger_Hughes]

It can't build more pressure than the radiator cap will hold. Not sure what lb cap you use, but if it has a 13lb cap, the system will not build over 13 psi. If it does, the cap opens and allows fluid into the reservoir. The reservoir should start out at about half full when the engine is cold. If the system builds pressure, starts filling the overflow reservoir, and keeps filling it till the reservoir overflows, then yes you might have a problem.

I filled the reservoir just under half last week and that is when this issue started. It didn’t push coolant out of the reservoir though. In fact it wouldn’t even transfer pressure to the reservoir when lifting the pressure relief on the cap. So I drained the reservoir, refilled the radiator, and as the engine came up to temp there was coolant that expanded to the reservoir once pressure was on the system. But it leveled off once the truck was up to temp, it did not continue filling it. I guess my question is where do you think my issue lies? Do you think my upper hose could just be worn out or should I try something else? The hose is original equipment.

 

[2011Supercab]

the upper radiator hose starts leaking coolant out of where it slides onto the radiator

Either the clamp is loose, or the hose is bad, or worse case your radiator is cracked were the hose attaches.

The firm hose when up to temp is not the problem.

 

[Roger_Hughes]

Either the clamp is loose, or the hose is bad, or worse case your radiator is cracked were the hose attaches.

The firm hose when up to temp is not the problem.

I’m going to look at that this weekend when I get time to. Thanks for the input. I probably should’ve waited to post until after I checked it but wanted to try to get ideas before going into the weekend.

 

[Bgunner]

Having a coolant leak will have a couple affects.

Loss of coolant, which you have been experiencing.

It can prevent the system from fully pressurizing, this is caused because the pressure is bleeding off somewhere other than the overflow tank.

It can cause the engine to overheat if the leak is bad enough. This would be caused by the system not pressurizing properly and allowing the coolant to boil prematurely or loss of enough coolant.

It can prevent coolant being sucked back into the radiator. This would be caused because as the system cools it creates a vacuum which sucks the coolant from the overflow tank. If the system looses to much vacuum the radiator will not fill all the way back up properly.

Before going any further with a diagnosis get the system sealed up and see how it acts after that. Being you said the hose is factory then the hose is most likely old and wont seal properly on the radiator barb. Sometimes a new clamp can fix this but, on the other side of things, sometimes it will seal for a short time and you are back at it replacing the hose anyways. This is for you to decide when looking at the issue and removing the hose from the radiator.

When it come to the heater see how it acts after the system is sealed. If the issue continues try flushing the heater core in both directions. If the issue still remains then start looking at the blend door to see if it moves properly. Not moving properly could be a few things but lets go down that rabbit hole once we know it is an issue.

 

[Roger_Hughes]

Having a coolant leak will have a couple affects.

Loss of coolant, which you have been experiencing.

It can prevent the system from fully pressurizing, this is caused because the pressure is bleeding off somewhere other than the overflow tank.

It can cause the engine to overheat if the leak is bad enough. This would be caused by the system not pressurizing properly and allowing the coolant to boil prematurely or loss of enough coolant.

It can prevent coolant being sucked back into the radiator. This would be caused because as the system cools it creates a vacuum which sucks the coolant from the overflow tank. If the system looses to much vacuum the radiator will not fill all the way back up properly.

Before going any further with a diagnosis get the system sealed up and see how it acts after that. Being you said the hose is factory then the hose is most likely old and wont seal properly on the radiator barb. Sometimes a new clamp can fix this but, on the other side of things, sometimes it will seal for a short time and you are back at it replacing the hose anyways. This is for you to decide when looking at the issue and removing the hose from the radiator.

When it come to the heater see how it acts after the system is sealed. If the issue continues try flushing the heater core in both directions. If the issue still remains then start looking at the blend door to see if it moves properly. Not moving properly could be a few things but lets go down that rabbit hole once we know it is an issue.

I appreciate the input! I think this weekend I’m going to pull the hose (and probably replace since cheap), inspect the radiator barb, and see where I’m at. I’ll follow up with my findings!

 

[fixizin]

... Do you think my upper hose could just be worn out or should I try something else? The hose is original equipment.

Hold it, are you saying the upper hose (and possibly others) are 25 years old???
If so, then I vote to REPLACE that time bomb.