Radiator hose blows off thermostat housing

[JG1966]

I was driving my 72 340 RR today and all of a sudden I could smell antifreeze. I saw my temp gauge was starting to rise -- it never runs anywhere near hot -- so I pulled over, stopped the car and saw steam coming from under the hood. The upper radiator hose had blown off the thermostat housing, sending antifreeze everywhere. I cleaned it up, put in antifreeze, tightened up the clamp as tight as I could and drove three miles home with my fingers crossed. I made it OK, but what would cause that? I know the clamp wasn't loose. It seems like the system was overpressurized and had nowhere to go. I have an overflow tank. I'm not sure what PSI my radiator cap is (I'm thinking 16) and I haven't felt my hoses to see if they are soft or hard when hot. Any suggestions on where do I start? Thanks

 

[furious70]

Not to throw parts at it, but radiator cap isn't too expensive.
Deeper trouble could be found with the tester for hydrocarbons in the antifreeze

 

[Fran Blacker]

Check the lip of water neck. You need the lip so hose doesn't just slide up the neck.

 

[JG1966]

Check the lip of water neck. You need the lip so hose doesn't just slide up the neck.

Thanks Fran. This might be a stupid question, but if the pressure builds too much, shouldn't the overflow reservoir start to fill and relieve it rather than blow off a hose. I haven't checked the overflow canister yet but if it's empty, will that tell me something?

 

[PurpleBeeper]

I was driving my 72 340 RR today and all of a sudden I could smell antifreeze. I saw my temp gauge was starting to rise -- it never runs anywhere near hot -- so I pulled over, stopped the car and saw steam coming from under the hood. The upper radiator hose had blown off the thermostat housing, sending antifreeze everywhere. I cleaned it up, put in antifreeze, tightened up the clamp as tight as I could and drove three miles home with my fingers crossed. I made it OK, but what would cause that? I know the clamp wasn't loose. It seems like the system was overpressurized and had nowhere to go. I have an overflow tank. I'm not sure what PSI my radiator cap is (I'm thinking 16) and I haven't felt my hoses to see if they are soft or hard when hot. Any suggestions on where do I start? Thanks

You've got a tiny coolant leak somewhere. When the cooling system finally got low enough, the remaining coolant boiled and popped the hose off.

 

[toolmanmike]

Do you have a broken motor mount? Just thinking outside the box.

 

[JG1966]

You've got a tiny coolant leak somewhere. When the cooling system finally got low enough, the remaining coolant boiled and popped the hose off.

Thanks Purple. That makes perfect sense, because I just came out to look at the car and the radiator is almost empty (It's below the fins at least). I put in an entire bottle of antifreeze before I drove it three miles home and somewhere along the way, I lost a lot of coolant. The weird thing is the car was running hot for the first mile and then the temp started dropping by the time I got home. But a small leak makes a lot of sense.

 

[JG1966]

Do you have a broken motor mount? Just thinking outside the box.

No. Motor mounts are good

 

[Don Frelier]

How long had you been driving?
We're you maybe 5 minutes past the point when the thermostat should be open?
If so you might have a bad thermostat.

 

[QuickBpBp]

Thanks Purple. That makes perfect sense, because I just came out to look at the car and the radiator is almost empty (It's below the fins at least). I put in an entire bottle of antifreeze before I drove it three miles home and somewhere along the way, I lost a lot of coolant. The weird thing is the car was running hot for the first mile and then the temp started dropping by the time I got home. But a small leak makes a lot of sense.

If you filled it, drove it home and it's low again and you don't see it leaking anymore that's not good... Is it burning out the exhaust? Is the oil still just oil or is there Anti-freeze in it? Is the passenger side floor wet? Other issues could be going on. Hopefully it's something simple but losing coolant after you fix a leak could be something more serious.

 

[JG1966]

If you filled it, drove it home and it's low again and you don't see it leaking anymore that's not good... Is it burning out the exhaust? Is the oil still just oil or is there Anti-freeze in it? Is the passenger side floor wet? Other issues could be going on. Hopefully it's something simple but losing coolant after you fix a leak could be something more serious.

I'm beginning to think I didn't fill it all the way. I put in one gallon-- that was all I had -- and it filled the radiator above the fins. But it holds four gallons and it wasn't running when I filled it. I imagine the block was fairly empty after the hose blew off the thermostat. The radiator level probably dropped as soon as I started it. There are no symptoms of a blown head gasket, and my heater core was yanked long ago. I have no heater hoses.

 

[JG1966]

How long had you been driving?
We're you maybe 5 minutes past the point when the thermostat should be open?
If so you might have a bad thermostat.

Yes Don. That's about exactly how long I'd been driving. But if the thermostat didn't open (and it's got the drilled relief hole) would that cause the hose to blow off? I'd think it would cause me to overheat

 

[Don Frelier]

The temperature rises pretty quickly and there's quite a bit of averaging built into the gauges.
It's quite possible that the thermostat is the cause.
Hard to say without being there

 

[JG1966]

The temperature rises pretty quickly and there's quite a bit of averaging built into the gauges.
It's quite possible that the thermostat is the cause.
Hard to say without being there

I'll check it tomorrow. But I'm beginning to think it was nothing more than a perfect storm of a slightly worn out radiator hose, a too smooth thermostat housing neck and a clamp that could have been tighter. That's what I'm hoping, at least

 

[1STMP]

Could also be your water pump. Run the engine
(warmed up, cap removed) and check for
circulation of coolant.

 

[1967coronet]

Those china worm gear clamps have been known to let loose . Over tighten them a couple times they should be tossed.

 

[Herman]

Paint on the neck of housing will cause the hose to slip off.

 

[MWbirdLOVER70]

Paint on the neck of housing will cause the hose to slip off.

I like to smear a little gasket rtv around the neck to help seal the hose/neck as added sealing but that’s me

 

[toolmanmike]

Did we ever see a photo of it? Photos of the hose on and off. Let's see what the t-stat housing looks like with the hose off. Who knows what's going on here.

 

[MWbirdLOVER70]

Did we ever see a photo of it? Photos of the hose on and off. Let's see what the t-stat housing looks like with the hose off. Who knows what's going on here.

You think it’s all pitted Mike? I’ve seen that and nothing JB weld wouldn’t fix