A couple days back, I finished re-gasketing my transmission and installing a new clutch set in my 76. Ran great for a couple days, and started up driving it to and from school again yesterday. Well on my way to school this morning, she decided to take a dump on me.

It was about 16 degrees this morning, so I let my truck warm up a bit while I finished getting ready, about 7 minutes. I got in, and started driving. By the time I got out of my neighborhood 10 minutes after starting it up, the temp gauge started moving up into the middle of the sweep. I didn't take much notice of it, even though prior to this it hadn't been reading (figured thermostat was stuck open, had plans to replace it today). As I'm driving down the county road at about 55 mph, the needle started reading warmer than "normal", yet the air coming out of the heater was ice cold and I smelled antifreeze. So I pulled over at our local parts house that I work out, and shut her down. Soon as I did that, steam started billowing out from the hood. I pop it open, and there was a big column of steam coming out from the overflow tank, which had it's cap blown off. So, she started to overheat. I think my chowder was saved partially by the fact that it was so cold, and maybe the cold air flowing through the bay kept things at the very least cooler than if it was warmer outside...

I did a brief inspection in the dark with a flashlight, and the freeze plugs, hoses, and radiator cap were all intact. So, what kind of things could have gone wrong?

It's occurred to me that the concentration of antifreeze to water may not have been great enough, so maybe something froze and it made the thermostat stick closed? If that were the case I would think that the hot water cycling through the engine would have un-frozen the thermostat...


Thanks in advance
Jameson

 

Definitely sounds like some kind of blocked passage in the system in order to cause enough pressure to blow the contents into the overflow. I would pull your thermostat and go from there

 

Sounds to me like a maybe a collapsing bottom hose. Did it have a spring in it when it was put in?

 

Nope. I replaced both upper and lower hoses at the same time, and the lower came sans spring. FWIW, the one I took off didn't have it either

-Jameson

 

If you have 15 lbs of pressure on a system, do you really think the bottom hose can collapse? Just my thinking.

 

I've seen them collapse before. Makes sense that it's under vacuum basically from the water pump. Why would the radiator cap puke into the tank if the thermostat was stuck closed? I know pressure makes them pop but if it's stuck why is the radiator screaming hot too at highway speed? Sounds like a blockage of some sort.

 

On my 460 I once had a thermostat fail by pushing the pin through the bail. Basically the thermostat tried to open, but couldn't. The temp gauge never read hot until the upper radiator hose exploded. Sounded like a 12 gauge shot gun went off under the hood.

 

You were right about a blockage. The mix of water/antifreeze was so bad that the radiator froze solid.

Warmed up a bit, everything thawed out, threw a good mixture of antifreeze/water, and down the road I go

 

Glad you got it figured out. Antifreeze is no joke. Lucky you didn't crack the radiator, blow a freez plug or worse.