Coolant

[knash0727]

Well... Long Story...

I had a block heater and at one time it fell out. I put a expendable freeze plug in its place.

The other day I took a road trip and all of a sudden I saw smoke. I was kind of ******* the throttle at this time so I thought that was what it was until the High engine temp light came on. I stopped and realized that the plug had come out draining the coolant all over I45.

I replaced the plug, but my coolant seemed to not be leaving the radiator. After I filled the radiator up it kept getting hot. I got the truck home and pulled the thermostat. I boiled some water and put the thermostat in and it did not open.

I went to Ford and ordered the motorcraft thermostat. This thermostat looked very different from the old one. I replaced the thermostat and not it is still not working. I refilled the coolant and let it idle for a while and it did not get to hot. There was a huge amount pressure in the top hose, but it didnt get warm at all. When I backed off the radiator cap a little bit, the coolant just ran into the overflow. It sounded like it was boiling. I dont know if it has air in it or what.

I drove it 2 miles to my brother's house, and the temp gauge got up to hot. I shut it down for about 5 mins, then looked at the temp gauge and it was back down to the o in normal. I drove it home, and on the way over the gauge said it was hot again. When I pulled in I shut it down and popped the hood. The top hose was very hot and had very high pressure in it, and the bottom hose was stone cold.

Now I am confused. What should I do?

Sorry for the long post, but I am so confused on what to do.

 

[knash0727]

If it helps any here are pictures of my old tstat vs new.

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Seems like a very big difference to me.

 

[OLDBULL8]

That new t'stat is OK. Just a new style. Your motor should take 32 Qts. of coolant, 8 gallons, if everything is drained including the block. You sure you have the t'stat in with the copper gizmo faceing down.

 

[suv7734]

If it helps any here are pictures of my old tstat vs new.

Seems like a very big difference to me.

Wrong t'stat was installed previously.
These engines take a while to 'burp' out all the air so there might be some still in there. There is a bypass check ball in the thermostat housing. If it is blocked up or missing that can cause problems as well.

 

[knash0727]

I put the thermostat in with the dome part sticking out of the block, and the rubber part going in. How do I burp the system? The air check ball is there, but is kinda rusty. can I hit it with a shot of wd40? Lastly, I have heard that it is bad to run our engines without the thermostat, but is it okay, at least temporally?

 

[Exekiel69]

If the top hose is getting hot and too much pressure in it then the inlet to the radiator or the radiator is blocking the flow.

 

[Agnem]

I wish I had good news for you, but more often than not, by the time the overtemp light comes on, you've cracked a head. Start it with the engine cold, take the radiator cap off and see what happens. The new thermostat looks like the right one. The old one is wrong.

 

[knash0727]

When I start it with the engine cold and I have filled the radiator up to the top, I take the cap off and the coolant shoots out.

 

[Agnem]

Your toast.

Fab up an adapter to allow you to connect a source of compressed air to the hole that a glow plug fits in. Take a glow plug out, and hook up the compressed air. When you find the head/cylinder that is cracked, you'll know it. Could be a head gasket, but that would be extremely optimistic.

 

[knash0727]

That is no fun.

 

[Agnem]

Looks like either your thermostat stuck closed, and the engine overheated and blew out your expansion plug, or the loss of coolant ate your thermostat. Either way, it would have been good to assume the worst at first discovery, and replace both the plug and the stat. We will never know if the head cracked before you discovered the bad thermostat, or after. If you had installed a real water temp gauge like we are always telling people, you might have saved yourself from this grief. Let this be a warning to others who persist in ignoring this fact. The 80-86 trucks have an instrument voltage regulator that works the gauges and those things are horrible, supplying an average voltage to the gauges that will vary with ambient air temperature, and if your dash lights are on or not, and if your heater is on or not. The 87 and up don't really have guages at all. The oil presure is an analog idiot light. None of the gauges have any values on them, which means you don't really know what the temp or presure is. You just know what it's relationship is to "normal" and you don't know if "abnormal" is a difference of 5, 10, 15, 20, etc. The high end of the normal range may well be 240 degrees for all we know. The high temp switch closes at 242, which is about 10 degrees too late.