thermostat, overheating, refilling coolant? | Ford Explorer Forums - Serious Explorations

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thermostat, overheating, refilling coolant?

dsfii93sport

Well-Known Member
Joined
August 11, 2004
Messages
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City, State
Indy, IN
Year, Model & Trim Level
93 Sport
My truck had recently started overheating, sometimes dropping back down to the normal temp. I figured it was the thermostat, took it and and naturally it was stuck and old. Replaced it, no leaks. Great! But...

I'm still having an issue with it running into the hot temp range, and then burping fluid out of the resivoir! Is there a trick to filling it with coolant? Like a vent I'm suppose to open when filling.

Was wonder if I have air pockets in there and this might be why its still overheating, then dropping back down. And of course the interior air gets cold when it does it.

Any suggestions?
 



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Generally, this truck will burp itself fairly easily, but it seems as if you are having problems. You might try parking it with the nose uphill and see if that helps.

Alternatively, find a vacuum filler and use that to totally fill the system. They draw a vacuum on the entire cooling system, then back-fill against that vacuum draw to fill every nook and cranny.

One futher thought. Is your water pump circulating well? When I had that issue, I discovered that my water pump was trashed.
 












Thanks! Is there anyway to check a water pump without just replacing it?
 












How hot does it get, and does the temp remain constant? Also, is it drawing from and discharging into the overflow bottle properly?
 






do you know that" barrs stop leak" was ever used on it ? barrs coats everything in the system and even the impeller on the pump ...also the rad core lines and yes even your water temp sensor.

if yes then for like the pump ,the impellars have so much build up on them that are preventing water to circulate properly .
 






Well, "how hot would it get"

First problem is I've always noticed my temp gauge to forever run just barely above the cold area when at normal operating temp. Dunno if that is normal. But when it started overheating, the needle would creep quickly up to the high end, not reaching it fully (cabin air getting cold) and then drop back down to the normal spot (normal for my truck).

After replacing the thermostat, it worked a little better, at least I thought things were settling in. But now it runs up to about 3/4 and stays about there. And when I park, there is antifreeze draining from the top of the overflow tank.

I got the truck used so I have no idea if anyone ever put any stop leak or the like in it...
 






well honestly. try to rev it up while filling it. but to check the water pump while it is running no.
 






well well.. I finally got around to getting a new water pump, took the old one off and was sad to see the pump physically looks fine, BLAH.... So I'm highly guessing that the pump wasnt the problem but oh well at least I have a new pump on!

So new thermo, new pump.

Granted I haven't tried it out with the new pump yet, what could I be missing here?

Could it be a faulty temperature sensor? Or maybe the cooling fan clutch? (havent payed any attention to the fan yet)
 






I have a very similar problem. No clue what the problem is. I know the pump is good, the t-stat is good, the radiator is new, everything is fairly clean inside, and I lose no coolant. I've just let it be and it works. Sure it's probably not the best thing for the motor, but I've been driving it like that for a year or so and it's been fine. I'm out of feasible solutions.
 






have you tried either getting another temp guage and see if it's giveing a false / higher reading ? have you tried hooking up a mechanical temp guage.also i don't know but if the temp sending unit is bad it would be reading cold but who knows it could be bad and giveing a hot reading.fan clutch gone bad ?


was barrs stop leak ever used in it ????
 






my 1994 EXplorer 4.0 would burp into overflow and had to replace cracked head ! Try pulling plugs to find very clean plug that was washed with antifreeze. this also caused a miss. Compression forced air into water jacket. Ialso watched the overflow with engine running and saw air bubbles--rising to the top!




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carthings




























































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I wonder if I put the thermostat in backwards? Does anyone have a picture of which way the thermo is suppose to face!?

David
 






I wonder if I put the thermostat in backwards? Does anyone have a picture of which way the thermo is suppose to face!?

David

I was always told that the end with the spring on it goes into the block.....
 






Head gasket

I had same sequence of events... temp gauge goes up to hot, then I'd take off the gas and it would go back, replaced thermostat still ran hot... bubbling in the reservoir. Turned out to be a minor head gasket leak.
 






Before we jump to head gasket, there is a valve and I forget what it is for (I'll check Haynes), but when your dash levers are on a certain function i.e. a/c or defroster. Maybe one of the old timers will chime in on the name. This valve will be closed and the temp gauge will heat up and then fall back down once the valve opens. You stated that once it goes down it will run at 3/4 hot. What letter is it on in NORMAL? When you said it was running right above the "C", that is too cool for an Ex. You were right to change the thermostat. However, if the old thermostat was bad (open) and you ran at "C", then a new one 195* will run hotter. Also, did you replace the radiator cap. Sometimes your overflow will fill up because your spring is shot in your radiator cap. Start with the cheap stuff first. Just my two cents. Thanks, Matt
 






hmm, cap.. Smart, I'll check that.

here's the scoop!

I took the darn thermostat back out, went and got a new one. Changed it again and assured it was in correctly. refilled coolant.

Thought things were good but here is the same symptoms again... I'm 99% the temp gauge is correct in its reporting so we'll rule that out for now.

What happens is, when the truck reaches normal operating temperature it will periodically spike into the 3/4 hot region. I can tell from looking at the gauge when the termostat opens cause it drops back down. But the major issue seems to be when it regurgitates the coolant out of the reservoir tank! As it does this (each time it spikes) it slowly looses coolant therefore over time it keeps spiking higher in temp cause.

How often a spike? I'd estimate it does this about every few minutes. So strange. You'd think if it were a head crack/leak it would do this constantly, unless I guess it was only evident when the engine got hot. I mean, if the system is full of coolant, it almost runs perfect, until of course it has a spike and burps the goods out.

I even checked the radiator and it flows fine, no clogs...

I think I'm gonna look at that cap for fun later today...
I hope its not a head issue :(
 






My 94 4.0 had a rebuilt head that was repaired - welded . We ran a compression test and only one cylinder was some what low but with in spec. The bubbles in the radiator indicate a bad gasket or a cracked head. The crack is probably Very Small with only the high compression able to push air into the water jacket through the crack. The head gasket removal appeared to show no signs of leaks. the cost of head gasket led me to replace the heads for a good fix. I found new cast heads on internet at J&C Enterprises. Good luck.
 



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One other symtom I discovered. I decided to drive it 60 miles on the interstate yesterday. Amazing enough but at high speeds that entire 60 miles kept the temp at normal level. Granted you could see it trying to rise, which it did everytime I came to a stop.

How can one test the cooling fan clutch?
 






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