My truck overheated and I dont know why. | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

My truck overheated and I dont know why.

MustangShane

Well-Known Member
Joined
October 30, 2003
Messages
416
Reaction score
0
City, State
Lake Orion, Mi
Year, Model & Trim Level
1991 4dr XLT 4x4.
Okay I'll start off by telling you that a last year I replaced my water pump and thermostat. Then a month ago my upper hose went and I limped it home (I was within a couple miles). So I've replaced the upper and lower hoses and basically the sysem has flushed itself. I used the premixed antifreeze and last night I added 1/2 a gallon of water to the overflow bottle because it was empty. Then I ran it for 20-30 minutes. Now on my way to go wheeling this morning I noticed the guage was running higher than normal at about the "m" to be somewhat exact. I decided to turn around and good thing I did. I was half way home and it overheated and died. The only reason I ran it so long was I had two of my kids with me. I let it cool down and called my wife to come and get them and drove it home. I checked and the overflow bottle was frozen and there's antifreeze on the drivers side and I know the lower hose isnt torn. I checked the oil and no water in it. The cooling system was fine yesterday, and from the overflow bottle being frozen it doesn't seem the antifreeze was diluted by the water and froze my radiator. So I'm conerned about the headgaskets and with 180,000 miles on the original motor I know they would be suspect. But I dont seem to have any other signs of that, soooo anyone please tell me what you think it could be as far as an educated guess. Thanks in advance for any advice.
 



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





Did it get so hot that it killed the motor? If so, you could have blown a head gasket. Start it up when cold, and remove the rad cap, give it some rpms and see if it bubbles out of the radiatior. If so, it could be signs of a blown head gasket. None of this explains your original overheating problem.... maybe a stuck thermostat. Are you sure you had a good mix of antifreeze in the rest of the system?
 






Yes I'm POSITIVE I had a good mix. The only thing I can think is a stuck thermostat. Hasn't given me any problems before but there's always a first for everything. Yes I did run it until it died. I know that its bad, really bad. But when you have two kids in the back seat under seven. I felt if I pushed it a little further I could make it home. The guage wasn't moving past "m" when it died so I didn't think it was that hot. Man... you know what now that I think about it the thermostat probably did stick. Which when It built up enough pressure it back flushed the system and forced its way back through the radiator cap. Which explains the antifreeze sprayed on the drivers side.
 






The overflow-reservoir is supposed to allow hot coolant to expand and then flow back into the radiator. If the line into the reservoir also was blocked by ice, this might have caused the engine to overheat earlier than expected. I wouldn't trust the gauge 100%. Especially on older Explorers they tend to work not very accurate.

Does the engine run now after it cooled down?
 






It runs fine. The thing heated up way too fast. Yes the overflow was frozen but it would still have flowed through the rest of the system.
 






ok, the frozen resivoir does not worry me a bit. If your truck needed to blow off coolant, it has enough pressure that it would blow the small rubber hose right off of the radiator neck, so that's not a problem.

doesnt sound like a frozen radiator either.

AIR POCKET.

i've fought these devils in mine also. when you change hoses, you get one of these bad boys, i know because i've done the same thing. the reason that the gauge didnt read that high is i think that's right where the sendor is. it's sits in hot air, not hot coolant, so it didnt register how hot the motor got. Once it cooled down, your coolant level should have dropped way down, and the air eventually bled it's way out.

Hopefully you didnt let the smoke out. these 4.0's have a tendency to crack heads when they get that warm. I'll cross my fingers for you. :)

I'd fill the radiator as high as it will go. throw the cap on, run it for less than 5 minutes. shut it off, let it cool for a minute or two, and pull the cap. do this a few times until the coolant level stops dropping. It's a process, but it ensures you that you get that pocket out.
 






When you replaced the thermostat, did you take care that this little hole in it was installed on the uppermost side of the plate? This hole's got to be in position to allow air in the system to go through it and not block the coolant-circulation.

As long as there's not much or no air in the system, it doesn't make any difference. But if for any reason air gets inside (or remains in it after replacing a hose...), this can cause overheating...
 






homerbundy said:
When you replaced the thermostat, did you take care that this little hole in it was installed on the uppermost side of the plate?

You know I dont remember if that was at the top or not. I've bled the system out a couple times before and it seemed a bit rough to do. This could be why. Well I'm tearing it apart today and we'll see what the deal is.
 






Okay you guys will love this. I removed the upper hose and checked the thermostat. The bleeder hole was on the top as it should be but the system was completely dry :shock:. So next move crawl under the truck and check freeze plugs. When what to my wandering eye do I see but the lower radiator hose is completely off the radiator. It seems I placed the clamp just below the neck. It looked like it was on the neck but no. So over time it worked its way off and drained my whole cooling system in one swoop. So now that I've made this discovery I have a question that I think I have the answer to. Is it bad that I didn't have any big air pockets and all that was happening were small bubbles? It would slowly bubble down and Id refill it. I think the gaskets went or worse. I changed the plugs and did an oil change. The plugs were black from the motor trying to cool the cylinders by dumping more fuel in them. The oil was burned but no water. Sooooo here I am, glad I have another set of heads.
 






Okay you guys will love this. I removed the upper hose and checked the thermostat. The bleeder hole was on the top as it should be but the system was completely dry. So next move crawl under the truck and check freeze plugs. When what to my wandering eye do I see but the lower radiator hose is completely off the radiator. It seems I placed the clamp just below the neck. It looked like it was on the neck but no. So over time it worked its way off and drained my whole cooling system in one swoop. So now that I've made this discovery I have a question that I think I have the answer to. Is it bad that I didn't have any big air pockets and all that was happening were small bubbles? It would slowly bubble down and Id refill it. I think the gaskets went or worse. I changed the plugs and did an oil change. The plugs were black from the motor trying to cool the cylinders by dumping more fuel in them. The oil was burned but no water. Sooooo here I am, glad I have another set of heads.
 






Small bubbles while refilling the system aren't necessarily a sign for a blown head gasket. At least no as long as they stop coming up after a while. Try to give the engine some more rpm once you're pretty sure that most of the air has left the system.

If again more bubbles come up and they don't become less, you might actually have blown a gasket... :(

It's too sad that such a small mistake like placing the clamp half an inch out of its proper position can cause so much trouble...
 






Well I drove it tonight. No excessive smoke and it runs fine. But I'm still waiting for the drive to work tomorrow. It seems to be passing bubbles into the overflow bottle. I left a halogen light under the hood as a make shift block heater. Plus there was still a little ice in the bottle. So I'll keep you guys informed.
 






do you have pressure in the system
 






Hey, that sounds a lot better already! :thumbsup:

I'll cross my fingers for you, but I'm quite optimistic you got away with just some extra adrenaline. ;)
 






Billy177 said:
do you have pressure in the system
Yeah I have pressure. I could see the coolant flowing. It runs a little cooler with the 180 thermostat which is okay. I made it to work today and it drives like it always did (before sat.). So Looks like God had his hand in this one. I'm going to keep an eye on things for the next few days. Making sure the levels right and there aren't any leaks. Hey also I found a noise in the engine bay I've been looking for because of this. So double points.
 






[. The plugs were black from the motor trying to cool the cylinders by dumping more fuel in them.

Never heard of that happening. In fact I don't think thats possible. If anything it would make the engine run hotter as your putting more fuel in the cylinders to be burnt. It'd be like pouring gas on a fire to put it out.
Doug
 






[/QUOTE]
Never heard of that happening. In fact I don't think thats possible. If anything it would make the engine run hotter as your putting more fuel in the cylinders to be burnt. It'd be like pouring gas on a fire to put it out.
Doug[/QUOTE]

No it does. Running the cylinders rich will actually cool them down. So they program it to do that if the motor gets hot.
 






that is kind of the oppisate of what happnes the 1st and 2nd gens do not do it but the newest models will actually shut off multiple fuel injectors in an attempt to help cool the engine
 






A rich mixture runs cooler than a lean mixture. There are several anectdotes to validate that. In light planes, the mixture is left full rich during climbout (high power, low airspeeds so little cooling). Then the mixture is leaned (manually). If the plane has exhaust gas temperature (EGT) gauges, the mixture is leaned watching the EGTs rise. When the EGT peaks and starts back down, the mixture is enriched to 75 degrees rich of peak temperature.

Your Bronco runs at stoich (about 14.7 air to fuel ratio) most of the time. This is pretty balanced, neither rich or lean and is the mixture indicated by balanced O2 sensor switching. When you step on the gas, the wide open throttle (WOT) enrichment mode is entered. The engine can only operate near stoich in closed loop (using the O2 sensors) so the engine goes into open loop where the injectors are controlled using input from the MAF. The mixture is enriched at WOT to prevent overheating, to protect the pistons from melting, and to prevent knocking.

That being said, recent cars have a limp home mode for overheating. In this mode, cylinders are enabled and disabled in a round robin fashion keeping 1/2 of the cylinders firing at any given time. They are disabled by not firing the injectors and coil packs for that cylinder. The cams still operate causing just a flush of air through the cylinder when disabled. This does not enlean the mixture, just running a cool air flush through the cylinder.

Bottom line. To cool, run rich (all you could be before COP and sequential injection) or alternate cylinders between running and not.
 



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





Well bad news this morning. I looked in the overflow bottle and found oil floating on the top. So it looks like I was wrong. Seems that one of the head gaskets did go. So now the it looks like some things are going to change. I'm looking into swaping in a 302. :eek: I'm going to need a manual trans and the foot pedals and a few other things. No more lack of power and worrying about the trans blowing. If anyone knows someone with these parts please let me know.
 






Back
Top