overheating...or temp guage problem. 1994 X

[backfrmcolorado]

Ok so it just started today...driveing down the road my twmp guage spiked all the way to the L of normal then back to halfway and finaly down to the N where the guage normaly is.Both the upper and lower hoses are hard when the truck is running with plenty of pressure and the coolent is full in the radiator but empty in the overflow res. Does anyone have any ideas on what this problem could be. Im about 250 miles from home for the weekend and have to drive home today. Anyone please help.... Thank you.

 

[Roadrunner777]

Your immediate problem is that you are low on coolant. Make sure it's not going into the oil pan (check dip stick for contamination). Buy a couple of jugs of 50/50 coolant and top it off. Every 20-30 minutes, pull off and top off the overflow until you get home. Might not hurt to have a cell phone and a friend on stand-by.

The next question is: Where is the coolant going to? If it's leaking, you will figure it out soon enough. If it is not leaking out, it is leaking... 'in', either to the oil pan or a cylinder.

Get yourself home first, that's all I would worry about for now.

 

[backfrmcolorado]

Thats the thing tho...there is no leak. No coolent in oil, no smoke out the exhaust pipe or anything like that.i have a grill thermometer in the radiator and it shows 145 and my dash guage shows high orr above the M of normal.

 

[94Eddie]

I had an issue with my '94 Explorer losing coolant and not being able to track down where the leak was located. One day I found out the hard way when all the coolant dumped out at once. It was a plastic piece up near the firewall where the heater hose connection is located. This piece routed coolant to the heater core and I think it had some sort of valve built into it to send excess coolant back to the main coolant lines.

It looked to me that enough hose vibration over time cracked the hose nipple connection from the main body. It had a slow leak for a very long time and it dripped near the passenger side exhaust manifold and evaporated the coolant before it could dip to the ground. When the engine cooled it didn't leak at all. You might want to check this because when it really goes out you will be stranded where it happened. You can't keep fluid in the cooling system long enough to go anywhere.

 

[Maniak]

I had an issue with my '94 Explorer losing coolant and not being able to track down where the leak was located. One day I found out the hard way when all the coolant dumped out at once. It was a plastic piece up near the firewall where the heater hose connection is located. This piece routed coolant to the heater core and I think it had some sort of valve built into it to send excess coolant back to the main coolant lines.

It looked to me that enough hose vibration over time cracked the hose nipple connection from the main body. It had a slow leak for a very long time and it dripped near the passenger side exhaust manifold and evaporated the coolant before it could dip to the ground. When the engine cooled it didn't leak at all. You might want to check this because when it really goes out you will be stranded where it happened. You can't keep fluid in the cooling system long enough to go anywhere.

That piece is called a heater control bypass valve, and started to come on 1st gen explorers around 1994, although some of us earlier 1st gen owners have added that to help the a/c work better.

~Mark

 

[backfrmcolorado]

Thanks for the knowledge guys....yeah i just recently fell upon that heater hose thing the hard way last winter. But i just got done putting in a new thermostat and temp sensor. Went thru burped the system added fresh coolent and some additive that says it lowers temp by 20*. So far it seems to be the fix....ill find out as soon as i get a few miles down the EWay. Sorry for any typeos or bad spelling...im in a parking lot useing my androiid phone. Ill post back my results when i get home or if something happens

 

[Anime]

Sounds like it might have just been an air bubble in the system from being low on coolant. When an air bubble gets trapped behind the thermostat, it blocks the flow of coolant since the air making contact isn't enough to get the wax in the 'stat to melt and have it open. If some coolant gets by the air bubble, it can "pop" it once the 'stat opens just a bit, and coolant goes rushing through as normal. This is why the gauge would go higher than normal, and then suddenly drop back lower than normal temp as well.

In the worst case, the air bubble never breaks, the 'stat never opens, and the temp gauge needle skyrockets, while the motor overheats and pressure builds up in the system to the point it overflows the coolant reservoir with boiling coolant.

You probably would have been ok just topping off the coolant and/or burping the system to be sure no air was trapped, but better safe than sorry. A new 'stat and coolant with a purged system should solve any issues, or at least let you know any issues are something else.

 

[backfrmcolorado]

Yeah....so far so good. It only cost me $40 for new stat,stat gasket,jug of 50/50, temp sending unit and the super cool coolent additive. Its running nice and cool now. Let me tell ya...it was a very uncomfortable feeling being that far from home and have to fix it or breakdown.

 

[mr cribb]

I had a similar problem when I first got mine. Pretty much same symptoms. Fortunately it was winter time and there was zero heat. My prob was the heater core. Spent $23 and it fixed everything.

So I guess it's kind of a back of the mind thought if your issue persists.

 

[rustbucketMI]

maybe a stupid question was the the coolant res. bottle and rad filled when you started? Wouldn't surprise me if you started out a little low on coolant.

 

[backfrmcolorado]

The rad was full but the res has a small leak. Need to get a new one eventualy lol