Overheating

[Bruce]

I have a1994 Explorer that seems to want to overheat at times so here it goes. Driving down the highway at sustained speeds any where from 60 to 85 temperature is fine but if i stand on it to pass or if im pulling a an uphill grade hard like 6 -10 % grade or more where you have to stand on it pretty hard the engine temp will go way up( driving it with scanner on it will show about 240) but once you level out it will fall back to normal 195 temp. Here's what i have changed in it Radiator(which is 4 core),clutch fan, thermostat 4 times, and radiator cap.

Thanks in advance.

 

[MAKG]

There is no 4 core radiator that fits RBVs.

There is a 2 core.

Is it an automatic transmission? Is the transmission slipping? That can cause overheating. As can a blown water jacket or other leaks.

 

[mjonesjr]

A bad water pump would cause this also.

 

[gotmudd]

A bad water pump would cause this also.

check your water pump, sounds like it's not working right and unless you bought your radiator custom made brand new i would be checking that too, i think someone yanked your chain on that one

 

[rangerbert]

It could be you r temperature sensor. also check your freeze plugs on the block they may be rusted out and leaking coolant. I had this problem one time on a 89 F-150 I owned. I changed every thing related to the overheating problem then I heard about checking the freeze plugs in the block sure enough one was leaking. changed it out didn't have any more overheating problems. Just something else for you to check out.

 

[Bruce]

There is no 4 core radiator that fits RBVs.

There is a 2 core.

There is a 4 core for the 1994 i do have one in there and the old 4 core is in my brothers V8 Ranger.

I failed to mention that i did replace water pump also as i have been chasing this problem for some time. Trans not slipping it pulls to good to be slipping matter fact i threw the stock external cooler away and put in a 28,000 pound cooler with a 9" fan on it. It doesnt seem to be losing coolant anywhere that i can see. Someone told me it may be head gaskets leaking under the hard acceleration, that the fire ring on the head gasket has a tendency to leak.

Thanks for the response. Bruce

I just went out and measured Radiator and its almost 2 1/2 inches thick thats the core.

 

[Big Jim M]

If your head gasket is leaking you will observe the radiator puking it's guts out. I'd be changing the fan clutch. That engine should be running bout 210* with the 195* in it. 240* don't hurt a thing as long as the coolant stays inside the engine NO PART of the engine is too hot.
The only reason the temp is kept at 210* is to keep the coolant inside. If pure ethylene glycol is used (which won't boil until 450*!) constant 260* won't hurt any part of the engine or the lubricating oilneither.
Big JIm

 

[289-tiger-]

94 ranger overheating

I had a similar overheating problem with mine that was cured by replacing my heater core.

I knew my heater core was clogged over the winter months due to lack of full cabin heat but ignored fix until I had time.

Warm weather came and the radiator began to leak, replaced along with all hoses and thermostat and Cooling system sealant. After refilling system at start up a slight gurgling noise could be heard in the passenger side footwell and reminded myself to pull the core before winter.

I began to see strange temperature spikes as you described and diagnosed it a bad thermostat. Second thermostat produced the same results but when I purchased it I reminded myself to buy the heater core. I had heard the gurgling noise of the coolant pushing through the clogged core in the footwell when I refilled the system after replacing the second thermostat. I told myself that "this does not make any sense" but replaced the core and all temperature problems went away plus I have interior heat for winter months.

I do see that the 94 4.0 does not have a coolant shut off valve or bypass in the heating system, perhaps this causes a vapor lock of some kind in the system when the core gets clogged. A former Ford mechanic friend of mine calls them "sediment traps".

I hope this is of help, Good luck.