1994 Ford Ranger Overcooling

[JTX]

I'd change the Tstat first, its a simple thing to change and tstats are designed to stick open when they fail. If yours is stuck open the water wont heat up enough. Another thing to do is when you get a new tstat buy a higher temperature one.

 

[jp50662]

My explorer was doing the same thing, the temp gauge never went past the cold mark, then today it started going up to normal and then to hot, i started noticing a grinding noise. turns out the water pump is bad...weird. but im going to change that tomorrow and see where that gets me.

 

[xyj6p9k4]

Whether your fan is on always should not matter to some degree. The fan and rad only come into play when the thermostat is open and water pump is circulating heat through it. When the engine coolant temp comes down, the thermostat should close and allow the engine to keep hot. You have to monitor your thermostat housing coolant temp sensor area with a heat gun and your upper rad hose as your engine warms up to 195. The rad hose should be cold until it opens, if the thermostat is ok. The cooland temp should drop off after the thermostat opens from the rad circulation. Then close again until the temp comes back up. Put a motorcraft thermostat it. I put three stants in mine. They kept sticking open. Hope this helps.

 

[V8Z]

Mine does the exact same thing, I have the heater core bypassed, so I dont know what kind of heat it puts out. This is on a 99 3 liter. The gauge always reads cold. it gets a little warmer when I drive it but its still cold.

 

[bergie44]

Freezing My A** Off!

My 94 Ford Ranger had the same problem. It was the fan clutch. After replacing it the temp. needle rises to about 1/4 of the way up. I did like you and changed everything, it was driving me crazy.

 

[patarch1]

Hi,
Before I start a new thread, here is my question:
On a 97 ranger with a 3L, each time I start the truck, the fan is on, it gets to normal temp (that is what the guage shows) after 5 good minutes but the fan has been turning all the time.
From what I read in the replies above, the fan shouldn't spin unless the engine needs to be cooled so should I be concerned that my fan turns all the time?
Thanks

 

[BrooklynBay]

Do you have an electric or clutch style fan?

 

[patarch1]

Hi
It is a viscous clutch type. SO far overcooling was not an issue, I am trying to understand how should work.
Thanks

 

[BrooklynBay]

A thermostatic clutch varies the amount of slippage in relation to the temperature. The bi-metal spring tightens as the temperature rises. It should never free spin. This would imply a bad fan clutch.

 

[patarch1]

Thanks for the information, I always had relay activated fans and never clutched ones.
Best.

 

[dangerranger88]

the thermostat has been takein out and not put back in......with that out it wont allow ur truck to heat up.....cuz it has nothing there to stop the flow of water in the block of ur motor.....replace ur thermstat and it will allow it it heat up right

 

[alwaysfixin]

Anyone found a solution yet?

Hi, I've been having this issue with my '94 Ranger since I bought it used. Not a problem 'till it gets cold for real, (like around 20 deg. or less), then it just won't heat up. I have read about similar problems, but no successful fixes that I've heard yet. Has anyone actually beat this problem down?, other than waiting for the weather to warm up?

I have researched this issue a bit and all the answers/guesses seem to fall into a few different categories that I have a hard time thinking it would work and no one has come back to say "yeah, that was it, problem solved".

Thermostat: We've all replaced them already, most of us multiple times. Is there really one brand that works while all others fail? Is that just a Ranger thing? Or are 95% of thermostats sold today just defective?

Temperature sensors: The problem is not that the temp is READING cold, the problem is that it is ACTUALLY cold. Sensors cannot make the coolant actually HOTTER can they?

Coolant Blockage: Failure of the coolant to circulate through the heater core OR past the temp sensor would indicate a MAJOR failure to move heat from the engine to the radiator. Even if the engine somehow managed not to blow up from this condition while it was 20 below, a nice hot summer day should send such an engine right through the hood, would it not? Mine has been exhibiting this overcooling problem for over 100,000 miles and that has included a number of Texas summers during which it ran nice and cool, but at least in the normal range.

Fan/Clutch: It's not the fan. Or the clutch. Any malfunction of the fan system can only move more or less air through the radiator than it should. Coolant temp is regulated by the thermostat, not radiator air flow, right? I should be able to blow a hurricane through the radiator and still maintain the proper coolant temperature. It's not the fan.

It seems like somehow the thermostat is being partially bypassed and it doesn't show up as an issue until it gets cold enough outside that the bypass amount itself is doing all the cooling and then some. I just don't know how yet.

Anyone have any other ideas? Or maybe I've overlooked something? I would love to find a solution to this as there does seem to be a number of vehicles out there with the same problem, and I'm sure it can't be good for the engines to run cold like that. Not to mention a warm ride to work on a cold morning would be nice.

 

[zekew64]

What I'm thinking is that most people have issues with a stuck-open thermostat. I say this because when it comes to coolant flow, if it's constantly flowing, then it will never heat up. The coolant has to stay in the engine for a time until the thermostat opens to cycle warm coolant to the radiator, and at the same time cycle cool coolant to the engine.

To fix this issue, there are three things that need to be checked:

1. Thermostat (all engines)
2. Temprature gauge (yes, they do go bad, after a time; all engines)
3. Temprature sending unit (OBD-II vehicles only, as OBD-II uses the information to more accurately tune your engine through the engine management system so you use less fuel).

If any of these items are not operating in spec, replace them.

To tell if your thermostat is operating properly, start the engine and let it idle. After about 10 to 15 minutes, put your hand on the upper radiator hose. If the thermostat is operating properly, you should feel, through the hose, a rush of fluid as the coolant cycles, as well as the hose itself becoming warm, if not hot.

To tell if your temp gauge is operating correctly, test whether or not there is power coming to the gauge from the temprature sending unit. If there is no power coming to the gauge, test for power at the sending unit. If there is power at the unit, replace the gauge. If the sending unit has no power, repair the circuit first and retest. If the circuit has been fixed and there is no power still, replace the sending unit (making sure that it works). If the gauge still doesn't work, in that it doesn't rise, replace the gauge. Also make sure that the ground(s) for the temprature gauge circuit and sensor is good as well; otherwise there is no path for power to return to the battery.