Fan runs when the engine is cold
 

Hi guys,

Looking for some help, if you could, with my 1991 Ford Ranger 2.3L 5spd.

It runs but:
- doesn't get to operating temperature
- doesn't produce heat
- doesn't move the coolant temperature gauge into the operating range (well maybe barely in range)
- doesn't shut the cooling fan off when the engine is cold per coolant temperature gauge

A few years back and not many miles (this is the Home Depot truck and not much more as it has no ac, no head restraints, no radio ...), I replaced the engine temperature sensor to correct a smog test failure (very high HC). Can't recall if I did the t-stat or the coolant temperature sensor.

Now, I'm thinking it is the fan clutch but am open to other ideas.

Never done a fan clutch as the coolant fans on my other cars (Subarus) are electrically driven and switched.

Easy enough for someone who likes doing jobs like radiators, alternators, and spark plugs? (Well, it is a stretch to say I like doing the plugs on this 8 plug 4 cylinder ...)

Thanks a bunch. I need to smog this car again yesterday and I'm not sure it will pass if it won't reach temperature.

I do have the weird old computer reader for this vehicle if there is something useful I might check.

Thanks.

Welcome to the forum

The 2.3l Lima engines don't warm up real well, they are a very heavy engine, 400+ pounds, so lots of metal to heat up, and keep warm
Many use cardboard in front of the radiator in Winter months to keep these engines warm, AND the HEATER WORKING!!!
Radiator is usually not used in winter, the cardboard is to stop the COLD AIR from blowing into engine bay
You probably have noticed Semi-Trucks use zippered grill covers in your area during the winter, same reason, to keep engine bay warmer

Fan clutch is easy to test
After engine sat over night(5+ hours) open the hood
Spin the fan, it should be Cold Locked now and barely spin
Start the engine, count to 15, shut off the engine
Spin the fan again, should now be unLocked and spin easily
If not replace fan clutch
There is a Wrench Set(2) for doing this, they can often be rented
Or you can devise other methods with the tools you have on hand

Google: removing ford fan clutch
Loads of ideas

Thermostat test
Start cold engine
Feel the heater hoses at the Firewall
Feel the upper rad hose
All Cold of course

Let engine idle 3 or 4 minutes
Feel hoses again
Heater hoses SHOULD BE warming up to the touch
Upper rad hose should still be COLD as the first time
If upper rad hose is warming up then thermostat is stuck open, they are suppose to fail that way, OPEN, so engine can't over heat

If you change thermostat use 192 to 195degF model NOT 180degF
When you refill a cooling system always remove BOTH heater hoses at the firewall, then refill, the hose will let the air out of the engine
Then REVERSE the two hoses at the firewall when you put them back on, this reverses the flow thru the heater core and will keep it cleaner, should do the Reversal every two years on ANY vehicle

The dash temp gauge uses a 12volt temp SENDER, it is located on drivers side of engine toward the back
Drawing here: https://www.autozone.com/znetrgs/rep...5280077d27.jpg
Under the oil pressure unit

The computer uses a 5volt Sensor, the ECT sensor

Because of the location of the temp gauge sender it shows a bit lower temp that it should, most temp sender are located at the top front of the engine where coolant is the warmest
But after driving for 5 to 8min it should show above 1/3 on the temp gauge