93 ford ranger won't heat

Discussion in 'Shop Talk' started by raymilosh, Mar 23, 2010.

  1. raymilosh

    raymilosh Well-Known Member

    Jan 12, 2005
    Hi all,
    So 2 years ago, all of a sudden, DaveO's engine temp gage began reading cool and the heat stopped working very well at all. Barely enough to take the bite out of the air. It's a 93 Ford Ranger with a 4 cyl, 3.0 L with 370 K miles on it (It is all original cept for the clutch, runs fine and it still doesn't burn oil)
    Two years ago, we replaced both temp sensors, flushed the radiator and the heater core with water and compressed air, replaced the water pump and the thermostat, checked the operation of the thermostat in a pot of water, checked that all hoses were unrestricted and that flow through the heater core was unrestricted. the heat didn't work unless the radiator hose was clamped shut. It would work a little better with cardboard in front of the radiator. Of course it used to work just fine and suddenly stopped working, so it should work jsut fine without any need for weird modifications.

    Last weekend, we needed to change the timing belt, so while we were in there, we re-replaced the water pump and thermostat with motorcraft brand stuff, we checked the operation of the thermostat in a pot of water, replaced the radiator and burped the system very very carefully and thoroughly using a funnel mounted to the top of the radiator (with the front end jacked up and the engine repeatedly revved and heated and cooled and reheated to get out all the air. Air came out for a long long time

    The heat works marginally now, but not like it should. the engine temp gage is reading cool, too.

    I am completely baffled.
  2. Ray

    Ray Well-Known Member

    Dec 5, 2002
    I'll ramble in my mind a little here, going through some trouble shooting steps you probably already know, but here goes. Like you said make sure thermostat is good, check engine flow, check to make sure heater core isn't plugged, make sure mechanical controls, pneumatics or what ever operates diversion doors to control flow of air is working correctly. some are electronic and are by wire, ( computer electronics), some used to have a pull wire like the lawn mowers use for gas, some are pneumatic, or vacuum. I would look at the heater core, last as the rest are pretty easy, then you can take the hot feed hose and hook a garden hose to it and take the return hose off and see if water flows through well. this will also help flush it out if it is partially plugged. you can pick up a flush kit at wally world cheap. if every thing turns out ok you can get a higher temp thermostat. some people put low temp thermostats in where some cars are meant to run on higher temps and just plane run better at the high temperatures, but you can check the book and find out what temp. thermostat your vehicle is recommended to run at, and get that temperature thermostat, put in it, best wishes ray
    Last edited: Mar 23, 2010

  3. agmantoo

    agmantoo agmantoo Supporter

    May 22, 2003
    Zone 7
    You are going back in year model to where some of the Fords had a vacuum operated valve out near the front of the vehicle on the passenger side. If that vacuum link leaks or if the vehicle has weak vacuum you will not get much heat as the water flow is restricted. Does the heater work best at idle or low speed? That is an indicator of the problem I am referencing.

  4. seagullplayer

    seagullplayer Well-Known Member

    Nov 6, 2008
    Southern Indiana
    I had a Ranger of the same make and year, my brother still owns it.

    The water pump gave up the ghost as I pulled into the parking lot at work one morning. So I took it to a repair shop just yards from the factory to get it replaced.
    The heat always worked great before the change, really good, I had the truck three years, after the new pump it never worked right.
    I gave the truck to my brother shortly after.

    Over the years he has replaced the water pump, thermostate and it has a new heater core, he ever replaced the hoses. He still complains about no heat! I agree, it takes forever getting the air out of this system.

    If you figure it out, please be sure and post about it, I will let him know. He still drives the truck to work everyday, he hates it in the winter!

    He has an electric defrost unit he plugs in to keep the windows clean in the coolest weather.

    BTW: You might try your question here:


    I never asked about this problem after I gave him the truck, but they where a help with a couple of other issues.
    Last edited: Mar 24, 2010