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suzikg 12-16-2007 08:43 AM

Ford Ranger Thermostat Problem?
I have a 93 Ranger (205K miles on it) & a couple of weeks ago I noticed the temperature gauge on the dash was not coming up...staying all the way below the "Cold" mark. Thought the problem might just be the gauge but with the weather turning cold I've noticed that the heater is not putting out like it should.

Some days the heater seems to work well and the gauge registers a little above the C but not where it usually was & some days neither seem to work. Could this be a thermostat sticking? I have a backyard mechanic I am going to call & visit this week & would like to get some suggestions before I take the truck in to him. Don't want to get taken for a ride.

I have no doubt that if it is a thermostat problem, it may need to be replaced. Major or minor $$$ on my make & model???

Any suggestions will be greatly appreciated.

suzi g

Clutchcargo 12-16-2007 09:08 AM

63 Attachment(s)
It might be the thermostat but when you don't get heat to the heater core, it could be that the coolant is running low.

suzikg 12-16-2007 11:29 AM

so it could be as simple as the coolant? i'm going to borrow a tester today and check it out. i had the water pump go out a couple of years ago and that's the last time the system was serviced.

i found this blurb on the net while researching the problem...

"The heater core draws its hot coolant from the cylinder head and returns it to the pump -- so the heater works regardless of whether the thermostat is open or closed."

is that true? if so, it sounds like it would not be the thermostat. i am going to deal with this tomorrow but what are the consequences/damages of driving around like this for the past 2 weeks. i know that overheating is serious but how about underheating? other than the fluid freezing while sitting overnight, expanding & YIKES...not cold enough for that right now.

thanks so much,

suzi g

DrDave 12-16-2007 12:13 PM

Make sure your engine is cold when you do this!
Open both the overflow tank, if it has one, and the radiator cap to check the coolant level. The radiator should be almost full and the overflow tank should be full to the COLD level mark on the side of it.

If these are not up to those levels, then fill them as instructed, put the caps back on and take it for a short ride to see if your gage is showing the temperature rising to where it normally is (about 195 to 210 degrees). If the temperature doesn't indicate on the gage, take it to a trusted mechanic to have it evaluated. An estimate should be free.

If you are female, take a male firend with you and you will get a more honest quote. My wife, before we were married got taken advantage of every time she took her car in for an oil change. They got her for oil plugs, oil pans and other stuff every time.

UBoiler 12-16-2007 08:21 PM

If it were my truck I'd check the coolant level. Then I'd look at my weep hole on my water pump just to be sure it isn't dripping (dripping from the weep hole means it's failing). Then I'd replace the thermostat. Those days of checking a thermostat by putting it in 180 degree water or 196 degree water to see if it opens are long gone. If I go through the little trouble of pulling a thermostat I just replace it with new. And I don't have a shelf for broken parts. My 96 Ranger with the 4 cylinder had a thermostat that also included a housing. So instead of buying just a simple thermostat with a gasket for $7 - 10 the part at my best price was $25 - 30. If you price from a dealership or a NAPA store be sure to ask if there is any way you can get a little help on the price. Be sure to call around for best pricing unless you are money-tree-horticulturist. Send me a cutting. That person just ahead of you or just now walking inthe door would get that exact part for 10-40% less by asking for a discount. When you find a supplier that'll help you with price you be sure to give them your business and steer your friends to shop there. They don't have to be nice. Simple part with just 2 bolts to remove. Sounds like you have a shade tree mechanic buddy that could help you out by showing you where your thermostat is and if you can replace a light bulb, I'm confident you can replace thermostat yourself. Be sure to work on it when it's cool and control the coolant you drain so something doesn't come along and drink it. Apparently it tastes sweet and it is definately a danger to ingest. Good luck. Cliff I

DrDave 12-16-2007 08:45 PM

Uboiler makes 2 good points. NAPA told me the other day a hose I needed was $33.98, I told them to search my address (my son does auto repair) and the price dropped to $20.39. Funny part is it was under my wifes name.

The other point is the coolant, cats and dogs will drink it and it will kill them.

UBoiler 12-16-2007 09:21 PM

Dr Dave I've had parts guys at dealerships give me their discount. I've had a store manager pull up all the different discount codes and tell me an airline gets extraordinary discount on electrical parts and whenever you come in to my store give this certain account code tell any clerk it's a cash only sale and you will never find that item cheaper in any store. LOL And he was right. And sometimes I can not get any discount and I cut my losses, buy the part , and get it done. Good lluck. Cliff

suzikg 12-18-2007 08:06 AM

thanks for the responses. i tested the coolant & it is registering at minus 34F. the water pump is not leaking. i've been through that scenario already a couple of years ago and had it replaced.

so, i guess i'm off to go get a thermostat. i'll post again after that is replaced.

thanks again!

suzi g

suzikg 12-20-2007 04:19 PM

Thanks to everyone for responding to my post :thumbsup:

It WAS the thermostat & I got the part & the gasket for under $10 including tax. Had to replace some of the coolant that came out during the interchange, but all-in-all a very cheap fix.

It's in and working like a charm and my heater is blasting me out. No more freezing fingers and toes :no: :no:

Y'all are the best :yes: thanks for all the tips & a very merry "everything" to you and yours this holiday season!!!

suzi g

slayer09 07-29-2009 11:33 PM

Jesus! Where the heck do u live? I had to replace mine and costed me 283 after labor was included

newbsauce 07-30-2009 02:09 PM


Originally Posted by slayer09 (Post 308440)
Jesus! Where the heck do u live? I had to replace mine and costed me 283 after labor was included

OEM thermo for me, 60 bucks..the aftermarket unit, 20. You probably paid 2 hours of labor.

To the OP: You are very fortunate, when my thermo stuck closed, it caused crazy overheating. I'm assuming yours was stuck open.

Clutchshiftburn 12-03-2009 08:26 PM

a number of things
so you have heat on and off and your gauge goes haywire, well this could be caused by a number of things,,,and to answer your question about the heater core,,no if the coolant is not circulating through the core than u will not have heat and it will cause your gauge to fluctuate and may cause a gasket issue. but if it were me i would start with a thermastat OEM and if that doesnt work the temp gauge sending unit which is measuring the amount of coolant and the temp it is at if thats reading wrong than its tell your engine to give more gas to heat the engine up,,,,the worse case scenerio is a blown head gasket u can tell if the oil is milky or if there is leaking coming from the heads, or white smoke coming from the tailpipe which is your coolant burning through the exhaust. also make sure when ever you break the seal on your coolant system you must burp it properly to get all air bubbles out.

meatmonster 12-05-2011 12:21 AM

similar problem
So i have a 94 ranger and heat won't kick on I feel the engine and gets warm biting cold season takes longer for temp to read normal. Could it be thermostat or maybe even heater vote and when do you know when heater core us bad???

polarzak 12-05-2011 05:30 AM

Wow. You have resurrected an old post.
You could have the same problem as the original poster.....a bad thermostat.
Newer thermostats usually fail in the open position, thereby not allowing the coolant to remain in the engine long enough to heat up, therefore little or no heat.
First check if you have sufficient coolant in the vehicle. If so, go to Step 2.
Step 2. Change thermostat

Heater cores are "bad" when they become clogged or when they leak. Nothing else goes wrong with them. If you do not have a leak (sweet smell or fogging on the inside windshield) the core "could" be clogged. You could check the output and see if you get a good stream out. Careful, it could be hot.

Tboneb 01-24-2012 06:04 PM

I have a 2000 Ranger. I by passed the Heater coil today. Now the Tempature guage is bottomed out below C. I drove about 30-40 minutes and never came up. Any ideas?

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