# Ford Ranger Thermostat Problem?



## Clutchcargo

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.


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## suzikg

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


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## DrDave

_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.


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## UBoiler

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


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## DrDave

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.


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## UBoiler

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


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## suzikg

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


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## suzikg

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


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## slayer09

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


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## newbsauce

slayer09 said:


> 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.


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## Clutchshiftburn

*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.


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## meatmonster

*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???


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## polarzak

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.


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## Tboneb

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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## Joe Tilghman

*Price shopping*

For those of you price shopping give rockauto.com a try. I bought a thermostat housing, gaskets and thermostat for a Sport Trac came to about $49 with shipping. housing was genuine Ford parts. The dealer was $200 plus. I ordered my parts sta. afternoon and got them Monday night FedEx Ground.


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## em4

*Ford Ranger '96 brown sludge in the radiator*

I know this is an old post, but am looking for some insight into the Ranger cooling system. 

Like an older post, I've noticed the temperature gauge doesn't get much higher than the very lowest level on the gauge. When I sit and idle in traffic, the gauge begins to slowly creep up - nowhere near overheating. And even if the engine is hot, I can turn the cab heat on, and it will blow cool. 

Adding coolant makes a world of difference  when adding coolant I noticed there is thick brown sludge near the cap, and I'm assuming in the radiator in other places too. 

What causes this sludge ? Last November I had the thermostat housing & thermostat changed because it was leaking. They told me at the time, that the housing is caste aluminum and if there is any imperfection it will begin to leak over time. The leak, or letting air into the system causes the sludge. But I don't know - is that just another line in the mechanics vast repetoire of bs lines ??  

It is a 1996 with 209k on it - before changing the thermostat housing, & thermostat, there was never a problem with the cooling system or internal heat. It was extremely reliable, always predictable on the engine temperature gauge. Plenty of defrost and cab heat. 

Also, the same mechanics said all the hoses were getting old and would soon need replacement. They said it would be expensive to replace the hoses. really!?!?! Hoses are that expensive ??? 

What causes the sludge ? any other pointers ?


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## ratherbefishin'

Oil mixing with coolant. Bad intake manifold gasket and/or head gasket.


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## em4

Wouldn't the oil also look strange ? It looks perfectly normal. Like the day it was filled. 

thanks .


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## cjm94

Did they put leak stop in with the repair that will turn the coolant brown and plug the Heater core


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## Maintenance 6

When you replaced the thermostat, did you flush the cooling system and replace the coolant with fresh stuff? The corrosion inhibitors in anti-freeze don't last forever. And if you buy the cheapest anti-freeze you can find, it's a good bet that the one place they'll skimp is in the corrosion inhibitors. Drain the coolant, give it a good flush and refill with some decent quality anti-freeze mixed properly and see if the brown stuff doesn't go away. Oil getting into the cooling system would show up as milky white oily deposits floating in the coolant. Brown sludge is rust and corrosion from the iron parts of the engine. It's also hard on an engine operating it in a cold condition. If the thermostat is stuck open, you need to get it fixed as soon as you can.


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## eric woodall

suzikg said:


> 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


Just a quick reminder having been a mechanic for 27 years. If your temperature gauge is not getting above cold, check the engine coolant level NOW. I do not mean just the overflow jug. The coolant level needs to be checked in the radiator itself. It may be a faulty thermostat, but it may also be an extremely low coolant level, in which case the gauge will not register properly and could lead to overheating, damaging an engine beyond repair before you know it. Just because the temperature gauge isn't showing an overheat doesn't mean the engine isn't cooking. Gauge will not register if there is no water there for it to sense.


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