2.3L ('83-'97) Coolant temp question

[mdiiorio]

Hello I just have a general question.
I have a 1995 Ranger XLT 4 cylinder 2.3l, and I recently replaced the thermostat due to the old one being stuck open and the engine not heating up very fast or blowing hot air properly with the heat on. I also replaced the coolant temp sensor due to accidentally breaking the old one during replacement.
With the new thermostat it is blowing hot air great now and the engine heats up much better, but sometimes the needle goes up above the symbol in the middle of the gauge. It never goes more than 3/4 of the way up the gauge, and when it does go up it never stays there long and always moves back down to the middle pretty quickly, within 10 seconds. Goes up and down pretty predictably while driving and does it much less with the heat on. Drives great, still getting about 25 mpg on every fill up, and no engine codes. Is this movement of the needle normal with this truck?
For the record I changed the coolant and burped it before driving.
Thanks,
Mike

 

[RonD]

Your heater core is getting clogged up

Reverse the hoses for heater core at the firewall to reverse the direction of the flow thru the core, that might clean it out(back flush) enough so it doesn't do that up and down thing on temp gauge

You pretty much have to pull the whole dash out to change the heater core on 1995 and up Rangers

 

[mdiiorio]

Your heater core is getting clogged up

Reverse the hoses for heater core at the firewall to reverse the direction of the flow thru the core, that might clean it out(back flush) enough so it doesn't do that up and down thing on temp gauge

You pretty much have to pull the whole dash out to change the heater core on 1995 and up Rangers

thank you for the response. Would you recommend flushing the core first with a garden hose before swapping the hoses? And my heat does blow very hot and seems to be functioning very well, you’re saying it could still be the heater core getting clogged? Only reason I ask is because almost everyone I’ve ever talked to with a clogged heater core has had loss of heat or no heat when turning it on.
Thanks

 

[Dirtman]

@RonD is the resident genius. He knows all.

What you are describing to me sounds like typical example of the thermostat opening and closing like it should. Temp should increase, thermostat opens, then temp drops fairly quick, then the thermostat closes, and repeat. Just normal engine operation. It should never get "high" but up and down is normal.

Is the new thermostat the same temperature rating as the old one? They do come in different varieties. The thermostat controls how hot the engine gets before it opens, so a higher temp thermostat will obviously cause the gauge to go up farther. Stock temp is usually 195 there abouts. If the previous owner had a 180 degree or 160 thermostat in there and you just replaced it with an OEM one, the guage is gonna read higher.

 

[mdiiorio]

@RonD is the resident genius. He knows all.

What you are describing to me sounds like typical example of the thermostat opening and closing like it should. Temp should increase, thermostat opens, then temp drops fairly quick, then the thermostat closes, and repeat. Just normal engine operation. It should never get "high" but up and down is normal.

Is the new thermostat the same temperature rating as the old one? They do come in different varieties.

the new one is rated at 192. And yes it never does get high, if my heat is turned off the highest is gets is maybe 70% up the gauge, but it quickly goes back to the center when the thermostat opens and repeats this pattern during driving, more pronounced when it is hot outside. Most of the vehicles I’ve owned seem to stick like glue somewhere around the center of the gauge, maybe this one is just different. I’ll definitely try swapping the hoses at the firewall and see if that makes any difference.

 

[Dirtman]

If its never been done, a garden hose in the heater core is not a bad idea before hooking it back up in reverse like Ron said. It'll clean it but also let you see if a bunch of gunk comes out so you can verify that it was clogged up.

 

[RonD]

Yes, you can back flush with garden hose, first find out which hose at the firewall is IN and which is OUT
After engine is warm and heat is working, feel each hose, the IN will be warmer that the OUT
Flush with garden hose on the OUT first, that will push any larger "bits" out the way they came in
Then you can flush in both directions

You should reverse heater hoses on ANY vehicle, every 2 years, it will make the cores last longer

The two heater hoses, one from upper front of engine(the OUT) and one from water pump(the Return) are the by pass for circulation when thermostat is closed

So there always needs to be good flow thru these hose
There is often a By pass valve, only used for MAX AC, to cut flow thru heater core BUT maintain full flow between the two hoses

You can still get good heat unless core is almost fully blocked but the up and down temp gauge can show up with partial blockage
What happens is as Dirtman described, as flow slows thru heater hoses and temp gauge goes up, thermostat responds buy opening up more, so gauge goes down, then repeat.................

"Good heat" is also a relative temperature, lol, based on previous heat and outside temp
At 30degF outside, heater with 120degF is HOT, where it should be 190degF, operating temp

 

[mdiiorio]

Update: Flushed the heater core and it was very clean, water came out as clean as it went in. Swapped the hoses and no difference. Not sure what it could be at this point. Some are telling me that some movement on the needle is normal. Every other car I’ve owned though it seems to come right around the middle and stick like it’s glued there. Any other ideas on what it could be?

 

[RonD]

Maybe its the sender itself, its just a variable resistor that changes resistance by heating it up, gauge reflects that resistance

Yes, Ranger temp should run just under 1/2 after full warm up, 185-195degF, center of gauge is approx. 200degF

Just out of curiosity feel the heat coming out of the heater when gauge starts to go up above 1/2 to see if its an actual increase in coolant temp(air gets hotter) or just a gauge malfunction

 

[mdiiorio]

Maybe its the sender itself, its just a variable resistor that changes resistance by heating it up, gauge reflects that resistance

Yes, Ranger temp should run just under 1/2 after full warm up, 185-195degF, center of gauge is approx. 200degF

Just out of curiosity feel the heat coming out of the heater when gauge starts to go up above 1/2 to see if its an actual increase in coolant temp(air gets hotter) or just a gauge malfunction

I feel the heat it doesn’t seem to get any hotter once the car is heated up, regardless of where the needle moves to, so it might just be the gauge...if the car overheats or the coolant is consistently getting too hot it should trigger an engine code right?

 

[RonD]

No, there is no "Temp" code, as far as the gauge goes, there is a Check Gauge light for high temp, or low oil or fuel on some years

If air temp doesn't change when temp gauge shows above 1/2 then I would change the SENDER on the engine
There are two different ones
ECT sensor, 5volt, only used by the computer, always 2 wires
Temp sender, 12volt, only used by dash board gauge, in 1995 should have 1 wire, a red/white wire

On a 1995 2.3l it should be on drivers side of block at the rear by bellhousing, seen here: https://cimg4.ibsrv.net/gimg/www.ranger-forums.com-vbulletin/500x441/0996b43f8021b7e1_d3c13ce3af4920cf917bb86d6913e996a27c731c.gif

Do NOT use tape on the threads, it needs a good a ground to engine block, via the metal threads
Make sure you get a SENDER, most places will give you a "sensor"

 

[franklin2]

Update: Flushed the heater core and it was very clean, water came out as clean as it went in. Swapped the hoses and no difference. Not sure what it could be at this point. Some are telling me that some movement on the needle is normal. Every other car I’ve owned though it seems to come right around the middle and stick like it’s glued there. Any other ideas on what it could be?

Bouncing of the gauge is normal, especially in the winter when it's cold. The thermostat is closed, the engine is warming up, and it warms up enough to open the thermostat. That suddenly pushes a bunch of cold coolant that has been out in the radiator into the engine and that makes the thermostat shut. Then this cycle happens again and again. The colder it is outside,, the more it does it, since the coolant in the radiator is very cold. It will eventually even out in some middle temperature.

Most of the thermostats I have used will let the engine go above the thermostat temp some before they open. And then let it drop a little low before closing. So if you watch the gauge in the winter, you can make a good guess after awhile where your thermostat temp is in the "normal" range on the gauge. Or if you really want to know what is going on, buy a aftermarket gauge with numbers on it. I have never liked Ford gauges, they never put numbers on them.

 

[Jazzer]

It may be that you still have air pockets running through the coolant system. I seem to remember reading that because air doesn’t absorb heat as rapidly as coolant does, that the coolant film in the air pockets can steam up, and if they go past the temp sensor, they can bounce the temp needle. Are you keeping an eye on your coolant level? I had some mild temp needle spiking after I last replaced my coolant. It took about a week to settle down, and I added coolant as necessary.

-Jazzer

 

[mdiiorio]

It may be that you still have air pockets running through the coolant system. I seem to remember reading that because air doesn’t absorb heat as rapidly as coolant does, that the coolant film in the air pockets can steam up, and if they go past the temp sensor, they can bounce the temp needle. Are you keeping an eye on your coolant level? I had some mild temp needle spiking after I last replaced my coolant. It took about a week to settle down, and I added coolant as necessary.

-Jazzer
[/QUOTE
I thought it was air bubbles at first so the first thing I tried doing was burping it again, I’m not loosing any coolant at all and when I burp it the level in the radiator and overflow reservoir remains exactly the same. It’s been doing this for over a month and my coolant level has been perfect...never overheats though...

 

[Jazzer]

Just out of curiosity, what was the brand of thermostat you used?
Rangers, at least the 2.3’s, really really like Motorcraft thermostats.

-Jazzer