Troubleshooting car underheating

[0]

There is one thing that wasn't mentioned yet, and could be a possibility. I had a similar problem with my 95 Transport. The cooling system has to be 'burped' to get all the trapped air out of it to work properly. Many coolant systems today can get air in them, especially since you had the thermostat housing out. The way I burped mine to get all the air out was to elevate the front end with ramps, and then open the radiator cap and top off. By elevating, all the air moves to the highest spot in the cooling system, and is allowed to release to atmosphere. Perhaps that might be it?

 

[KK]

Originally posted by: Black88GTA

Originally posted by: KK

Originally posted by: drum
I have a 94 ranger with 133k miles too :shocked:
I was going to say thermostat or coolant problem but you've obviously eliminated that.
I had trouble with overheating last summer and put an aftermarket radiator in which fixed it, but your problem is obviously opposite.
do you have the 3 or 4 litre?

3 or 4 litre, I wish. 2.3L

My 92 Mustang had the same motor, and oddly enough, the exact same problem as yours - temp gauge staying much lower than normal, very little heat. The cause of mine was very obvious when I opened the thermostat housing...the thermostat had split and was in a number of pieces, causing unchecked flow of coolant and not allowing it to reach proper operating temp. That's why I originally thought it was the thermostat (I'm still not 100% convinced that's not it )

I wouldn't completely rule out the new thermostat either but it's seems like by the fluctuation its working somewhat. Maybe the rubber gasket that goes around it is not completely sealing it, allowing some water to bypass it. I dunno.

I also noticed that since this started my gas mileage has gone down to around 290 miles per tank(~14-15 gallon fill up) from a normal tank mileage of 320-330. It's never got under 300 before this episode.

 

[KK]

Originally posted by: funboy42
Im guessing since you replaced your thermo, and assuming fluids are topped off that it is one of 2 things.

Electric fan is on all the time if so equipped or clutch on bolted on fan is not operating properly and it sucking it too much air through the radiator cooling it off to much.

If electric just start the truck and if the fan is on all the time, well there you go, it shouldn't, it needs to only come on once and a while.

If a bolted on fan to the engine when you start the truck is it really loud and making a loud whooshing sound all the time when you give it gas, if so the fluid in the clutch is worn out and the clutch is not letting the fan "relax" and the whooshing sound is it really sucking the air through the radiator. These are the only two things that would come to mind since your saying your temp gage isnt reading in the norm like it used to and the heat coming out isn't as hot, meaning the coolant is getting cooled off too much and only thing going to do that is the fan and air passing through it since its really not sub zero out where your at.

The fan has a thermal fan clutch. should it be spinning all the time? I looked on rockauto and their price for that is around 52 for the clutch assembly. I hope that isn't the problem. Also if that was the trouble would that keep the engine that much cooler than going down the road 55MPH?

 

[Black88GTA]

Originally posted by: KK

Originally posted by: Black88GTA

Originally posted by: KK

Originally posted by: drum
I have a 94 ranger with 133k miles too :shocked:
I was going to say thermostat or coolant problem but you've obviously eliminated that.
I had trouble with overheating last summer and put an aftermarket radiator in which fixed it, but your problem is obviously opposite.
do you have the 3 or 4 litre?

3 or 4 litre, I wish. 2.3L

My 92 Mustang had the same motor, and oddly enough, the exact same problem as yours - temp gauge staying much lower than normal, very little heat. The cause of mine was very obvious when I opened the thermostat housing...the thermostat had split and was in a number of pieces, causing unchecked flow of coolant and not allowing it to reach proper operating temp. That's why I originally thought it was the thermostat (I'm still not 100% convinced that's not it )

I wouldn't completely rule out the new thermostat either but it's seems like by the fluctuation its working somewhat. Maybe the rubber gasket that goes around it is not completely sealing it, allowing some water to bypass it. I dunno.

I also noticed that since this started my gas mileage has gone down to around 290 miles per tank(~14-15 gallon fill up) from a normal tank mileage of 320-330. It's never got under 300 before this episode.

Mine did the same thing. The car is designed to operate at ~195 F or so, regulated by the thermostat. If kept significantly below that, the tolerances in the engine close up a little, causing the motor to have to work a bit harder for the same power output. This causes a drop in mileage.

Interesting though...this means that your heater core is probably not the problem, since blocked coolant flow through only this part would not cause the drop in mileage. From what you are describing, it seems like the coolant is just not reaching the proper temp. I would really take another look at the thermostat and that gasket, make sure it's sealed properly, etc. You can test it by putting it in hot water on your stove and boiling it. Watch it, and check the temperature at which it opens with a thermometer. If it opens between 180 - 200 F or so, it's probably good. If it opens way too early, or not at all, then you've found what's wrong.

Your gas mileage will return to normal once the problem is fixed.

 

[KK]

Originally posted by: 0
There is one thing that wasn't mentioned yet, and could be a possibility. I had a similar problem with my 95 Transport. The cooling system has to be 'burped' to get all the trapped air out of it to work properly. Many coolant systems today can get air in them, especially since you had the thermostat housing out. The way I burped mine to get all the air out was to elevate the front end with ramps, and then open the radiator cap and top off. By elevating, all the air moves to the highest spot in the cooling system, and is allowed to release to atmosphere. Perhaps that might be it?

After I drove it back to my house ~10 miles, then to work ~15 miles, i went out to check it 3 hours later and had to fill it alittle as it sucked more into the radiator. I'm not sure if that helped out yet or not.

 

[funboy6942]

Originally posted by: KK

Originally posted by: funboy42
Im guessing since you replaced your thermo, and assuming fluids are topped off that it is one of 2 things.

Electric fan is on all the time if so equipped or clutch on bolted on fan is not operating properly and it sucking it too much air through the radiator cooling it off to much.

If electric just start the truck and if the fan is on all the time, well there you go, it shouldn't, it needs to only come on once and a while.

If a bolted on fan to the engine when you start the truck is it really loud and making a loud whooshing sound all the time when you give it gas, if so the fluid in the clutch is worn out and the clutch is not letting the fan "relax" and the whooshing sound is it really sucking the air through the radiator. These are the only two things that would come to mind since your saying your temp gage isnt reading in the norm like it used to and the heat coming out isn't as hot, meaning the coolant is getting cooled off too much and only thing going to do that is the fan and air passing through it since its really not sub zero out where your at.

The fan has a thermal fan clutch. should it be spinning all the time? I looked on rockauto and their price for that is around 52 for the clutch assembly. I hope that isn't the problem. Also if that was the trouble would that keep the engine that much cooler than going down the road 55MPH?

OK yeah I wasnt sure if it was the bolted on or electric on there, to tired to look. Sometimes the thermal fans go bad, when they do they are either to slow, spins the fan to slow and the engine gets too hot, or to fast and you can tell this because when you give the car gas it kinda roars from the fan area ALL the time, and sure it will keep it cool going down the highway you still sucking more air through it. If you took it off and went done the highway you wouldnt have enough air pass through it, it needs to be pulled through it, hence the fan.

The coils of the radiator are to tight and the wind hitting it from the front would still be like hitting a wall. The fan basically sucks the air through it, or pulls it through it, so without it going down the highway you will still overheat, and why cars overheat going down the highway when the electric fans give out or break the fan belt

 

[KK]

Last night I drove it over to my fathers(~15 minutes) and it did the same thing. Took a meat thermometer to the radiator and it read around 135. Right now I dunno what to look at, I'm leaning towards the thermostat again. the heater core seems fine, the hose going to it is hot, yet the return is cooler, therefore I would think the flow is good. The fan clutch is what my father thinks is the problem as its spinning at a good rpm cold. I just can't see that being the problem. wouldn't keeping the antifreeze cold thru the radiator not affect the engine operating temp, it seems as though the thermostat would close with the cold liquid, thus keeping the engine and heater core hot.

 

[funboy6942]

Originally posted by: KK
Last night I drove it over to my fathers(~15 minutes) and it did the same thing. Took a meat thermometer to the radiator and it read around 135. Right now I dunno what to look at, I'm leaning towards the thermostat again. the heater core seems fine, the hose going to it is hot, yet the return is cooler, therefore I would think the flow is good. The fan clutch is what my father thinks is the problem as its spinning at a good rpm cold. I just can't see that being the problem. wouldn't keeping the antifreeze cold thru the radiator not affect the engine operating temp, it seems as though the thermostat would close with the cold liquid, thus keeping the engine and heater core hot.

Well you just answered your problem I think and what I been saying is the problem and your father agrees upon.

You say the hose to the heater core is hot but the return is cold, you say if the fan was keeping the fluid cold then the thermo would have to shut and keep the engine hot, well yes this is true.

But in order to have hot water go through the system it needs to flow, but it cannot if the radiator is supplying super cold water all the time which means the thermo is always shutting or very close to shutting so the system is not flowing like it should, hence the hot water going into the heater core, and not so hot coming back, also its not flowing as hard as it would if the thermo was wide open. My 88 firebird had a electric fan that ran all the time, had a working thermo in it, yet because the fan always ran it never saw 195 temp, it always registered 180 or just barley depending on how it was outside.

So again I say, your system is working fine but your just cooling off the water too much, and more food for thought, why is there a thermo clutch fan on there is the first place if it wouldnt matter how much air passed through the radiator? Why not make it 1:1 and fvck a clutch its pointless, right? Its not on there so its not loud or called a thermal clutch fan for the hell of it now is it? Its so when the engine gets hotter it spins the fan more to draw more air through the radiator to cool the engine off. Now what happens when that breaks, in cold weather, and your engine is not running hot, and its sucking air through the radiator like mad
Like OH MY GOD!

 

[KK]

Originally posted by: funboy42

Originally posted by: KK
Last night I drove it over to my fathers(~15 minutes) and it did the same thing. Took a meat thermometer to the radiator and it read around 135. Right now I dunno what to look at, I'm leaning towards the thermostat again. the heater core seems fine, the hose going to it is hot, yet the return is cooler, therefore I would think the flow is good. The fan clutch is what my father thinks is the problem as its spinning at a good rpm cold. I just can't see that being the problem. wouldn't keeping the antifreeze cold thru the radiator not affect the engine operating temp, it seems as though the thermostat would close with the cold liquid, thus keeping the engine and heater core hot.

Well you just answered your problem I think and what I been saying is the problem and your father agrees upon.

You say the hose to the heater core is hot but the return is cold, you say if the fan was keeping the fluid cold then the thermo would have to shut and keep the engine hot, well yes this is true.

But in order to have hot water go through the system it needs to flow, but it cannot if the radiator is supplying super cold water all the time which means the thermo is always shutting or very close to shutting so the system is not flowing like it should, hence the hot water going into the heater core, and not so hot coming back, also its not flowing as hard as it would if the thermo was wide open. My 88 firebird had a electric fan that ran all the time, had a working thermo in it, yet because the fan always ran it never saw 195 temp, it always registered 180 or just barley depending on how it was outside.

So again I say, your system is working fine but your just cooling off the water too much, and more food for thought, why is there a thermo clutch fan on there is the first place if it wouldnt matter how much air passed through the radiator? Why not make it 1:1 and fvck a clutch its pointless, right? Its not on there so its not loud or called a thermal clutch fan for the hell of it now is it? Its so when the engine gets hotter it spins the fan more to draw more air through the radiator to cool the engine off. Now what happens when that breaks, in cold weather, and your engine is not running hot, and its sucking air through the radiator like mad
Like OH MY GOD!

I took the fan completely off and ran it around the neighborhood. It did the same thing. The temp gauge never came up to where it should be. I got back home and the hoses were alot hotter than they had been. I took a temp reading and it read around 180. This tells me that the flow across the temperature sensor is restricted. There are two hose going to the heater core and 1 of them is as hot as the main hose going to the thermostat and the other hose is a fair bit cool, it still warm, just not as hot. The temp sensor is on the cooler hose, which I'm guessing is the return from the heater core. I guess I'll try swapping the heater core in the next day or two.

 

[funboy6942]

Well before you go doing that why dont you see if indeed you have a colg or what ever, swapping heater cores isnt a easy task on some cars and requires the removal of the entire dash and at time ac parts as well.

Try flushing the system out. Take off the hose you say is colder and the top rad hase and pump water through the heatercore hose back flushing the system. The heater core is like a mini radiator so one side should be cooler then the other but if you took the fan off and drove it around then damn maybe you go a busted thermostat. You got the gage, pull the stat out, see if it is open when you take it out, if not put it in some water and start to boil it and see what temp it start to open at.

Did you get a colder t-stat by chance when you bought it? Im just trying to think of other things here since you say you took the fan off and drove it around without one, should of been plenty hot and not 180. But damn dude HC is the last thing I would want to tackle if it isnt leaking, if it has good flow when you back flush it I wouldnt fvck with it at all. I would surrly see where that tstat opens or just go back and buy another 195 tstat and screw it all.

In all the tstats I have done I have never come across a bad one, may of stuck it in backwards (when I used to work on my stuff when I was younger and drank heavily with friends), but never a bad new one. I always buy 2 gaskets though, always seem to mess those up good somehow

 

[KK]

Originally posted by: funboy42
Well before you go doing that why dont you see if indeed you have a colg or what ever, swapping heater cores isnt a easy task on some cars and requires the removal of the entire dash and at time ac parts as well.

Try flushing the system out. Take off the hose you say is colder and the top rad hase and pump water through the heatercore hose back flushing the system. The heater core is like a mini radiator so one side should be cooler then the other but if you took the fan off and drove it around then damn maybe you go a busted thermostat. You got the gage, pull the stat out, see if it is open when you take it out, if not put it in some water and start to boil it and see what temp it start to open at.

Did you get a colder t-stat by chance when you bought it? Im just trying to think of other things here since you say you took the fan off and drove it around without one, should of been plenty hot and not 180. But damn dude HC is the last thing I would want to tackle if it isnt leaking, if it has good flow when you back flush it I wouldnt fvck with it at all. I would surrly see where that tstat opens or just go back and buy another 195 tstat and screw it all.

In all the tstats I have done I have never come across a bad one, may of stuck it in backwards (when I used to work on my stuff when I was younger and drank heavily with friends), but never a bad new one. I always buy 2 gaskets though, always seem to mess those up good somehow

THe thermostat was a 195 degeree one.
I just back from purchasing a new heater core. From what I have read it's a 10 minute job. I sure hope so. The replacing of the thermostat took around an hour atleast, as we had to file alittle bit and figure out what to take off to get to the thermostat housing. So if this is just a few screws and fooling with some hose that'll be welcome relief.

Edit. took the original heater core out and sprayed some water into it. Couple good chunks came out, kept flushing it for a few minutes, and put it back in. Took it for a drive and it seems to have brought the needle up about 50%, still not what I remember it going up to, but I just took it around the block, so it may not have went as far as it would have. I'll take the new heater core back to the store. The new core wouldn't have worked anyways as the pipes were too far off.

 

[KK]

Took it to work alittle while ago, seemed to come back up to where it normally was. so it was a clogged heater core that caused the lower than normal temperature. Of course it was in the mid 60s, maybe tonight on the way home it'll be cool outside.