This anamoly has now been noted for the last two winter seasons.

I do so much thinking for other people, helping to fix their every need, that I often get weary trying to solve some of my own weird quirks.

I thought I'd give you guys a shot at this one.

It's in a 2.5 liter 4 cylinder Dodge with over 266,000 miles. No a/c is hooked up. New radiator was put in in May '07. Distilled water/anti-freeze mix. Never smell hot engine smell. Different thermostats have been put in between last year and now -no difference. Gauge goes up to beyond 7/8 towards 'hot'. In 90 degree summer it is 1/2 or less.

Am running heater blower, but believe I have seen it read hotter even WITHOUT load of blower motor on - I do believe.

 

Hard to believe YOU haven't solved this. You seem to be as knowledgeable as anyone. That said, maybe in winter(when the a/c is not working-I think you said the a/c was not hooked up) the a/c cooling fan(I'm guessing it has 2 fans-electric) is the only one that was working and the other is not working or not working properly.(You probably checked that).
I know I had a fan that wasn't working all the time and it would run a little hot until I turned on the a/c and that fan would cool the engine down. Don't know if this makes sense but something to consider.

 

that is very interesting.....but puting in some thought the coolant temp sensor is what is moving the gauge...... so that said the temp in the engine could be the same but the air temp on the bimetal sensor could change the reading....just a thought but maybe the center post is somehow in contact with the outside edge of the sensor

 

My first thought is the engine temperature isn't the source of the oddity, but the gauge reading. It could be in the gauge or sensor, but those temperatures should be close to the same without regard to outside temperature after everything is warmed up.

However, the grounding of the gauges to engine/frame may be the problem. That could be expanding to form a better ground in the warmer weather and contracting to compromise the ground in cold weather. I've seen something similar in a Ford Ranger and the ground was the problem.

Just a thought - but the best one I got.

 

I think of my OWN stuff, up to a point. My mind is swimming with stuff, and oddball things that happen with everyone elses stuff.

I thought maybe that under load from the heater blower being on, that the car has to make bigger explosions to maintain the same speed on the highway(due to more load on the alternator), combined witrh 266,000 mile car with perhaps compromised water jackets, even though I changed the radiator. Until I found it does same thing with blower off. So much for THAT theory.

Or that the belt slips on the water pump pulley easier in cold weather. Sort of like how your hands get dry and slippery in cold weather and you have to spit on them to get a grip. I have tried spraying belt dressing down there in the past, and it does not really seem to help anything as far as I can tell, as my belt will still squeal under certain load conditions.

The belt only comes in contact with about 1/6 of the circumference of the pulley, by design. And the belt is flat and the pulley is practically polished. The belt could be more slippery in cold weather. The engine exceeds the half-way mark on the gauge at about 3 miles out of town at highway speed. When I slow down, the temp gauge gradually backs down. If I quickly stop and look under the hood to see what is going on when it is idling, the water pump appears to be turning fast.

But I do not know what is going on down there at highway speed. I hear no squealing of the belt as I often do when I put a big load on my alternator. But then again, that squeal may be coming from some other pulley and not the water pump pulley that has the very little surface area that it hits. That is the weirdest design I have ever seen. So much so that I thought my belt was looped around it wrong. But I compared to my next door neighbor's (same car/same engine/same year), and his was that way also and his gauge would not go high, and he also had good heat in the winter. IF I had good heat at idle, I would almost know for sure that the belt on that pulley was the cause. But the fact is, at idle, when I see the water pump pulley spinning, I still have bad heat. In fact it is worse. And the fact it(cabin heat) is worse means that if it(cabin heat) gets better at highway speed, that gives me the clue that the probelm is NOT from slippage on the water pump pulley -that the pulley must be turning good. And the belt is quite tight, and I am afraid to tighten it any more, actually.

My car has no a/c compressor and belt in it anymore (no additional belt goes around the water pump, just the one that is on it now) but still has the condensor coil out in front of the radiator. But say if it got plugged up, and I had a clogged water jacket issue augmenting the problem, I should also have this problem in the summer time, which I do not.

I think what I should probably do, now that I am spending more time thinking about my own issue, is take my infrared thermometer on it at idle after the car is up to full op temp, and then also take the infrared temp after the gauge goes towards hot and QUICKLY stop and take that temp. That may prove interesting so I know whether to address engine cooling issue or gauge, I guess.

 

Didn't mean to sound sarcastic, it's just that it seemed llike the students were teaching the teacher! It really sounds like a thermostat that is to low(180). I like 195 in winter and maybe even year round(depends on the car). Running the heater blower will actually keep the engine running cooler. Doesn't matter in winter, but when mine have been getting too hot, due to some problem, I run the heater fan until I get it home to repair. I know you said you changed the thermostat several times, but, like you, I seem to be at a loss. It has to be something simple that is getting overlooked.!?
You said you replaced the radiator, but what about the pump? Has it ever been replaced? 266k is a lot of miles on a pump. Maybe the impeller in the pump is slipping and not turning when the motor is at RPM. It may turn at slow speeds but not at higher speeds, sort of like a clutch fan. When I want to know the water temp., I use my thermometers for the a/c and tape them, or just hold them, to the place I want to check. It will read the temp. in just a few seconds. Check water temp on inlet and outlet of heater hoses and at inlet and outlet of radiator. Keep us posted!!

 

I think you are on the right track by getting out the therm. to see what is really going on. Some time we have several unrelated problems that we try to diagnose as one and this gets us in trouble. Your poor heat could be a plugged heater core for instance.The change in gauge could be resistance change due to weather conditions. I never have the run of the mill problems,,I prevent them so,when I have a problem it is usually a doosy. Good luck RW

 

belt squealing is a large hint, it should never squeal, if it is you need either a new belt or a new belt and tensioner. sounds like it slips at highway speed and doesn't move water at the proper speed. most people don't relalize just how much load a water pump puts on the belt. JMO

life begins when the kids leave home and the dog dies

 

Thanks for the replies guys.

Yes, problems may be unrelated and two issues at same time. I have been closely monitoring this mystery since last post. We had some 'warmer' days in 30's, and gauge not quite so high. This morning, it was about 15 out. The temp gauge gradually, slowly but surely, kept creeping up higher and higher as I was cruising at highway speed about 3 miles out of town and headed directly into a stiff NW Alberta wind, and I could tell I had to press down harder on the gas pedal from normal. So THIS was not helping matters as this was causing larger explosions while traveling at same speed.

I did notice though that as the gauge went past the 3/4 mark, that the thermostat must have kicked in and it went lower than that for a bit, but then creeped back up over the 3/4 line again. It stayed up there more than below there.

Then as I aproached small town to slow down, the gauge went lower. And when I went in store to get donut and coffee, and came out, the temp said below 1/4 on gauge!, while I had the car idling in the parking lot.

So actually I am convinced that the car temp is going up, at highway speed, and not from some stuck or out of calibration gauge.

I will have to assess that belt situation more I guess. Oddly, like I said, it is on there pretty tight. Unfortunately, it is not a v-belt, and the way it does not even loop around the pulley, but simply rides on a 1/6 quadrant of it, is quite an odd set-up. But the flat pulley it rides on is very shiny and smooth. I never do hear belt squealing at highway speed though. It only does this only idling about town after I had blower on, maybe headlights too and my after market d/c-a/c inverter going with my heat lamp running in my car, for heat. (P.S. - but load of heat lamp is not cause since it still has high gauge reading in cold weather without that being turned on.)

 

What about a lower hose sucking shut???RW

 

Well. Huh. Just a while ago this morning it was 12 degrees out. There she was again creeping well over 3/4 on the gauge. So I stopped the car quickly in a neighboring town I get my morning java at and threw open the hood and felt the upper hose and it was only warm. So I thought, "Uh HUH! NOW I gotcha. The engine will be HOT, with thermostat stuck shut!" Huh. No such such thing. Radiator fan not on and infrared temps of 110, 147, 175 off top of thermostat housing. Wellllll -

So then I let the car idle while I went in and got cofee and when I came out, the temp gauge was down to normal. Now when it got down to normal, then the upper radiator hose got hot and the radiator fan came on and then I discovered that at plug #2, I got my highest infrared reading of (only) 212.

So it appears to be some anomoly gauge related, since I know my fan works and the upper radiator hose was only mildly warm when gauge read high, and yet engine itself not all that hot.

Now just little bit ago, I made a house stop for work. I was there quite a while (20 minutes?), and had the engine idling. The gauge read about 3/8ths. I came outside and the fan kicked in and at that moment I threw open the hood and felt the upper hose and it was hot, due to circulation kicked in and pointed gun at #2 plug again and it said 236. But the gauge only said 3/8! Where when it says 3/4 -7/8, it now appears the engine is actually COOLER and the fan has no need to even come on! Well!

I'll be doing more such testing and keeping you abreast of this.

BTW - Murphy happens to be a good friend of mine, and I think he is somehow behind things that seem vexxing in my life.

 

You must have the patience of Job! I think I would have looked for a sledge hammer by now!Ha!

 

All kidding aside - that IS one of my virtues that others have told me I have. I am a - 'by hook or crook, it ain't getting the best of me-, person, in everything I do. However, I do have a breaking point, and then the screaming starts. But at least I do not start throwing objects as one relative of mine used to do.

I am still intrigued by this, and need to do more temp testing with my gun. I have not bothered in the last couple days. But I will.

For one thing, I want to see if there is some sort of fluky thing where the cold gets through my radiator or from under the car in such a forceful way that it shoots cold air up at the thermostat housing. Because the last gun reasding I got off that housing was only warm and the upper radiator hose was cool indicating no circulation. Now if the stat housing was hot, and that was happening, I'd say the stat was stuck shut.

 

The engine may not even be getting hot, it appears. We had 3 degrees out while driving down the highway, and gauge quickly went up to beyond 3/4 and stayed up there. No belt squeeling. When I got to my coffee town I quickly opened the hood, while it still was at 3/4, and noted no fan running, upper hose cool, I could touch the thermostat housing without feeling pain, and the highest reading I could find anywhere, waving my gun all over the place, down in cubby holes of spark plugs, was 201. All the other numbers were all over the place like 110, 147, 173, etc. Low number on the stat housing.

Yet oddly the gauge functions and mimicks how gauge would move if overheating down the highway and then come down to normal when you stop for a while and let the engien idle, or even driving around town.