[Bob Lincoln]

Are you sure the thermostat is working properly? At what point on the gauge does the fan turn on? Does the radiator have enough fins left on the tubes? Any chance the system has a clog?

This doesn't seem normal for this car. That temperature seems dangerously close to blowing a head gasket.

 

[ImperialCrown]

The torque converter will generate a lot of heat if it is unlocked and climbing a hill, but a standard radiator in good health should be able to dissapate the heat.
Has the radiator been replaced? If it is the original, it may be in trouble.
Does the t/conv clutch remain locked? Is the coolant mixture a good 50/50 mixture of water and antifreeze?

 

[David Eidell]

The steepness of the grades forces the transmission to downshift into 3rd, and if I should round a hairpin curve (20kph), sometimes the transmission shifts into 2nd for a moment. I don't believe I am confusing 3rd gear with 4th, nor converter lockup. But should I be looking for a locked converter when the transmission decides to downshift into 3rd? Am i mistaken in believing that given gas pedal pressure to maintain speed, this transmission first abandons lockup and 4th gear and downshifts as needed?

The last time this happened I used a laser thermocouple thermometer all over the radiator and it indicated 240 - 250 F., with no cold spots. Quite a feat with rags wrapped around my arm to protect it from getting burned. Wouldn't a clogged radiator at least show some symptoms? Looking down the radiator cap opening, when cool with the coolant drained, the tube ends look spotless. Like aluminum (?). The exterior fins look like brand new. Until I got the car with 18,000 miles on it a few years ago, it had been garaged. I changed the coolant, and put in a 60% mix of anti-freeze and distilled water in the states.

With the A/C on, the fan is on all the time, plus has been running through an ignition signal relay 100% of the time. Upon startup, th temp gauge will rise one needle width into the operating range band on the gauge then drop back to the edge of the band, then slowly rise to about two needle-widths up into the "normal operating band". It's when I climb a hill with the A/C on that the gauge rises, on a hot day. The transmission fluid has been serviced with a new MoPar filter and synthetic fluid. The old fluid looked brand new and there was a tiny, very tiny bit of grit in the pan. A pin-head's worth.

I might add, when I shut off the A/C the temp gauge settles back to 50% or a bit lower. Driving in 100F weather with 70% humidity is not my idea of fun. On level ground and 70 mph the temp gauge never gets beyond say 2/5ths of the way up. With a head wind it goes down noticeably. Could it be a water pump? This is frustrating since I got the "this is abnormal" responses :-(

 

[AllanC]

I believe you are subjecting the vehicle to a prolonged driving situation which was NOT a design scenario contemplated or was ignored by engineers. Many years ago while on a family vacation I drove a 1988 Dodge Caravan into Sequoia National forest in California. It was in July and I remember that the climb on the mountain rode to the top took about 20 minutes and was steep. Van had a 3.0 L V6 along with the 3 speed automatic transaxle. Most of the climb was made in first gear with an occasional shift into second when uphill speed allowed the shift to happen. Speed most of the time was below 25 mph. I noticed and was greatly concerned that the engine temperature gauge had the needle at 3/4 travel from left to right. It was not overheating but was very close.

On that van the AC condenser sits adjacent to the radiator. It was not in front of the radiator so AC heat was NOT dumped into the cooling radiator. The single electric cooling fan for the radiator was not sufficient in size and airflow to provide adequate cooling other than at idle. Engineers assume that at higher engine speeds the ram air effect of moving the vehicle forward at 30 - 60 mph will provide increased air flow through the radiator and so a minimal sized fan is installed just to barely provide adequate cooling for the radiator and AC condenser at idle. In your situation you have additional heat load because the engine is running faster than at idle but you do not have the forward motion to generate the increased ram air effect for cooling the radiator and condenser.

I would suggest you add 2 large pusher type fans in front of the AC condenser. On that particular car there is sufficient space ahead of the condenser and behind the grill for such an installation. Get as high a CFM (cubic feet per minute) air flow as you can find and will fit. Wire it such that you can control it manually with a switch from the driver's seat.

Adding 2 additional fans will tax the electrical output of the alternator but since you will only be using them during your hill climbing activities, engine rpm is way above idle and alternator output is much higher than at idle. I believe you should have adequate electrical capacity but you will need to test. You may find that you will have to adapt a different alternator used by Chrysler with higher output capacity.

 

[David Eidell]

Oops, my mistake, the hairpin turn mph thing was to describe the transmission shifting. Pardon me. The engine does get too hot then but even at 60 mph the temperature gauge climbs way too high. I ommitted a full description of the symptoms and I apologize. If you know the Grapevine grade climb in Interstate 5 in California, this is a perfect example. So is I-80, leaving Sacramento, headed toward Reno. When it was 122F in Lukeville, AZ, I had to shut off the A/C and drive 45 mph to keep the needle three-quarters or less up the gauge. I should also mention that a very honest radiator repair guy examined inside the radiator with some sort of umbilical gizmo (a camera?) after draining the radiator and told me replacing it would be a waste of money. He charged me $30.00, sort of low I guess because I'm a senior citizen. Would the fans help even though the car overheats at 60 mph going up a grade with the A/C on? This is when the outside temp is perhaps 90 or higher. Another omission: I had a relay fail on a 70 degree day and the fan stopped working. Lucky for me I was at a gas station on the interstate and the car cooled right down with no A/C when I returned to freeway speed. I exited at San Ysidro Blvd, just before the border and bought a new relay at O'Reilly Auto Parts (or something like that).

This problem is a real pain-in-the-rear. I want to connect a new thermostat fan control but what's the use if the car overheats even when the fan is on sometimes?

Thanks for helping. I just need to do my job here describing the problem right.

 

[Oklahoma Wolf]

On my last 1988 New Yorker with the 3.0/A670, the original radiator had lost nearly all its cooling fins which blew the head gaskets. When I got the car, I replaced that original radiator with one from a 3.3 equipped 1990 Imperial. Had to do some modding of the overflow bottle hose, but otherwise it was a straight up swap. Kept the old cooling fan.

Used to be a lot of fun watching the digital temp gauge on that car on real hot days. You could tell exactly when the thermostat was open by watching for a full two bar drop on the gauge. I don't know exactly how much difference there is between the 3.3 and 3.0 radiators on AC/AY body cars, but I never had a cooling system problem on that car again no matter where I drove it. Then again, this area doesn't have a lot of uphill low speed climbs, either. Or too many 40+ degree Celsius days. I imagine in your area I'd have probably taken the Imperial's dual cooling fans, too.

 

[fjb37]

One hot day while driving my 92 3.3L Caravan, I heard a ding from the dash and the check gages light came on and the temperature gage went high. I turned the A/C off and this settled down the temperature a bit until I got home.

What was the problem?

When I opened the hood I squeezed the upper radiator hose and found that it was not pressurized. The vacuum poppet in the radiator cap was not closed and that prevented the system from pressurizing. A new Stant cap with the lever vent solved the problem. You might want to check your cap to be sure. When you pull the vacuum valve down it should snap back into place. If it doesn't, get a new one. Just my $0.02.

FredB

 

[AllanC]

Oops, my mistake, the hairpin turn mph thing was to describe the transmission shifting. Pardon me. The engine does get too hot then but even at 60 mph the temperature gauge climbs way too high. I ommitted a full description of the symptoms and I apologize. If you know the Grapevine grade climb in Interstate 5 in California, this is a perfect example. So is I-80, leaving Sacramento, headed toward Reno. When it was 122F in Lukeville, AZ, I had to shut off the A/C and drive 45 mph to keep the needle three-quarters or less up the gauge. I should also mention that a very honest radiator repair guy examined inside the radiator with some sort of umbilical gizmo (a camera?) after draining the radiator and told me replacing it would be a waste of money. He charged me $30.00, sort of low I guess because I'm a senior citizen.

Hmmm. If the engine temperature gauge rises as you drive faster then the problem is a restricted radiator. I think the repair guy that charged you $30 to tell you a new radiator was a waste of money is unknowledgeable. Even though radiators can appear from a view into the filler neck to be clean and clear, there can be corrosion in the passageways which restrict flow. That radiator is cross flow and about 24 inches in width. How could a camera look 12 inches deep into an individual tube row of the radiator and show corrosion? The tube diameter is extemely small. A camera would only show corrosion at the tube end where the header tank is located. Corrosion typically occurs deep within the tubes and not at the header tank. I would replace the radiator first and I bet your cooling problems will disappear.

When driving on relatively level highway at 60 mph you do NOT need an electric cooling fan on the radiator and condenser. The ram air effect of moving forward provides more than ample air floor on the radiator and condenser.

On that model with V6 engine it is easy to remove the thermostat. You can run for a period of time without the thermostat and determine if that is the source of the problem. I am still betting that the problem is a radiator with partially resticted internal passages.

It is also possible that a bearing on the water pump is starting to drag. At higher engine speeds the water pump shaft is dragging and causing the water pump pulley to slip and reduce its output. The water pump is located in the V between the heads and is driven by the smooth backside of the camshaft belt. If the pump is dragging it will do that only so long and then the heat generated from belt slippage will destroy the belt. Once the timing gets off the engine will stop. Again this is a possiblity but I would investigate radiator replacement first. Accessing the timing belt is an expensive and time consuming task.

 

[valiant67]

I agree, I’d also suspect the radiator. They can look nice and clean but still don't flow properly to keep it cool under extreme conditions.
A low mileage car is likely to have a radiator full of scale. I'm not sure just how much the guy could have seen with his camera. I think having a larger core installed in the factory radiator would do more than any other add on, though I'm betting a stock one that's not had 17 years of corrosion may still be enough radiator.

 

[bguy]

I think you need a new rad. At the very least you need it flushed.

 

[AC TC]

I would start with the thermostat...
Do not exceed a 50/50 mix as since you wont gain any freeze protection and
glycol hasent got the heat transfer capabilities of water.
Do not use propyleneglycol( non toxic) its the same as above compared to ethyleneglycol.
Use old green or G-05 not "all makes" or dexcool.

 

[B10alia]

I would recommend a Stant Superstat thermostat. They flow better than stock. I've noticed that my '95 Spirit (2.5 instead of the 3.0) cools off much faster when the thermostat opens as compared to the stock thermostat. A themostat is an easy replacement, and will give you an inside look at the cooling system. If the old thermostat is covered on deposits, that's probably what the rest of your system looks like. Think of it as an investigative upgrade. It's one of the cheapest parts you can put in the system.

 

[chuzz]

I agree with AC/TC on the blend you're running. Go to a 50/50 mix of anti-freeze and distilled water and see what happens. It seems that the coolant mixture you're running is holding too much heat.

 

[ImperialCrown]

I don't think that being 10% off in the antifreeze/water mix will make a really huge difference, although a 50/50 mix is ideal.
A cooling system flush won't remove hard deposits in the narrow passages in the system.
Rapid coolant flow through the radiator may not allow the heat to dissipate in a properly heat-shedding radiator, you want some regulation that an OEM thermostat will provide.
A properly operating radiator cap is often overlooked even though it is the easiest part to replace.
Does operating the heater for a hot hill climb make any difference?
With all the useful suggestions here, I feel that this really needs a good 'hands-on' cooling system appraisal and diagnosis.

 

[David Eidell]

Wow trying to describe an exact description of what the heater does is tough. Putting the heater on high with the windows down does not seem to do much, it goes does a little, I am guessing here, maybe two needle width's worth. More info. A Dodge agency in San Franscisco took care of this car, and I found several receipts in a bundle in the glove box. Service orders that said "Flush system, make up coolant". Oil change, inspect chassis, etc. They even put in a new Mopar battery in 2002. I had to replace it in 2011. When I scanned the radiator with the thermometer it doesn't work like I thought it would. A new radiator here costs about $348.00

If you guys are pretty sure then I guess half of my next month's income has to go for a new radiator. Thank you sincerely for the help!

 

[Doug D]

When you blast the heater, is the air hot? I'm thinking the heater core could be partially or totally plugged. A blocked heater core can play havoc with the cooling system. As a temporary measure, you could try bypassing the heater core by T'ing the heater hoses together.

It does sound as though the radiator has lost it's ability to transfer heat. The usual symptom of a scaled radiator is hotter than normal temps at hwy speeds and pretty much normal at low speeds. If it's the OEM, 17 years is a long time for a radiator - even if it doesn't have a lot of miles on it. Corrosion can still occur. A good coolant mix will slow it down, but it can never completely stop it.

 

[David Eidell]

That is what so frustrating. I can operate the car at 80 mph (interstate) on an 80F day and it actually runs cooler than it does at 30 mph. The heater is a furnace especially out of the dash ducting in 30 degree F weather. The radiator fan is on all the time (ignition) which I do not like at all.

I was thinking that I could somehow "cheat" and bypass the transmission cooling through an aftermarket trans cooler and relieve the heat load on the radiator. But how much heat does the transmission develop? I would hate to live on beans and catsup for a month and find out the radiator was not the problem. Transmission coolers are a fraction of the cost, but would one help? Agh!

 

[Bob Lincoln]

It's normal for the fan to be on all the time that the A/C is on, but it is not supposed to be on all the time that the ignition is on. If it is, then either the Coolant Temperature Sensor has failed or is unplugged, or someone rewired the fan controls. Check fault codes for a code 22.

 

[bguy]

That is what so frustrating. I can operate the car at 80 mph (interstate) on an 80F day and it actually runs cooler than it does at 30 mph. The heater is a furnace especially out of the dash ducting in 30 degree F weather. The radiator fan is on all the time (ignition) which I do not like at all.

I was thinking that I could somehow "cheat" and bypass the transmission cooling through an aftermarket trans cooler and relieve the heat load on the radiator. But how much heat does the transmission develop? I would hate to live on beans and catsup for a month and find out the radiator was not the problem. Transmission coolers are a fraction of the cost, but would one help? Agh!

I would believe that a healthy cooling system would be opposite. Cooler a slower speeds.
Is it possible that the air flow through the heat exchanger and rad is somehow restricted or misdirected? Make sure that none of the rubber and plastic flaps that go around the front of the radiator support are missing.

If the dealer flushed the car years ago this may not be a new symptom/complaint for this car.

Does anyone here know if there are different water pumps for different years? Some with reverse flow possibly?