No Extra Coolant Temperature Port In Toad Engine

[MEXICOWANDERER]

Mitsubishi 3.0 V6 engine in a Dodge.

Wonderful. It has a temperature gauge to stare at once the engine overheats. When the gauge reaches the top of the "operating range" sweep the engine radiator is boiling over. LONG before the last mark before "H"

I can compensate for that. The lower mark of the temperature sweep line is normal operating temperature. Disconnect the wire, the check engine light comes on, the drive train goes into limp mode meaning it sucks.

There is another sensor. One for the engine control module. It must be working because if I disconnect that one the same thing happens as with the coolant temperature sensor. The car passes California Smog easily and gets great fuel economy -- no problems there.

But the original equipment fan motor for the radiator never came on the moment I purchased the car, way back. So I had to rewire the fan motor to start and stop with the ignition via a relay.

This gets ripe - Doodge in their wisdom decided to use a ONE ROW radiator. Bottom line is if the radiator fan quits, and air temps are above 80F, the engine overheats at less than 30 mph and more than 55 mph. Overheating in this case means imminent danger of cracking the cylinder heads. The car needs the fan except in cool weather.

Real life scenario -- outside air temp 65F. Start engine. Drive 3 miles or 15 minutes in typical city traffic and engine temperature climbs past the "normal" range without the fan.

I'm trying to decide whether to install a thermal switch for fan on/off OR an alternative. An Armageddon thermal switch that would trip an audio buzzer and light in the dash. I have some 105C switches that would serve. 220F

Seems pointless to put in an on/off auto switch if the fan is on that much...what do you think?

Here is an adapter mid hose gizmo that requires a caeserian section of the upper hose near the thermostat outlet.



I'd love to find a 2-row core radiator that would fit. Alas the cheapest one costs almost $400 and then the fit is "universal".

I need to buy a spare fan motor and carry an extra Tyco relay.

[MEXICOWANDERER]

Found a box-gauge-alarm on eBay $60.00


It does have a lug like body for the thermocouple. 6mm bolt hole.

Having a lamp as an alarm is next to useless. Time to start searching for a sonic alert that does not startle.

[MEXICOWANDERER]

Car is weird. It's a '95 Dodge Spirit with the 3.0 V6, a Mitsubishi drive train. It passes smog with numbers so low it astonishes the smog places. Excellent fuel mileage and still on 5W-30 oil.

[PaulJ2]

MEXICOWANDERER wrote:
Nyet about the sensor. The ECU sensor was changed three times. It has a genuine MoPar replacement now. That is the sensor the fan is controlled with. The temp gauge sensor was only changed twice. Both sensors are near the thermostat housing and EITHER sensor when malfunctioning throws a check engine code and everything goes into limp-home mode.

The thermostat bolt sensor has me intrigued -- especially since I cannot find any online.

Never ran into a fan control sensor in the block, ECU and temp gauge yes but fan control in the radiator. Usually near the radiator outlet where the cooled water returns to the block.
Having said that: I don't know the year of your rig so am going by what i have replaced only. Yours may be newer and different now. A lot more complicated--ah yes technology!

[MEXICOWANDERER]

I think I'll leave the fan on via ignition because after 15 minutes of doing anything it comes on anyway.

A real neat note that the car will overheat doing under 25 mph and over 50 mph without the fan. More air! More cooling! Wrong. And there are no mechanical problems with the engine. Even down to combustion leak, radiator tube cleanliness, new water pump halves. ECU malfunction, cap, pressure testing, temperature readings verification. The car is a snotrag cooling system wise.

But I need a 210F - 215F sensor, two wire switch for an in-cab audible alarm. I have caught too many errors, both failures and human leaving me stranded. I don't want to blow the heads off that engine. I am also getting a new backup fan motor and stowing it.

[Gjac]

I would put a simple toggle switch on your dash to control the fan manually. I did this in my MH and when I see a hill I turn the fan on and I don't have to wait for the water temp to rise before the fan comes on. You don't say how old the car is but thermostats do go bad and radiators cores get blocked. They sell HD stats with a small bypass hole to allow more water flow. You can check the radiator with an IR gun to see if it is blocked from top to bottom or side to side in a grid pattern depending on where your inlet and outlet are located, cold spots would indicate blockage. I don't know why but they seem to block in the center of the radiator.

[MEXICOWANDERER]

Nyet about the sensor. The ECU sensor was changed three times. It has a genuine MoPar replacement now. That is the sensor the fan is controlled with. The temp gauge sensor was only changed twice. Both sensors are near the thermostat housing and EITHER sensor when malfunctioning throws a check engine code and everything goes into limp-home mode.

The thermostat bolt sensor has me intrigued -- especially since I cannot find any online.

[PaulJ2]

Usually these have a coolant temperature sensor screwed into the radiator itself. When a certain temperature is reached it grounds a relay circuit turning on the cooling fan. When air conditioning is called for, it activates the relay again causing the fan to run when the compressor clutch is engaged.
I would guess just a defective coolant sensor.
Usually there is another sensor screwed into the engine block somewhere that has to do with all the operating parameters of the engine control module.

[wa8yxm]

They make a sensor that "Bolts on" basically you remove a Thermostat housing bolt (Carefully do not crack the T-Stat housing like I did) and slip it over the bolt like a washer and replace and re-torque bolt.

[gotsmart]

If the rest of the cooling system is OK, an electric helper fan can be mounted to the front of the radiator - assuming there is space for it.

[MEXICOWANDERER]

I bought the car in the summer. So when I started the engine the A/C started up. Then one day I shut the A/C off and caught the temperature headed toward boiling over.

The car was virtually new. Painstaking trouble-shooting, junction by junction showed the fan malfunction to be in the ECU. Not even Caig D100 improved the ECU connection. A San Francisco car driven 400 miles per year. To a church and to a store 1/2 mile from their house.

[Gjac]

What year is the car? You said the fan never came on since new but has it always overheated since new or is this a more recent problem? Also does the car have a clutch fan or just an electric fan?

[JaxDad]

Aren’t you in the land of old vehicles being nursed along ad infinitum?

There’s got to be a bunch of old school rad shops, find one that will make you a multi core rad with larger tanks.

[MEXICOWANDERER]

I also have the Tecate beer can radiator. Lose the fan and you'd better have the ability to drive 45 mph with no slowdowns 😞

[landyacht318]

I have a one row aluminum radiator, except that tube is 1 1/4 inch wide and the fins are 1.5 inches wide.

Maximum brass tube width is 5/8"