wanting to lower temperture

[profo]

I have a 2002 m1078A1 with a 1999 cat 3126, I am uncomfortable with the operating temperture, it goes up to 215 before the fan kicks on, I would like to lower if possible, I have checked with a separate temp gauge in the thermostat housing and confirmed its within a degree or so according to gauge in truck, I was able to find a wiring diagram for a A1 somewhat!, and on it it shows a contact SWITCH, on P36 and R36 plug and receptacle, I do not have this wire on my vehicle, I have went through every wire label, I do have two temp sensors (varies resistance as temperature increases and decreases) and one temp switch (opens/ closes), from what I have found so far,one sensor in the thermostat housing (one wire) is for the gauge in truck which i confirmed, one sensor on side of block on driver side (goes directly to the engine ecm), and one switch rated at 230 degrees in the thermostat housing also this is the engine coolant overheat dash light. I also when went to a friends to shop to turn on the cruise control and recailbrate the speed0meter, looked through all the menus that he could see (not cat software) and there is no setting that we could find other than fan control with air conditioner, I did see that a wire 11 on the ecm should go to the fan solenoid under the dash on passenger side, So my question is does the engine directly control the fan via ecm by reading the sensor in the side of block and turning it on when the ecm determines it , and if so would the CAT software which I understand you go can deeper into the ecm maybe have the setting in there!

Thanks Marty

 

[snowtrac nome]

I have CAT ET on the c-7 ECM the ECM controls the fan and engine brake for extra retarding you can even set it so the fan comes on with the engine brake. As for the a-2 models I didn't ever have any problems with them in Iraq and the fan always came on because of the ac running on high. Because of your engine being electronic I would caution you about trying to force it to run cooler. you might try changing the thermostat to a cooler model. out here in north western Alaska my fan only came on about 6 times this summer those trucks cooling system is really huge

 

[profo]

I have CAT ET on the c-7 ECM the ECM controls the fan and engine brake for extra retarding you can even set it so the fan comes on with the engine brake. As for the a-2 models I didn't ever have any problems with them in Iraq and the fan always came on because of the ac running on high. Because of your engine being electronic I would caution you about trying to force it to run cooler. you might try changing the thermostat to a cooler model. out here in north western Alaska my fan only came on about 6 times this summer those trucks cooling system is really huge

I remember seeing that part where you can turn on fan for engine brake, the fans turns on and off but in Louisiana at 95 degrees it climbs to around 190-195 quick less than 2 minutes on hwy which I am pretty sure that means the thermostat is closed till then, then it slowly just a few more minutes climbs to 215-218 then fan come on and temp drops to around 200 I would like to get the engine to run a lil cooler if possible and maintain 200 even if it means the fan come on sooner , I am just uncomfortable running a engine at 215 most of the time. I have found out because of the new emissions that engine manufactures are running engines hotter to burn fuel more complete,etc. but its at the expense of the life of the engine oil thins more and wear and tear is increased. do you remember seeing anything in the Cat software?

Thanks Marty

 

[scottmandu]

I remember seeing that part where you can turn on fan for engine brake, the fans turns on and off but in Louisiana at 95 degrees it climbs to around 190-195 quick less than 2 minutes on hwy which I am pretty sure that means the thermostat is closed till then, then it slowly just a few more minutes climbs to 215-218 then fan come on and temp drops to around 200 I would like to get the engine to run a lil cooler if possible and maintain 200 even if it means the fan come on sooner , I am just uncomfortable running a engine at 215 most of the time. I have found out because of the new emissions that engine manufactures are running engines hotter to burn fuel more complete,etc. but its at the expense of the life of the engine oil thins more and wear and tear is increased. do you remember seeing anything in the Cat software?
Thanks Marty

A few things to consider:

The thermostat controls the minimum operating temperature, the fan controls the maximum operating temperature.
The LMTV fan is controlled by the fan switch located on the pipe for the radiator inlet. There are different temp switches available, but they are not cheap, they run $150 to $220.00.
Today's modern synthetic motor oils are far better at controlling viscosity and hold up to much higher temperatures.
Expect a significant drop in fuel economy and oil contamination issue by running the engine too cool.
Putting a cooler fan switch in the truck will cause the fan to continuously cycle on and off much more frequently, wearing out your fan clutch much faster.

You want oil temps above 220 degrees to boil off accumulated water and lighter hydrocarbons.

The only problem with running higher engine temps is the transmission as 100% of trans temp control on the M1078 is via the engine cooling system.

 

[DiverDarrell]

Maybe a radiator flush, and a good wash down of the fins would help. Remember when your running on the highway your pretty high in the rpm range helping to build heat. Also you could pull the grill off to see if more air to the radiator helps. Maybe the thermostat isn't opening all the way restricting flow.

 

[snowtrac nome]

I still would start with a t- stat and flush the system. You can always un plug the fan solenoid, and run the fan all the time, but you are just masking a problem I would start with cleaning the cooling system and changing the thermostat, as fast as you come up to temp sounds like you have a cold climate t- stat or restricted cooling system.

 

[Kodyman]

Does anyone know where i can find a new fan/clutch switch (the one on the radiator inlet(2-wire) as well as the other sensor that is on the driver's side radiator pipe (also a 2-wire)(images). Ive searched several surplus parts sights with no luck