Running temp for an LMTV

[astacey1403]

Good morning everyone!

Just got my 1998 M1079 running and was able to drive around a bit yesterday. Still have a few things to work out but could not be happier with how far I have gotten so far. I was wondering what kind of operating temps you guys see with your rigs? I believe that my temp gauge was working correctly however I saw the temp approach 200f yesterday and then the fan did kick on. was not sure if this was normal or not. Let me know what you think!

Thanks for your time,

 

[Guruman]

Good morning everyone!

Just got my 1998 M1079 running and was able to drive around a bit yesterday. Still have a few things to work out but could not be happier with how far I have gotten so far. I was wondering what kind of operating temps you guys see with your rigs? I believe that my temp gauge was working correctly however I saw the temp approach 200f yesterday and then the fan did kick on. was not sure if this was normal or not. Let me know what you think!

Thanks for your time,

Seems pretty much like mine. I'd call that pretty normal.

 

[Ronmar]

Most diesels are happiest approaching 200F. Maintaining a temp above the thermostat opening point(178F) is good as it means it is controlling temp with a steady coolant flow thru the radiator. Thats a good thing. That being said The way they plumbed the 3116 makes it notoriously cold blooded(they sent the bypass coolant to the transmission cooler). What are your outside temps now? A lot of people have reported dirty radiators and have removed tons of dirt From the air passages. it closing in on winter in colorado, you would have to be getting some work out of it to push it to the 205F necessary to engage the fan…

Steady coolant flow thru the radiator is good, gulping ice cold slugs of coolant is bad for the engine. As the air temps drop in winter you want to think about restricting radiator airflow/cooling capacity. There is another recent discussion on the cold wx restrictor which can go on any time the temps are below 40F.

 

[serpico760]

Most diesels are happiest approaching 200F. Maintaining a temp above the thermostat opening point(178F) is good as it means it is controlling temp with a steady coolant flow thru the radiator. Thats a good thing. That being said The way they plumbed the 3116 makes it notoriously cold blooded(they sent the bypass coolant to the transmission cooler). What are your outside temps now? A lot of people have reported dirty radiators and have removed tons of dirt From the air passages. it closing in on winter in colorado, you would have to be getting some work out of it to push it to the 205F necessary to engage the fan…

Steady coolant flow thru the radiator is good, gulping ice cold slugs of coolant is bad for the engine. As the air temps drop in winter you want to think about restricting radiator airflow/cooling capacity. There is another recent discussion on the cold wx restrictor which can go on any time the temps are below 40F.

I have recently seen somewhere online a radiator shield thing or whatever you call it that restricts the air flow through the radiator in cold weather. I don't remember where I saw it though.

 

[astacey1403]

Most diesels are happiest approaching 200F. Maintaining a temp above the thermostat opening point(178F) is good as it means it is controlling temp with a steady coolant flow thru the radiator. Thats a good thing. That being said The way they plumbed the 3116 makes it notoriously cold blooded(they sent the bypass coolant to the transmission cooler). What are your outside temps now? A lot of people have reported dirty radiators and have removed tons of dirt From the air passages. it closing in on winter in colorado, you would have to be getting some work out of it to push it to the 205F necessary to engage the fan…

Steady coolant flow thru the radiator is good, gulping ice cold slugs of coolant is bad for the engine. As the air temps drop in winter you want to think about restricting radiator airflow/cooling capacity. There is another recent discussion on the cold wx restrictor which can go on any time the temps are below 40F.

Thanks for the great info! Yesterday the temp outside was about 50f. The fan kicked on once for less than 30 seconds or so and did not come on again. I was testing out the mode function and driving in the local dirt church we have in leadville, climbing some hills and what not. This morning its snowing and around 28f outside. Took the truck for a spin and I did not see the temp get above 165f to 175f. I was wondering just because this is the trucks first few miles in probably 13 years or so.

Thanks for all the feedback guys!

 

[Ronmar]

Thanks for the great info! Yesterday the temp outside was about 50f. The fan kicked on once for less than 30 seconds or so and did not come on again. I was testing out the mode function and driving in the local dirt church we have in leadville, climbing some hills and what not. This morning its snowing and around 28f outside. Took the truck for a spin and I did not see the temp get above 165f to 175f. I was wondering just because this is the trucks first few miles in probably 13 years or so.

Thanks for all the feedback guys!

Yea that sounds about right for a 3116. It basically sends all the engine heat to the transmission. Below about 65F outside air temp, Untill the transmission warms and starts generating heat, the engine wont even get warm enough to open the thermostat.

You can see thw cold weather radiator cover in a current discussion here on this forum.

fmtv winter front cover .

I received my winterfront cover, I cant figure out how to install it, and cant find any references in the tm about it. Any one got any pics of one installed, -30 is coming in a couple days and I don't want to be fiddeling around than trying to get it on.

www.steelsoldiers.com

 

[serpico760]

I have recently seen somewhere online a radiator shield thing or whatever you call it that restricts the air flow through the radiator in cold weather. I don't remember where I saw it though.

I found it it's on eBay search fmtv lmtv cold weather radiator cover it's for $29.95

 

[TomTime]

Here.

fmtv winter front cover .

I received my winterfront cover, I cant figure out how to install it, and cant find any references in the tm about it. Any one got any pics of one installed, -30 is coming in a couple days and I don't want to be fiddeling around than trying to get it on.

www.steelsoldiers.com

 

[Chief 15]

I drove our 1997 M1078 about 4 hours in about 80 degree weather and I don't think it got much over 200. Fan cut in and out and kept things pretty consistent.

 

[Ronmar]

Fan should kick on at 205F.

 

[waynegpugh]

Hello all. I have a 98 M1078 also. I’m in Durango Colorado and it’s been in the in the mid 90s up to 100. Mine seems to be running hotter than the temps you all have been mentioning and I actually overheated today on my way to Navajo dam in New Mexico and had to stop on the side of the road. I’ve noticed pulling hills it wants to heat up to around 220-230 and hit 240. I just did a flush in hopes that would help but anyone have any ideas what it could be? Also I have the winch bumper that covers a portion of the radiator. Not sure if that works make that big of a deal.

 

[waynegpugh]

Hello all. I have a 98 M1079 also. I’m in Durango Colorado and it’s been in the in the mid 90s up to 100. Mine seems to be running hotter than the temps you all have been mentioning and I actually overheated today on my way to Navajo dam in New Mexico and had to stop on the side of the road. I’ve noticed pulling hills it wants to heat up to around 220-230 and hit 240. I just did a flush in hopes that would help but anyone have any ideas what it could be? Also I have the winch bumper that covers a portion of the radiator. Not sure if that works make that big of a deal.

 

[TomTime]

Hello all. I have a 98 M1078 also. I’m in Durango Colorado and it’s been in the mid 90s up to 100. Mine seems to be running hotter than the temps you all have been mentioning and I actually overheated today on my way to Navajo dam in New Mexico and had to stop on the side of the road. I’ve noticed pulling hills it wants to heat up to around 220-230 and hit 240. I just did a flush in hopes that would help but anyone have any ideas what it could be? Also I have the winch bumper that covers a portion of the radiator. Not sure if that works make that big of a deal.

When I flushed my system, I put radiator flush in it, ran it and drained. Then flushed it 4 more times with distilled water to make sure all the green was gone and replaced it with the red all metal coolant.
Removed the coolant overflow tank along with the engine oil cooler and flushed both. The coolant side of the oil cooler was a little clogged.
I also used A/C foaming coil clearer on the exterior fins of the radiator to make sure the radiator was clean and clear. A lot of bugs in there.
Also replaced both of the thermostats.
It all made a big difference for me.

Use an infrared temperature gun to check the temperature of the radiator against the interior gauge.

Good luck.

Tom.

 

[Third From Texas]

Hello all. I have a 98 M1078 also. I’m in Durango Colorado and it’s been in the in the mid 90s up to 100. Mine seems to be running hotter than the temps you all have been mentioning and I actually overheated today on my way to Navajo dam in New Mexico and had to stop on the side of the road. I’ve noticed pulling hills it wants to heat up to around 220-230 and hit 240. I just did a flush in hopes that would help but anyone have any ideas what it could be? Also I have the winch bumper that covers a portion of the radiator. Not sure if that works make that big of a deal.

Spent a lot of winters in Durango way back in the day. Most of my old haunts and the people I knew are long gone. Miss that place...

Never had my 3116 on a grade at any alt but I imagine it should handle it w/o to much overheating. I take it your fan is kicking in at ~200 degrees?

The winch blockage should be negligible, but w/o seeing it it's hard to say fr certain. Keep in mind that the later grill S&S used on the A1R trucks was FAR more restrictive than the original fiberglass ones like your truck has, so there should be plenty of flow where it counts even with a slight obstruction. You could always open up some air flow at the forward skidplate, but again w/o knowing the real cause of the overheat it might not help.

Personally, if I lived up that way I'd mod in an additional trans cooler but that's more to keep the trans alive longer.

Good luck and I hope you solve it !

 

[waynegpugh]

When I flushed my system, I put radiator flush in it, ran it and drained. Then flushed it 4 more times with distilled water to made sure all the green was gone and replaced it with the red all metal coolant.
Removed the coolant overflow tank along with the engine oil cooler and flushed both. The coolant side of the oil cooler was a little clogged.
I also used A/C foaming coil clearer on the exterior fins of the radiator to make sure the radiator was clean and clear. A lot of bugs in there.
Also replaced both of the thermostats.
It all made a big difference for me.

Use an infrared temperature gun to check the temperature of the radiator against the interior gauge.

Good luck.

Tom.

Great thanks for the info. Im going to do all that. I just did a simple flush but didn’t know it was that involved. I’m going to start there. Thanks again.

 

[waynegpugh]

Spent a lot of winters in Durango way back in the day. Most of my old haunts and the people I knew are long gone. Miss that place...

Never had my 3116 on a grade at any alt but I imagine it should handle it w/o to much overheating. I take it your fan is kicking in at ~200 degrees?

The winch blockage should be negligible, but w/o seeing it it's hard to say fr certain. Keep in mind that the later grill S&S used on the A1R trucks was FAR more restrictive than the original fiberglass ones like your truck has, so there should be plenty of flow where it counts even with a slight obstruction. You could always open up some air flow at the forward skidplate, but again w/o knowing the real cause of the overheat it might not help.

Personally, if I lived up that way I'd mod in an additional trans cooler but that's more to keep the trans alive longer.

Good luck and I hope you solve it !

Yeah i love it here In Durango. Yeah the fan is kicking on. I have highway gears so im wondering if that’s adding to the problem too. Ill look into the additional tans cooler. I had my trans rebuilt at S&S while i was in Houston and it wasn’t cheap so i want to protect that as much as i can also. The bumper covers about 9” of the bottom of the radiator. Ill try removing the winch housing cover to see if that helps. I’m hoping for the easy fix haha.

 

[Third From Texas]

OK, looks like you've only covered the six slots on the lower bumper. It's possible. Airflow can be funny. If that is the culprit, you should be able to come up with a solution to ram a little air over and down behind that winch mount or something.

 

[coachgeo]

Maybe I missed it. in a message... but does your fan come on? You would know they say. Loud as hell.

 

[Ronmar]

I doubt the winch is blocking much, as there is plenty of room for air to get around in behind under the intercooler. These trucks have horrible natural rolling/ram airflow and the fan is a necessity when you are making heat. With the truck turned off, the fan should be locked and you should be unable to turn it by hand. As mentioned, should be a loud roar when the fan engages… if the air tanks are full, if you turn on the ign switch, this should power the fan control solenoid and send air to the fan clutch, you should then be able to spin the fan freely by hand(wiggle it front to rear also to check the freewheel bearings).

Were you getting a high coolant temp or a high trans temp light in the dash. There is a temp switch in the thermostat housing that turns on the coolant temp light at 230F. The trans controller has a programmed output contact that should light the trans temp warning light at ~220F oil temp. A handheld IR tempgun can help you to confirm the gauge is reasonably accurate, but if you were getting 230-240 temps indicated, you should also have had at least one idiot light…

next as suggested, I would foam the radiator let it set for a bit and hose out all the air passages. this is probably easiest if you pull the upper fan shroud…

I would also drain out a couple of gallons of coolant and remove the elbow on top of the thermostat housing and inspect the thermostat. If you are that far in, probably best to just go ahead and replace the thermostat It is a bypass type,, which closes the bypass port as the thermostat port opens to allow flow to the radiator. On a 3116 the bypass port sends all the coolant to the trans cooler/heat exchanger, so if it is not fully closing the bypass, any coolant leaking that way is not getting pushed thru the radiator…

The highway gears should actually help you. Pumping load thru an engine increases with RPM. Any time you run an engine past the peak torque point, its like driving with an exhaust brake on. Your available torque output drops by nearly half between peak torque(1550RPM) and max governed RPM(2600).

and of course a little added load goes a long way to increasing engine and trans heat output. Are your hubs and drums all the same temp after a highway run?

 

[Lostchain]

Hello all. I have a 98 M1078 also. I’m in Durango Colorado and it’s been in the in the mid 90s up to 100. Mine seems to be running hotter than the temps you all have been mentioning and I actually overheated today on my way to Navajo dam in New Mexico and had to stop on the side of the road. I’ve noticed pulling hills it wants to heat up to around 220-230 and hit 240. I just did a flush in hopes that would help but anyone have any ideas what it could be? Also I have the winch bumper that covers a portion of the radiator. Not sure if that works make that big of a deal.

My 2003 ran hot and cycled the fan frequently. I pulled the thermostats and tested them and they were opening way hotter than the stamped temperature. New ones from Cat solved the problem. Fan rarely kicks on now and temps are very stable.