LDT Engine Temp In 30F Weather

[74M35A2]

Just changed the thermostat in an LDT engine with a new 180F NAPA unit. Temp will not exceed 180F, but will drop to 160F or so when driving in about 30F weather without the winter front cover on.

Is this "normal" for this vehicle/engine? If so, is this likely due to the direct drive cooling fan?

Thanks in advance.

 

[cranetruck]

It's normal.
It's rare to ever reach 180°F on a short drive. I used a "permanent" radiator cover year around to keep the engine reasonably warm.

 

[Wildchild467]

I drove my Deuce yesterday and it was 31 degrees out. I let it warm up to around 150 before I left my house. I took a 8 mile trip with it and it never went above 160. It has a 180 degree thermostat in it. I don't understand why it does not at least hit 180. My pyrometer was between 900 and 1150 during the whole trip. Even if I drove farther, I really don't think it would have gotten any warmer. The Thermostat is new as of last fall. I say it was new, but Ii probably bought it 2 years ago waiting for me to put it in. Am I wrong thinking it should at least hit 180 driving down the road in 31 degree weather? It seems odd.

 

[gimpyrobb]

Nah, most of these trucks run cool. Throw 5000lbs in the back, I bet its hits 180* then.

 

[dmetalmiki]

Running light they simply do not get hot. I use the radiator covers all year round as well to keep the temperature up to a reasonable level. My thermostats are 180s as well.

 

[steelandcanvas]

I keep my Arctic cover on year-round. In the Winter I close 1/2 the grill area, and she will hit 180* with a short run on the interstae. In the Summer months I open the cover up all the way and with that same highway run, I'll get a more respectable 200*. Without the cover, I would never hit 180* unless I was towing or pulling a good grade.

 

[Jeepsinker]

Mine is the same even in the heat down here with a leaking radiator at the moment. Running cool is better than running hot. Count your blessings and stop worrying.

 

[barefootin]

Mine even in summer is in the 160-165 range... With a heavy load, pulling hills, and EGT's around 1K it might hit 180 on a 90 degree day as I crest a hill with the go pedal on the floor in third gear and starting to lug. As soon as the go pedal is off the floor and a higher gear has been selected it cools back down pretty quick... As another has said, count your blessings that it isn't running hot.....

 

[gimpyrobb]

Mine is usually cool, till I'm flat towing a 5ton. I'll hit 190 then.

 

[74M35A2]

There you have it wildchild467. If you really want the reach and hold 180F, then you'll have to switch to an on-demand fan.

 

[rustystud]

There you have it wildchild467. If you really want the reach and hold 180F, then you'll have to switch to an on-demand fan.

Actually that is not a bad idea. Diesels run better hot, and since our multifuel runs cold due to an extremely efficient cooling system it would be a good idea to allow it to reach at least 190F . Personally I hate having to depend on electric fans, but if our engines run better and get better fuel economy I would switch. Maybe I'll try it this summer.

 

[Jeepsinker]

If like to see a phneumatic fan clutch that would work on my truck. Prefer that over electric.

 

[dezert ratt]

i run 180-200 degrees here in southern California. I also have bigger tires, and my ip is turned all the way up. Egts play a big role in how hot my truck runs. If im pulling a big grade and running 1100 to 1250 Egt, i notice she gets warmer than usual. I have never seen over 200 degrees yet.

 

[74M35A2]

This is solved. We changed thermostats again with a brand new NAPA unit. Engine now warms up even faster than it did, and holds 180F rock solid with the winter front cover off in 41F air on the freeway. Same ambient temp with winter cover on and we saw 190F in the city streets prior to freeway entrance.

 

[Jeepsinker]

Sounds like the old one was stuck open.

 

[acesneights1]

If like to see a phneumatic fan clutch that would work on my truck. Prefer that over electric.

the only way I could see to make that work is move the radiator forward like an A3.there simply is not enough room otherwise.

 

[saddamsnightmare]

April 4th, 2015.

We have to remember that these trucks were conservatively designed to run in almost any climate, with any load, at reasonable speeds, so the radiators are probably a little large, figuring better too cold then too hot. When I put a new brass radiator on my truck in Texas, I suspect even 106*F days didn't do much to get her warm (at least I didn't have to face -30*F days).... Figure also what mud and heavy dust build ups are going to do to these trucks running in convoys in places like Vietnam and Afghanistan, and I figure the engineers did a pretty good job on the truck.

 

[Wildchild467]

I just wanted to post an update to this thread. I bought the thermostat from Napa and I might have kept it for 3 years or so before I actually put it in. Anyway, 74M35A2 and I put the thermostat in and like we talked about in this thread, it never warmed up very well at all, even with 50 or 60 degree temps outside. I just couldn't see where anything like that should have been normal where it does not meet the 180 degree operating temp that was marked on the thermostat. I respect everybodys opinion on here but it just was not making sense to me that the cooling fan could cool down an engine that was pulling 1100 degree EGTs. So I bought a new thermostat from Napa again and just like the old thermostat, 74M35A2 was nice enough to change it for me while I worked on other projects. The performance of the same part number thermostat from Napa was a lot better than the first thermostat! It warms up just as it should and holds a solid 180 degrees on this 35 degree morning on my way to work. I guess to people out there that their engine does not warm up to 180 as it should and think they need a radiator cover, I say change your thermostat. I was shocked that even though "brand new thermostat number 1" was new (but sitting in the box for 3 years) that it would not have worked as expected. It only worked briefly when we first changed it, and then did not work well. I kept adding coolant to it thinking it might be an air bubble, but it wasn't. I bled it and everything, so I really don't think that was the problem. When "thermostat number 2" was installed, it acted like any other typical thermostat change I have done. Changed the thermostat, bled it and then topped it off with coolant a couple heat cycles after. It has been working great and having no problem so far reaching 180 degrees on these cool Michigan mornings. The engine reaching the 180 degree temps helps combustion and engine performance with WMO as fuel. I would also add that the heater has been working good also and am happy with the performance even without the winter front cover on. I think if it did get a lot colder like into the 20's, the winter front would help out the cab heater performance even more, but I am still pleased even with the heater fan on low (I have an A3 style heater installed in my truck). I hope this information helps out other members because I am very happy that the thermostat is working like it is expected to.

 

[gimpyrobb]

Did you test the one you took out? Might be interesting to see what its does.

 

[Wildchild467]

I did not. I still have it even though it should be tossed.... but I couldn't be happier with the performance. Like any typical diesel, it takes a little while to warm up, but it goes to 180 and then just stops. Its beautiful!