Can anyone confirm what temp Thermostats they run?

Lots of guys run the 9 dollar 160* T stats in the 8.1's,
and they run cooler, both water and tranny temps becasue of it.

(They still run about 180-185* when cold out and around 190 when
towing at 90* + outside temps.

Anyone know what temp t-stat a D-max runs? And is it beneficial to
run a cooler one on a diesel?

My thoughts are that the stock 195* that are in gassers are plain just too hot and too hard
on belts, hoses, and everything subject to the heat under the hood.

Can you run a cooler one in a diesel?

I read that until the water temp gets to 168*, nothing works right as far are fueling and the ECM and timing goes.

Also that they are designed to run between 180 and 192*F. Thats acceptable.

This also makes me believe they have a 180 Thermostat, or maybe even less since the 8.1 gasser idles in cold weather with a 160* Verified Tstat at around 180* when its 60-70 degrees at night with no air on.

It just wont get any hotter towing at night, They still idle around 195 during the 95+ degree days though.

True the Dmax has 2 thermostats?

I think ive seen this question before.......... ;)

because the dmax has a large cooling system and because it is a diesel, the temp generally remains constant unless the ambient temp is VERY cold, or something is wrong with the cooling system. Ive found that whether its 0 degrees or 100 degrees, towing or empty, once the truck gets up to operating temp, it stays there. Only difference is in the cold weather, the t-stat opening and closing can VERY easilly be seen because the temp drops down again so quickly. In the winter (10 degrees or so), ill be watching ECT (not on the instrument cluster, reading it from the data bus) and it driving it will slowly climb to 192*, t-stat opens at 192* and BAM drops back down to 180 within literally 3 seconds or so because the ambient temp is so low and the cooling system is so large. In hot weather it does the same thing, except the 192 down to 180 time takes longer. Towing up a long hill in very hot weather my truck might get to 198-200 before it stops dropping again, but that is the hottest I have ever seen my truck get.

However you have to remember diesel engines are COMPLETELY different than gas engines. When a diesel idles unloaded it literally makes no heat. The actual exhaust coming directly out of the exhaust valves, even before the turbo, is only around 200*. You have to really put it under a load and drive it or else it will never heat up. If its 10 degrees outside, I could start my truck and let it idle for literally 45 minutes and the temperature guage will not even move off the peg. Start driving and within 10 minutes the temp guage starts to come up. If I drive it when its that cold and its up to temp, then go to a gas station, fill up with the engine running, when Im done and get back in the truck, the temp guage has gone almost all the way down. After driving for an hour, I stopped at a store and let the truck idle, and when I came back out the ECT had dropped to 159* :eek:

ben

I have the same questions as asked by Frotax...

In my area and throughout much of my driving area the ambient temps are over 100 in summer and more often than I like in the 105+ area during peak periods. Reading the ECT on the cluster guage, not the data bus, I see ECTs in the 195-205 range in 100+ ambient, loaded or unloaded. If the thermostat opens at 192 then obviously it remains open, at least for me or my cluster ECT guage is off the mark. Is it possible to run our engines at lower operating temps...say like 180-190 by replacing the thermostat with one that opens earlier and/or change out the clutch fan to engage earlier?

Also, my engine oil seems to run at or about the same temps as my ECT, and I'd rather see my engine oil temp around 180-190 rather than in the 195-210 range. No doubt about it, ECT and EOT is directly impacted by ambient temps in a big way. If ambient temps are in the low 80s or lower my engine oil temp and ECT run around 180-190.

As a rule, Diesels like to be hotter than gas motors. They are much more efficient. Running synthetic oils makes this a lot easier on the motor.
My ex Coast Guard Motor Mac buddy always said,
"Keep 'em warm on the inside, and feed them lots of cold air"

all of the cluster guages are off. They usually point right at "210" or just the slightest bit below 210 even when they are running their normal 180-192.

read it on the data bus; you will see 180-192.

I would not be worried about the oil. Its fine. 270 degrees, start to worry.

I think ive seen this question before.......... ;)

because the dmax has a large cooling system and because it is a diesel, the temp generally remains constant unless the ambient temp is VERY cold, or something is wrong with the cooling system. Ive found that whether its 0 degrees or 100 degrees, towing or empty, once the truck gets up to operating temp, it stays there. Only difference is in the cold weather, the t-stat opening and closing can VERY easilly be seen because the temp drops down again so quickly. In the winter (10 degrees or so), ill be watching ECT (not on the instrument cluster, reading it from the data bus) and it driving it will slowly climb to 192*, t-stat opens at 192* and BAM drops back down to 180 within literally 3 seconds or so because the ambient temp is so low and the cooling system is so large. In hot weather it does the same thing, except the 192 down to 180 time takes longer. Towing up a long hill in very hot weather my truck might get to 198-200 before it stops dropping again, but that is the hottest I have ever seen my truck get.

However you have to remember diesel engines are COMPLETELY different than gas engines. When a diesel idles unloaded it literally makes no heat. The actual exhaust coming directly out of the exhaust valves, even before the turbo, is only around 200*. You have to really put it under a load and drive it or else it will never heat up. If its 10 degrees outside, I could start my truck and let it idle for literally 45 minutes and the temperature guage will not even move off the peg. Start driving and within 10 minutes the temp guage starts to come up. If I drive it when its that cold and its up to temp, then go to a gas station, fill up with the engine running, when Im done and get back in the truck, the temp guage has gone almost all the way down. After driving for an hour, I stopped at a store and let the truck idle, and when I came back out the ECT had dropped to 159* :eek:

ben

Good information....thanks.

I pulled my 37' toy hauler to Beaver, Utah from Las Vegas on a hot afternoon and I would see my temps go to 220 and then you could hear the fan kick in and bring it back down. This especially happened on step grades and even when the temp dropped from 114 out side to 99. I was worried the first part on leaving vegas withthe outside temps at 113.:eek: BUt the truck pulled great and never got much above the 220. The tranny would also go over 210 and it took a little longer to drop back after topping over the hills. My 03 never got this hot aking the same pulls.

ben, you're saying that the temps drop to 180*.

That tells me that the thermostat must be a 180* stat. Because they wont circulate until they get to the opening temp.

Now on the 8.1's with a 160* stat, even cold outsay 40-60*, they idle around the 175 mark, if its 60+ outside, they idle around 180* and stay there.
If its 95+ out without airflow and the AC on they idle around 195. If there is a breeze and the nose parked into it, even if its 105 out, they idle around 180 since you've got some airflow to cool things off.

Ive never seen one in temps below 40* to see if they would idle below about 170. I suppose if it was zero, it would run colder down to the Tstat opening temp.

Now saying the temps drop on the Dmax to well below the tstat opening, do they really make so little heat that the Tstat closes and never opens unless you drive it with a load?

Now the other comment about when hot out and driving the temp never goes below 180. Makes it seem like they run a 180* stat, or do they really have that efficient of a cooling system?
The 8.1 with the same stuff isnt that efficient at all.