Low temp Thermostat for D-max??

Frotax · July 30, 2006

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?

My thoughts are that the stock 195* 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?

duramaxHD · July 31, 2006

I dont think anyone makes one, and it woudlnt be beneficial in a Dmax. Diesel's are completely different; they NEED to be at the designed operating temperature in order to run correctly. Isuzu designed it to run at 180-192* (rough stat closing and opening temps) so that is where its happiest

also, the ECM wont even access the proper fueling and timing tables for its rated power output until the coolant temp is above 168*, so if you were to put 160* stats (yes, the dmax has two) in, it wouldnt run well.

Ben

Frotax · August 1, 2006

I dont think anyone makes one, and it woudlnt be beneficial in a Dmax. Diesel's are completely different; they NEED to be at the designed operating temperature in order to run correctly. Isuzu designed it to run at 180-192* (rough stat closing and opening temps) so that is where its happiest

also, the ECM wont even access the proper fueling and timing tables for its rated power output until the coolant temp is above 168*, so if you were to put 160* stats (yes, the dmax has two) in, it wouldnt run well.

Ben

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Great info.

So from what youre saying, the Dmaxes sound like they come with maybe a 180* Thermostats?

Thats not too bad. I just cant dig on the gassers and these 195* ones. Way too hot. Plus the tranny temp runs so much cooler also with the 160* Tstat.

The interesting part is with a 160* stat in a 8.1(Temp verified with a pan of water and thermometer) unless its really cold out, even at night and 60* outside, the truck idles about 180* and stays there towing etc.

Idling in the daytime at 100* with AC it runs about 195. And moving runs about 190 becasue of the airflow. Thats acceptable.

But when they are at 195* even when super cold out, OUCH, thats hard on everything under the hood.

Has anyone ever tested, or have specs on the Dmax Thermostats to verify the temps?

KICK · August 4, 2006

Thats not too bad. I just cant dig on the gassers and these 195* ones. Way too hot. Plus the tranny temp runs so much cooler also with the 160* Tstat.

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funny how some people want to second guess the college educated peeples who design, test , calibrate and validate these vehicles.

Often wondered why some people think 180 is a better cooling system temp than 195??

engine is made out of metal, 195 degrees isn't hot to metal, just o humans.

50/50 mix of coolant with good pressure cap on it boils in the 250 degree range so 195 is more than 20 % below that setting.

OnyxMAX · August 15, 2006

yep agree with kick on this one. heat is good for diesels. now you know why all them school busses and semi's have the grill covered in winter.

if your worried about the heat on your transmission you can add a aux cooler with fans. or bigger replacement for the stock.

duramaxHD · August 20, 2006

165-200* is a perfectly happy range for the Allison.

Frotax · August 23, 2006

Good info.

So what is the temp rating on the Dmax Thermostat? I cant find anything anywhere showing and the dealer says his book doesnt say. Thats weird.

I know 195 isnt hot for metal.........but all that extra heat is hard on all the belts, hoses, wires batteries and everything under the hood.

Most the gasser guys with 6.0 and 8.1s run the 160* Tstats, but they still idle around 180 during a normal 60-90* day, but they just run around 190-195 towing, instead of 210. SO that means that even with 160* stat......when its warm the cooling system isnt efficient enough to let it stay that cool(maybe in winter)

Thats hot under there.

duramaxHD · August 25, 2006

you can put in two new thermostats if you want, but I am just telling you that the engine runs the temp it does for a reason. Its not a BBC.

diesels dont make any heat at idle. You could stick your finger into the exhaust valve at idle and it would not get burned. The temp guage will sit at the far left stop forever unless you start driving it.

OnyxMAX · August 28, 2006

most stuff under the hood is good for 500+ degrees only exceptions being some computer stuff but it's shielded.

most problems with heat under the hood come from uncoated headers in the gassers. the old heatshields don't fit and gas makes lots of heat at idle you can even overheat. if you have any concerns just remember most stuff nowadays is more silicon then rubber or some hightec plastic compisit stuff, and resist heat as good as sparkplug wires.

what will hurt them is constsnt heat/cool like delivery service and such. most belt damage will come from engine acceleration causing the belt to slip on the pullys producing lots of friction heat fast. a good 0-60 will put more heat in the belts the the engine at a full day of ideling.

forgot to add the 195 stat in the gasser is a emmision thing the hotter it gets the faster it lights the cats keeping it hot keeps the cats hot meaning lower emmisions and goverment brownie points.