Ok gentlemen, my 200F dodge stat came in and i swapped it into the truck. This experiment is based on comparisons of the 200F Mopar stat to the 195 Napa one. I decided to take the plunge in this, and will post up pictures later from my phone showing the two T-stats. The Mopar one is definitely looks Cummins to me, and is very beefy to start with. My Mopar one cost roughly 60 bucks out the door at the stealership, im sure one can find one cheaper elsewhere. I'll also grab a part number, but there is another thread somewhere on CF that lists it. Its a 6 series though. I decided that since no one else will play with this monster i should be the first. This is in reference to this thread here http://www.cumminsforum.com/forum/98-5-02-powertrain/579307-what-kind-thermostat-best.html So far, some baseline stats. Highway speed @ 65mph, temps 184-188, IAT 89-94 @ 45. GPD @ level, 2.40Gph(aproxx) Short idle, temps 184, IAT 105-114@ 45, GPH@ .74-.80 long idle , temps 179, IAT 96-105@ 45. GPH@ .80-.90 All units are in F. Also a short idle is say a stop ligt, to up to 7Mins. Anything over 5-7 Mins is considered a long idle. thus far today since i swapped it in, (and it burped), my temps are holding a stead 200-203F, idle gph was between .54 and .67! Thats amazing. Now we should also note that the scan guage that im using also is calibrated for the current running MPG. i expect this to change. I also took a short trip this afternoon. and we shall see over the next week or so how the temperatures handle. Tonight will be the first night of idling to say after i get to work, so we shall see.

You need to keep in mind that on most vehicles anymore the guages are nothing more that idiot guages, in other words they are programmed to show a certain point as long as the range is what is expected. As an example, the oil pressure guage on Michael's 24 valve truck will rise when the switch is flipped fooling the ECM into thinking it is cold outside and drop back down at the flip of a switch. I remember the video on here, but can't find it.

 

The day I bought my truck it was around 40 degrees outside and I drove it home 4 hours, temp never really broke about the 160 mark on the factory gauge. I made a winter front that covers just the radiator and my temps still only read around 165-170 with normal driving. A few trips down the interstate at 68-72mph and I can reach 180 ish but on my return trips the temp wont break 165. I bought a 190 thermostat from napa last week but havent had time to install it, after reading this I'll probably spring for the 200* instead. I usually fill up about half a tank (about 300 miles) and my mpg's have been steady a 15 to 17 (hand calculated). Its been in the teens and single didgets in the mornings, and I usually let the truck high idle before I leave in the mornings and before I leave work in the afternoon.   Maybe Friday I'll take a drive out to Cummins and pickup a 200* thermostat and see what kind of a difference that makes.

This is why the hype isn't worth the time as most drive these rigs as cars and never see loads capable of warming them up to even 190 most days on short trips in winter. on my 05 I can drive close to 20 miles at interstate speeds before the t-stat even opens for the first time at 190ish this with the grill inserts and no load in the summer it still takes close to 10 miles to open it up, throw a load on and it is a ton better, this is why most car driven cummins engines will never see the life of a worked diesel engine within reason.

I'm lucky where I live with all the distance from everything. So I've got just about 15 miles to work by about 5-7 miles I can typically start getting heat (south Pollock) but 8-9 miles I'm at full 190*F temperature (north Pollock). Then if I go the other way to McCall to the store then I've got a grade to climb to get out the canyon. No problem there I'm fully warmed up typically in under 5 miles from the house. So mountain living with a diesel you can most certain hit full temp within a few miles typically. This is of course with full cover of the grill area.

My cummute to work is about 22 miles, the truck makes heat in the first 8 or so miles just doesnt build any temp on the gauge. This truck was from the southern part of the state and by the looks of it wasnt driven in the winter months, so I'm assuming its only got a 160* thermostat in it. My last 24v was a 5 speed and would litterly roast you outta the cab in 5 miles.

 

 I work with a guy who recently got a 99 24v, and his drive to work is 2 miles, he drives that truck every day.

My truck after the new thermostat is maintaining 190ish, even at an idle it only drops a few degrees below.

Edited November 28, 201410 yr by eddielee

I recently installed a 195* thermostat in place of the stock 180 in my 95. I also flushed the engine out with water and put in a new radiator. I lost 1.2 mpg hand calculated too so the 180 is going back in. If anyone is interested, I have a 195 with new rubber gasket that has 350 miles for sale. It's one of those off of eBay that's not supposed to fluctuat. It rides here pretty steadily

I think you jumping the gun a bit too fast. 1.2 MPG could be just the winter. Not to mention possible driving habit changes. Like myself with the lower price of fuel I'm driving a bit faster now and seeing a 2 MPG drop just from that.

I typically drive under the speed limit with this truck since it has 4.10 gears and I don't race from light to light. Winter in fl is not really winter at all. I couldn't believe it myself, was hoping for at least a 1mpg improvement.

The reason that it affects 98.5+ trucks, is due to the dynamic timing in the ECU that takes many sensors into consideration.

Ed

Being Florida is already warm it might not net much of a gain at all. Were up north here might actually help the numbers because of the extreme cold. 

I recently installed a 195* thermostat in place of the stock 180 in my 95. I also flushed the engine out with water and put in a new radiator. I lost 1.2 mpg hand calculated too so the 180 is going back in. If anyone is interested, I have a 195 with new rubber gasket that has 350 miles for sale. It's one of those off of eBay that's not supposed to fluctuat. It rides here pretty steadily

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curious...

Did you notice the  cooling fan  running more with the hotter stat?

No, couldn't tell a difference with the fan.

Does this drop coincide with the new tighter trans you just installed?

No, first tank after trans was .5 higher than normal