203 thermostat or not

Bugman

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My stock 195 thermostat never did get much above the N in normal on the stock gauge. But it will run on the M with the 203 degree one from Diesel Site
 

euroford

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I'll add my experience with the 203 degree thermostat.

I use my truck in the mountains allot, for a variety of reasons, but a major way it gets a lot of high altitude miles is skiing. Unlike a normal person who stays home when its dumping snow and way too cold, that's a reason for us to get up way to early, grab the gear and head for the hills.

When my truck was "new to me" about 6 years ago and in a relatively mild state of tune (intake, exhaust, edge tuner) I had a heck of a time keeping it warm during the winter. Heading westbound was no problem as your gunning it uphill and working it pretty hard, but at the end of the day heading eastbound and down on i70 i'm literally coasting with the trans in neutral (ZF6) for long stretches. Under these circumstances the engine would really cool off, to the extent that i would have trouble defrosting my windshield.

I tried covering the radiator, but that's a bandaid that only helped somewhat and has other negative effects.

Swapping to a 203 degree thermostat however SOLVED that problem. with the new thermostat in I had no problems, was a big fan of it and drove it that way for a couple of years.

Then it was time for a serious power upgrade so I swapped to a set of hybrid single-shot 250/100 swamps injectors and performed an assortment of other supporting mods. (highly recommended btw)

During the first summer following these mods, my wife and I went for a kayak trip on the upper Colorado river. This involved loading up the truck with the pop-up bed camper and hauling our 20' 14k trailer with my wifes Ford Escape loaded up. (The Escape is used as a shuttle vehicle to get us and the kayaks up the river to the put-in while the truck and camper is camped out at the take-out)

On the way home, it was about 90 degrees outside so we had the air-con blasting and heading up to the top of Vail pass (something like 12 miles of 7% grade topping over 10k') while blasting right past everybody we saw oil temps top out at 254 degrees. Sure... I could have slowed down, could have turned off the a/c, whatever... 254 is hot, but it is still within the operational range, and i like to party.

but... I didn't want to just leave it that way and would be thrilled if i could pull that pass at mach-looney without even looking at the gauges. So, i pulled the radiator and intercooler, cleaned everything out really well, flushed the whole system, installed a 195 degree thermostat, removed my license plate from in front of the grill and refilled with new ELC coolant.

now... the truck warms up quicker, stays warm in the winter, provides plenty of cabin heat regardless of conditions or road grade and stays cool during the summer, even when pushed HARD. my oil temp tends to hover right between 198 and 204 now, if i'm positively BEATING on it i can get it up to about 225, but it then drops down really really fast as soon as i'm out of the go pedal.

so... this is my take-away from this experience.

I don't think there is anything wrong with running the 203 degree thermostat. if your having trouble keeping your truck warm, adding one of these (and the nice billet housing) is probably the cheapest and easiest way to keep your motor and your interior warm.

but... I think the REAL solution is give your cooling system a good once over and clean out with some high quality coolant. This has proven to be both beneficial in keeping the engine warm, and cool, depending on the circumstances required.

i'm going to go out on a limb and suggest that if your cooling system is working great, the thermostat may not really matter all that much, and may only really matter for those of us with bigger injectors that drive too fast, up steep grades, at high elevation and in that case the 203 might let it get warmer than you like, but then again, maybe not.

i have no intention of swapping the 203 back in, heck if anybody want it, and is willing to head up towards louisville co, i'll make you drink a beer in the garage and bull**** about powerful vehicles for an hour and then its yours.

edit: as an additional aside... my idiot gauge in the dash has never done a dang thing. as soon as it warms up, it sits in its spot a little below middle and has never moved. i do monitor my oil temp via an edge cs unit that i use only for information, not tuning.
 
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