Question: I am in the process of finishing up the building of a DIY serviceable thermostat (found plans over on the other KJ site and contacted the author for cleaned up plan versions). Is it better to put in a 192 degree Hemi thermostat or go with a 205 degree Hemi thermostat?

I live here in the desert in SoCal with summer temps around 95 to 105 and with winter temps in the 40 to 60. Also, have the heavy duty cooling clutch and 11 blade fan mechanical fan install for the local trail runs. I have not overheated with this setup and the factory thermostat but I also wanted to improve the reliability of this engine and make improvements where I can.

Thoughts?

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05 CRD; Rebuilt top end w/ARP studs, EGR delete, SEGR, 3.7L HD cooling fan, Samco hoses, in tank pump, JBA coil overs & control arms, KK clevis fork, 1/2" cradle drop, 1/4" motor mount lift, WJ rear upper trilink w/WW mount, WJ lower control arms, 4:10 gear, front/rear air lockers, ARB bumper, Rock Lizard sliders/roof rack, Mod T-stat

I am setting up 2 CRD's with the 001 model thermostat from Jeff. In my daily driver(here in MN) I am leaving the 203F thermostat that Jeff puts in when he sells them.

In the CRD that I am putting in my fj40(which will not get run in the MN winter) except to go on a trailer to go somewhere warmer. I am going to change that one out to a 190 or 195F thermostat.

Hope that helps. Just my .02

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2005 KJ Crd 2.8L swapped into 1976 FJ40 with 2010 auto trans
Head studs, deleted
Yeti tuned
Suncoast torque converter
Sasquatch turbo
Cummins lift pump
HDS 001 stat housing w/190 thermostat
Trans temp, egt, ultra gauge gauges
email 84landcruiser(at)gmail(dot)com

Yeah thanks for your inputs. I think I may stick with the hemi 192 and see how it performs. Anyone else?

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05 CRD; Rebuilt top end w/ARP studs, EGR delete, SEGR, 3.7L HD cooling fan, Samco hoses, in tank pump, JBA coil overs & control arms, KK clevis fork, 1/2" cradle drop, 1/4" motor mount lift, WJ rear upper trilink w/WW mount, WJ lower control arms, 4:10 gear, front/rear air lockers, ARB bumper, Rock Lizard sliders/roof rack, Mod T-stat

I have the 203 deg. T stat in both of my CRD's. They have been in the Oregon desert, hot and humid Florida to the Canadian winter. Never a problem. One of them has well over 100000 miles on the original T stat supplied in the HDS 001 unit.

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2006 KJ Sport CRD, 2006 KJ LTD CRD, 2013 Subaru BRZ 6spd., 1994 Ford F150 XLT, 1969 Dodge Charger R/T 4spd. (Yes it's a Hemi).

I'm running the 203 degree T-stat as well in my HDS-001 housing for two years now. I'm in Florida, so the A/C is always on. The temp gauge is just to the left of 12:00 (call it 11:45ish)... never seen it go higher than that regardless of driving conditions or weather!

I also have the NAPA HD Fan Clutch / GM 11-Blade Fan setup on my Liberty.

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2005 KJ CRD Limited 4x4
ARP Head Studs
GDE Hot Tune / Trans Eco Tune
HDS Model 001 Thermostat (203°F)
Suncoast TC / Transgo Kit
Full EGR Kit
Bosch 5V Glow Plugs
NAPA HD Fan Clutch / GM 11-Blade Fan
Samco Silicon Charge Air Hoses
Carter In-tank Fuel Pump
Provent 200 with Sasquatch Install Kit
Sasquatch Silicon Turbo Inlet Hose
Bilstein Shocks

What opening temperature thermostat you should use depends upon several factors and assumes that you have a fully functioning cooling system.

1) ... your driving conditions.

2) ... the kind of "do it yourself" thermostat assembly you are creating.

If your DIY thermostat is one based on a plan to re-use the cheap cast aluminum O.E. thermostat housing, I can tell you that the chamber the HEMI thermostat valve rests in is not properly sized for this massive valve and there may be coolant flow issues. I discovered this years ago when I first set out to create a serviceable thermostat assembly for the Liberty CRD engine. That is why I created an entirely new housing with a properly sized chambers; exactly the same size as the one in the HEMI engine water pump housing.

If there are coolant flow issues you may have a problem with rising engine temperatures in high demand situations. I therefore would be cautious and run the 192 degree valve as a hedge against overheat events.

RDBUL, mrhemi, and fjdiesel:

Thank you very much for your input and endorsements for the Hot Diesel Solutions Model 001 engine thermostat assembly.