Another Motorad 195° thermostat failure

C

Chris142

Joined
Jun 5, 2003
Messages
32,040
Location
Apple Valley, California
Driving to work this morning. Heater isn't working well at all. Looks like the Motorad thermostats last about a year at best.

OE thermostat is no longer available. It's been replaced by a Motorad in a jeep box.

IMG_20251205_074409520.webp


IMG_20251205_074518006_HDR.webp
 
Chris142 said:
Driving to work this morning. Heater isn't working well at all. Looks like the Motorad thermostats last about a year at best.

OE thermostat is no longer available. It's been replaced by a Motorad in a jeep box.
Click to expand...
Chris, this should be the OEM Mopar thermostat (195 degrees) for your '02 TJ with the 4.0 liter motor:

MOPAR 52028186AC

Or you can try a 197 degrees Calorstat thermostat for the Jeep.

Calorstat TH596292J
 
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Is Motorad likely what I got when I bought a "Duralast" thermostat for my Sierra? That lasted a year. I installed an AC Delco from Rock Auto this time. Hopefully this one lasts as long as the factory thermostat. (7ish years?)
 
Get a Facet thermostat. The part number is 7.8204S
You can get it from Rock Auto, but a gasket is not included, so you will need to buy one separately.

Although RA doesn't list it in their catalog for your Jeep, it does show up as fitting in Facet's catalog

Rock Auto has an Aisin thermostat for your 2002 Wrangler. I don;t know how good that Aisin would be for your Jeep, though the price is low enough where it might be worth it.
 
I'd give a Aisin or Calorstat a try from Rockauto. The Aisin is less than $5.

AISIN THRAZ0008

I've been following your thermostat woe's as I'd like to replace my working 10yo thermostat in my Ram when I do a coolant flush... But I don't want a reboxed motorad and I wouldn't be surprised if that's what I got even on the Hemi.
 
Chris142 said:
The same exact Motorad that autozone sells but in a jeep bag. Already been there with those.
Click to expand...
The frequent failure mode of Motorad thermostats is that they get stuck in the partially open position due to the exclusive design of their "Fail-Safe" technology (see video below).



This patented design is intended to lock the thermostat in a partially open position with two brass "wings" to prevent the engine from overheating and possibly blowing a head gasket.
1764973134555.webp


According to my research, the MOPAR branded 52028186AC thermostat is now manufactured by Motorad; however, it was spec'ed by MOPAR to be constructed without the patented "Fail-Safe" feature. This appears to be a fact since the profile photo on the Rockauto site shows a thermostat w/out the "Fail-Safe" brass "wing" hardware.
1764972896746.webp


I would be tempted to pull out the defective Motorad thermostat and try to delete the "Fail-Safe" brass "wings" to free up the thermostat flow valve. You really don't have anything to lose at this point.
 
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Nukeman7 said:
The frequent failure mode of Motorad thermostats is that they get stuck in the partially open position due to the exclusive design of their "Fail-Safe" technology (see video below).



This patented design is intended to lock the thermostat in a partially open position with two brass "wings" to prevent the engine from overheating and possibly blowing a head gasket.
View attachment 313474

According to my research, the MOPAR branded 52028186AC thermostat is now manufactured by Motorad; however, it was spec'ed by MOPAR to be constructed without the patented "Fail-Safe" feature. This appears to be a fact since the profile photo on the Rockauto site shows a thermostat w/out the "Fail-Safe" brass "wing" hardware.
View attachment 313472

I would be tempted to pull out the defective Motorad thermostat and try to delete the "Fail-Safe" brass "wings" to free up the thermostat flow valve. You really don't have anything to lose at this point.
Click to expand...

Mine is NOT a failsafe design. I won't use those.
 
I have never had a motorad thermostat failure in the past fifteen years. Granted, I replaced them when doing timing belts and water pumps on VW TDI's as Maintenance or when an OEM Thermostat failed, such as in a Hyundai 2.0 "Nu" and "Beta" motors or a Toyota 2GR-FE water pump failure as preventative maintenance. They all ran for several years without issue before selling those vehicles. Maybe it's "just a Mopar thing"?
 
TheBig2003 said:
I have never had a motorad thermostat failure in the past fifteen years. Granted, I replaced them when doing timing belts and water pumps on VW TDI's as Maintenance or when an OEM Thermostat failed, such as in a Hyundai 2.0 "Nu" and "Beta" motors or a Toyota 2GR-FE water pump failure as preventative maintenance. They all ran for several years without issue before selling those vehicles. Maybe it's "just a Mopar thing"?
Click to expand...
It's a very common number. It fits many cars including gm,Ford Jeep and maybe more. You would think they could get them right.
 
Nukeman7 said:
How about buying this NOS Stant 330-195 unit for ~$14 shipped? The original thermostat in your TJ was likely made by Stant (long before being bought out by Motorad).
Click to expand...
Motorad bought stant in 2020. They started throwing motorad parts in stant boxes - or did for rad caps for my Nissan's. That one does look promising however since it stamped with Stant.
 
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