My daughter has been mentioning that her Jeep GC takes forever to warm up, very slow to defrost, etc.
I suspected a stuck open thermostat
She drove here (about 50 min) on the interstate. Then about 10 minutes on a 45 mph road.
The second she arrived she popped the hood and I thermal temped the upper rad hose 145 deg. The t stat housing was about the same.
The OAT was in the 30s
So today I changed the thermostat.
That was a lesson in thermostat manufacturers.
Napa, Advanced, Auto Zone, O'Riley all had their "house" brand in stock. I started to notice that the images for a particular thermostat (premium/economy) were the same. Even Napa!
So I figured I'll check the dealer (knowing I would pay 2x the price) they had one in stock so I bought it figuring it would be the most likely to last more than a couple of years like the last parts store one did.
When I got it home I looked at it for a manufacturer...
Mororad. An Israeli company and appetantly the leading manufacturer of thermostats.
I would have bought a Stant but none had one today
It might be that Stant was bought by Motorad according to a website I found.
So I changed out the thermostat, guess what, it was a Motorad also.
I tested the old one
YES I KNOW I SHOULD HAVE TESTED THE NEW ONE.. but I did not.
it would start to open at about 150 deg and be fully open around 170.
As a 195 thermostat it should have started to open closer to 190 to 195.
I know there is a lot of debate about what temp a thermostat should start to open, I am not intending to rehash that debate.
Another thing I noticed about the old thermostat is it would not close square to the housing, one side would be open while the other side was still touching the base.
The spring is not ground flat and there is no recess for the ends. Bad design!
I'm waiting till tomorrow morning to fill the system to let the sealer fully set up.
I will know tomorrow if the t stat is working correctly.
Last time I looked at her car about this issue it ideled on the driveway for 30 minutes and never got up to temp.
My 273 dart will get up to operating temp ideling in about 20 minutes.
I suspected a stuck open thermostat
She drove here (about 50 min) on the interstate. Then about 10 minutes on a 45 mph road.
The second she arrived she popped the hood and I thermal temped the upper rad hose 145 deg. The t stat housing was about the same.
The OAT was in the 30s
So today I changed the thermostat.
That was a lesson in thermostat manufacturers.
Napa, Advanced, Auto Zone, O'Riley all had their "house" brand in stock. I started to notice that the images for a particular thermostat (premium/economy) were the same. Even Napa!
So I figured I'll check the dealer (knowing I would pay 2x the price) they had one in stock so I bought it figuring it would be the most likely to last more than a couple of years like the last parts store one did.
When I got it home I looked at it for a manufacturer...
Mororad. An Israeli company and appetantly the leading manufacturer of thermostats.
I would have bought a Stant but none had one today
It might be that Stant was bought by Motorad according to a website I found.
So I changed out the thermostat, guess what, it was a Motorad also.
I tested the old one
YES I KNOW I SHOULD HAVE TESTED THE NEW ONE.. but I did not.
it would start to open at about 150 deg and be fully open around 170.
As a 195 thermostat it should have started to open closer to 190 to 195.
I know there is a lot of debate about what temp a thermostat should start to open, I am not intending to rehash that debate.
Another thing I noticed about the old thermostat is it would not close square to the housing, one side would be open while the other side was still touching the base.
The spring is not ground flat and there is no recess for the ends. Bad design!
I'm waiting till tomorrow morning to fill the system to let the sealer fully set up.
I will know tomorrow if the t stat is working correctly.
Last time I looked at her car about this issue it ideled on the driveway for 30 minutes and never got up to temp.
My 273 dart will get up to operating temp ideling in about 20 minutes.















