Do the cummins brand of t stats have a fail safe?The question is when they go bad are they made to brake in the open position? My engine gets hot 190.The t stat housing is hot. The radiator fluid is cold.I am thinking water pump. The radiator and heater core were flushed in summer.

Just thinking of that what did you do about jiggle pins? Curious what you had to do to make it work?

Jiggle pins? The stock one is a lot wider, it is just as wide in diameter as the whole housing so it barely comes out if rust forms. You put a gasket in that is just as wide and then the thermostat on top of it, then another biggg gasket, then the engine lift bracket. The new thermostat was not as wide. It did not sit on the machined edge on top of the gasket, it was about 1/4" smaller diameter. However, it fit perfectly inside of it on another surface, like it was meant to be there. The only thing was sealing it off. I couldnt use any gasket under it but I used that bigger gasket which by big I mean it was the same diameter as the housing, but was really thick so it would cover the edges of the new thermostat. So I just threw it on top and made it so the engine lift bracket would smash it a little, which is actually how it is supposed to be on the oem thermostat as well so it wasn't really rigged. Then I bolted it all up. Works like a charm.

What parts do i need when i take my dash out.I will replace the heater core and the condenser for the ac.What is the flapper door part?

What parts do i need when i take my dash out.I will replace the heater core and the condenser for the ac.What is the flapper door part?

Well normal tools to get the dash out of the way... But to release the A/C lines you need the special collar tool to do it... http://mopar.mopar1973man.com/cummins/2ndgen24v/hvac/evaporator/evaporator.htm

Jiggle pins?

The Cummins thermostat incorporates two pins on either side of the thermostat that allow air to escape up thru the thermostat into the radiator to bleed the system of air. From the reading I have done most folks have issues with non-OEM (Cummins) thermostats. I also have found that our engines are very hard on thermostats. The cooling system is so large that unless your always loaded the thermostat only has to crack open to keep the block full, it takes a lot of heat to get it to fully open. This causes wear spots on the thermostat, which if they get bad enough can limit the amount the thermostat can open. This also fatigues the spring and makes it slow to react, causing the huge temp swings. Before I replaced my thermostat last winter I would get to 202-206 on every initial thermostat opening and drop into the high 180's. Now I get to about 193-195 and drop to about 190 in the summer and high 180's in the winter. My thermostat was only 5 years old with 52K miles on it, nothing crazy.

The Cummins thermostat incorporates two pins on either side of the thermostat that allow air to escape up thru the thermostat into the radiator to bleed the system of air. From the reading I have done most folks have issues with non-OEM (Cummins) thermostats. I also have found that our engines are very hard on thermostats. The cooling system is so large that unless your always loaded the thermostat only has to crack open to keep the block full, it takes a lot of heat to get it to fully open. This causes wear spots on the thermostat, which if they get bad enough can limit the amount the thermostat can open. This also fatigues the spring and makes it slow to react, causing the huge temp swings. Before I replaced my thermostat last winter I would get to 202-206 on every initial thermostat opening and drop into the high 180's. Now I get to about 193-195 and drop to about 190 in the summer and high 180's in the winter. My thermostat was only 5 years old with 52K miles on it, nothing crazy.

There is this hose and I think it bleeds everything. Could be wrong but it looks pretty convincing. I have had 2 thermostats in it before, both swayed like crazy from the get go. This one has been perfect from the start. I will never use anything different now. It was 30 yesterday morning when I tried it and it went straight up to 200, dropped to 195 and just went around 195-200 the whole time.

http-~~-//www.youtube.com/watch?v=9C_8sHWdzmA

That hose doesn't exist on the 24V or CR heads, so I am not entirely sure of its plumbing. If the thermostat bypasses that hose I can see how the 12V's would be very slow to heat.

That hose doesn't exist on the 24V or CR heads, so I am not entirely sure of its plumbing. If the thermostat bypasses that hose I can see how the 12V's would be very slow to heat.

Ever since I put that thermostat in it heats up just as fast as 24V's I have seen. I got to looking at it some more and that hose seems to route the same as the thermostat, so it would bleed all the air through it. It is only like a 3/16" hose.

So today i removed the flap door motor.It moves good.Then i moved the door all the way to hot reinstalled the motor with the power plug unpluged.It blows 115* at the floor, it was 40* here today.That sound normal?

So today i removed the flap door motor.It moves good.Then i moved the door all the way to hot reinstalled the motor with the power plug unpluged.It blows 115* at the floor, it was 40* here today.That sound normal?

You might test it a little more. I might have to stick mine in the floor to see, I have the temp gauge in the middle vent by the radio. Was that on recirculate? I get 100F over ambient if it is on regular vent, but on recirculate I get up around 160F. So you should be running a little hotter, I assume it was warmed up to 190.

You might test it a little more. I might have to stick mine in the floor to see, I have the temp gauge in the middle vent by the radio. Was that on recirculate? I get 100F over ambient if it is on regular vent, but on recirculate I get up around 160F. So you should be running a little hotter, I assume it was warmed up to 190.

It was not on recirculate.Just the floor setting.I just dont get it.Heater core is hot under glove box.Both pipes.I am missing something here.