Lookin' to replace these pretty soon. anyone have the NAPA part #'s for these? How often are you all changin' out the t'stat? If I do change out the stat, should I stay with stock, or is there one better in the aftermarket? Please advise, and thank you in advance.

 

Thermostat- have you changed it in the past couple years? If it's working good and or it hasn't been more than a couple years since you changed, I'd leave it be. Cummins only t-stats. $30 piece, so if it's not old, leave it be. NAPA has the best hoses IMO. I don't know the numbers on them, they'll fix you up. By no means though, don't get a NAPA t-stat. Junk out of the box, cycle worse than a Cummins stat. Don't get me wrong, I'll use them in my gassers, but the 6BT.

 

The correct thermostat is Cummins 3917324. I would change it every 4-5 years.

Brian

 

All NAPA
Upper Hose: NBH8620-$17.69
Lower Hose: NBH8327-$18.69
Misc. Heater Hoses: NBH7296-$4.50. You will need 2 of these 90 degree hoses.
1- 5" piece of straight 5/8" heater hose. This will need to be trimmed to fit.
Round up your clamps and that should do it.

 

I didn't know any better and picked up my thermostat at Advance.

It works fine; the temperature gauge reaches a certain point and remains there, mile after mile, up hill and down, loaded and empty.

 

I did the same thing about getting a 180 thrmo at napa but I tested it in hot water and it dident open untill 195o. I dont know the difference between a cummins. Can anybody explain?

charliex25

 

Cummins is fully open at 180*, NAPA starts to open at 180*. I run a Cummins one in summer and a NAPA one in winter for more cab heat.