new Cummins thermostat for my '92

[DMcLeod]

I purchased a '92 W250 last year and the engine temp gage kept swinging wildly and was mostly on the cold side once winter set in. I put a new Cummins thermostat PN 3802968 in recently and now I watch the engine temp come up normally to 180 degrees. The temp still swings some in the severe cold due to the massive cooling system, but this is to be expected, and nothing like before. The thermostat I removed was aftermarket, and I'm not sure on it's age. I suppose I should test the radiator cap to complete my work. I'll flush the cooling system this spring.



Along with my new thermostat and seal was a blue plastic piece that looked like a gasket, but printing on it read "Not a gasket. " Anyone know what this thing is for? It has PN 3920336 printed on it. I didn't use it.

 

[Paychk]

I never could figure out what that was for ... til now. It is a template to make sure the head doesn't crowd the T-stat, so it can function correctly.

TSB 07-01-91

 

[TBartlett1]

Not a Gasket

The first of the first gens had a casting interference with the thermostat which needed to be removed using a die grinder to allow proper operation of the thermostat.

Install the template to check for intrusions that may touch the thermostat.



Tim

 

[DMcLeod]

Well, now I know. Thanks fellas.

 

[DVolk]

Im betting your radaitor is getting dirty and usally a flush wont clean it , thats a wasted service sold by shops and most of the time does nothing , Its dirty or clogged you will need to go to a radaitor shop and have the core rodded out , also a good rustin hibtor is a must , I use watersolible oil in my radaitor a cup a year and have no issues .

My dad was a 30 year automotive radaitor service man and thats what they used.

 

[Shadrach]

I don't know why they still put that in the box. It just confuses most customers. Shad

 

[RSchwarzli]

The first of the first gens had a casting interference with the thermostat which needed to be removed using a die grinder to allow proper operation of the thermostat.

Install the template to check for intrusions that may touch the thermostat.



Tim

Always good they put not a gasket on it! Wonder how many still tried to use it! :-laf

 

[Mikey-KE7LBB]

I'm sure that someone has in the past :-laf



I'm also pretty sure that a few people have even installed a thermostat upside-down as well!!! :-laf:-laf



It goes right along with the labeling on the small package that comes in the box with electronics!! :-laf:-laf:-laf



I won't be quoting Bill Engvall on this one, but y'all get where this one is going??

 

[DMcLeod]

DVolk - Not sure what clues you in that the radiator may be clogged. The truck does not overheat.



What I meant by "flush" was that I would drain the coolant, flush with water, and refill with new coolant. I do this every few years.



I will look into water-soluable oil. Thanks for the advice!

 

[DVolk]

The fluctuating of the heat like that you talked about . Antifreeze dont reley ware out just the inhibtors breakdown is all