i just throw a torch at it on the work bench

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i dont think the head gasket is blown, no smoke, oil and atifreeze look good, no blow by either
and once it kicks the first time it doesnt get in the red any moe but it does go up and down alot

 

gotta be tight workin on it then... havent had to change one but i know i've peeked at it once of twice and figured easiest and quickest way would be to remove the alternator; then again it wouldnt be the first time i'm wrong

 

mine will get up to 180. then it starts to move alot
hops back and forth from 180 to 150. they said thats normal tho

 

some thermostats seem to be either open or closed; not much in between. it peaks to opening temp and then opens allowing cooler coolant to flow thru the block resulting in the temp drop... until coolant temp from the radiator to the engine is somewhat close to the same temp typical thermostat operation will cause this. so i guess it could be considered "normal" i know in the gasser industry they've gotten the stats to be "linear" in terms. i'm sure the new stats for diesels are the same.

 

It was before Cummins came out with the updated thermostat.The newer thermostat stopped the fluctuation completely.

It is also of note that many have tried the NAPA and Awful Zone(opps,Autozone) thermostats and have had ALOT of issues with them.This is why you will find about everyone telling you to use only the Cummins Thermostats or you will be doing the job twice.......andy

 

yea but how much is that cummins thermostat??

 

How much is a Cummins engine? I know at least 1 guy that lost an engine to a cheap parts store thermostat.

$50 is going to kill you?

 

50 bucks would be fine. just didnt want it to be like 70 to 80 dollars

 

i didnt have to take my alt off just move the bracket