ted_pulliam

I have been using my truck (173000 miles) to commute back and forth to work lately since my "cheap" car is temporarily off-line.

I notice that any time the truck warms up (unloaded) it initially hits about 200 on the temp gauge. Then, I guess, the thermostat opens up and takes it back down to around 170 or so.

From that point on, the temp fluctuation is not as great, and the truck hovers between 180 and 190. Is this normal? I don't want to mess with the thermostat is it isn't broke. I can't say when the last time the coolant was flushed in the truck since I just took ownership of it last month.

Changing the coolant is on my short list of things to do for my truck, including changing the fuel filter and flushing and refilling the NV5600 with the expensive 4874464 fluid from the dealer or if I can get away with it the Valvoline Synchro-Mesh stuff that reportedly is an acceptable subtitute.

Many thanks for your input!

SIXSLUG

That's pretty normal for temp ranges on this truck. Also make sure your radiator isn't all gummed up from the puke bottle for the crankcase breather. Cleaning this out can significantly help w/ running temp fluctuations. The factory Cummins suggested thermostat is a 190.
Running the stock fluid isn't really advantageous costwise. I run the Redline MTL in mine and it shifts a lot smoother than the stock fluid. Also fill it 1 quart over to help lube the rearmost bearing in that trans. I run 6 full qts w/ no problems. its hard to overfill though. The easy way is thru the top cover, just don't drop anything into the trans if you go this route. Good luck, Kurt PS the Amsoil lube is highly rated by others on this site also.

ironbutt

Hey Ted:
You most likely need to clean the radiator. I know that when I cleaned mine the temp never went above 180. But before it was cleaned it could get up to almost 240 and the clutch fan would lock up and make a loud howling sound. Due to the oil vapor drip bottle making everything in the front of the engine oiley, and then the dust sticking to the oiley residue. my radiator was almost totally plugged.

dozer12216

It only fluctates 10 degrees. That's good. Mine will sometime change even more. Has to do with coolant volume. Theromstat closed. Water heats up in engine and cools down in radiator. Theromstat opens. Cold water and hot water are switched. Theromstat closes and gauge moves.
Ever wonder why large trucks have shutters in front of radiator?

ted_pulliam

Thanks everyone for the information! I will definitely flush the fluid next weekend (around payday)!

Ted

ted_pulliam

Hey kurtaing,

where can I buy the Redline MTL?

Ted

1-2-3

When you drain that radiator, remove it. Only takes a few more steps. You will be in shock when you see what's stuck to it from the oil film that gets on there from the puke bottle. You can't see it with it in place. Someone has some pics of thiers. Maybe someone can link to them.