Palmetto_kid

Once up to operating temps, my truck stays about a needles width above 190deg. Im ok with this. But sometimes I notice that the temp goes to about midway between 190 & max safe range. THis happens just as the engine reaches operating temp. It doesnt stop at 190, it just goes up to about 215(i guess), and hangs there for about 30 seconds, and goes back down to where it is supposed to be.

I dont like this. Has anyone else experienced this? Is it my thermostat?

gamiller31

Sounds like a sticky thermostat. I would start there.

firestorm

I agree with gamiller31, check your thermostat.

BigBlue

I'd change the thermostat ASAP. Otherwise you might end up like haulin.

AggieJustin

Definitely pull that thermostat and take a look. I've always seen them run about a needles width below 190 or right at 190 for operating temp. I had a couple of friends who had bad thermostats that worked fine empty, but would overheat the minute they put a load behind the truck.

I turned out the frame on the thermostat broke allowing it to hang up only partially open. Enough to keep from overheating under normal conditions, but easy enough to burn up once you started working it.

Palmetto_kid

yup....it does it when i pull a trailer mainly. well. guess im getting a new thermo....shucks!

RustyJC

Mine has always run about a needle-width under the 190* mark when empty and about a needle-width over the 190* mark when towing our 13,500 lb 36' 5th wheel. On a warm day, it might try to climb higher when pulling the 5ver up a long, steep grade, but it drops back quickly when the fan clutch kicks in.

Rusty

Palmetto_kid

Well, I just ordered a new thermostat. part# 3946849

The guy at Cummins SouthernPlains said they only sell Valvoline antifreeze. I could have swore someone said they bought FLeetguard from a CUmmins outlet.


Did i get the right thermo? I dont want to go thru what haulin did....

I PASS GAS

I looked up Haulin's post and you do not have the same part number as his bad one, but I'm not sure if it's the right one you got.

Knowing that I did not have the part number of the bad one would make me feel a WHOLE lot better.

KATOOM

Now you all got me wondering. My temps climb to about a normal 185* IF I allow it to warm up slowly while driving. If I push it at all before total warm up then the temp will hit 190-195* for a few seconds then drop to the normal 185*. When I tow the temp stays around 190-195* depending on outside temps and if I'm climbing a hill. It never gets any hotter than that. Does this mean I also have a sticky thermostate? Man I hate this site! Every time I log on I see a new thing I need to investigate!

KATOOM

Oh yea, forgot to ask for the correct part number for the 185* thermostate. Thanks.

Palmetto_kid

They guy at Cummins said that the part number for thermostats have changed many times.

This is the number for Haulin's bad thermo: #3954194
THis is the number for Haulin's good thermo: #3967195
This is the number for the one I just ordered: #3946849 (190deg)

who knows what is right..... I just know I'm not buying the bad one...(i think...lol)

RowJ

Noticed mine doing same thing 2-3 times this winter. Pulled it-could see nothing out of ordinary - no crud or cleaning required - so reinstalled it. Not happened since?? Maybe warmer weather...maybe jiggling it helped...maybe letting some air in??
I suspect problem will return, but hasn't so far.
Rowland

Palmetto_kid

Got it changed. No probs. Changed it out friday afternoon.

Worked cows all weekend, and hualed 20' gooseneck with 5 horses in it for 2 days. Never above 190!!!

cant beat that. The liquid in the radiator looked good. So I just drained it out, and refilled with 2.5 gallons of distilled water, and 1.5 gallons of anitifreeze. I know my mixture is a little off, but I think it will be ok.

duner

mine has always run a hair over 190, if it gets about two needles over, the fan
kicks in. that always made sense to me.