travelingman

My 01 with 47re has started running cooler than normal its always ran 180
or a hands width below give or take, unless hauling then it would go past maybe 1/8 of a inch then back just normal thermostat an engine fan cycleing
stuff . Now normal seems to be halfway between cold an 180 . I hauled a tractor last night outside temp about 65 an it would climb to 180 on long pulls
then go right back to half way between cold an 180 . My engine fan seems ok
I did not hear it kick in an I raised the hood with engine off an by hand it turned with very little resistance . So am I pretty safe in thinking I,ve got a sticking thermostat ? This truck has 150000 mi on it an i,m guessing that is the original although I did change the Anti Freeze when I bought it at 130000 mi . An do these trucks call for a 180 degree stat ? The only other thing I can think of is a bad Temp sending unit or radiator cap . I can check the cap but don,t know how to check the sending unit .
Thanks
George

Junk Man

Start by confirming that temp on gauge matches actual radiator temp. Use a $3 meat thermometer if you don't have one of the fancy schmancy $15 gauge from Harbor Freight. If the 2 match, sending unit is good.

IF you need a TStat, get a Cummins. The aftermarkets let the temp cycle up & down & are a waste of install time. They are good for scavenging the gasket before returning to store for refund. You could boil you current stat & see where it opens.

travelingman

Ok sounds like a plan these 01's did take a 180 don't they . I've got access to a infared gun , but something I could actually stick into the coolant proubly would give a more accurate reading I'd think ?
Thanks for the input junk Man .

SIXSLUG

The 01's take a 190.

KATOOM

Bad thermostat is most likely the cause. Mine did the same thing too but it wasn't quite so cool. I've heard that you have to be careful where you get a new thermostat too. Some will even tell you to stay with OEM because over the counter stuff is garbage. I got mine at NAPA and it works great. I checked and it seemed to be the same quality and size opening as the OEM one.

travelingman

Sixslug I see yours is a six speed would the Auto take the same Stat ? Thanks guys I'll dig into this tommorrow . I'm sure the parts man will ask me if theres a difference i'll call the local cummins
distribitor or Dodge .

Junk Man

Cummins is less expensive than the dealer. Local truck shop may be less expensive than Cummins. I usually call Cummins for part # & inventory then have Rush (truck repair place) order & pick it up for me. Rush is open all night.

SIXSLUG

My service manual shows a range of 181F-203F for opening and closing temps regardless of trans.

My inquiry re: the correct stat in the past resulted in a 190F for my 01.5.

travelingman

I put the the oem Cummins Stat in it 190F . Its back to normal now.
It appeared the one i took out was not the original,it was fully closed though I was exspecting it to be partially open .

Junk Man

Aftermarket tstats are only good for the gasket in the event that you have an OEM Cummins tstat that needs the gasket. The gaskets become brittle & cause a leak but can be repaired with aftermarket. Gasket is not available alone.

johnh

mine does not have a gasket, only a O ring