Thermostat experiences minus big C.

[bgilbert]

Just wondering whose brand thermostat's other than Cummins have you used? I'm not paying $30 for one again from Cummins. I have Autozone, NAPA, Advance, and OReilly's in town. I'm not too found of NAPA t-stats in my gasser use, plus from reading over the years they are known to be junk. That said, I'm not going to run one from NAPA. This will be for my crew cab btw. I've only used Cummins stats in my other two trucks. Looking to save a few bucks for a truck that won't be driven much and won't be on the road for at least a year.

 

[NIsaacs]

Well..... if ya won't use Cummins or Napa, that leaves Auto Zone, Advance or O'Rileys. I used a Napa on my 91' years ago, it still works fine. Ya might go and look at each one from each parts house and pick the best looking one?





"NICK"

 

[Bob4x4]

Just wondering whose brand thermostat's other than Cummins have you used? I'm not paying $30 for one again from Cummins. I have Autozone, NAPA, Advance, and OReilly's in town. I'm not too found of NAPA t-stats in my gasser use, plus from reading over the years they are known to be junk. That said, I'm not going to run one from NAPA. This will be for my crew cab btw. I've only used Cummins stats in my other two trucks. Looking to save a few bucks for a truck that won't be driven much and won't be on the road for at least a year.

If you really want to save the bucks just cut a disc with a hole in it like some racers use... ... ... no stat to fail,just a bit of experimenting with the hole size.



Bob

 

[dpuckett]

I used one from O'Reilley's in my 91. It swung like some of the originals did, but never overheated or even got hot (water temp; exhaust temp was another story).



If/when I put a t-stat in my 92, it'll likely be a $30 "C" unit. It may not, either- O'Reilley's is about $9.



Daniel

 

[1stgen4evr]

This is an item that painfuly needs some attention from Cummins. Perhaps there is someone who can get a housing cast that would allow a dual thermostat like the larger trucks. A thirty (or fifty dollar for that matter) thermostat can roast your engine to the tune of several thousand bucks. Had that happen years ago on a small block Chevy. Don't skimp on this.



James

 

[BSchweers]

I bought a NAPA thermostat and it was made by the same company that the dodge house sold. Go figure.





2004. 5 2500 4x4 600 Engine, Hot Juice,Magnaflow Muffler,Afe Proguard 7,Heavy Duty Front & Rear Bumper,Ranch Hand Tool Box,Walbro lift pump



471 HP, 994 TQ 03/09/07 (Stock turbo) American Racing Technology Dyno

 

[Don Tanklage]

someone needs to take the time to figure out what size orfice works for these things



someone with some sheetmetal and the tools to do it



i think the high flow stat that was in this thing may have actually flowed too much? (would have been like having no stat at all)



my truck seems to run cooler going over the grades with the cummins 180 than it ever did with that high flow model



it could have been sticking from the day i got the truck tho...



has anyone tried no stat at all?

 

[JLEONARD]

I wish I knew what thermostat is in mine. The temp holds pretty rock steady... varies maybe a needle width or two.

Awsum heat in the winter also. . blasts me out of the cab.

Hope I never have to replace it... from the sounds of things it's a crap shoot how the temp will react.

As far as NO thermostat... I would not do it unless in an emergency. Every engine I have ever run with no T stat (and they have all been gassers) the temp stays waay to cold. . 100 to maybe 130 deg F. You really want the engine to be at 180/190 to be most efficient.

 

[Don Tanklage]

maybe a orfice of a unknown size would do just that?

 

[PSU-CE]

I have experimented a little in my pulling truck with this. I have clipped the water pump and took out the t-stat and replaced with a grade 8 washer for a 5/8 bolt. I don't know the i. d. off hand. My truck will idle around 100 degrees with the stock fan and goes to about 160 after a pull and within 10-15 minutes is back down to 100. I don't drive the truck so I don't know what road temps would be. I did leave the fan off and the truck got up to 160 before I put the fan back on (didn't want it to get warmer than that). This is without a fan shroud also.

 

[Greenleaf]

The Cummins B manual states that the coolant will bypass the rad if the thermo is removed. So I have always used one. Besides, a hot engine is a happy engine. I'd shoot for 180°F as an operating temp.



My 92 has the new thermo that swings wildly. I'm ordering the updated 3934373 . The current thermo is 3802968 which swings like a chimp from a tree.

 

[RoryTek]

So where does one get a 150F Tstat like that was in my truck? Not happy with the 180F one.

 

[Shadrach]

P/N 3934373 is for a 2nd gen engine and is a bigger diameter - 63mm vs 54mm. It also uses different seals. Shadrach

 

[Greenleaf]

OK, I didn't know that. However, the thermo I installed is from a second gen engine and it fit fine.

 

[Don Tanklage]

i knew it, gl has a 2ng gen motor in his truck... that is why it runs so good!

 

[PSU-CE]

The Cummins B manual states that the coolant will bypass the rad if the thermo is removed.

I wonder how it bypasses the radiator? I can take my radiator cap off and watch the coolant flowing through the cores so I can assure you it isn't bypassed. I would say if the thermostat is blocked that it may bypass but not if removed. Or is it flow from the head, etc. that is bypassed? My engine gets hot enough during 300 feet!

 

[MMiller]

Its interesting, in the last 239,000 miles my 93 has had 3 thermostats in it, and none of them would vary the water temp, the truck always ran the same temp. I replaced the stock one with a cummins thermostat, and then replaced it again when I was chasing a coolant leak... ..... I have occasionally had the 93 and the brown 90 swing up pretty warm before opening up the first time for the day, but never gets hot... ... .



My dads 95 would run cold then swing up then cold, and keep bouncing as long as you drove it. The t-stat was changed as an "update" through Dodge, I think it fixed it... ... .



Michael

 

[Shadrach]

The only way a 2nd gen stat will work in a 1st gen engine is if you use the 2nd gen thermostat housing as well. You will have to use the vent hose also since the 2nd gen stat has no jiggle pins. The jiggle pins alow air to escape so as not to get an air lock. Some people drill a small hole in a non vented stat but this will cause warm up problems for those of us who live in an area that get cold in the winter. The Cummins stats have a disc on the bottom of them that shuts off the bypass circuit when the stst is open. Some cheaper stats don't have this, Shadrach

 

[Don Tanklage]

The Cummins stats have a disc on the bottom of them that shuts off the bypass circuit when the stst is open. Some cheaper stats don't have this, Shadrach

no kiddin? now i get it! i was wondering how no stat could bypass the rad!



so, if you are going to try to figure out a orfice size what do you have to do? tap and plug that hole i guess



but you better end up getting it right because after you tap it a stat may not seal it up again...

 

[JonathanAyers]

If you really want to save the bucks just cut a disc with a hole in it like some racers use... ... ... no stat to fail,just a bit of experimenting with the hole size.



Bob

The engine uses bypass cooling system which is controled by the thermostat. Section 8 page 3 of bulletin 3666087-01 "Troubleshooting, and repair manuel B5. 9 series engine" States in bold text "Never operate engine without thermostat. Without a thermostat the coolant will not flow to the radiator and the engine will overheat. "

A plate with a hole in it is not going to allow effiecent and proper water flow to the radiator when the termostat opens, and it will prevent proper coolant flow within the engine when the engine is cold or below the opening temperature of the thermostat. Thermostats rarely fail and are very important to proper operation of the engine. Fuel injection timing is controlled by the KSB valve which on the engine quickly reaching it proper operating temperature, hence the bypass cooling design.