Thermostat cycling

[Archive]

I have a 97-3500 2wd 5spd , basically stock
truck . I changed the Stat to the new (fixed
stat)? the same weekend i went on a road trip
the stupid thing cycled for a long time,then it stopped . after getting off the x-way it started again . I talked to people at Mich Cummins but have'nt recieved a sutiable awnser. Shouldn't the engine run better with more temp around 180-190 deg? It would seem so since a Diesel runs better with consistant
temp. I was even thinking of making a device that had a 1/2in dia hole or maybe smaller ,
depending on how the test would keep constant temp. Any suggestions or awnsers ?
All help would be appreciated .

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Scott Burton

 

[Archive]

Scott,

You're trying to fix something that's not broke. Mine has been doing that for 150K miles and no problem. There is a million mile truck in a Dodge showroom in Las Vegas so it must have survived. The few degrees it cycles really doesn't impact anything. Actually, I suspect that the stock stat opens more thus has better cooling potential when needed.

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Joe George
Eureka, CA

'95 2500 CC auto 4X4,3. 54,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver

 

[Archive]

When I bought my 95 C/C new at Thanksgiving 1994, it was doing the same dance. Dodge, Cummins SE and I went round-n-round on this and all determined that its normal. We had a laser pyrometer in the open radiator cap to see if it was the guage or sending unit, but no, the actual water temp was changing! The new owner of my truck calls me periodically, and with 200k on it, it still runs fine! My newly aquired 97 does the same thing... do your best to ignore it.

 

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Been there done that. You did the right thing by trying a different thermostat. I was convinced mine was sticking so I changed to a new one and got the same results. Now the only time I really watch the temp gage is if I have a heavy load. I notice the temp settles in at about 190. In the ole days we used canvas in front over the grill for more heat.

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Stephen's 1995 Dodge Cumming Automatic 3500 in Sanger CA. Pulling 35 Foot 9600 lbs 5th wheel. BD fuel plate 230HP,Air Filter Boot Removed, Gutted Cat, Vibrating Mirrors, Sreaming Tubro

 

[Archive]

On long freeway trips, the radiator gets adequate cooling from the incoming air charge and the engine is very thermally efficient, so the thermostat does not cycle as much. Don't waste your time worrying about it. #ad


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Chris Timochko
1997 5sp 4X4, HX40, BD 4" Brake, Marine Compression, Custom Tuned Injection Pump, 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, Water Injection, NOS Diesel Kit, 6" Chrome Exhaust System, No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc, Goodyear Wrangler AT/S 305/70/16s. Test mule for Auto Wurks Diesel race program

 

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My 97 2500 5Sd has been cycling since new. Everyone consulted concurs that this is normal, even Cummins. Not to worry!


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I have had the same problem with my engines thermostat but this summer when we where having temps in the 110-115 degree range I noticed that the fan run continuously to cool the engine and the themostat did not fuctuate at all,so I think the fan clutch is not adjusted to properly allow the engine to warm up and stay at constant temp,what ever that temp is, does anybody know?

 

[Archive]

Just more of the same. It's normal. The higher the air temp the less the drop in coolant temp in the radiator and the more often the stat opens so you don't see it on the gage. If the air is cold then the coolant is cooler so it cools the engine more when the stat opens and it doesn't open as often and the coolant temp drops more so you see it on the gage. That's one reason that the guys in the cold climates put a weather front on the truck. Otherwise the "heater" will freeze your butt off.

 

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Just a reason for the Diesel Technicians who work on the Cummins B series to join me and take a bow for ourselves. We work on an engine that has more personality than most of the people I deal with. We do our jobs well and we know how to see through the personality of the engines to make the job right the first time. Kudos to all... Mike, Piers, Bill, Ted, Bruce, Joe, Mark, forgive me if I'm forgetting anyone.

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Chris Timochko
1997 5sp 4X4, HX40, BD 4" Brake, Marine Compression, Custom Tuned Injection Pump, 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, Water Injection, NOS Diesel Kit, 6" Chrome Exhaust System, No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc, Goodyear Wrangler AT/S 305/70/16s. Test mule for Auto Wurks Diesel race program