BIG temp reading fluctuation

['956Wheel]

My '95 3500's temp. gauge (stock) goes from low to mid gauge and back down in a matter of 10-15 seconds. It does this all the time. Anyone see this before? I'm thinking changing out the sending unit.

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9535hunderd

 

[BCFAST]

yup... . normal.

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97 2500 CC 4x4 3. 54 5spd, #12 plate, 4inch open exhaust, 235/85 Michelins, PrimeLoc, Red Tops

 

[illflem]

Mine will do this when the t-stat is first starting to open,sometimes for five minutes,after the truck is good and warmed up it settles down. This is normal,I think if your's is doing long after warm up that you might have a bad thermostat. The tsat will be cheaper to replace than the sender,start there,it's an easy job.

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95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(Play truck)95 3500,5 speed,Driftwood,Banks&Phscotty,34,000 GCVW apple and tractor hauler(work truck)

 

[ray1933]

You can have the sender checked to see if it
is okay if you want. Mine (Sender) did go bad about 85,000 and they put in a new one. Last year it would not get warm enough. The T-Sat was stuck open. Put in a new one,easy job.

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95 3/4 4x4 5 Spd K&N Air Filter 100,000
Ride Rite Air Overloads
10 1/2 Cabover Camper

 

[bertyz]

I had the same problem. Put in the new design thermostat. Didn't change a thing. Put on a Lund cold front. Not much different. Stopped worrying about it. 96 std cab full bed auto 3. 50 gears

 

[BCFAST]

My old 95 did the same thing... changed fan clutch, changed thermostats... same thing. Thought it was a sending unit, so we put a thermometer in the radiator cap, revved it up and sure enough, the fluid temp actually changes that much! The new owner has over 200,000 miles on the truck now, still does the fluxuation thing and no problems!

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97 2500 CC 4x4 3. 54 5spd, #12 plate, 4inch open exhaust, 235/85 Michelins, PrimeLoc, Red Tops

 

[Joe G.]

Statland,

If you check you'll see that the fluctation is only about 35 degrees or so. Not nearly enuff to be a problem. All these trucks do it and they last a LONG time so it's obviously not hurting anything. It's more noticeable in the winter because it takes longer for the engine to get up to 'stat opening temp (all that iron is radiating heat like crazy) and the coolant is exposed to cold longer while it's just sitting there. Pulling a load in hot weather it moves hardly at all. Don't worry about it. In fact, I think that more stable 'stats probably open slower to avoid this symptom, but do they open as much? Most of us don't bother spending money to fix something that is not broke.

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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

 

[Missouri Mule]

Just Cummins quirk. Mine does it especially with a/c on. Usually at highway speeds it will settle at 180 and stays there. Since it never goes over 190 I don't give it a second thought now.

 

[jkh]

It's normal due to the highly efficient cooling system. Coolant gets hot,t. stat opens ,cold fluid comes in and closes t,stat & reduces temp. gauge,cold coolant now begins to heat up again while the hot coolant is getting cooled quickly because of the efficiency of the cooling system,and the whole cycle starts all over again. They due have a revised t. stat to reduce the fluctuation but I wouldn't worry about it until the fluctuating stops;then you may have something wrong.

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1997 2500 4x4,Auto,Cal. e. g. r. (for now),3. 54's,Amsoil throughout,DiPricol egt/trans temp/boost gauges,ready for more power

 

['956Wheel]

I guess its that GIGANTIC radiator! We will just shut up and drive!!

Thanks guys #ad




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9535hunderd