temp gauge spiking ?

[hendo]

i have just bought a 94 2500 4x4 with 210k miles ,it runs great but the temp gauge spikes to the red mark then goes back to around 190 ,i have replaced the thermostat and it still does it
my question is ,do i have a bad sender or gauge ?
or is this normal and i should,nt worry about it ?
thanks

 

[argve]

I would check the wiring and the coolant level... I know mine moves but it goes from 190 to cold then works it's way back up (normal operation as the tstat opens and closes) but spiking to hot...

 

[hendo]

i flushed the whole system out aswell as change the t stat , checked the wiring and it still does it

 

[argve]

can you put another gauge on it - like a cheap mech gauge from the autoparts store to verify that this is really happening. When I start to see funky stuff from the factory gauge sets I like to double check before moving forward.

 

[hendo]

thats a good idea i will try that thanks

 

[hendo]

well found out the gauge is good ,the clutch fan is good , and i had looked inside the radiator when i flushed it looked good ,but i guess the radiator is bad as it has cold spots on it when my temp is high
so now i think i will try and find a reasonable priced radiator or a custom made one from maybe becool ,does anybody now of a bigger and better radiator ?

 

[MMeier]

Just get that one redone, should be a decent radiator shop nearby that can recore that thing.

 

[hheynow]

Just get a good mechanical water gauge. Try Summit Racing.

 

[argve]

The stock rads on these are more than enough to cool them - even the ones that are turned up in power.

Like mentioned I would find a local rad shop and have them recore it.

 

[hendo]

can you put another gauge on it - like a cheap mech gauge from the autoparts store to verify that this is really happening. When I start to see funky stuff from the factory gauge sets I like to double check before moving forward.

where do i install a mechanicle sending unit on a 5.9 diesel ?

 

[argve]

any port that leads to the cooling system will work. I'm not under my hood at the moment but I would suspect that she's got a pipe plug some where holding back some coolant. Your not looking for actual numbers but to see if the coolant temp is making a big swing like the factory gauge is showing.

 

[hendo]

got all figured out thanks to all,it was a combination of a bad radiator,a new thermastat being bad so both were replaced but it still spikes but alot less

 

[argve]

Glad you got her figured out - when you say still spikes from what temp to what temp?

 

[hendo]

now it goes up to around 205 and within two seconds goes down to about 165

 

[argve]

What you are seeing there is the action of the thermostat - you can get an updated one from Cummins that will stop the temp swings

Cummins Part number 3934373 - Cummins has a habit of updating their part numbers but they should be able to cross it over for ya.

The updated part number will cause the engine to warm up slower but will make her run steady on the temp. I never worried about the temp swings I just run the stock style one and watch the temp gauge swing... It creaps up to just above 190 then rockets down to around 160 then starts creeping back up then rockets back down...

I don't have the Dodge Part number but an experienced parts guy should know it.