I know alot of folks have temp fluctuation but I think it usually swings low instead of high. I had this trouble a few months ago and fixed it with a new water pump but its back again. I just had the radiator cleaned and rodded but it hardly had anything in it. Its got another new water pump and I have ran two different radiator caps. I have 3 different t-stats and they all fluctuate the same, two are 190 from napa and one is a cummins 180. I generally see swings from 190-203 or so, usually cruising it stays around 190-194 but will jump up to 197-199 for a second then back down. That doesent bother me as im reading those temps from the ultra-gauge and I think those are fine but when im getting on the interstate or accelerating it gets up to 203 or so and stays there for a few seconds on both the ultra-gauge and the dash gauge. I took it to the radiator guy yesterday and he put some kind of tester on it that is supposed to change colors if there is carbon dioxide present and it didnt change so im hoping its not the headgasket. When I come to a stop or so it goes back to 190 and pretty much stays there or gets cooler so i dont think its the fan clutch. Also after it idles for 10 minutes or so and I turn it off the fan clutch will spin for a few seconds after I turn the engine off but if I get off the highway and let the egts cool to 300 then turn the engine off the fan will stop just about as fast as the motor. I dont think I could put any kind of loaded trailer on this truck or it would probably overheat. Im lost here and just shy of pulling the head.:banghead:

:cry:I will check compression before I do it all, its my last resort.:banghead:

Smart idea!

i see in your sig that you dont run a "box"? so you are verifying that off of the instrument cluster guage?seems like there is a key on off trick or something that when you do it...it "tachs" everything out and then goes back to zero...and this maybe on the c.r. trucks..not sure....so doing this moparman...is it recalibrating the guages per say?what if possiblely the factory guage is faulty?i would love to help get this figured out so you dont have to be "down" and be out alot of out of pocket $$...your oil level is o.k. still....see any white smoke in the last couple of days?

Im using an ultra-gauge to see exact temps but both it and my dash gauge move accordingly.

i see in your sig that you dont run a "box"? so you are verifying that off of the instrument cluster guage?seems like there is a key on off trick or something that when you do it...it "tachs" everything out and then goes back to zero...and this maybe on the c.r. trucks..not sure....so doing this moparman...is it recalibrating the guages per say?what if possiblely the factory guage is faulty?i would love to help get this figured out so you dont have to be "down" and be out alot of out of pocket $$...your oil level is o.k. still....see any white smoke in the last couple of days?

sig says Edge Comp.. what's the hp on those 7x.010s? Am I mistaken in thinking those are about 140hp sticks??

I believe they are 125-150hp. I put another t-stat in it and it doesnt fluctuate as much but still jumps up to 197-199 or so. I am gonna put my other ultra-gauge in it and see if it says the same thing.

I believe they are 125-150hp.

that's still a big injector, inducing a lot of heat, for a stock turbo..

Turbo handles it well, I went all out at the pull last weekend with the comp on 5x5 and saw close to 1400 toward the end of the pull. With it on 2x5 I never broke 1200.

i dont believe it to be related but this problem started right after I installed the vulcan big line kit. Absolutely no problems and then on the first run after the big line kit it started fluctuating.

I was suggested a gates t-stat because they only have 1 jiggle pin so I ordered one from rockauto. Well it came today and looks just like the napa t-stats with 2 jiggle pins. I put it in and it acts the same way but then I remember my buddy with a d-max saying something about electrical something or another in the radiators of chevys hurting something. When I had my radiator cleaned and rodded I put it back on and just ran water for a day or two and it acted perfect but when I put antifreeze back in the same ole fluctuation starts again. I never had a problem when I ran the green stuff but have had since I started with this red fleet stuff. I wonder if there is any connection?

I would switch back to standard green or yellow coolant and see what happens... Would be weird to find out the coolant is a factor to wild swings..

Dont know if I mentioned it or not but this problem all started directly after I put on a vulcan big line kit. Are there any wires or something I could have hit during the install?

Mine started long before the big line kit I installed. I might have to make sure I try purely old style anti freeze next time. I believe I have been using the type that works in both newer and older. I will give it a try with just water and see what happens with mine. I know we have the opposite problem, but it would be worth experimenting.

I just drained and flushed mine with hose water and took it up the road with no change. I just wish it was more evedent waht was wrong so I could fix it.

It is:mad::mad::mad:ing.

Also, I just had problems with my tq convertor locking and unlocking in the rain but after I cleaned terminals and resset apps it was fine until I flushed the engine out. There must be something that is getting wet on the passenger side when it rains and I got it wet again tonight because on the last run it was acting a fool again. Anybody wanna swap a 1st gen 5 speed for a 98 24v auto?

Just yank that auto out and stuff a manual 5 speed in...

I have been considering it more and more lately but this temp thing is driving me up the wall. When I get it fixed there will be another problem so I dont know why im letting this one bother me so much.

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If I were to put another temp gauge in the location of the oe sensor and not even have the oe sensor hooked up would the truck run right or without a temp reading would it think the engine is cold? Mike, what ohm resistor would it take to make it think its running about 190? I may hook up another gauge just to see if it fluctuates, if it doesnt I will hook the oe sensor back up and move the external gauge down the head a few ports.

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Lookin at this gauge

http://www.ebay.com/itm/261052269133?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

hopefully things start falling into place for you man. i hate issues like youre having

I just ordered that mechanical gauge and hopefully it will be here mid next week.

I might try that one my self. I could not tell in the picture if it might just thread into the existing whole for the oe one. I could not see the whether it had male or female threads.