Im new to diesels, and I just purchased a used 90 f250 7.3idi. Im bleeding the fuel system, after servicing o-rings, fuel return lines, fuel filter, GP and the truck isn't running yet. It ran before the servicing. My concern is when I crank the engine the temperature gauge on the dash immediately begins to move its way all the way to hot(i'd say it would touch H in less than 10 seconds. I noticed that it moved quickly before but the motor generally started up in a couple of seconds, and it ran cool after starting. Is this quick movement of the gauge normal? Im thinking it's not, but whatthefugdoI know. Explanation/Cause?

Thanks for seeing if you can help a poor, frustrated fella out.

 

If the truck has not been ran (engine at ambient temp) then there is now way it can be overheating just cranking over. Your sender or gauge is messed up.

 

yeah,probably a bad sending unit.
she can't warm up this quick.

oh.you'd probably like to know where it is hey?
here ya go:

 

Definitely a bad sensor. Does it stay pegged? Check your electrical connections to and from the sensor F250 posted.

 

I appreciate the knowledge, and pictures are really helpful. Ill check it out in the morning.

 

After start up it would stay very close to cool("C"), maybe 1/4 of the way over.

 

Yeah I have the same problem, its not a problem. Just keep cranking until the darn thing turns over(taking about 10 minutes or something like that inbetween 10-15 seconds of cranking unless you wanna get that thing started) ANother idea is hit her with a shot of ether just to get it to turn over....

 

Thanks, I went with it, and disregarded the temp. gauge. I'm back in business. I'll be fixin it soon.

 

Yeah I dont worry about it. Its a sending unit, does your engine ever just "overheat" at some periods of time? I am gonna replace the sending unit and go from there.

 

i dunno what that has to do with this thread. lol ......... i feel bad for your poor starter.
sounds like how my chipper is starting now though.
ever since i got that bad batch of diesel (that caused my only breakdown in my truck) she's never started good.
i need to get a water separator on that,and i guess new injectors now.
least it's only a 3 cly diesel.
replaced the pricey starter and just been lighting her up with the old starting fluid while cranking.i don't like this though.

 

My 1990 always done the same, while cranking, just moving up, when fires up and running, returns back down an slowly creeps up as engine warms.

ALways ran around the N of NORMAL or under.

 

Do yourself a big favor and get a sent of mech. gauges for it. The ones with actual tubeing to the oil and the cappilarry line to the temp gauges. They react faster to pressure/temp changes and I feel give much more accurate readings.

 

Well F250 i dont crank on it that much, I just turn it over for the recommended amount of time then let it cool down for a good bit.

 

x2 on real gauges....


But i'm for electric gauges. I just don't wanna risk a oil or water tube break in my nice clean cab.....