Engine temp idiot light on

[gdhillon]

My engine temp idiot light just came on today after a couple minutes of driving so I pulled into the closest parking lot and shut her down. I checked the oil it was right above the fill mark (but i assume some oil was in the engine still). Then checked the overflow thats fine still at the cold mark (it never really fluctuates in level). Lastly i checked for leaks and didn't see anything. So then i fired her back up (with heat fully on mix) and about a minute of driving the light came back on so i just slowly made my way home. I checked my manual it doesnt specifically say "engine temp light" so i looked in the engine overheating section. Possible causes are leaking coolantsystem or oil cooler system or defective coolant recovery system, slipping or damaged belt, thermostat stuck closed or leaking head gasket. What it tells me to check is; adjust or replace belt as necessary ( i just put a new one on with the new idler and new tensioner ). Check and replace if necessary the thermostat and head gasket.

My thoughts are the thermostat but i do get warm air when I turn the heater on.

Maybe I should replace the hose going from the rad to the overflo...it does seem a little hard

I dont think its the head gasket or oil cooler (no oil in coolant...i resealed the oil cooler last year)

O and the temp gauge on the truck was still pretty close to cold.....Any1 have any other input on this?

 

['94IDITurbo7.3]

get a real gauge on it to see what it is really running at. my bet is your just fine. my factory gauge constantly reads cold. i had the temp light come on a couple times. real gauge showed 190*F....

 

[OLDBULL8]

You have two temp sensors. One operates the temp guage and the other operates the over temp (idiot) light. What did your temp guage show, was it above normal? Did you check your radiator coolant level after it cooled down? That hose to the overflow tank will not cause a high heat problem, it only overflows if the coolant level is too high, then after it cools, the coolant returns to the radiator. What pressure is your rad cap rated? Should be 13 PSI.

 

[FORDF250HDXLT]

i notice that idiot sensor is effected by under hood temps,just like any electrical sensor.iv seen mine light when my gauge reads good.
today i tossed that thing and installed a mechanical gauge in it's sensor hole.my under hood temps get high and mess up my readings.iv had enough of that and cured it.now i'll only get actual coolant temps and nothing else.this way i can insure im not turning my e-fans on needlessly too early.
now to figure out a way to lower under hood temps still with my low air dam.she's just blocking all the suction from under there.
just when i was about to just ditch it,i pulled 15 mpg running solo with this 8k lb dually box truck,so i don't want to take it off lol.

 

[gdhillon]

Can the 'real gauge' just be put into place where the factory sensor goes? I assume I'd have to drain the coolant for this?

The temp gauge in the cluster was a bit under normal, ya its a 13 psi cap I have seen some red around the cap tho..almost like it leaked a bit of coolant out the cap a long time ago. I replaced the cap when I bought the truck..nov '11...when I have removed the cap before coolant starts to pour out. I havent removed the cap after the temp light today..I just went outside to remove it but the trucks still warm. Ill post pics of the red around the cap though and the overflow now.

Mind giving me a quick run down on how you put the sensor in/where you put it in f250hd?

 

[gdhillon]

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[gdhillon]

No idea why its always like this but you have to click the pic to view them

 

[FORDF250HDXLT]

well i had used the upper factory sending unit location when i was using the electrical gauges in the past,up behind where they put the vacuum pump on the 92-94 serpentine belted idi's.it's up behind the a/c pump too.
but the autometer mechanical come with a larger 1/2 fitting,which screws right into the idiot light port in the front end of the drivers side head,just down in back of the power steering pump.iv read the temps can appear a little less overall even of your true coolant temps here as it's a hot spot,but that was ok with me.as long as i keep her under 240,im not picky.

 

[gdhillon]

I'll have to look for that, did you use the old wiring route through the firewall for the new sensor?

 

[TahoeTom]

I put my gauge sender in the same spot, front of drivers side head. I didn't drain coolant. With engine cold and radiator cap off, work fast and you will loose a small amount of coolant.* You mentioned your overflow tank level never changes. Your radiator cap should allow coolant out when system heats up and the coolant expands.

*Edit: Correction. Remove radiator cap to verify no pressure in system, then REPLACE CAP before removing sender to reduce coolant loss.

 

[Agnem]

While your installing gauges, take that factory sender out and swap it for one that is set for 130 degrees. This way, your engine overtemp light is a warning, instead of a notification that it's too late.

 

[gdhillon]

I checked the coolant in the rad this morning, its just a wee bit under the nek of the rad.

So Mel your saying to change out the probe or whatever it is that checks temp then also change the sender unit? Or is the sender built in the probe?

 

[gdhillon]

I put my gauge sender in the same spot, front of drivers side head. I didn't drain coolant. With engine cold and radiator cap off, work fast and you will loose a small amount of coolant. You mentioned your overflow tank level never changes. Your radiator cap should allow coolant out when system heats up and the coolant expands.

Do you have a part number for me, is it something I can grab off fleebay?

 

[TahoeTom]

The gauge I have is an inexpensive Sunpro I bought at AutoZone. The sender is permanently attached to the gauge. It has worked without a problem for three years. I removed the factory overtemp (idiot light) sender and put this in it's place. My factory gauge is still hooked up but hasn't been reading very high lately. I didn't know there were different temperature options for the idiot light. There are other 1/2" pipe plugs in the heads that could be removed and used for sender locations. It might be worth trying another radiator cap if your overflow tank level isn't changing.

 

[gdhillon]

ok ill have to grab one from napa and see if they have the temp gauge to