Cooling issue...

[Jgreemo]

Hi all, I recently noticed my temp gauge is running about 20-30 degrees hotter than before, even on cool evenings. As the engine and radiator is new (6 mos.), I am suspecting a gauge/sender issue as it happened mostly at once. The radiator is a high capacity modine and after warm-up, I can see the thermostat open at a higher temp then drops back, but levels off at a higher temp. Almost like I had a across the board 30 degrees added to the reading.

One question, where is the temp sender located? I noticed a sender on the back left, on top of the head, opposite of the glow plug controller. I picked up a new sender and it was a single spade, the current sender is dual spade. Is this possibly a glow plug cutout, or is this the temp sender? As I can't find my manual, any help would be appreciate. I figure if the sender doesn't help, i'll look at the stat next. Don't really want to go to an aftermarket gauge at this point.

Thanks,
Jon

[britannic]

The temp sender is on the driver's side cylinder head at the front, it should have a single spade with a green wire.

[Jgreemo]

Hi Britannic, I ran out and took a look, but no dice. The only senders I see are against the firewall. The large gp controller, the oil pressure sender way in the back, and a small two spade sender on the passenger side.

Nothing up front or around the injection pump. I am wondering if Napa gave me the wrong part. Any ideas?

Thanks,
Jon

[john8662]

The sender is on the drivers side head of the engine (so if your standing in front of the truck with the hood up its on the right side of the truck). The sender is kinda hidden its probably just underneath the airconditioning compressor. It has ONE green lead wire attached to it, its near a glowplug lead. But the connector is different from a glow plug connector in that it is a "spade". The other sender on the passengers rear head is simply the glow plug temperature inhibitor switch (two prongs). The temperatures that your seeing could also be the thermostat. I have seen "Stant" thermostats and similar designes do what your talking about. So from now on I ONLY use the robershaw extreme duty (high flow) thermostats. They look like an OEM chevy thermostat, but you can get one in 180 ot 195 degrees. Hope this helps..

John