This is my second IDI, but I'm confused. I have a 1990 F250 Lariat with 112,000 on the clock. It's new to me as of a month ago. It has the main Radiator, a second smaller radiator in front of the main radiator and a third even smaller radiator that looks to be fairly new in fornt of both of these. Do I just trace the lines to see where they go?

The reason for this question is the temp gauge reads 165 and the chiltons manual says if an aftermarket trans cooler is installed, it will run cooler, but 165 seems way to cool.

 

The big one is your main radiator, another is for your AC system, and the last is likely an aftermarket trans cooler.

165 is your engine temp? That's cold. Way cold. Where is the sensor installed?

Mike

 

The PO said he replaced the temp sensor, which he had the reciept for and said he thought the T-stat should be next. So before I ordered the t-stat I wanted to verify that this was indeed not normal temps, with the aftermarket trans cooler.

 

I second this, that should be what your 3 radiators are for, and 165* engine temp is way too cold. If your temp sensor is where it should be something is up, you should be reading about 190* (give or take 10*) engine temp. Mine usually hangs out about 190-195* empty driving normally, as did the other IDIs I've ridden in.

If when talking about a temp sensor do you mean an aftermarket sensor & aftermarket gauge? If the stock temp sensor is hooked up to an aftermarket gauge you're going to be getting a false reading at the gauge and that could explain why it says your only at 165*. And just to be more clear, make sure your sensor is in one of these 2 spots, I have mine threaded into where the temp warning light sensor used to be.

 

Definitely sounds like your gauge and your sensor aren't compatible to one another, or one of the two just isn't working properly. That's the only thing I can think of that would lead to a temp that low. Maybe, MAYBE if the truck was run without a t-stat it'd be that could, but even that's a stretch.

Mike

 

I'll open it up this week-end, thinking the T-stat is stuck open. Since I had the heat on full and it blows warm and this was after a 90 minute run at 65 mph. I've got the recommended rt 1049 t-stat on order. My 86 sure blew alot warmer than this.

 

yeah she's stuck open.you should be around 190-200 all easy and have real hot heat in the cab.my heavy truck runs around 210ish and the heater will cook me right out of the cab.