roughstock

I read thru several other treads on over heating, but I don't think my truck is overheating. This is what happened:

I took off for Oklahoma with a load of hay, total trailer and hay = 13,000#approx. and temp gauge was working fine, I really had to keep my foot in it with some of the hills. About 4-5 hours in to the trip, my gauge stood still at 190 deg. Then several miles later, it climbed up just before the red zone, then it stayed there. I turned the heater on, rolled down windows, and slowed down. It still stayed there, so I pulled over, no obvious problems under the hood. The engine didn't feel really that hot, could even hold radiator hose in my hand and wasn't really that hot, but the upper hose was very tight and firm with pressure. IS this normal? Coolant was full.
So I took off again and the temp was about 190 once on the road. Then it started to rise again, it stopped before the red zone and I kept going down the road. About 50-80 miles later, it started going down. Stayed just above 190 for the remainder of the day.
The next day i unloaded the hay and took off unloaded and still the same problem. it stopped at 190 for most of the return trip.
Usually it goes up to 180-190 and dropps off radically down to 150 or so.
Once at home, i hosed out the radiator and replaced the thermostat and still the same problem. It goes up, and the thermostat opens and goes down once then back up to 190 and stays there for hours. it will randomly drop and go back up and stay at 190, not the usual therostat opening and closing. Is the gauge/ sending unit going bad and is there another problem here. Sorry for the long post just wanted to paint the senario.
Thanks
also EGTs never got very high 6-900, 1000 once and a while.

infidel

I see much the same towing heavy on hot days.
I figure as long as it doesn't get into the red all is fine.
Are you hearing your fan lock up?
It's very obvious, sounds like a jet plane taking off.

roughstock

Yes, i do hear the fan engaging. But, it is 70 deg here and it is still going over 190, nearing 210. I am not pulling any trailer now. THe thermostat seems to be opening at 210-215, and cools to near 150, THe new themrostat I put in was a 180 deg, which makes me thing the gauge/sending unit is bad.

wilderness

I bougt one of those cheap laser temp gauges that you can shoot the engine in any area and get a pretty accurate reading. Take a look at some of thoose wholesale tool companies on the web. Handy for trans temp too. Usually air pockets in coolant will cause temp flux.

roughstock

All Right, I drove to work: 10-12 miles, two stop signs all highway, no trailer, 65 deg, no hills. My temp gauge went up to 180-190 held there for a minute, then went up to 210 and stayed there for 3-5 minutes, then dropped to 145, by the time I got to work, it was up to 190 again. I have a 180 thermostat in the truck. Why is it not working properly. What to do? Is the water pump not working right?
The fan clutch is only engaging during highway speeds, usually during pulling. Is this normal?
Where is temp sensor located?

seven iron

My gauge is not working right either. book says to disc lead to sending unit and ground lead out and turn key on. the needle should deflect. if it doesn't its the gauge. I'm saying this from memory, so I hope its correct. I'll check my book tomorrow.