1. where is the temp sending unit on a 85 22re? I thought is was on the top of the thermostate housing?

2. would timing not being set right and no knock sensor cause over heating issues?

3. are 22res prone to air in the cooling system?

I have a new radiator,water pump and thermostate on my rebuilt motor and it was over heating at idle so i changed the rad and there was no thermostate in it so added one now it runs great around town but on the interstate it over heats guage goes right to max but when i slow down guage drops, poor thing just hates to go 70 when I pulled over truck really was not running that hot, water was not boiling over and man i had the guage maxed. but when i got home the water level was down. so i was thinking air pocket or maybe me not having a knock sensor and the timing set by ear might have contributed to this over heating. anyone have seen this befor???
-Rob
-Floral City
-Florida

Incorrect timing can impact engine cooling, yes.

Do you have anything in the way of your radiator / grill? Winch / bumper, etc?

Fan shroud?

Water boiling out of the overflow?

Gauge sender is along the intake runners, between #2 and #3 cyls. IIRC. Might be seeing the temperature overshoot problem or with trapped air, maybe a small hole is needed in the t-stat flange:
- http://www.4crawler.com/4x4/CheapTricks/index.shtml#Thermostat

fan shroud is good, new radiator and nothing blocking it. thermostate is new maybe i got a bad one only opening alittle, i guess that would be easy anough to check.

oh yea and it does not seem to be boiling over, the guage was max in the red and the rad was not boiling?? but it was really hot.

Diesel ,compare your temp gauge to a known thermometer. Starting cold with the radiator cap off, try running your engine up to temp in the shop with a digital thermometer in the radiator neck. You don't need to make it boil just bring it up and compare your gauge , the thermometer and at what point the thermostat opens (you'll see circulation in the top of the radiator). You should see circulation of coolant before the time your gauge redlines. If your guage redlines before you see circulation and/or you hear popping/gurgling sounds in the cooling system , shut it down ,let it cool, pull the thermostat and put it in a pot of water and bring to boil to see how and at what temp it opens if at all.

Be careful

i will check that but i am sure it will not over heat at idle, i checked the timing and it was really close, set to 0.