'65 F100 Custom cab, 352.

The water temp gauge was not working, i replaced the temp sending unit (C3AZ-10884-B) and now the needle goes up a little but stays below normal.

All hoses/radiator etc. are getting hot and cab heating works a little but it is not getting hot in the cab at all. (i really dont know how warm it should get the cab at all...)

Can anyone tell me if i used the correct sending unit? Or do i have another issue, maybe thermostat stuck in open position? How can i check and what will be the replacement part for it?

Thanks,
rob

 

 

My '66 with a 240 is the same way and I have changed t-stats and flushed the lines and heater. My '64 with a swapped in 390 will roast you when on full. Is your heater valve fully open?

 

Which heater valve do you mean? the handle under the dash is open and i pulled the switch on the dash next to the choke out and turned it to the right on high.

 

Both hoses get hot, so i just gone try to replace the thermostat then and see what happens. How can i check if anything is blocked?

 

2x on what Tedster9 said. You'll want at least a 180 t-stat to make sure your engine can drive moisture out of the engine oil otherwise you'll get watery snot build up on your valve covers and rocker train.

 

Could try backflushing the heater core when everything is apart. If both hoses get hot, it sounds like you're in good shape.

One thing you can do is check thermostat before installation for correct opening. Suspend thermostat from a piece of string in a pot of water and bring to a boil. Note the temperature that it begins to open. Probably a 352 is spec'd for opening at 185 to 190 and fully open 200 - 210, the temperature that it opens is also the temperature that it closes, if you want to think about it that way. And you should, because the minimum temperature the cooling system will try to maintain. Not the maximum.

Would recommend a Motorcraft thermostat. The parts houses have cheaped out and the thermostats are not particularly good. Another trick when installing, is force the spring open and install a piece of hard candy in the opening. This will allow coolant to flow initially and help prevent air pockets, then it will dissolve, etc. Some people advocate drilling holes in thermostat flange, this never made any sense to me. The hard candy was Ford's answer. Can also just fill the intake from the upper hose etc.

 

With the deluxe heater, there is a cable operated heater water valve spliced into the inlet to heater core heater hose.

The standard heater has a manually operated heater water shut-off valve in the same location.

 

What I'd do first is use a modern highly accurate Infrared thermometer to check the engine temperature at the location of the sending unit and a few other spots (radiator fluid in the neck, radiator hoses, heater hoses) and get some sample temperatures of these items when the engine is completely warmed up. Temperatures will vary from location to location on the engine and components some but this will give you a baseline. If you then were to need to change the thermostat to another rating or to fix an issue you can recheck the temps and make sure they have been corrected by the change.


Next I'd probably double-check the thermostat, pull it out and inspect it. See what it is rated at (usually stamped on it someplace) and check it to make sure it functions properly using the boiling water on the stovetop method. I have pulled out thermostats before that were stuck partially open and would neither open or close fully. Sometimes the soldered joints can come loose and let the thermostat spring push the valve partially open. It's broken and needs to be replaced but symptoms were it took longer than expected to warm up and never got *quite* to full temperature.

If everything else seems good and it seems like it is either the gauge or the sending unit - and we assume for the time that the sender is working OK and is correct - then it is possible to adjust the gauges. I recorded and uploaded to youtube this quick video on how to adjust them. Same exact technique applies to the fuel gauge in the 1965-66 Custom Cab trucks. Most gauges have a similar adjustment method.


Chad

 

I have the same 65 , 352 Manuel 4 speed I also have AC. would you use the same 190 or drop to a 180 if you hav AC on the truck