maillemaker
Jun 03, 2018Explorer
Overheating and questions thermal sensors
So my 1990 Winnebago Warrior started overheating on a 1300 mile trip a couple of weeks ago.
Thought it might have been the thermostat, since at one point the temp spiked and then dropped within seconds, but when I started draining the coolant and looked down in the fill neck I could see all kinds of mineral deposits around and in the radiator cores.
So I drained the system and put in 2 bottles of Prestone Flush and used the RV as my daily driver, letting the solution work for a week.
Today I drained the system again. The fluid that came out was pretty clean. I looked down the filler neck and the deposits are still there:

I took the RV for a test drive down the interstate and sure enough when running for 30 minutes between 65 and 70 it was running hot.
Before doing this I put in 2 bottles of Blue Devil radiator flush and filled the system up with distilled water. I'm going to drive it for another week but I suspect I'm going to have to replace the radiator.
I want to put in a dual temperature gauge to monitor both coolant temperature and transmission fluid temperature.
This is the kind of gauge I want - wish I could find one that was cheaper:
https://www.amazon.com/dp/B00Z25HM68/?coliid=I3MLPVUV4CCRPX
The question is, where to put the sensors?
My rig is a 1990 Winnebago Warrior, built on a Ford E350 chassis with a 460 engine. I don't know what kind of transmission it has, though it does have automatic overdrive.
I have heard of a test port on the side of the transmission that can be used as a plumbing port for a temperature sensor. Is this it?


One thing I noticed is the bottom radiator hose, rather than going straight to the water pump, first passes through this aluminum block thing. I think this might be an oil cooler?


So if I understand the flow right, the water comes out of the radiator and goes back to the inlet on the outside of the water pump, and then enters the engine through an opening in the block behind the pump. Then it comes out through the thermostat opening and goes back into the radiator. is that right?
I see there are also some bypass hoses going from the water pump up to the thermostat area, and then out and up to the heater core (and also tees off to go back into the house to heat up the motor aid water heater and the internal cabin heater). There is also a bypass return line going back to the pump. Is that right?
I'm thinking of using this fitting in-line with the top radiator hose to insert a thermal sensor for the coolant:
https://www.amazon.com/Water-Temp-Joint-Pipe-Temperature/dp/B01FTLUQ4O
Though I'm not sure which size to get for my radiator hose. I think this is my hose:
https://www.autozone.com/cooling-heating-and-climate-control/hose-upper/dayco-hose-upper-/66528_0
This hose varies in ID form 1.5" [38mm] to 1.81" [46mm]
So I guess a 40mm fitting should do.
Of course being in the middle of a rubber hose run I will have to run a ground wire to the fitting (no doubt what the screw is for).
What do you think about my choices for hooking up thermal sensors? Any suggestions?
Steve
Thought it might have been the thermostat, since at one point the temp spiked and then dropped within seconds, but when I started draining the coolant and looked down in the fill neck I could see all kinds of mineral deposits around and in the radiator cores.
So I drained the system and put in 2 bottles of Prestone Flush and used the RV as my daily driver, letting the solution work for a week.
Today I drained the system again. The fluid that came out was pretty clean. I looked down the filler neck and the deposits are still there:

I took the RV for a test drive down the interstate and sure enough when running for 30 minutes between 65 and 70 it was running hot.
Before doing this I put in 2 bottles of Blue Devil radiator flush and filled the system up with distilled water. I'm going to drive it for another week but I suspect I'm going to have to replace the radiator.
I want to put in a dual temperature gauge to monitor both coolant temperature and transmission fluid temperature.
This is the kind of gauge I want - wish I could find one that was cheaper:
https://www.amazon.com/dp/B00Z25HM68/?coliid=I3MLPVUV4CCRPX
The question is, where to put the sensors?
My rig is a 1990 Winnebago Warrior, built on a Ford E350 chassis with a 460 engine. I don't know what kind of transmission it has, though it does have automatic overdrive.
I have heard of a test port on the side of the transmission that can be used as a plumbing port for a temperature sensor. Is this it?


One thing I noticed is the bottom radiator hose, rather than going straight to the water pump, first passes through this aluminum block thing. I think this might be an oil cooler?


So if I understand the flow right, the water comes out of the radiator and goes back to the inlet on the outside of the water pump, and then enters the engine through an opening in the block behind the pump. Then it comes out through the thermostat opening and goes back into the radiator. is that right?
I see there are also some bypass hoses going from the water pump up to the thermostat area, and then out and up to the heater core (and also tees off to go back into the house to heat up the motor aid water heater and the internal cabin heater). There is also a bypass return line going back to the pump. Is that right?
I'm thinking of using this fitting in-line with the top radiator hose to insert a thermal sensor for the coolant:
https://www.amazon.com/Water-Temp-Joint-Pipe-Temperature/dp/B01FTLUQ4O
Though I'm not sure which size to get for my radiator hose. I think this is my hose:
https://www.autozone.com/cooling-heating-and-climate-control/hose-upper/dayco-hose-upper-/66528_0
This hose varies in ID form 1.5" [38mm] to 1.81" [46mm]
So I guess a 40mm fitting should do.
Of course being in the middle of a rubber hose run I will have to run a ground wire to the fitting (no doubt what the screw is for).
What do you think about my choices for hooking up thermal sensors? Any suggestions?
Steve