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Temperature Sensor Removal

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BT7Doug

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I am slowly putting my '62 AH 3000 tri car BT7 back into its original configuration. A previous owner for some reason removed the dual oil pressure coolant temperature gauge and replaced it with separate gauges. The fuel gauge was relocated to a fabricated panel mounted below the heater control assembly along with an Amp gauge. The replacement gauges are black where the correct configuration is white. I purchased the correct dual oil pressure water temperature gauge from Moss and going to install it found the existing sensor to head attachment very strange indeed as the pictures show.

The Moss sensor attaches with a 5/8" nut where the existing sensor has what appears to be a 7/8" nut. There are abrasions on the nuts which indicates it was tightened with a chisel. There is also another nut between the sensor nut and the head which might be some kind of adapter to get the correct thread to the head. I cannot get a wrench or vise grips on the nut to turn it. Even if I cut the cable there is insufficient room to get a socket onto the nut.

The temperature gauge is working fine and I would like remove the sensor without damaging it so someone can reuse it in another application. I have not figured out how to get this nut off. Any ideas out there??
 

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Take an open end wrench , grind off the sides of the open end till its a skinny fork shape that will fit the flats . Heat up the hex with a gentle propane torch flame , just get it warm , spit sizzle hot not cherry red etc and try with the modified wrench .
 
Thank you for that. Will report back on how it worked. Much more elegant than a chisel and large hammer.
 
BT7Doug - where's your fuel gauge? Your non-standard temp gauge is in its place.

My mechanic used a heavy duty deep socket with a slot cut in the side for the tube.

You might want to remove the thermostat and drain enough of the coolant so you can hit the threads with a penetrant from the inside as well as the outside.
 
The brass nut looks to be very close to the head casting, you will be lucky to get a socket onto that with cutting a huge slit on the side and then you may have difficulty in turning it. I would go for the ground down spanner approach but take off just enough metal to get the nut to turn, otherwise there could be a danger of opening up the ends of the spanner.

Best of luck

:cheers:

Bob
 
I have usd the socket technique many times it works well , U may want to place a hose clamp over the socket before applying pressure so it does not open up.However, this depends on the quality of socket used OK
 
Success! I used something along Steve's suggestion. I found a wheel nut wrench from a '60s era VW or Austin Mini (never throw out old and obsolete tools), ground down 3 sides to clear the cylinder head and cut a 5 inch grove to accommodate the cable. A large screwdriver through the wrench popped it right off after applying a little heat from a plumbers torch. This probe required an adapter which also came off easily with a normal socket. A followup test of the unit showed ~108 F in the boiling water test so will try and find it a new home.

The correct fuel gauge was mounted on an extra instrument panel located under the heat controls. It share that panel with a non standard Amp gauge.
 

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BT7Doug said:
A followup test of the unit showed ~108 F in the boiling water test so will try and find it a new home.
Click to expand...

That's a significant error. However, if you are going to throw the bad gauge out, throw it to me!

If you are planning on keeping the gauge for future repair, try the DIY method shown in the link below. I have used it to fix a half dozen Smiths dual gauges and a couple of other types. As long as the temperature gauge needle is resting on its stop peg when cold the method below has worked for me.

https://www.ply33.com/Repair/tempgauge
 
I'd carefully pull the needle off its shaft, immerse the bulb in boiling water, then replace the needle in the correct position. Do that first and it may fix the problem. Needle is a friction fit on the shaft.
 
Those wheel nut tools always come in handy. Everytime I go to a swap meet, I pick one or two up. Have a few in the drawer, but best tool to cut for use.
 
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