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Resolved Does anyone have the thread size for Mighty Max thermostat housing?

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1985D50

Probationary Member
21
9
Jun 19, 2020
Medellin, Oregon
I need to find out the thread size for the side hole in the thermostat housing MD061791. I had assumed it was 1/8 npt but that is too big, see pic for reference.

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Solution
OK problem solved a lot easier than I thought it would be. I went forward with the tap idea. once I determined what bit to use 21/64 I drilled the hole. The bit fit inside the threads but cut the should at the bottom of the hole that was left behind by manufacturing. The shiny spot in the picture. Once that was cut the sensor fit right up to the threads but I did not try. :)
Then I ran the 1/8NPT tap down the hole far enough so the switch screwed in and left the sensor in the flow. It worked out fine and the system works great.
Thank you very much for the help everyone.

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That housing is not from my D50 truck. BTW the motor is a DSM 2.0 G63B. I just bought that housing. I am putting in an electric fan and I need to use a temperature grounding switch. I want to put it there. Anyway that housing just arrived from UAE if that helps. Not that either of you are wrong I just realised this info might matter.
That fitting in the pic is US 1/8" not tapered pipe thread. The taper thing makes sense. I hope they make a temp grounding switch in this size I don't want to monkey with trying to get that thing set in a position so I can drill & tap it.
 
Last edited:
That housing, part number MD061791, was at one point used on the Mighty Max or D50, though. I’m assuming you got it new - so unmodified.

If that truly is the right part number for the part you received, it is a simple jog through ASA to verify the plug part number (MD014929). The part number’s note in ASA reads 1/8 Taper. And, as stated, same plug is used on the 4G63 which will be a BSPT thread, guaranteed.

1/8 NPT will have 27 threads per inch.
1/8 BSP or BSPT will have 28 threads per inch.

The temperature sensor for the gauge on 4G63 DSMs is 1/8 BSPT.
 
That housing, part number MD061791, was at one point used on the Mighty Max or D50, though. I’m assuming you got it new - so unmodified.

If that truly is the right part number for the part you received, it is a simple jog through ASA to verify the plug part number (MD014929). The part number’s note in ASA reads 1/8 Taper. And, as stated, same plug is used on the 4G63 which will be a BSPT thread, guaranteed.

1/8 NPT will have 27 threads per inch.
1/8 BSP or BSPT will have 28 threads per inch.

The temperature sensor for the gauge on 4G63 DSMs is 1/8 BSPT.
Thank you. yes it is new. Can you tell me what ASA is? Is there a link to it as I will probably need it in future.
I'm having a heck of a time finding any fan temp switches that are BPST. Or are you saying that part number you supplied is a fan temp switch?
 
My temp gauge sensor goes into the block. I need one that grounds itself to turn on the fan when it reaches a certain temp. When it cools down to a temp usually 15 degrees lower it switches the ground off.
 
No luck finding any kind of anything that is BSPT. I went out to the garage and took out my tap & die sets. Both the metric and standard have a 1/8npt tap & die in them. To make sure i went to screw the sensor into the die and it won't go in. the thing barely starts on one thread and then it takes force to make it go and it is obviously cutting I went around twice. It did not get easier. It makes me wonder about the actual size of it. Technically if I drill out the hole and tap it then run the die down the threads on the sensor that should solve my problem right?
Now I'm torturing myself it just hit me that the extent of the sensor protruding into the path of the water coming up out of the thermostat might affect its flow.......ugh. :)
 
What is the actual sensor that you have?
It is a grounding temperature switch. It grounds at 190 and turns the fan on. When it cools to 175 it will break the ground and turn the fan off. Here's a pic to see the whole thing
EDIT- I feel like I will probably just drill and tap it eventually. I have seen no sign of these grounding temp switches that would fit.

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I meant like brand and part number.

Drilling and tapping the housing is the way I’d be leaning, especially since you have the sensor already. No downside unless you want to put an original Mitsu sensor back in there at some point.
 
I meant like brand and part number.

Drilling and tapping the housing is the way I’d be leaning, especially since you have the sensor already. No downside unless you want to put an original Mitsu sensor back in there at some point.
IDK the brand or name of the switch. Undoubtedly it is Chinese. I got the wiring kit with the switch in it from American Volt. What OE sensor goes in that hole? Is it a grounding switch temp sensor? I do not have most of the OE equipment that came with it and it has a Weber carb. I'm just putting this electric fan on to help cool it better when I carry loads or drive in the heat.
 
I do not know of a Mitsubishi sensor for what you are doing.

I meant any other Mitsubishi sensor like the one I mentioned earlier for the temperature gauge. It doesn’t seem like you have a need for anything like that so I see no reason not to tap it and go.
 
OK problem solved a lot easier than I thought it would be. I went forward with the tap idea. once I determined what bit to use 21/64 I drilled the hole. The bit fit inside the threads but cut the should at the bottom of the hole that was left behind by manufacturing. The shiny spot in the picture. Once that was cut the sensor fit right up to the threads but I did not try. :)
Then I ran the 1/8NPT tap down the hole far enough so the switch screwed in and left the sensor in the flow. It worked out fine and the system works great.
Thank you very much for the help everyone.

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Solution
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