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Discussion Starter · #1 ·
I've been playing around with MicroSquirt3 Temperature Sender alternatives because I wanted to delete the external plumbing I used to rig up the standard GM Temp Sender (p/n 15326386 ) on my 9A install. I had all sorts of brass plumbing hooked together to form a "tee" that was inserted in my unused heater core hoses.

I wanted to plug the GM sensor into the 9A head in place of the thermo-time switch (not used in my setup). That hole is an M14x1.5 thread. I considered drilling the hole larger and tapping it to 3/8NPT for the GM Sensor but didn't have a scrap head to try it in, and I'm not real comfortable drilling into any head with the tools I own.

After talking with a machinist friend, he said he wanted to try to turn down my GM sensor on a lathe and see if there was enough metal left to cut sturdy threads. I figured it would be worth the $20 for a new sensor to find out.
The result is... PERFECT! There is plenty of metal on the GM sender housing to turn it down and cut M14x1.5 threads, and a relief for the crush washer. I had him use the VW Thermo-Time sender as a model because the threaded depth of the hole in the 9A head is less than you'd think and I didn't want to bottom out the threads before I got a good seal at the outer end. The GM sender is also 9/16" shorter than the VW Thermo-Time sender, but looking in the hole you can see the end of the GM sensor will be immersed in water in the jacket.
He's cutting a second one down today for a spare.
This works for me. Cleaned up my MicroSquirt install for a price I was willing to pay.
Machine Fastener Engineering Automotive engine part Nut

54244
 

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Discussion Starter · #4 ·
It was worth the effort for me, although it may not be for anyone else. I'm using KR/PL/9A heads from 1993 and older, not the newer 16v heads. The older heads, before EFI, had single wire temp sensors and that signal isn't clean enough to use with MS.

You have my curiosity peaked though.
Are you using MegaSquirt or MicroSquirt?
Can you share the part number of the sensor you're using?
Did you have to create a new temperature map for MS or is the default GM mapping working for you?
These were all stumbling blocks for me. All surmountable, but at the end of the day it was easier for me to just cut threads on the sensor DIYautotune recommended.
 

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Megasquirt 2, I used the same sensor with MS1 before.
026 906 161
0°C/32°F 5550ohm
60°C/140°F 670ohm
100°C/212°F 195ohm
55102

I have seen this sensor first time in my PL, not sure if it was original, but the same sensor is used in mk3 2.0 16v ABF and many other vw's.
 
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