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**MikeB** · 09-15-2023, 05:10 PM

I bought this coolant temp gauge last year from LMC truck. It was advertised as a direct replacement for a stock 67-72 gauge. The part number is 36-2013, but I don't see it on their website anymore, and they have literally no tech support.

The problem is it reads very low. The needle doesn't even start moving until 150 degrees. And at 175 it is just at the second mark on the left. I've checked it in the truck connected to a new sender, and on the workbench using potentiometers. When I dial in the resistance for 210 degrees, the needle is about mid-scale. As for a shunt resistor, anything less than 500 ohms, causes even less needle movement.

If I can't get this working I'll use the OE gauge. But it reads high! I know that adding just a little resistance in series with the sender will help, but I'm not sure that's the best solution. I'll probably attach a potentiometer to the shunt terminals to see if I can find a value that will solve the OE gauge problem.

LMC #36-2013

09-15-2023, 05:10 PM	#1
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 4,035	Mystery Gauge I bought this coolant temp gauge last year from LMC truck. It was advertised as a direct replacement for a stock 67-72 gauge. The part number is 36-2013, but I don't see it on their website anymore, and they have literally no tech support. The problem is it reads very low. The needle doesn't even start moving until 150 degrees. And at 175 it is just at the second mark on the left. I've checked it in the truck connected to a new sender, and on the workbench using potentiometers. When I dial in the resistance for 210 degrees, the needle is about mid-scale. As for a shunt resistor, anything less than 500 ohms, causes even less needle movement. If I can't get this working I'll use the OE gauge. But it reads high! I know that adding just a little resistance in series with the sender will help, but I'm not sure that's the best solution. I'll probably attach a potentiometer to the shunt terminals to see if I can find a value that will solve the OE gauge problem. LMC #36-2013 Attached Images __________________ Mike 1969 Custom/10 LWB -- owned for 37 years. 350/TH350, 3.08 posi, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. Hedman stainless headers. Old Air installation in progress. 1982 Custom Deluxe 10 SWB -- converted from 250-six to roller cam 350 w/ Vortec heads -- sold 1981 C10 Silverado LWB, 305, TH350C -- sold, but wish I still had it! 1969 C10 (not the current one) which I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 26 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!