Difference in water temperature gauge readings

[N31569]

When I picked up my 102a3 and brought it home my dash water temp gauge was reading 175 and would climb to 250 plus. It would also bounce around all over the place. I stopped a couple time and checked the gauge in the engine compartment and it was always right around 175 a 180. I replaced the dash gauge with a new unit from MCI and it now 125-130 when warm consistently and the rear is still running at 175-180. Should I be looking at replacing the sending unit also?

Jason

[Iceni John]

Yes!   Gauges and their senders are matched;  if you use brand A gauge with brand B sender, you probably won't get useful readings.   I had that issue with my transmission temperature gauge  -  originally a Teleflex from the factory, someone had replaced only the gauge with a Stewart-Warner, resulting in some very weird readings.   Now that I have a new Speedhut gauge and sender, all's right once more.   Also, make sure the grounds are good and all connections are clean  -  if the sender's not making good electrical contact with the engine block it will give funky readings, so don't use PTFE tape on those threads, just a thin smear of paste or grease so the threads still touch metal.

John

[N31569]

I will check the connections in the morning. The both gauges were Stewart warners. Hopefully it's just a bad connection.

[Scott & Heather]

Jason, I just used an autozone electronic gauge. It comes with a sending unit. Unscrew the old one and be ready to screw the new one in fast so you don't lose coolant. Then attach the sending wire to the new sending unit. At the instrument panel, install your new gauge and connect all the appropriate wires and it should work flawlessly. The electronic is better than the resistive type older gauges for a 40 foot run in my opinion. I've had excellent performance from my cheapo autozone gauge.


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[B_K]

1st thing to do is make sure the whole dash has a good grounds!
Older MCI dashes are notorious for bad grounds which lead to funky gauge readings!
And I also like Scott's idea too!
  BK 

[luvrbus]

Scott's gauge uses a stepper motor

[Scott & Heather]

I was worried that the gauge wouldn't be accurate, but for a couple of years now I've tested it against both the brand new engine bay gauge and my laser temp gun and all three agree so I'm golden


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