Sensor location for gauge?

[62 Cutlass Convert]

Those of you who have fitted gauges, where did you locate the sending unit?

And what temp do you run in warm weather cruising at 60 on a level road and when pulling a long hill?

Thanks.

[62 Cutlass Convert]

Sorry, talking about electric coolant temp gauge .

[jensenracing77]

I think the only place you can put the sender is on the front of the intake manifold pointing forward. You will have to take out the original and leave it out to use the aftermarket one.

Our automatic car on a hot day in stop and go will get to 210. I don’t really like it but that is how that one is. My 4 speed car I can’t get to over 190 no mater what I do. Both cars are cruising speed on the open road run at 170 area

[joe_padavano]

What Eric said. The sending unit for a temp gauge must be in flowing coolant, and there is only one such location on the stock intake. You can get an aftermarket part that fits in the upper radiator hose and has an NPT port for a sender, but that is a little less accurate location.

[62 Cutlass Convert]

Great info.
So what I did was build up the small boss in front of the carb/behind the thermostat and drill and tap it to drop a sensor in at that location. Seemed like a good spot and I could keep the factory light sensor in orig location. So I am running at about 185 while cruising and hitting 205 when on a long uphill grade, hotter than I thought I should. When going downhill it cools way down with my 160 thermo. I have now blocked the thermo bypass and am running a Stewart Components Robert Shaw style thermo with bypass holes in it. Basically ALL coolant is now routed through radiator.

Placed a multimeter temp sensor probe in the thermo outlet hose just past the thermo and wow, 10to20 degree cooler reading! So I thought sensor off, but put.a new one and same result. New gauge and same result.

So I thought maybe it’s a bad spot and would switch to factory location, but that’s right in the outlet from the head so I doubt that will show cooler. I’ll try it anyway.

So looks like the hose location will run cooler than an eng placement. Still think I should at least run cooler while cruising and we haven’t hit the hot wether yet. I’ll post further results and any further comment welcome.
Thanks you guys.

[62 Cutlass Convert]

Are you guys using elect or mechanical/capillary tube gauges? I’m running a Stewart Warner Deluxe type electric gauge, 100-280 range.

[62 Cutlass Convert]

BTW my sensor has the probe fully in the coolant flow pretty much directly above where the coolant returns from each bank and enters the manifold center cavity behind the thermostat.

[62 Cutlass Convert]

So I put a gauge sensor in the factory location and wow, a 20 to 30 degree difference from my location behind the thermostat. Factory location higher. I already compared the two sensors and they perform the same. Same gauge, I just changed the sensor signal wire back and forth between the two sensors. Now I don’t know what to think!

[joe_padavano]

The coolant in the engine is not all one temperature. It is expected that temps will vary depending on where you measure them.

[62 Cutlass Convert]

Sure, I get that. My concern is that I seem to be measuring it at a spot considerable lower than the factory location. I have been checking ends other than the 215 and some measure in same spot, direct outflow from a head and some measure in n accumulation point behind the thermostat as in where I m set up.

I did just have a breakthrough of sorts. I have been partially draining and refilling while trying various combos of thermostat and bypass mods and over and above the changes I am running cooler. I think there must have been a stubborn air pocket that has finally cleared! Sat in traffic on a warm day yesterday inching along and never went over 175 on my location, maybe 195 at factory location, cooled down as soon as I started moving. 170 on long uphill, 160 cruising on level moderate day. I’m happy.

Left factory light sensor in place. Factory manual says it sets the light at 238 degrees!

Thanks for all the feedback.

[Author]

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