My weird temp sensor mount

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Alecb

Alecb

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So I spent some time at my local Ace Hardware assembling an adapter for my 1/2 inch aftermarket temp sensor to fit in the factory 3/8 inch hole. This is what the manager and I came up with. Naturally, the temp gauge doesn't read any temperature. Any thoughts or ways I can make this better?
20200524_194734.jpg
 
The gauge doesn't read because the sensor isn't grounded. You've got to find a way to ground the sensor, like mounting it into the block. Delete the rubber hose.
 
Not only that but that will never be accurate, and will fail when you need it most. If air--from flash boiling say, or low coolant---leaves the sender "high and dry" it will never tell you the engine is hot
 
Very simple to tap the hole bigger for the sender fitting to screw in. Looks to be a mechanical gauge so grounding would be a non issue. While your setup technically fits, it will be inaccurate to the point of being unusable. Tap the hole bigger, if you ever decide you want to put the factory sender in, that will just be a simple downsize adapter.
 
Should have T’d into the heater hose. You would at least get a reading.
 
Tooljunkie said:
Should have T’d into the heater hose. You would at least get a reading.
Click to expand...
The sensor would still have to be grounded. The heater hose is not a ground.

Edited to make a correction to my error.

You are correct, that will work just fine,. It'd help if I were to open the link that you provided before I inserted my foot. My apologies. :usflag:
 
Could I put the sensor here in the radiator? I noticed this fitting that looks to be about the same size as my temp sensor probe
20200529_152146.jpg
 
It looks too high,and it will be diluted by cooler coolant in rad.
 
The radiator location will be just fine. Coolant temp there (at the outlet of the top rad hose) will be extremely close to coolant temp at the cylinder head sensor location (at the inlet of the top rad hose). There will be no dilution because that's where the coolant enters the radiator from the engine. Being on the other side of the thermostat from the original location, it will change the behaviour of the temp gauge a little: you will be able to see the thermostat open because the temp gauge will more suddenly swing up from the cold peg.

Another option: drill and tap the water outlet/thermostat housing. Attached pic is from an article by Doug Dutra in the March '92 Slant-6 News.

Me, I'd probably either use the radiator location or drill out and retap the cylinder head hole. If you do the latter, put a strong magnet under the hole to catch the drilling chips.

Screen Shot 2020-05-29 at 16.49.33.jpg
 
slantsixdan said:
The radiator location will be just fine. .
Click to expand...

Actually it is a damn poor location. If and when the water pump / hose / other has a slow leak overnight, and in the kind of wx where you are not using the heater.......and don't notice it went cold....the radiator location may again be high and dry, and never send 'that warning'

A temp sender should be as low as possible and still see engine heating. Intake manifold on a V8 ain't bad, for some reasons the Chev "in head" location is better. Higher the worser
 
Tooljunkie said:
It looks too high,and it will be diluted by cooler coolant in rad.
Click to expand...
when i added an after market gauge to the 74' i moved the stock sender to the radiator bung, worked fine and kept the stock gauge alive, but i agree with 67Dart273. had that happen on my truck. rainy day, parked at work all day and the plastic radiator split a seam. realized it wasn't warming up in the cab and dove into a gas station.
 
slantsixdan said:
The radiator location will be just fine. Coolant temp there (at the outlet of the top rad hose) will be extremely close to coolant temp at the cylinder head sensor location (at the inlet of the top rad hose). There will be no dilution because that's where the coolant enters the radiator from the engine. Being on the other side of the thermostat from the original location, it will change the behaviour of the temp gauge a little: you will be able to see the thermostat open because the temp gauge will more suddenly swing up from the cold peg.

Another option: drill and tap the water outlet/thermostat housing. Attached pic is from an article by Doug Dutra in the March '92 Slant-6 News.

Me, I'd probably either use the radiator location or drill out and retap the cylinder head hole. If you do the latter, put a strong magnet under the hole to catch the drilling chips.

View attachment 1715537425
Click to expand...
If I go the route of drilling and tapping the cylinder head, does the head need to be removed from the block? Or can I just drill and tap it and make sure I catch as much of the metal as possible?
 
Drill slow,a little at a time with grease on the bit,clean and regrease as needed. Same goes for the tap.
I made up a can,like a catch can,connect to shop vac to gather debris and coolant. 3/8” hose on inlet if can to get into tight spots.
 
Alecb said:
If I go the route of drilling and tapping the cylinder head, does the head need to be removed from the block?
Click to expand...

No. Just remove the thermostat housing and stat, put a good magnet under where you'll be drilling, and proceed as Tooljunkie describes.
 
slantsixdan said:
No. Just remove the thermostat housing and stat, put a good magnet under where you'll be drilling, and proceed as Tooljunkie describes.
Click to expand...
yup, it's the coolant passage so if a chip slips by you it won't be the end of the world, not like your making a hole in the intake
 
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