Wrong Water Temp Sensor?

[himself]

I bought a new water temperature sensor to install in place of the old one since the old one had only 1 wire and I need 2 wires for the MS. The one I pulled out has smaller threads than the new one and is a bit shorter. Did I get the wrong one or am I going to have to drill out the original hole to make room for the new one?

[christoc]

Have you tried any othe the other holes on the thermostat housing? I've got two housings, one off a 78 2+2 and one off a 83 L28ET. Only 1 or two of the four holes seem to match up with threads. It's the weirdest thing trying to find plugs for them so far.

[hoohaa]

Is that a GM CLT sensor? If so you will need a 3/8" NPT bung. as you can see, the threaded area is much wider on the new sensor.

[himself]

I only have 2 tapped holes in the therm housing and 2 untapped ones. I plan to take it to a machinist tommorow and tap one of the larger untapped holes and fit the new sensor there. I'l plug one of the others with the old sensor but not hook it up and the third has my thermal sensor for my heat gauge so it will stay put.

Just thought maybe there was a water temp sensor that fit perfectly that I missed or whatnot, guess they don't make 'em that small anymore.

[Matt Cramer]

The Megasquirt can use a one wire sensor as long as the sensor grounds through the engine block. It doesn't require a two wire sensor.

[himself]

I did not know that the water sensor could be gronded through the block. I'll check and find out, thx for the info.

[mario_82_ZXT]

The one you pulled out is the sender for your water temp gauge.

 

Mario

[zbigtim]

 

The picture above is out of the '76 FSM. I know it is not exactly like yours, but it should be similar. In the above pic. you can see four sensors. The one on the top left is the sensor for you Temp. Gauge. The bottom right sensor is for the ECU. This is a two wire sensor that can be used for the megasquirt. You can use the standard bias resistor supplied with the MS, and use Megatune to calibrate the temperature range. (This is what I did)

 

I assure youall of your factory gauges in the dash are not controlled by the ECU. They have their own sensors and are seprate from the EFI.

 

Hold on the the GM temp sensor you bought, you can use it for the Air Temp Sensor. When you remove your Air Flow Meter the factory Air Temperature sensor goes with it. (Its built into the Air Flow Meter).

 

In the photo below you can see how I inserted the GM Temp sensor into the rubber boot. You can also see the yellow (single) wire going to the Gauge Temp. Sensor. And the two wire sensor at the bottom of the Thermostat Housing. (Going to the Megasquirt). I wish I had thought of what Randy 77zt did with the TPS Mounting, before I made my "adapter plate".

 

Best of luck...

Tim

[randy 77zt]

on my car there was an untapped boss on tstat housing-i drilled it and tapped it for the gm sensor.tap is pipe thread-buy it at osh,lowes.megasquirt is about build it yourself-get ready with the welder,taps,drill press,cutoff saw,soldering iron-mucho tools

[himself]

I didn't test whether or not the old water sensor was grounded to the block, seeing as the block is aluminum the ground would not be that effective and no other parts are grounded to the engine itself. Instead I took my therm housing to a friend who owns a drag shop and had him tap out a new hole for the GM sensor. Got a new gasket for the housing and will install it today.

Thanks for all the info.

 

In regards to the IAT, I had an unused factory-tapped hole on the 4th tube of my intake that the IAT fit perfectly into with no modifications so I put it there.

[mobythevan]

seeing as the block is aluminum the ground would not be that effective and no other parts are grounded to the engine itself

 

Aluminum is fine for grounding. I am not just saying that in theory, I grounded all of my electronics to the aluminum intake manifold. My engine block was then grounded to the car frame. No problems.

[himself]

I understand that aluminum is a fine ground, heck that is what residential a/c units use to connect to the 220 in CA, but I prefer to keep all the grounds as close to each other as possible and grounded to the same object.

All my grounds except for the engine itself is grounded to the inside of the body so I wanted to put that one there as well.

 

Though I was unsure about mixing grounds, all mine go to steel and I did not want any interference by grounding that one to aluminum, thought maybe the currents might flow slightly different between the two.

[mobythevan]

Sounds good. When in doubt add ground wires between everything, battery to engine block, engine block to frame, car body to frame (doesn't really apply to z cars) etc etc

 

I understand that aluminum is a fine ground, heck that is what residential a/c units use to connect to the 220 in CA, but I prefer to keep all the grounds as close to each other as possible and grounded to the same object.

All my grounds except for the engine itself is grounded to the inside of the body so I wanted to put that one there as well.

 

Though I was unsure about mixing grounds, all mine go to steel and I did not want any interference by grounding that one to aluminum, thought maybe the currents might flow slightly different between the two.