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This 1.6 I have just rebuilt had a broken thermoswitch (fan switch), so I ordered a new one.
Since I just did a reroute for this engine, made a nice housing for it on the rear thermostat adapter, installed and wired it to the fan relay.
The car is stock otherwise.
Fired the car up, no fan. I had to jump #3 and #4 in the diagnostic box to kick the fan on.
Removed and tested the switch in boiling water, "open circuit" on my multimeter. The fan switch is supposed to come on at 97C (207F).
Ordered another one. It has 90C - 85C (194F-185F) printed on it.
I wanted to make sure, so, I did the boiling water test again, no dice.
So I took the sensors home and heated up some vegetable oil - I can see as high as 200C (392F) with oil, it gives me a much wider heat range.
The first switch finally came on at 138C (280F)... Damn.
Second switch consistently closes to ground at 110C (230F) and opens the circuit (stopping the fan) at 93C (200F).
I now have two useless new Miata switches, and I am thinking about getting a bunch of random M16 threaded switches and installing the one with the lowest temp response.
This is how I tested them. Am I doing this damn simple test wrong?
I took the two pics above while the oil was heating up.
Temp probe checked out in boiling water, btw.
And, I normally hold the probe very close to the tip of the sensor to get the reading right.
I would suggest submersing the probe at least up to the mounting interface. As in to the top of the threads if the sealing surface is a crush washer beneath the hex.
It it is possible that heat transfer to the air is cooling the switch and causing it to not respond properly.
The amount of heat lost into the (very hot) air from the unsubmerged portion of the sensor is miniscule as compared to the amount of heat going into it from the liquid.
Please, please post a picture of that car from the top.
Everything on the bottom screams 911 but the floor pan.
That is German ****!
911 motors are "modified" dry sump and the pick up for scavenging is under the little round cover but...
02-12-2021, 09:25 PM
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