|
|
Thread: Sensor identification
|
mwpayne
Hauling
Posts: 195
|
posted July 15, 2007 12:39 PM |
|
Sensor identification
There's a couple of sensors (I think) on my 74 that I just can't figure out what they're for, but they are heat/coolant related.
The large one on the center/top of the engine block. I've unplugged it and messed around seeing if it will trigger a lamp, nothing.
Also, the sensor on the themostat housing. Emissions, maybe? The sensor for the gauge is just under the oil filter, that I know.
If anyone can enlighten me so's I can tie back (never EVER cut) a few unneeded plugs to clean up my engine bay, I'd appreciate it.
|
|
dhood
Hauling
Posts: 134
|
|
posted July 16, 2007 07:36 PM |
|
|
I don't know what the one is on top of the block, but the one on the stat housing is the water temp switch which controls the electric choke. The switch is no longer available but I do see them in the wrecking yards once in awhile. They're obsolete so the used ones are pretty wasted, try to get as many as you can.
|
|
mwpayne
Hauling
Posts: 195
|
|
posted July 16, 2007 08:46 PM |
|
Electric choke, huh? Interesting, as I have the manual choke. The sensor does plug into the harness, however.
I bet it is what shuts the choke solenoid off after warm up. Makes sense, thanks!
I took the sensor off the top, it actually has a probe that sits in the coolant! THAT one is driving me nuts as to what is purpose is.
None of this really matters, I'm just the kind of guy that likes to know how stuff works.
|
|
Klaus44
Redlining
Posts: 365
|
posted July 17, 2007 08:25 AM |
|
A wild guess:
...could it be a low coolant sensor, that goes to a wee little red idiot light...?
|
|
mwpayne
Hauling
Posts: 195
|
|
posted July 18, 2007 02:30 PM |
 Edited By: mwpayne on 18 Jul 2007 14:34 |
Good theory, but I no can find itty-bitty idiot light that means 'low coolant' in my owners manual.
The 'probe' is a metal rod that is about two and a half inches long sticking down into the water jacket. The top has a two prong connector.
What in all that is holy...IS that thing????
|
|
Klaus44
Redlining
Posts: 365
|
|
posted July 18, 2007 04:40 PM |
|
Mazda Part #...:
1663 18 920... Sensor, Thermo ...(Discarded, 9/74).
(So says REPU Parts Manual!)
|
|
roaddancer
Hauling
Posts: 127
|
|
posted July 18, 2007 05:00 PM |
|
Some of the early rotaries had a temp sensor that shut off part of the ign. to change warmup curves...could this be one of those? I have a thin memory of it being located there, but I am not too sure..I have a 76 cosmo factory manual that probably says, but it is buried until after my house move. If it is that one it may be "off" until the engine warms up..then on to energize the ignition circuit, unless it works through relays... ...And by now is probably wired out by a P.O.
We fanatics know enough to warm them up properly before beating them...
____________
formerly
rx2/3/4/cosmo,repu,94 rx7,
|
|
mwpayne
Hauling
Posts: 195
|
|
posted July 18, 2007 07:59 PM |
|
Fascinating stuff!
Klaus, does that manual show a picture, or exactly where it is located? Mine is on the top of the engine, just behind the alternator, on the same section of engine as the oil fill tube.
If it's no longer needed, I'll probably need to fab up a blockoff plate of some sort.
Gentlemen, thanks for the assistance!
|
|
Klaus44
Redlining
Posts: 365
|
|
posted July 19, 2007 08:27 AM |
|
It most definitely does!
It is indeed the sensor on the center steel, right on top of the housing--. (Silly me, I *should* have looked it up right away, instead of guessing! Better yet, I must *remember* these facts...). ;)
|
|
ovquick
Redlining
Posts: 253
|
|
posted July 19, 2007 10:06 AM |
|
Sensor
If you are refering to the "low coolant" light on a 77. The sensor is in the overflow container.
____________
Manteca Mazda Asylum
where a boy and his cat live, without adult supervision
|
|
mwpayne
Hauling
Posts: 195
|
|
posted July 19, 2007 04:40 PM |
|
Mine's a 74, no low coolant sensor of any sort.
Klaus, I think you've solved the mystery (Scooby snack to you!_ :)
|
|
RotaryRob
Revvin Up
Posts: 53
|
posted July 19, 2007 07:21 PM |
|
either-or
I don't remember, for sure, but it is either, as suggested by earlier reply, intended to disconnect the leading ignition during warm-up, or to override the air control valve during warm up. I presume that was because of the chance of overheat during warmup with the choke on and a very over-rich mixture.
|
|
mwpayne
Hauling
Posts: 195
|
|
posted July 19, 2007 09:24 PM |
|
Looks like it's unneeded, so thanks to all of you for taking the time to check into this and post.
Now all I need to do is fab up a blockoff plate and tie off the connector neatly.
Thanks again y'all!
|
|
|
|
