Official s52 temp sensor without tapping the head thread

[FredK]

I was just testing the m20 temp sensor now when I realised it.

If its not linear its not worth fucking with. The only way to make a stock gauge work would to make a PIC processing unit of some fashon to do the math. Which would take time to figure out and at the cost of tapping the head or setting up a VDO system its not worth the money or the time when you can have something better cheaper.

Uh, it'd probably be easier to put the correctly calibrated thermistor into the S52 sensor than to make a programmable IC. Seriously.

A THERMISTOR DOES NOT HAVE A LINEAR R vs. T.

Your results are exactly what you should have expected. Whether you're talking about the S52, M50, M10, or M42 temperature sensors, they are all of the NTC type. The calibrations are different.

Anyway, tapping shouldn't put too many chips into your cooling system.

Did you collect any data?

[hugh jass]

In talking with Jon at Treehouse, he made it sound like drilling and tapping the head wasn't a big deal (assuming the engine is out of the car). he said have a shop vac close by to suck the shavings out, go slow, and it should be a pretty easy process.
That said, drilling a hole in a very expensive aluminum head casting would be pretty nerve wracking.

[arsevader]

m20

91 F low speed fan kicks on
99 F hign speed fan kicks on


m20

12 ENGINE COOLANT TEMP SENSOR 1-POL 1 12621710512 $17.52
13 TEMPERATURE SENSOR, WATER 20CEL 2500 OHM 13621357414 $44.36

Not sure if this helps.

Those are 3 different sensors. Your readings on the top one is the Aux fan switch which is mounted in the radiator. Nothing to do with the engine.

Middle one is the dash gauge and is generally refered to as the sender.

Bottom one is the Engine Sensor and controls motronic.

The values for the sensor (blue type) (bottom one) from the Bentley are:

-10 CEL > 8200 - 10500 ohms

20 CEL > 2200 - 2700 ohms

80 CEL > 300 - 360 ohms

[equate975]

A THERMISTOR DOES NOT HAVE A LINEAR R vs. T.

Yes yes I know, I didnt know that before I tested though. I am going to see what happens if you stick an e36 gauge in your e30 cluster now.

I will get what data I have up soon

[FredK]

Cool cool. I'm sure a workaround can be done, hopefully it's not complex. :)

[mpowerjon]

Cool cool. I'm sure a workaround can be done, hopefully it's not complex. :)

Sorry, There's not a work-around. The M50 DME needs one range of signal and the E30 Cluster needs a different range. Don't F__ with this.

THERE IS NO SPLICING.

You DO NOT need to pull the engine. (Who said that!?) Pull the intake, Drill the head in the blank spot, tap it, put the sensor in.
BAM! Put that in your "Official thread".

Jon

[MGYVER]

E30 Temp sensor

What I did seems a lot simpler and works perfectly.

I used the M20 sensor which threads directly into the rear port where the E36 sensor was.
The E36 sensor is a different range (as you know). The two wires are a ground loop from the ECU ie. one is the ground signal from the ECU and one is the ground signal back to the ECU (the variable signal based on the sensor).

The E30 sensor is a single wire because the body of the sensor provides the ground signal. Soooo using a simple probe I identified which of the two wires was the one that was the return to the ECU and this is the wire I connected to the sensor. The other wire I just taped up.

The sensor works perfectly, the signal is linear ie. smooth sweep with gradual engine warmup and the operating temp is right in the middle.

Hope that helps you.

[equate975]

Sorry, There's not a work-around. The M50 DME needs one range of signal and the E30 Cluster needs a different range.
Jon

Yeah thats exactly what we were trying to do, change the "range" so the cluster can read the new signal....

[rede30]

So your saying all you need to do is connect one wire to the m20 sensor and screw it in the hole and your done? Thats beautiful.

[hugh jass]

What I did seems a lot simpler and works perfectly.

I used the M20 sensor which threads directly into the rear port where the E36 sensor was.
The E36 sensor is a different range (as you know). The two wires are a ground loop from the ECU ie. one is the ground signal from the ECU and one is the ground signal back to the ECU (the variable signal based on the sensor).

The E30 sensor is a single wire because the body of the sensor provides the ground signal. Soooo using a simple probe I identified which of the two wires was the one that was the return to the ECU and this is the wire I connected to the sensor. The other wire I just taped up.

The sensor works perfectly, the signal is linear ie. smooth sweep with gradual engine warmup and the operating temp is right in the middle.

Hope that helps you.

Which rear port are you talking about? I just want to be clear on what you're saying.

[Skafrog]

What I did seems a lot simpler and works perfectly.

I used the M20 sensor which threads directly into the rear port where the E36 sensor was.
The E36 sensor is a different range (as you know). The two wires are a ground loop from the ECU ie. one is the ground signal from the ECU and one is the ground signal back to the ECU (the variable signal based on the sensor).

The E30 sensor is a single wire because the body of the sensor provides the ground signal. Soooo using a simple probe I identified which of the two wires was the one that was the return to the ECU and this is the wire I connected to the sensor. The other wire I just taped up.

The sensor works perfectly, the signal is linear ie. smooth sweep with gradual engine warmup and the operating temp is right in the middle.

Hope that helps you.

Man, I hope I am misinterpreting your statement, but you are not talking about a 3.2 OBD2. All the obd1 M50/S50 varients have two temp sensors, a brown and blue. However, a 3.2 only has one sensor, hance the whole tapping thing.

[MGYVER]

e30 Sensor

Hugh Jass
I'm referring to the temperature sensor that is positioned closest to the firewall (the rearmost one).

Skafrog
My assumption is that all e30 engine swaps using a S52 3.2L engine require the OBD 1 conversion. Does this not make it more similar to a M50/S50 ? I helped my mechanic figure out the temp sensor problem and AFAIK he just swapped the intake manifold etc. for the conversion - I don't think he swapped the entire head because I sure didn't provide him with a new one !
Would this explain why there are two temp sensors in the S52 ?

[Skafrog]

On an 3.2 s52, There is only one temperature plug stock, hence the need to drill and tap a second plug - one for the DME, one for the cluster. On an m50/s50 variant, there are three "ports" on the head - two temps, one coolant bung. On a stock s52, there is only two ports, one temp, and one coolant bung.
If you have two coolant sensors in your s52, your mechanic either A) swapped the head, or B) drilled and tapped another port. When swapping to OBD1, you get to a point where it is very accessible and easy to drill and tap the head to accept the second sensor. Hell, the casting is still remnant from the old style head.
Yes, doing an OBD1 conversion on a 3.2 makes it like an s50 on crack.
-Rob

[ericzz]

What Size Tap Do You Use I Searched And Could Not Find The Answer !!!

[LINUS]

What Size Tap Do You Use I Searched And Could Not Find The Answer !!!

I know I've typed that answer out before, but the very best thing you can do is to get your sensors first, thread one in the hole you have presently, then go to the autoparts store and find a nut that fits the sender you still have in hand - now go buy the tap based on the thread pitch of that nut.

There is a great satisfaction you get from getting some of the simpler stuff taken care of without asking, especially if it's within your ability to get the answer. Save questions for the hard stuff, like when your wiring harness is laughing at you.