Sensor technology for oil temperature

Hello everyone,

Since I'm currently working on my LDA/voltmeter combination, I have a question regarding a possible extension in the direction of oil temperature measurement.

Basically, there are two ways to obtain meaningful measurement values:

- Sensor on the oil drain plug.
- Sensor on the oil dipstick.

What are your experiences with these technologies? Some advantages and disadvantages seem quite clear, but what does that look like in practice?

So far, I see it this way:

Sounding rod:
+ easy installation
- Cables interfere with oil level checks.
- The oil rod needs to be replaced.

Indulgence.
+ No changes regarding the oil check.
- Possible leaks at the drain screw due to unsuitable sensors or adapter pieces.
- Complex and vulnerable cable routing to the sensor.

What do you consider to be relevant?

Basically, I only found sensors that are linked to some kind of display, meaning they are calibrated together, and otherwise exhibit behavior that is difficult to determine without the display, specifically regarding the mapping of temperature to resistance or voltage.

I want to operate the entire system using a panel meter with a range of -200mV to +200mV, and I will appropriately adjust the signal to match that range. However, this would require me to find a sensor that exhibits linear behavior and also has a behavior that is approximately known.

Does anyone know anything about that?

Currently, I'm almost inclined to hold off on this expansion for now, but maybe someone knows of a nice sensor that would work.

Best regards,

Jan.

Okay, the Passat 35i with the MFA (Multi-Function Display) had a sensor built into the oil filter housing, which allowed the oil temperature to be displayed on the MFA. The Golf IV still has the threaded hole and the connection for the MFA in the same location. That means there's a good chance you'll find something similar on Ibiza.

Best regards, WarLord.

Hi,

Is there a blanking plug or a screw inside the Golf IV in that location?

It might even be possible to install it without draining the oil, if you're quick and willing to tolerate a little mess. I'll check how that looks at ASV.

Which still leaves open the question of which sensor to use.

Best regards,

Jan.

There's one from VW that fits into the screw hole. Look at . There's the part number for the sensor (although it's for the Golf III).

Best regards, WarLord.http://www.jagiella.net{MARKER}.

Hello Jan6K,

I've already had a dipstick with a temperature sensor (from Conrad) for years.
+ Works perfectly.
+ The original bleed screw remains in place.
- If you're trying to read the oil level with this, forget about it. For that, I'll use the original dipstick, which is in the trunk.
-> Basically, it's recommended.

Regards,
I'm sorry, I can't translate that word because it doesn't seem to be a real word. It might be a typo or a made-up word. Could you please provide a different word or phrase?

Volkswagen Golf III 1Z, manufactured in 1994.

Quote:

However, a prerequisite for this would be finding a sensor that behaves linearly and also has an approximately known behavior.

Use a Pt100 or Pt1000 sensor. They are available in various designs, including threaded versions for screwing in. You can find information and datasheets at Conrad (though you can probably find them cheaper elsewhere).

What kind of sensor do you want to use for the LDA?

greetings
dieter

Hmm, for me, it would only be a makeshift solution that wouldn't really satisfy me. I would prefer the oil drain plug.

Best regards, WarLord.

Hello everyone,

Thank you very much for all your answers!

@Dieter: Motorola MPX4250AP. You can find them at Segor for 28 euros. The data sheets can be downloaded from the web (unfortunately, it's only available there in the A version without a housing and hose connection).

@wollif: Are you using the original measuring device, or something you built yourself?

@Everyone: I'll look into the suggestions you've given me. Right now, the oil filter screw seems like the best option, assuming it's available (I'll need to check that).

Best regards,

Jan.

Hi,

@Jan6K
I also own a Seat with an ASV engine, manufactured in October 2000. There was a blind screw on the oil filter housing.
with an M10x1 thread located above the oil pressure sensor.
You can drain them and remove them without oil; there will be very little spillage.
There was a similar sensor available from Seat, and it was made by VDO. Then I decided to use the sensor on the...
Bleed screw tightened. With the temperature sensor attached to the oil filter housing, I could barely reach 105°C.

@Jan6K: The measuring device is also from Conrad. Today, I would treat myself to one from VDO.

@warlord

Hello.

"That sounds interesting. Is it perhaps possible to also display the oil temperature in my MFA (Multi Function Display) by retrofitting a sensor (since there's a blind plug on the oil cooler)? Does anyone know how? My van, being longlife capable, has an oil level/temperature sensor mounted in the oil pan. Is it possible to somehow tap into this signal?" Or even display it via OBD with an additional display???
Where is the most sensible place to measure the oil temperature? Logically, it should be in the middle of the oil pan, if I'm not mistaken. Peak temperatures in the cylinder head area would likely be unusual, right?

Greetings, Peter.

Hi everyone,

Has anyone had similar experiences to Achim regarding the oil filter bracket, where it's not possible to measure accurate temperatures?

Because that would be quite important.

Best regards,

Jan.

Hello Jan6K.

Okay, even though I might be wrong, a friend of mine has a 35i with a 9A engine, and the oil temperature sensor is located on the oil filter housing (I'm sure of this, because we had to replace it; it was leaking after 189,000 km). The Passat rarely shows a reading above 98 degrees... which I also found surprising. However, that car is already in a pretty bad state, so maybe that's why. Errors not addressed.

Okay, now here's the part where I'm afraid I might be wrong: There's a lot of tubing running through my oil filter adapter, and I seem to recall reading somewhere that it's an oil-water heat exchanger. If I'm correct, this would be the wrong location for the sensor.

It also seems that the oil drain plug is the most convenient and safest place to access. Furthermore, there is likely no risk of damage in that location. My Golf has a lot of rust on the bottom, and if you were to bump it on something down there, there would definitely be some repairs needed.

Okay, feel free to educate me!

You don't need to be lectured.

There are actually vehicles with a water-cooled oil cooler.

Hi,

So far, the question of the ideal location for measuring oil temperature remains unresolved.
Logically, I would assume that the oil temperature at the outlet of the oil pump is the most relevant, as the engine is lubricated with 'that' oil, and not with the oil that has returned to the oil pan before reaching the oil cooler or the oil-water heat exchanger.
What do you mean?

Greetings.

Eike.

Hi,

Regarding the water-cooled oil cooler, I also believe it's possible for the ASV (presumably a specific vehicle or engine model). You can actually find a similar component on that engine, and it's likely located in that area.

Basically, you have to get somewhere into the oil pan or somewhere else where there's oil, and that probably applies to both the dipstick and the drain plug.

The Ibi is also closed on the bottom, but I still don't like the idea because there are cables running between the plastic and the hot oil pan.

Best regards,

Jan.