Drain Plug Oil Temperature Sensor

[JoeInTUS]

I decided an oil temperature gauge would be more useful than an altimeter, so where to place the sensor. Initially I was going to tap into one of the oil gallery plugs as others have done and then I found this VDO sensor (323 092) that fits the drain plug hole. A female spade connector fits on the round connector of the plug. The plug fully threads into inside portion of the pan, so the sensor portion of the plug clears the threads in the pan.

Sensor Unmounted Compress.jpg

It sticks out about a 1/2" below the plug guard on the oil pan and just slightly below the exhaust.

Drain Plug Sensor Compress.jpg

I used an old starter terminal boot to protect the connection.

Drain Plug Sensor with Cover Compress.jpg

Since it is brass I was was concerned with over torqueing the plug, so I only torqued it to 10 ft lbs (Note: I later found a spec sheet on the VDO web site that specified a max torque of 11 ftlbs for the plug). After about fifty miles it seems to work fine with no leaks.

[steve murdoch icoa #5322]

Looks trick, Joe.
I have a very similar set-up on my '81 installed by the previous owner.
The only issue i had was the gauge itself. It always registered much higher than the real temperature. Calibration?

[JoeInTUS]

Steve, best I can tell it is accurate. I checked the indicated temp vs IR temp of the plug and they were close.

Maybe your sensor is not correctly matched to your gauge.

[EMS]

I am a big fan of that concept vs the sensor in any other place.
I do not ride any of my vintage bikes or cars to be concerned about the oil temperature to be too high. An oil pressure gauge is a better safety item.
I am concerned, however, about the oil not being up to the right temperature. Oil too cold could have insufficient lubrication qualities and also, any moisture in the oil sump/tank will not evaporate unless your oil is above 212° in the coldest spot - which is usually the bottom of the sump. Well done!

[daves79x]

Excellent Joe!

Dave

[AshishNJ]

Nice work there. What type of oil temp gauge you are feeding this signal to ?

[cross]

And how do you know which gauge is calibrated to work with, any VDO?

[JoeInTUS]

Bottom line I think any VDO gauge with a max temp of 150C/300F will work.
(Edit: as posted below VDO confirmed that this sensor will work with any of their 150/300 gauges)

I am using this gauge:
https://www.amazon.com/dp/B000CCBNAC?ps ... ct_details

Looking through the VDO webpage (which is clear as mud) I concluded that they had two primary calibration curves for their temp senders; one with a max temp of 120C and one with a max temp of 150C(300F). Since the drain plug sensor has a max temp of 150/300, I assumed it would work with 300F temp gauge. My comparisons of the indicated temp vs IR temp of the drain plug agree, so I believe it is accurate.

The VDO web page for the gauge provides a link to a sender table. Unfortunately that link leads to a pressure sender table.
https://www.vdo-instruments.com/instrum ... ender.html

A couple of issues installing the gauge since it is a tight fit due to the bar that supports the mirrors.

1. The connection for ground had a male spade lug at the bottom that interfered with the bar. I removed the lug and used a ring terminal and connected it to the stud that held the ground terminal.

2. The spinlock "nut" seen in the background was too fat to fit inside the fairing so I had to sand it down to reduce its height.

Hope this helps, Joe

[AshishNJ]

Very nice and useful add-on.
I am considering this to be hung somewhere on my 79. I don’t like the ones that protrude out from side of the engine.

[JoeInTUS]

I asked VDO if I had the right sensor/gauge combination, their response (which I got in about a minute):

TechSupport-US@Continental.com <TechSupport-US@continental.com>
Hi Joe,
Yes that sensor and gauge are compatible. That sensor will also work with any 150C/300F gauges we make.

[cross]

Thank you for the information

Sasha

[JoeInTUS]

Here is what the sensor looks like inside the pan. I meant to take this picture before I installed it and filled the engine with oil.

Oil Temp Sensor Inside Pan Crop.jpg

[AshishNJ]

I just bought same stuff but haven’t installed. Can any cable be used to connect the signal from sensor to gauge? Where can I find the rubber plug ?

Thanks

[JoeInTUS]

Any wire will work between the sensor and the gauge. The rubber boot I used was from an old starter cable we had laying around the shop.

[AshishNJ]

Thanks . Found a rubber boot on Amazon that fits perfect. I will install one of those heat shielded cables