Oil temp gauge

356 Porsche-related discussions and questions.
Post Reply
A Collaud
356 Fan
Posts: 51
Joined: Thu Jan 24, 2019 11:18 am
Location: France

Oil temp gauge

#1 Post by A Collaud » Sat Nov 02, 2019 6:14 pm

I'm still in the process of checking all before reinstalling everything in the car, and this afternoon it wad the oil temp gauge time
I connect everything for a test:
- 6V on the "+"
- Ground to ground
- and the sender (oil sensor = a VDO 801/1/26) on "G"
- and the sensor connected to the ground

And then different strange reaction :
- the gauge goes to the max (right) when the sensor is disconnected (infinite resistance)
- it goes to the min when I put the G to the ground (resistance = 0)

I tested with some other resistance and the result :
at 50 ohms it is to the max :
IMG_4747.JPG (94.38 KiB) Viewed 308 times
at 47 Ohms
IMG_4749.JPG (89.33 KiB) Viewed 308 times
at 40 Ohms
IMG_4748.JPG (105.1 KiB) Viewed 308 times

I understand that the sensor resistance is going down while the temp is increasing, which is not the way my gauge reacts, and it is very sensitive (from min to max in10 Ohms) !
I found this curve on the net for this sensor :
sensor.png (42.74 KiB) Viewed 308 times

I've open the gauge and check, no damage or anything else
IMG_4730.JPG (166.52 KiB) Viewed 308 times
IMG_4753.JPG (100.33 KiB) Viewed 308 times
The gauge reacts the opposite way it should and it is very sensitive. I've checked several time the connection, everything is OK
any idea ?

A Collaud
356 Fan
Posts: 51
Joined: Thu Jan 24, 2019 11:18 am
Location: France

Re: Oil temp gauge

#2 Post by A Collaud » Sun Nov 03, 2019 8:09 am

Digging a little bit more, I found interesting information : a new sender (323-416 or 801/1/26) doesn't work with an original gauge

The original (616 107 805 02) as the following resistance : (found here : viewtopic.php?f=1&t=48058&p=330079&hili ... ms#p330079 )
45 ohms at 180 F
41 ohms at 170 F
28 ohms at 72 F
=> resistance increase with temp
but it seems that such sender is no more available

Does someone has some information about the modification to be done on the gauge to make it properly ?
thank you, to be continued ....

User avatar
356 Fan
Posts: 252
Joined: Fri Jan 10, 2014 2:02 pm
Location: Carson City, NV

Re: Oil temp gauge

#3 Post by PaulLima » Sun Nov 03, 2019 9:52 am

I believe this is the correct sender for the older gauge: https://www.ebay.com/itm/143137335634

Martin Benade
356 Fan
Posts: 4366
Joined: Wed Nov 23, 2011 10:52 am
Location: Cleveland, Ohio

Re: Oil temp gauge

#4 Post by Martin Benade » Sun Nov 03, 2019 10:23 am

And the gauge was not rebuilt?

Post Reply