71 E motor / 1967 SWB gauges (this old chestnut)

[Matthew Barnes]

Morning,

I have searched all the previous posts about getting early gauges to talk to later mechanicals. Lots of great info. But like my school years, I need some extra help!

The specifics are as follows:
1971 E motor with MFI and full MFI engine harness.
Gauges are from a '67 912 (5 gauges)

Oil Temp Sender:

I checked the part numbers of the 912 oil temp sender and the later 2.2E sender.
According to our host, they are the same.

912 Oil Temp Sender unit
Part #: 901-641-632-00-OEM

911 Oil Temp Sender unit
Part#: 901-641-632-00-M253

So there shouldn't be a signal issue. Wiring continuity is all good.

No 12v power supply to the back of the gauge (yellow and blue wire) the temp gauge hits the stop on the right. When connected, along with the sender wire (green and black) the gauge drops to just below the red. As various threads describe, this indicates the sensor is bad. Can anyone confirm this is the case, and further, is there a way to test that the sensor is working? The only suggestion I could find was to place the sensor in a mug of boiling water and seeing if there is a change in the reading?

Oil pressure:

My gauges have no numerical reading for the oil pressure. Does anyone have experience of wiring in an electrical pressure gauge that can be added to the dash? I have used a short mechanical pressure gauge to check the running pressure and it's good. Surely the racing chaps have done this?

I have tried to use a 944 oil pressure gauge but no dice - obviously not compatible with the OE 1971 oil pressure gauge. The 924 forums suggest a VW/Audi pressure sender may work with the 924 gauge....seems to look identical to the Porsche 912 pressure sender. Suggestions greatly appreciated.

Tacho:

All good - I installed a TachAdapt and it works perfectly.

Many thanks for any input.

[jbell959]

All of the temp gauges through 68 use the 901.741.632.01 sender. The temp gauge was changed in 69.

Adding an oil pressure gauge is as simple and installing the correct sender in the engine and running a single wire from the sender to the gauge and providing 12V and ground. A 944 oil pressure gauge will work fine if you change the sender. The 944 used a 5 Bar sender and your 71 engine would have a 10 Bar sender.

[Matthew Barnes]

Legend.
Thanks very much for the info.

You're saying all the cars through 68 used 901.741.632.01?
Interesting that Pelican has 901-641-632-00 for 67 912 and 71 E.

With regards the 944 gauge, the one I have reads to 10bar (may be from a 924?).
Yet while I have signal from the new oil pressure sending unit, it does nothing to the gauge when I connect it. I assume this means the 9?4 gauge needs a different sending unit.

[jbell959]

That wouldn't be the only incorrect information on the internet.

If you have a VDO 10 bar gauge then it should work fine with a VDO 10 bar sender. When you say you have a signal from the sender, how are you measuring that? You need to check the resistance between the sender wire and ground.

[PeteKz]

Matt, a different sender may be the quick and cheap solution for now, but I suggest you watch for a correct oil gauge at a swap meet or in the classifieds. It will save you trouble in the long run (or a successor owner), to stick to the correct gauge and sender for your year car.