Stock sensors with VDO gauges.

[Arlo Cooper]

Does anyone know if you can use or either the stock water temp or oil pressure sensors would function giving info to aftermarket VDO gauges? Like the view line or something?

 

Thanks,

 

Arlo.

 

[Son of Marty]

The oil pressure gauge will need another sender as the stock one is just a off/on switch type, the water temp gauge would be possible if the vdo gauge matches the same ohm range. 

[jgerock]

For the oil pressure location, you will need an adaptor piece with banjo bolt along with a tee fitting to use the VDO sending unit and a "stock" 2002 oil pressure switch.  I recently (finally) connected the VDO oil pressure switch in my 69 and had to purchase another (different) BMW oil pressure switch with smaller threads that fit the tee fitting. BMW lists (2) different sizes.

Edited September 2, 2018 by jgerock

[jrhone]

1 hour ago, jgerock said:

For the oil pressure location, you will need an adaptor piece with banjo bolt along with a tee fitting to use the VDO sending unit and a "stock" 2002 oil pressure switch.  I recently (finally) connected the VDO oil pressure switch in my 69 and had to purchase another (different) BMW oil pressure switch with smaller threads that fit the tee fitting. BMW lists (2) different sizes.

 

 

Or you can buy the VDO sender unit that can run the VDO gauge AND the stock gauge.  

 

I run that one without issues. Something like this.  One wire for the vdo gauge and one for the dummy light in the dash.  Screws in where the stock oil pressure sender location. 

 

 

 

[Mike Self]

47 minutes ago, jrhone said:

Screws in where the stock oil pressure sender location. 

Unless VDO now makes a sender with the proper threads, you're still gonna need an adapter to fit the gauge sender, as it's fine thread, and the threads in the cylinder head are coarse.   

 

One other difference:  the factory warning light sender illuminates at .5 atmos (about 7.5 psi) while the trigger for the warning light on the VDO gauge sender triggers at 1 atmos (14.7 psi).  So when you fit it, don't panic if you see the oil light come on at a low idle (especially with a worn engine).  The good news is that it gives you more warning before impending engine disaster.

 

If you're gonna fit a temperature gauge, why not fit an oil temperature gauge; you already have a water temp gauge and it's pretty accurate so long as the sender threads are nice and clean, along with the terminal.  

 

cheers

mike

 

[bob02]

Not sure if they’re still available, but I use a vdo sender that’s m12x1.5.plenty of room and no need for an adapter.

 

  Bob

[jrhone]

Same here.  I guess maybe it depends on the head. Maybe different heads used a different size sender.  On my e12 Head I have a vdo adapter that works.  Yes the oil light used to flicker sometimes at idle after running it very hard but it did that with the stock sender as well.  After my rebuild it barely happens even after long hard runs.  

 

[jimk]

21 hours ago, Son of Marty said:

the water temp gauge would be possible if the vdo gauge matches the same ohm range. 

Not only the resistance range, but calibrated to the resistance curve.  The resistance curve is not a straight line plot (it is fairly so on a semi-log plot).  So it would be a wag (not a swag, no scientific input) to guess without plotting all the resistance point vs temperature and comparing what the VDO gauge uses for various temperatures on the face scale.  I have plotted resistance for several senders for EFI service, it takes all morning for one sender.

[Swiss 2002Tii]

I am looking to add an oil pressure gauge as well.  What range of pressure is suitable for a stock Tii motor?

I was thinking to match the AEM Analog UEFO AFR with AEM oil pressure and AEM fuel pressure, but they have a proprietary wiring from sensor to gauge, so this dual output sender won't work.

Also their instructions say: "Thread the sensor into a suitable pressure port that has 1/8” NPT female "... That sounds decidedly non-metric to me!

Jim, is that why you went with the banjo+Tee-mount?

Also wondering where I would mount the fuel pressure sensor... At the KF banjo?  I guess a female M12 Tee with two M12 8mm barbs fittings?

 

Per jrhone, VDO does appear to make a coarse thread dual output sender.

 

Probably much easier to sandwich a VDO oil pressure gauge between two AEM gauges, or have two VDO and one AEM.  They look quite similar.

Edited September 6, 2018 by Swiss 2002Tii
Additional info

[jimk]

Gerock's street brass tee looks a bit suspect because it is a std 1/8 NPT thread street tee and the needs a straight thread with a seal ring.  There are bushing adapters on eBay that will convert from NPT to straight thread.  I bought sack of assorted sizes when I mounted the radiator coolant out in the S14 thermostat.  Of the leftovers I am looking at a M10x18npt, 1/8nptx28BSP and a M16x1.5 (unknown).  Maybe some can be found.

[jgerock]

1 hour ago, jimk said:

Gerock's street brass tee looks a bit suspect because it is a std 1/8 NPT thread street tee and the needs a straight thread with a seal ring.  There are bushing adapters on eBay that will convert from NPT to straight thread.  I bought sack of assorted sizes when I mounted the radiator coolant out in the S14 thermostat.  Of the leftovers I am looking at a M10x18npt, 1/8nptx28BSP and a M16x1.5 (unknown).  Maybe some can be found.

At first, I threaded the VDO sending unit and stock switch into the brass fitting but both leaked oil on start up so I removed and added teflon tape to the (3) fittings. No leaks so far.  The fittings screwed together without any issues.

 

Guess I am a suspect person.

[ray_]

15 minutes ago, jgerock said:

At first, I threaded the VDO sending unit and stock switch into the brass fitting but both leaked oil on start up so I removed and added teflon tape to the (3) fittings. No leaks so far.  The fittings screwed together without any issues.

 

Guess I am a suspect person.

 

Well you are an engineer.

 

[Einspritz]

I  had those electric oil pressure gauges and hated them; not much resolution and a short needle swing.

 

Moved to the analog type wherein you run an actual nylon hose into the back of the gauge, which has IIRC a 270 degree swing. Very quick and accurate.

 

When warming up, I drive by oil pressure not to exceed 80-100 psi until it is warm. Of course I also have a shim in the oil pump to raise the pressure of the bleed valve.

 

Every 5 years or so I need to remove the oil in the line as it causes the needle to vibrate excessively.

 

 

[Simeon]

58 minutes ago, Einspritz said:

Every 5 years or so I need to remove the oil in the line as it causes the needle to vibrate excessively

 

Can’t you get an isolation diaphragm to stop the oil from getting to the gauge?

 

In fact, isn’t it a good idea to run one to minimise risk of catastrophic leaks?

[jimk]

3 hours ago, jgerock said:

I removed and added teflon tape to the (3) fittings.

I stay away from teflon tape.  Just a sliver of tape loose in the system if blocking an oil port can have exciting consequences.