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Howdy...
I just did a head gasket job on my '85, and was working through my list of other issues to deal with for the van... Installed a dual sender oil pressure setup from VDO... Looks like I have the typical low pressure syndrome. Good pressure until warm, and then I have no pressure at idle, and the idiot light comes on.
With the stock sensor I NEVER had the idiot light come on.
And three days after installing them, they arestarting to give wacky readings, like they are grounding out someplace...

I am about to drop the tranny to put in a new clutch and replace the seals in there.

1. Is it at all likely that my oil pressure will get better when I replace the leaky main seals?

2. Does anyone know if there is a way to test the gauges / senders with a multimeter?

3. What the minimum gauge wire that can be used for the sender to gauge connection can be?

4. The gauges say that they need "dedicated ground" I have seperate ground wires for each gauge, but they terminate at the same chassis ground point. (tied to the same screw under the dash. Do these need to ground at seperate locations? I figured that ground is ground is ground, and that it wouldnt make a difference if grounded them to different points under the dash, but maybe this is not the case.

5. Are VDO gauges to be trusted?


When I installed the gauges, saw that I had low oil pressure, and began to lose my mind, I went out and replaced my mineral 10/40 with Valvoline Synthetic 20/50. The pressure was AMAZING at startup, and resisted dropping pressure ALOT longer than the mineral oil.
In the end though, when the engine was fully warm (110 Celsius) The mineral oil showed 1 Bar @ highway speed, and the Synth showed 1 1/4 bar @ highway speed.

Thanks for any insight.

Jason

Today I removed the pushrod tube shield and used a 15/16" deep socket to remove the oil pressure sender between the push rods on our '86 Syncro.
we cranked over the motor ( with the #15 wire off the coil) and ran a 1/8"npt tap in the oil pressure hole then threaded in a 1/8"npt grease gun flex hose ( with a copper "O" ring just in case).
out to a Tee and remounted the stock sender( we soldered a ground wire to the tee)
out the other Tee end to a mechanical gauge .
I got 53psi cold @ idle and 35psi hot @ idle
the oil pressure runs at 45+ psi at high way speed

tomorrow I'm going to run 5/16" copper line forward and use another flex hose and a 90* to the gauge.

as for your questions

1 not likely any more pressure from replacing the seal
2
3 14 gauge wire
4. The wires can be grounded in the same place just make sure it is clean and tight
5. VDO is a good company and make good products they made a lot of different styles

can you put a Tee in and use a mechanical gauge to check the electrical gauge?
Maybe the VDO sender has a different pressure setting than the stock gauge.

just my 2 cents
have fun
hank

Well...
I grounded the guages to a better spot, and put Valvoline SynPower 20W-50 in there and my oil pressure crisis is less of a fright:

Cold 4.0 Bar=58 psi
Warm idle .5 Bar=7.25 psi
Hwy (3400 RPM) 2.25 Bar=33psi

Not as bad as before when I was getting

cold 3 Bar= 44 psi
warm idle 0 Bar = 0 psi!!!!!!
hwy 1 Bar = 14.5 psi

I guess I grounded the guages to a lousy spot, kinda glad that I did cause it made me finally read something about oil and I went forthe 20/50 synthetic which made a big difference even when I had my gauges grounded to shite!
Stuff is more expensive, but I am convinced for the moment that the Valkvoline SynPower oil is really good for business in my 1.9.

Nice!

Jason L.