Druck pressure gauge question

[dgraves]

After recent work by two mechanics on my dash wiring, my Druck Pressure gauge, which worked fine before, now hits 5 on start up and stays put until the key is switched off. Is it my gauge or mis-wiring? The car is a 1976 - 911.
Appreciate the help.
Dan

[Reiver]

Check the ground...that should be the issue..back of the gauge.

[dicklague]

you got too many drucking drucks and it is pinning the gauge. Use some "druck reducer", or drain some Drucks from the gauge.

[Walt Fricke]

Dan - this may be simple. The gauge has three leads which count - power, ground, and signal. The signal wire goes back to the pressure sender at the rear of your engine, just to the right of the fan housing on the oil line going to the right side cam.

If the signal wire is cut/broken/pulled off its spade connector (i.e., is an open circuit), the gauge will peg when power is applied to it. The sender is just a variable resistor, and the more resistance it has (resistance increases as pressure increases the way the gauge is constructed), the higher the gauge reads. An open is infinite resistance, so it pegs.

On my cars the usual problem has been the wire coming off the sender at the engine, but you ought to pull the gauge out of the dash to see if the sender wire is attached.

Look at the wiring diagram Pelican has on its site to find the color code of the signal wire, which might help you. The diagram will also show you what other connections there are as the signal wire travels back to the sender on the engine. It for sure goes through the 14 pin connector back there.

I am assuming you have a 5 bar gauge? I thought the gauges for your year were 10 bar (if they say Druck). It is important that the sender (marked on a side as either 5 or 10 bar or ATU) match the gauge (the face goes form 0 to 5 or 0 to 10 if in bar. A 5 bar sender (which by maybe the SC era was the standard) used with a 10 bar gauge will produce oil pressure readings which appear to be twice what they actually are. But you say yours goes to 5 and never varies, so I assume it is a 5 bar gauge and pegged.

[boyt911sc]

Dan,

Test the continuity @ 14/4 terminals:
Chassis side to pressure gauge terminal (dash).
Engine side to pressure sender terminal (engine).

Tony

[strictly]

go to the engine, take the wire of the oil pressure sender and put it to ground/earth with the ignition on, if the gague drops to 0, replace the sender

if nothing happens, pull the gauge out. On the gauge will be a G, thats the wire above, run an wire from earth/ground to it and if the gauge is now behaving, test continuity on the wire from the gauge to the sender. For a quick check take 10 feet of wire, and do a quick connect.

[dgraves]

I'll give them all a try. Best regards,
Dan

[dicklague]

Originally Posted by dicklague

you got too many drucking drucks and it is pinning the gauge. Use some "druck reducer", or drain some Drucks from the gauge.

I guess my attempt at humor was not humorous!!! h

[DRACO A5OG]

^^^ I chuckled :-) but did not want add salt to OP's wound.

OP +1, check the wiring at the DRUCK sensor, loose or frayed wire under the connector cap, that tends to go bad over time. I had to resolder mine after an AX the wire just broke off and pegged my needle up ( sign of NO GROUND )

[Walt Fricke]

My 2.7 (now a 3.0) was a Euro gray market car, so of course the oil pressure gauge said "Druck." And it was in bar. Are the gauges for cars made for the US market also marked Druck? In bar? Or in PSi? Hard to remember, although our 07 US spec turbo is in bar - the oil pressure sits at a nice 5 bar (top of the gauge) for quite a while before it all warms up and drops some and changes from idle (low) to cruise (much higher). I should remember from when we had a US 3.2, but I don't.

The 2.7/SC's temp gauge has numbers, though they are in centigrade. Bad decision for Porsche to have VDO make those gauges which had no numbers on them. Probably the marketing people said the numbers will scare people, and even Porsche drivers, at least in the US, are too stupid to be persuaded that 190 or 200 degrees F is a fine engine operating temperature. Or that 220 is fine on a hot day.

[Quasimoto]

Originally Posted by strictly

go to the engine, take the wire of the oil pressure sender and put it to ground/earth with the ignition on, if the gague drops to 0, replace the sender

if nothing happens, pull the gauge out. On the gauge will be a G, thats the wire above, run an wire from earth/ground to it and if the gauge is now behaving, test continuity on the wire from the gauge to the sender. For a quick check take 10 feet of wire, and do a quick connect.

Sorry for resurrecting such an old thread, but found this helpful today.

Gauge pegged, broken/bad connection in the boot at the sender. Resoldered and back working now.

Thank you!