My Pressed Druck ! (2 part question)

[Semba]

Hey all.
My "Druck" press gage works fine if all you want to see is the needle at 1 or 5 and all over in between. Is this a wiring short problem, sending unit, or the gage?
2nd part.
My oil level gage does the same thing, all over the place, usually pegged out at the top. I was told to keep the oil level between the two marks on the dipstick, about half way to avoid oil being spit out on the engine and burning? 911 myth?

Gary

[w21055]

The oil level needs to be checked while the car is running and at running temp, if it is between the two marks you are fine. Most of the gauges are suspect when expecting accurate readings.

[billybek]

Check your grounds for your gauges first before replacing parts....
Do a search for oil overfill, interesting things do happen with too much oil..
Welcome to the forum...

[Fritz Peyerl]

One of our local members, which has 2 left hands called few days ago and asked.
"where can I drain some oil out of my C2, I topped up the tank and now I have to much in the tank"
1 hr later he had it on a tow truck to our local dealer for some oil reduction treatment.
$185.00 later he was on his way.

some people don't learn

[Flieger]

"Druck" = Pressure auf Deutsch

"Oel Druck" = Oil Pressure

Druck Press = Pressure in both languages.

Your Pressure Gauge sounds like there is a bad ground. You can easily pull the gauges out of the dash to check the connections on the back for corrosion and properly seated terminals. Also check the fuse block in the front compartment for corrosion and rotate those fussy German style-fuses.

Your pressure sender may have failed, possibly.It is located on the front of the engine next to the thermostat on early cars. This can be hard to get to. On SC and later cars, it is on the rear on the engine near the camshaft chain housings.

You need the pressure gauge. Try to fix it ASAP.


The Oil Tank Level Gauge is not as critical. During normal operation, the reading will fluctuate up and down as the car corners and goes up or down hills. This is just the oil sloshing around in the tank. The reading is also sensitive to engine speed due to the variable flow ratios of the oil scavenge and pressure pumps over the rpm range. The scavenge pump can sometimes scavenge more than the pressure pump needs, causing the oil level to go up.

I use the level gauge as a trend moniter. As long as it generally goes down at higher rpms, up at lower speeds, and is not empty, I think it is good. To check oil quantity, use the dipstick while the car is idling on a level surface. Make sure it is at operating temeperature because hot oil expands and there is a lot of oil in there so the readings can be quite different.

If you think the gauge is faulty, the tank sending unit may be broken. There also is a ground wire from the sender on the top of the tank in the right rear wheel well. This needs a good contact to metal. If your car has been in the shop, this may have been disconnected and forgotten to be re-connected.

Please post your findings and actions.

[ChkbookMechanic]

On the pressure gauge, sometimes the connection to the pressure sensor on the engine by the fan becomes loose and you just need to tighten it.

[Semba]

I will let you know what I find, might take a couple days tho, gotta work..blah,blah,blah. Anyone know of a good outdoor car cover? There are soooooooooooooo many to chose from.

[ruf-porsche]

"Druck" = Pressure auf Deutsch

"Oel Druck" = Oil Pressure

Druck Press = Pressure in both languages.


Press Duck = Similar in taste to Pekin Duck

[Flieger]

Pressed Duck = Entenschnitzel (n.) 1. Duck meat pounded flat, breaded, and pan fried. Often served with Apfel Struedel. 2. What your engine will resemble after loosing oil pressure, overheating, and tearing itself apart under your Buerzel (Ducktail spoiler)

[Semba]

O.K., steering wheel off, gages loose, and I see one thing in commong amongst them all........NOTHING! Can't see anything obvious, loose or otherwise. Which wire(s) are the ground? By the way, speedo does seem to make a scraping? noise relative to speed....not moving, no sound. What do I look for and do now? I really do appreciate everyones help, at least until you get sick of me asking questions about my dream car I know nothing about. It is in gorgeous condition, just has some bugs to be worked out.

[Bill in OKC]

I recently fixed a similar problem - 84 3.2. Everything looked OK so I thought it was the sender and bought a new one. Then the problem of getting the old sender off popped up - my AC compressor bracket limited room to work and the muffler bolts were rusted solid (need to do something about that) - but in the process I found the wire had broken internally right next to the black sender connector. There is some kind of heat-shrink tubing over the wire/connector junction so it felt like the connection was solid. But after working around that area for a while trying to figure out how I was going to get the old sender out the wire came off the connector and from the wire color I could see it had been broken for a long time - just held close enough by the shrink wrap to permit intermittent contact. The connector can be disassembled pretty easy and the old wire removed with a soldering iron - and the good wire end soldered back in. I wish all connectors were serviceable like this one. My druck gauge works fine now I don't know if this helps, but good luck finding the problem.

[ChkbookMechanic]

Originally Posted by Bill in OKC

I found the wire had broken internally right next to the black sender connector. There is some kind of heat-shrink tubing over the wire/connector junction so it felt like the connection was solid. But after working around that area for a while trying to figure out how I was going to get the old sender out the wire came off the connector and from the wire color I could see it had been broken for a long time - just held close enough by the shrink wrap to permit intermittent contact.

It is pretty common for old wires in the engine compartment to break inside the shrink wrap tubing. Luckily, replacing them isn't too hard some new shrink wrap tubing, wire and a soldering gun make it pretty easy.

Tracing the wiring for the pressure sensors isn't too hard either.

[PeterRT]

Eww...
http://en.wikipedia.org/wiki/Pressed_duck

[Won]

Are you saying the pressure guage needle jumps around between 1 and 5 during operation? As long as it's not random, erratic twitches, that's how it's supposed to be. The oil pressure guage numbers should roughly match every 1000RPM of engine speed. Depending on the viscosity and temperature of the oil, you'll probably see higher pressure indicated for a given RPM.

If there was a broken ground connection or a failed sender, then the needle will be pegged at top (beyond 5) and never move. If there is corrosion between connectors it may cause the needle to jump around regardless of RPM.

Same thing with oil level guage, as long as the needle's not pegged or jumping around erratically, it's working fine. The scavenge side does pump more than the pressure side, so you'd expect to see higher oil level in the tank at higher RPM, but actually most of the oil is still sitting in the cam towers, etc. during driving so the level in the tank will in fact go down. That's why you should let the car idle on a level ground until the oil level in the tank stabilizes before reading the level guage, with the engine running. Factory sticker says measure it at 90C (first white tick on the 8 o'clock position on the temp guage, if you look "inside" the guage under the bezel it's actually labeled as well).

It's recommended that you keep the level between upper and lower marks so you have a bit of room for it to expand in case of higher than usual operating temperature (12 liters of oil expands a lot). If overfilled oil will get into the intake via the breather hose and cause the engine to smoke excessively. You can siphon out some oil through the filler tube or open the drain plug just enough in case of overfill, no need to spend $185 at a shop . Underfill can be also bad but only if you're severely low (few liters/quarts) and pulling high Gs (not enough oil gets scavenged). After an oil change you're advised to refill about 9-10 quarts (my car takes 9.5), bring it up to temperature and top off (again, to the mid point) accordingly.

[Semba]

O.K., ripped the dash apart and I should be looking on the other end...LOL So, where do I find this sending unit? Either of them in fact? Both gages just jump around, definitly not working, acts like a short to me anyway. Oil level gage is either pegged out or reading zero despite frequent oil checks with oil level good. With the gages out, how do I know what wire is the ground wire since I have easy access?

[ruf-porsche]

Originally Posted by PeterRT

Eww...
http://en.wikipedia.org/wiki/Pressed_duck

Sound Yum Oh

[Superman]

Originally Posted by PeterRT

Eww...
http://en.wikipedia.org/wiki/Pressed_duck

I should have known better than to click. Ewwww.......

[Bill in OKC]

Originally Posted by Semba

O.K., ripped the dash apart and I should be looking on the other end...LOL So, where do I find this sending unit? Either of them in fact? Both gages just jump around, definitly not working, acts like a short to me anyway. Oil level gage is either pegged out or reading zero despite frequent oil checks with oil level good. With the gages out, how do I know what wire is the ground wire since I have easy access?

The oil level sender is inside the passenger side rear wheel well (outboard of the oil tank). The connectors are exposed to road grime and are probably dirty/corroded. The oil pressure sender (on my '84) is on the engine low between the fan and the a/c compressor bracket. If you have a multimeter and several clip leads for distance you can test for continuity between the senders and the instruments. When I first got my car both gauges acted just like yours. The level problem was dirty connectors (after sorting a poor re-wiring job) and the pressure was the broken wire.

[Flieger]

Originally Posted by Superman

I should have known better than to click. Ewwww.......

Only the French...

[Semba]

O.K., cleaned, replaced, checked and greased all electrical connections to the oil level sending unit and oil pressure sending unit as well as on the dash gages. I still basically have the same problem, so I ordered parts. Thanks for all your help. I am sure I will have a bazillion more questions on other stuff, but I think I may have it once the parts get here next week.