Oil pressure reading 0 (but it does have pressure) - Page 2 - PeachParts Mercedes-Benz Forum

pawoSD · #16 09-20-2007, 02:31 PM

Ok...I ordered a VDO sender. I am officially broke now. If autohauz won't refund my broken one this will have cost me $104 to fix.

If they do refund me, only $73

I suppose I should have ordered a VDO in the first place....I was going to....oh well.

pberku · #17 09-20-2007, 08:30 PM

Quote:

Originally Posted by Johnt49

Try removing sender wire & shorting it to ground with key on. If gauge pegs, it's a bad sender. If it doesn't move, bad wiring or gauge.

Actually on these cars its the other way. If OPEN circuit, then gauge pegs at "3". If SHORT circuit then gauge show "0"

pawoSD · #18 09-20-2007, 10:24 PM

Quote:

Originally Posted by pberku

Actually on these cars its the other way. If OPEN circuit, then gauge pegs at "3". If SHORT circuit then gauge show "0"

??

Soo......when I put it to ground it pegged, but when I released the ground it stayed pegged.....turned the key off....it went back to 0....turned key on, stayed at 0. Grounded it, pegged to 3.

Sooo....is something wrong with the gauge or the sender based on that? Shouldn't it have gone back to 0 when I removed the ground?

pberku · #19 09-20-2007, 10:36 PM

Quote:

Originally Posted by pawoSD

??

Soo......when I put it to ground it pegged, but when I released the ground it stayed pegged.....turned the key off....it went back to 0....turned key on, stayed at 0. Grounded it, pegged to 3.

Sooo....is something wrong with the gauge or the sender based on that? Shouldn't it have gone back to 0 when I removed the ground?

From your description of events its not possible (at least for me) to tell what's going on. What I would do, is disconnect the plug at the gauge, and put an Ohmmeter on the wires leading to the sensor. I would then measure the resistance If open circuit then you have either a defective sensor or an open in the wiring.

In that case the gauge would have pegged at "3" If you have a dead short, then either a defective sensor, or a short in the wiring. In that case the gauge would have stayed at "0". If that checks out ok, I would then start the engine and see if the resistance to the sensor fluctuates when you rev the engine. If it does, then that's normal and I would then assume that the problem is with the oil gauge.

pawoSD · #20 09-20-2007, 10:47 PM

Also what I don't get is how it happened. Couple days ago, drove home from work, shut car off, was working fine when I did, next morning, dead gauge. Odd.

Hatterasguy · #21 09-20-2007, 11:13 PM

Quote:

Originally Posted by pawoSD

Ok...I ordered a VDO sender. I am officially broke now. If autohauz won't refund my broken one this will have cost me $104 to fix.

If they do refund me, only $73

I suppose I should have ordered a VDO in the first place....I was going to....oh well.

I replaced mine a few years ago because it was leaking, $80. No sympathy from me!

lietuviai · #22 09-20-2007, 11:46 PM

My 87 300D had an electric oil pressure gauge. I had problems with it too. It would drop to zero sometimes or not function at all or it would work erratically. Replacing the sender did nothing. A good whack to the top of the gauge pod would get it to work normally for a while. My guess you have something faulty with the gauge itself.

warmblood58 · #23 09-21-2007, 01:16 AM

I recall repairing my 0 reading by cleaning and tightening ground connection at number 5 glowplug, try it! It will cost you five minutes!

pawoSD · #24 09-21-2007, 07:36 AM

Quote:

Originally Posted by warmblood58

I recall repairing my 0 reading by cleaning and tightening ground connection at number 5 glowplug, try it! It will cost you five minutes!

What ground connection....the wiring harness in that spot has the wire to the glowplug....then a wire down to the sender, and thats it.

Where's the ground connection?

I guess I'll have to do further diagnosis tomorrow....

I'll check the resistance on the gauge with someone changing the engine speed...etc...

I hope its not the gauge pod.

The strangest part of this whole ordeal is that I replaced the sender first, and it functioned beautifully for over a week, then went dead.

pawoSD · #25 09-22-2007, 12:36 AM

Well, my VDO made in Germany sender came in ONE day. Via UPS ground!

Warehouse is in Ohio....truly amazing. So looks like tomorrow afternoon I get to work on it...hopefully it will be working when I am done.

lietuviai · #26 09-22-2007, 12:44 AM

Good luck!
If that doesn't work, try giving the gauge pod a good smack.

pawoSD · #27 09-22-2007, 09:21 PM

All fixed, it was indeed the sender that went bad. Was giving no reading at all with my tester. Put on the new VDO, fired it up, and sure enough, proper pressure reading. Finally!

From now on I use the good stuff....

Monday I have to send back the dead one, at least I'll get my $31 back....

...minus the shipping.....