Oil under the Dash - PeachParts Mercedes-Benz Forum

bigfredb · #1 06-16-2009, 12:49 PM

Recently, my '83 300SD hasn't been able to be shut down using the key. I have to open the hood and press the 'STOP' lever, then it shuts down no problem.

I figure it is a vacuum problem, but I am having problems finding the source. While checking under the dash, I found quite a bit of oil near the ignition key area. I couldn't see up there too well.

Is this 'normal'? Should I be worried?

Any hints on what the problem might be? How to fix it?

Any help would be appreciated.

DeliveryValve · #2 06-16-2009, 12:57 PM

Most likely your shut off valve at the IP has a torn diaphragm and is sending oil into the vacuum lines which one of the lines vent out to under the dash.

See link for repair.

http://www.dieselgiant.com/repairyourshutoffvalve.htm

toomany MBZ · #3 06-16-2009, 01:53 PM

I had the same issue with my SD. Replace the shut off valve. You'll need two paper gaskets that sandwich a metal one.
The DG instructions are more than what I did. You will need to get some things out of the way, but not anything on the booster vac line, at least I didn't.

rcounts · #4 06-17-2009, 01:04 AM

Your oil under the dash is probably due to a leaking oil pressure guage line or fitting. the fitting can be screwed all the way in by hand and it will still leak a little. It has to be tightened with a 10mm wrench to keep it from leaking - don't ask how I know...

H-townbenzoboy · #5 06-17-2009, 01:40 AM

Quote:

Originally Posted by rcounts

Your oil under the dash is probably due to a leaking oil pressure guage line or fitting. the fitting can be screwed all the way in by hand and it will still leak a little. It has to be tightened with a 10mm wrench to keep it from leaking - don't ask how I know...

This won't apply to this case. W126s have electric oil pressure gauges.

rcounts · #6 06-17-2009, 01:49 AM

Quote:

Originally Posted by H-townbenzoboy

This won't apply to this case. W126s have electric oil pressure gauges.

Even as early as '83?

shadetreemechan · #7 06-17-2009, 08:23 AM

I think all 126's had electronic guages. My 84 certainly does.

toomany MBZ · #8 06-17-2009, 08:23 AM

Quote:

Originally Posted by rcounts

Even as early as '83?

Yes.
I pulled this cluster from the JY, a close up of the date stamp on the plate with the multi pin connector.

brihawaii · #9 06-24-2009, 06:00 PM

[QUOTE=DeliveryValve;2225749]Most likely your shut off valve at the IP has a torn diaphragm and is sending oil into the vacuum lines which one of the lines vent out to under the dash.

I also have a leak under the dash. ('83 300D)
It doesn't seem to be near the pressure gauge line,
more to the right, above the accelerator pedal.
She shuts down fine.
Could it still be the shut off valve?
Also, the oil seems sticky, not like engine oil, to me.
I'm thinking it may be the refrigerant.
though I have no experience with that.
Is there a connection that might leak under there?
The AC was charged about 2 years ago
but it hasn't been working lately.
Is the refrigerant oil kind of thick and sticky?

thanks,
Bri

toomany MBZ · #10 06-25-2009, 08:25 AM

I don't know if refrigerant is routed that far. Check inside the brown vac line for oil. My car had more oil than I thought for the period of time the valve had failed, which leads me to believe there can be oil in it for some time.

volosong · #11 06-25-2009, 10:16 AM

Quote:

Originally Posted by rcounts

Your oil under the dash is probably due to a leaking oil pressure guage line or fitting. the fitting can be screwed all the way in by hand and it will still leak a little. It has to be tightened with a 10mm wrench to keep it from leaking - don't ask how I know...

I know it is not directly applicable to the point in question, but for other who are reading this thread...and as concerns a '80 240D...

I had leaking oil from under the instrument cluster on my '80 240D and it was indeed a leaking oil pressure gauge (or fitting). Been a long, long time ago and not sure if the gauge was just tightened or replaced, but after repair, no more leaks. Trashed the carpet pretty good, and got all over the shoes I wore while driving.

Renntag · #12 09-04-2009, 11:14 AM

Quote:

Originally Posted by volosong

I know it is not directly applicable to the point in question, but for other who are reading this thread..... I had leaking oil from under the instrument cluster... it was indeed a leaking oil pressure gauge ...

My '83 300TDT started to have the appearance of "darkening of the idiot lights" at the lower portion of the gauges. A busy schedule kept me from investigating. Fast forward another week and oil started to seep from the gauge cluster over the dash pad below the gauges and onto the steering column. I drove for a few days swapping paper towels strategically placed to mop up the ensuing mess.

Removing the lower panel, I found the insulation soaked with oil, I removed the gauges and noticed the oil line was tight and not leaking. Removing the cluster from the car and disassembling it, I found the trio of gauges with the Oil pressure gauge, covered in oil. The oil clearly was leaking from the gauge assembly itself. I had suspected the line attachment to the cluster.

I wanted to remove it from the cluster to look into replacement, but there appears to be no way to separate the trio. The 2 electric gauges are soldered to the board, thus not allowing access to the OP gauge.

In order to drive the car home from the shop, I cut a piece of Nitrile glove, stuck it in the oil port on the back of the gauge, and reinstalled the oil line.

Testing for leaks prior to final install of the gauges, it appeared all was ok.

The 1.5 hour drive home was without seepage. (no awful side effects...LOL). ...Well other than the death indicator of "0" bar.

Now moving on....is it cost effective to replace this gauge? Do I get another used assembly? I have no problem adding an aftermarket gauge as I wish to monitor Boost and EGT anyway. (those gauges not installed yet).

Any help/ suggestions would be greatly appreciated.

Jeremy5848 · #13 09-04-2009, 11:28 AM

I would replace the 3-gauge part of the instrument cluster from a similar car in a junkyard. If you don't have such access, there are people here who do. It would not be expensive, junkyards don't charge much for such things. An external oil pressure gauge would also work.

marybeth · #14 09-04-2009, 03:00 PM

X2 on oil pressure guage in dash.

I had a 1985 300D for sale.
A 16 year old wished to buy the 300D. The 300D was my wifes car and she treated it like a baby, clean and maybe drove 4K miles a year.

The lad did a test drive and liked the car. He promised to come back with Dad & Grandpa for final approval. That night I noticed one of the dash instrument lights was dead-so I pulled the instrument panel and replaced the bulb. BUT I had not tightened the oil pressure line to the instrument guage tight enough.

Next day the lad came back with Dad and Grandpa who took turns driving the 300D. They liked the car, we haggled on a price and they were off to the bank when both Dad & Grandpa noticed both their right shoes were soaked in motor oil (as was the drivers mat).

Despite my assurences it was just a lose oil line, and them watch me tighten the oil line-the group left never to return..

meltedpanda · #15 09-04-2009, 03:33 PM

i have a brand new pulloff ( shut off valve ) if you want to make an offer , I think they are pretty pricey\

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