Engine oil under the dash 83 300D - PeachParts Mercedes-Benz Forum

ah-kay · #1 06-13-2011, 02:54 PM

Do not notice any oil under the dash since I had the car for 4 years. I pulled the dash for the first time and replaced a burnt out light bulb and after I changed it I notice oil stain just underneath the dash. It is engine oil for sure. I did not pull the dash too harsh or too far out as I have enough room to replace the bulb, so it is unlikely I damaged anything by pulling it.

Once I noticed the oil stain, I check the connection between the pressure gauge and the metal hose and it felt very snug and no oil there. I felt underneath the dash assembly with my hand and there was a bit oil and I cleaned it all with a kitchen towel. I really do not know how the oil get there. My questions are:

1) Is the gauge leaking? If it does, would it keep dripping continuously and in what quantity? I do not notice any dripping oil before.
2) Is it possible it was left behind when the PO changed out the gauge or when the dash had to to come out completely previously.
3) What is the symptom of a leaking gauge? I am planning of pulling the dash slighly out and put a clean kitchen towel underneath to observe it for a few days.

It is my daughter's DD driver in Santa Cruz and want to make sure there is no major issue before I give it back to her.

Your thought is appreciated.

kerry · #2 06-13-2011, 03:02 PM

The other possibility is oil in the vacuum lines from a leaky shut off diaphragm. Any shut down problems with the car recently? Some people put fuel filters in the vacuum lines to stop oil from getting sucked up into the dash area when the shut off diaphragm fails.

ah-kay · #3 06-13-2011, 03:14 PM

Quote:

Originally Posted by kerry

The other possibility is oil in the vacuum lines from a leaky shut off diaphragm. Any shut down problems with the car recently? Some people put fuel filters in the vacuum lines to stop oil from getting sucked up into the dash area when the shut off diaphragm fails.

Thanks.

The car shut down OK without issue. Where and which vacuum line can I put the fuel filter?

kerry · #4 06-13-2011, 03:24 PM

In the brown line going to the shut off diaphragm.

digieditny · #5 06-14-2011, 11:38 AM

Interesting. I have have a leaky dash also (oily left sneaker). I changed the gauge and now I have less of a leak but still a leak. I just thought the gauge was leaking again. Now I'm wondering if it's actually coming from the vacuum line.

Would checking the line in the engine bay be the right way to check?

kerry · #6 06-14-2011, 01:21 PM

Yes, check, the brown line coming from the shut off valve.

layback40 · #7 06-14-2011, 09:02 PM

ah,
If it turns out its not the vac line, it could be a crack in the solder inside the gauge. it happened to me a long time ago.
I pulled the gauges out dismantled the cluster & then pulled the oil pressure gauge to pieces just enough so that I could get a soldering iron onto where the Borden tube is soldered to a fitting, let it all melt & then cool. the crack was gone & never gave trouble again.
Its not that harder job, just very fiddly.

Renntag · #8 06-14-2011, 09:15 PM

I also had a leaky OP gauge. Mine was a leak on the tube on the gauge itself. I replaced with another used gauge.

Disassemble your cluster. Should be pretty easy to tell where oil is coming from. Only two places. Vac or cluster. Clean everything really well, then place a clean paper towel under the cluster and one under the ignition switch (or any suspect area). If the leak persists, you'll have evidence on the towel of where it is coming from. (Worth a try).

If you are married, you might try using old garage towels rather than kitchen towels. I know my wife would be pissed if I took her kitchen towels out to wipe up oil.

ah-kay · #9 06-14-2011, 09:48 PM

Quote:

Originally Posted by Renntag

If you are married, you might try using old garage towels rather than kitchen towels. I know my wife would be pissed if I took her kitchen towels out to wipe up oil.

I meant paper kitchen towels. She would kill me if I use the cloth ones. I will try to confirm a leak first before I decode to re-solder it or get a used/new one.

Thanks for the advices.

charmalu · #10 06-15-2011, 02:17 AM

AH-KAY, this is how I added the vacuum line filters.

http://www.peachparts.com/shopforum/showthread.php?t=265761

I had a oil gauge leak back in 97. think we had the car about 6 months, and I get some black spots on my shoe and pant leg. If it had been leaking right along, I didn`t notice it because of the black carpet.

Took it in to the local MB Indy, and they said the gauge needs to be replaced. OH, ok, so I drop it off..... Pick it up after work and get the bill. $344 for the gauge, plus labor

Yikes.

I was getting my batism in the ownership of a MB.

this is long before I discovered the Forum.

Charlie

ah-kay · #11 06-16-2011, 01:27 PM

I pulled the dash assembly slightly out again last night and I found oil when I wiped the underneath of the assembly. I have not taken the assembly out on the 300D but I did with the 190D. I cannot remember that I need to remove any vacuum lines to pull the assembly out for the 190D.

If I found oil under the dash assembly, not under the dash area or the panel, does it point to leak in the oil gauge?

If the vacuum line is connected to the ignition switch then a leak there should not find its way up in the dash assembly area. Am I correct?

I probably need to pull the dash to take a look but any extra info is appreciated.

ah-kay · #12 06-21-2011, 03:28 PM

Put a paper towel under the dash assembly and see oil stain spreading every time I drive. Pulled the dash assembly out and found the oil gauge was covered in oil.

Clean everything up and screw a rubber tube ( use the vacuum line connector ) into the gauge thread and pull vacuum with a Mityvac. It does not hold vacuum so the gauge has a leak at the solder joint. It is very difficult if not impossible to remove the gauge without ripping temp/tank level/oil gauges apart, so I abandoned the idea of replacing it. Luckily, the solder joint of the Bourdon tube is visible from the outside. I smeared some solder flux around the joint and then blow touch it gingerly. Don't over do it as the tube may come apart. Added some solder to the joint and it looks good.

Re-do the vacuum test and it holds vacuum. It looks like the blow touch does the trick. Put the dash back together and so far so good. I will observe it for a few days to make sure the leak is fixed.

One issue is that the 'Seat belt' light is not coming on anymore. Not sure whether I busted something between removal and installation.

Need to get it taken care of.

ah-kay · #13 06-24-2011, 05:03 PM

I am not sure what is wrong with the gauge. After the blow touch repair, I threaded a connection to the gauge and it held vacuum over night. I thought it was fixed but when I hooked it back up the gauge leaks ever so slightly under pressure. I am running the car with no dash, only the oil gauge to check on the leak.

How can it hold vacuum but leak under pressure? Is there an O-ring inside somewhere? What else can I do to fix it or I just need a new one?

Any suggestions are welcome.

spdrun · #14 06-24-2011, 06:18 PM

Quote:

Originally Posted by ah-kay

One issue is that the 'Seat belt' light is not coming on anymore. Not sure whether I busted something between removal and installation.

Need to get it taken care of.

If you can't remember to put on your belt, then you have more serious problems

I'd count my blessings and be happy the car has one less nag.

ah-kay · #15 06-27-2011, 07:49 PM

Pulled an used oil gauge from JY and replaced the leaky one. It is not as easy as I first thought because the other gauges are soldered onto the PCB board. Basically I need to break the plastic backing to get the old oil gauge out.

Also took a relay ( buzzer/car seat relay ) from the junk car which fixed the car seat warning light. Now all is good. Move on to the next item on the list.

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