Ignition failure; vaccuum pump - leaky diaphragm? Is this right or wrong? - Page 3 - PeachParts Mercedes-Benz Forum

Blevinsax · #31 06-03-2007, 02:18 PM

Is the vac line to the shutoff valve the brown line that goes in right where the manual shutoff is? It goes into what looks like a white plastic cap that sits over the manual shutoff. Am I getting closer?

The line that I saw oil in was the line that appears to go to the ALDA, but the brown line doesn't seem to have oil in it - however I could easily be wrong. It just wasn't nearly as obvious as the other line because it was soaked in oil and the cap was falling off because it was so soft and deterioriated with oil. The two lines do merge very close by - about an inch or two back down the vac line.

Blevinsax · #32 06-03-2007, 02:21 PM

Also - just wanted to confirm - am I doing any damage by driving the car like this? I don't want to damage the car, but I do need to drive places today and will need to over the next few days, too.

And if the IP diaphragm is leaking, would that also cause the A/C center vents to fail and divert to the defrost vents, or am I looking at a seperate (and painfully coincidental) problem there?

Blevinsax · #33 06-03-2007, 02:26 PM

Sorry for the onslaught of new replies...

Wanted to add - I just went out and tested the shutoff with the ACC completely off. The car did the same and did not shut off. I know you mentioned that does not completely rule out an ACC problem, but at least I now know that much.

Blevinsax · #34 06-03-2007, 02:36 PM

Quote:

Originally Posted by Brian Carlton

http://www.tooltopia.com/index.asp?PageAction=VIEWPROD&ProdID=8121&ysmchn=BIZ&ysmcpn=Shopzilla&ysmgrp=Shopzilla&ysmtrm=MIT4000&ysmtac=CMP&utm_source=Shopzilla&utm_campaign=Shopzilla&utm_term=MIT4000&utm_medium=CMP

Hey Brian,

Is there any problem with this one?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=39522

I just checked and the local Harbor Freight has them in stock, so I could pick one up today on my way to pick up some WVO. Plus it's a little cheaper than the one you linked above - probably a different model, but would it suffice?

Brian Carlton · #35 06-03-2007, 02:43 PM

Quote:

Originally Posted by Blevinsax

Hey Brian,

Is there any problem with this one?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=39522

I just checked and the local Harbor Freight has them in stock, so I could pick one up today on my way to pick up some WVO. Plus it's a little cheaper than the one you linked above - probably a different model, but would it suffice?

It would suffice, but, it's not a good value. Plastic. No capability of pressure.

You get what you pay for.

See if Harbor Freight has the "Silverline".

Blevinsax · #36 06-03-2007, 03:20 PM

Harbor Freight does not have the silverline, so...

I am on the final order page of tooltopia ready to click "PAY NOW" to order the silverline Mityvac, but since it will take a little while to get here, please help me with this...

Will I do any damage by continuing to drive the car in its current condition while I wait for the Mityvac to be delivered?

Brian Carlton · #37 06-03-2007, 03:22 PM

Quote:

Originally Posted by Blevinsax

Harbor Freight does not have the silverline, so...

I am on the final order page of tooltopia ready to click "PAY NOW" to order the silverline Mityvac, but since it will take a little while to get here, please help me with this...

Will I do any damage by continuing to drive the car in its current condition while I wait for the Mityvac to be delivered?

No, you won't do any damage.

Blevinsax · #38 06-04-2007, 01:43 AM

Quote:

Originally Posted by Brian Carlton

No, you won't do any damage.

Thanks Brian - I drove it all day today and it seems no worse for wear.

Now I need to know which vacuum line goes to the IP shutoff valve - I have put a couple arrows on this photo to ask if this is it. It is partially obscured by that seemingly unused bracket (what is that, anyway? Can I remove it?) but I have put one arrow on the right showing the vacuum line itself, and another on the left showing its final destination (it curves down behind that bracket.) Is that the line going to the IP shutoff valve? I thought perhaps it is since the white cap that it goes into is directly above the manual shutoff lever.

If I am wrong, please let me know - and please try to tell me which one is the correct vacuum line.

Thanks to all for helping me get to the bottom of this!

Blevinsax · #39 06-06-2007, 09:52 PM

I picked up the car this afternoon and everything is fixed. My mechanic replaced the alternator (new 80 amp) and repaired all ALL the vacuum leaks. The car drives GREAT now - the transmission shifts super-smooth, the A/C works perfectly, and it shuts off instantly with the key. And he only charged me $490! This guy is great - he isn't a diesel expert, but he knows how to get in the and figure out what is wrong! Needless to say, I am thrilled and will enjoy driving the car again starting TONIGHT!! Hurray!!

Brian Carlton · #40 06-07-2007, 12:37 AM

Quote:

Originally Posted by Blevinsax

- the transmission shifts super-smooth, the A/C works perfectly, and it shuts off instantly with the key.

What did he repair on the vacuum system?

Hopster · #41 06-07-2007, 01:59 PM

Hey guys, i've been following this thread because i have been having the same issue with my 1985 Mercedes 300D. So I decided to join the forum. Just wanted to say thanks for all of the useful info.

Blevinsax - please explain what your mechanic fixed.

Thanks

arew264 · #42 06-07-2007, 03:47 PM

On a 300D I can help you

If you look from the driver's side of the car, with the hood open, you can see where the vacuum lines are forking off from the main line.
The main line is the large white semitransparent plastic line going from the vacuum pump (in the front of the compartment) to the brake booster (at the back)
You will see about halfway down where the lines first for engine components (most importantly the tranny) and then for accessories branch off.

You can tell the accessory line from the engine line because the accessory line splits into color coded lines, and you will see a check valve where it splits.

Okay, those are the main vacuum lines, and the general layout.

If you look at the four way connector where the accessories split, there is a brown line that goes back through the firewall and to the ignition switch. With the car on, this should hold vacuum (you do have a vacuum tester, right?)
You will see another brown line that comes out from the firewall and hooks into a nipple on the back of the IP. It's hooking into your shutoff. With that aforementioned vacuum tester, connect to this line, start the car, and pull a vacuum. The car should stop about the instant you get above 10 inches of vacuum. It should be obvious whether the actual shutoff pod is the problem.

One word of warning: if it turns out to be the shutoff pod not working, SEARCH THE FORUM BEFORE YOU TRY TO DO ANYTHING OTHER THAN TEST IT!!!!!!
If you remove it and reinstall it incorrectly, you will end up with a condition known as "runaway diesel" and you will lose your engine if you aren't prepared. The way it intuitively goes on is not the right way, so search first.

Blevinsax · #43 06-07-2007, 06:58 PM

My mechanic tested the vacuum pump and the ignition valve with a vacuum tester and both worked fine, so fortunately neither of them were bad. He went through and cleaned out all the contamination in the vacuum lines between the ignition, brake booster, and injection pump - they were very dirty, but now are clean and the car runs perfectly. It's amazing how much better the transmission shifts with all that junk out of the vacuum lines.

As for where the black oil came from that we found when this all started - I don't know where it came from and neither did my mechanic. As I mentioned, he tested the ignition valve with a tester and the vacuum pump is fine, too - so perhaps the oil built up some time ago and finally made its up to the ignition valve and blocked things off.

I'm just thankful that it is running much better now - but I will certainly be paying attention to see if any of the symptoms start to return. Thanks for all your help getting this resolved!