Could this be the last gasp for my 81 300SD? - PeachParts Mercedes-Benz Forum

dcotejr · #1 08-18-2014, 04:35 PM

It's been a while since I have been regularly involved on the forum (due to numerous reasons), but am back again.

It appears that my 81 300SD may be going down for the count. The engine won't shut off and the brakes are not working well at all.

Had a local MB mechanic take a look, and the vac pump is on its way out. I was told that the only option is a new pump at about $450 just for the part, as vac pump rebuild kits were d/c'd about 5 years ago. Obviously would not trust a used unit, unless it were rebuilt...

Surely there must be someone on this forum that could direct me to a rebuilt vac pump or a rebuild kit squirreled away somewhere?

If I can't get this fixed, I will have to sell the car which I have owned for over 17 years.

ichris93 · #2 08-18-2014, 04:42 PM

How many miles are on the car? It could be a vacuum pump or it could be a large vacuum leak.

You've been able to afford to keep the car for 17 years while having a mechanic work on it? wow.

dcotejr · #3 08-18-2014, 04:47 PM

The car has 323K miles. And I used to do most of the work myself. Have had back issues the last few years that have made it very difficult if not impossible to do any more... If I cannot get it repaired reasonably, will be time to go... I have put about 100K miles on the car during my ownership...

ichris93 · #4 08-18-2014, 04:51 PM

Here is the PN for the vacuum pump 000-230-13-65 I suggest searching for a new one. The forums sponsor, Pelican Parts, has one for $452.75.

mach4 · #5 08-18-2014, 04:57 PM

Quote:

Originally Posted by dcotejr

Obviously would not trust a used unit, unless it were rebuilt...

Interesting...you've been running with a used vacuum pump for 17 years and it was 15 years old when you got it.

They're not all that difficult to replace and can be readily sourced at the junk yard, if you have 123s or 126s in the local pick 'n pull. Just check the bearings to make sure they're good.

I'd bet on a vacuum leak more than a failed pump, all things being equal. Disconnect everything and install a vacuum gauge at the pump. You should see 21-24". If that's good, hook up the line to the brake booster and cap the other vacuum lines, you should see the same vacuum as before. If not, you've got a bad brake booster (or main vacuum line leak). If it's good then start investigating your various vacuum components one at a time.

Once you've identified the failed component you can focus on fixing it, not necessarily junking the car.

uberwasser · #6 08-18-2014, 05:01 PM

Before having your mechanic do anything else, I'd suggest doing your best to do some diagnosis of your own with a vacuum gauge. It would take about 60 seconds to see if the output from the pump was actually out of spec.

I have put hands on a half dozen of these over the last few years that wouldn't shut down, had hard brakes, had door locks that didn't work and in each case it was NOT the vacuum pump. That's not to say they don't fail, but I've not seen one yet. However, in several of those cases a mechanic had done "diagnosis" and said replacing the pump was the first course of action they suggested. It's an expensive part, with a good markup, and is easy to install...hmm. Anyway, I worry that if you do decide to bite the bullet and have your mechanic replace it you'll still be in the same position.

In each case it was, instead, a large vacuum leak from something like the door locks.

dcotejr · #7 08-18-2014, 05:06 PM

Mechanic said it was only pulling 2" of vacuum. I have no idea if / when the vac pump has been rebuilt or replaced. Nothing has been done in 17 yrs... I may try to take a look at it, but had surgery last week, so it won't be any time soon...

Skippy · #8 08-18-2014, 05:27 PM

If the mechanic failed to block off the source of the leak, then a perfectly good pump might still only pull 2".

sleepstar · #9 08-18-2014, 05:28 PM

i've found a pump online that is $100 less than what your mechanic quoted. cheaper ones are out there. replacing one is not difficult at all. also note that the check valve on top of the pump could be bad and that is known to cause low vacuum. but honestly if its the original pump, with 323,000 miles on it, it might be time for replacement. the replacement should last another 30 years.

mach4 · #10 08-18-2014, 06:25 PM

Quote:

Originally Posted by dcotejr

... but had surgery last week, so it won't be any time soon...

Well that changes things just a bit...

I'd be inclined to get a second opinion. I'm not necessarily suggesting that your mechanic is not doing a competent job of diagnosis, but but let's just say hypothetically that there was a vacuum leak somewhere easy to fix that was causing the symptoms, replacing the vacuum pump and then fixing the little leak would result in returning to you a repaired car where you would never know the difference...a multi-hundred dollar simple repair vs a few dollars for a line and some time.

Maybe there's a member in your area that might be willing to help out with a quick look see.

gatorblue92 · #11 08-18-2014, 06:38 PM

If you do decide to sell let me know. My brother is looking for a Diesel MB and he lives in Pell City.

dude99 · #12 08-18-2014, 06:47 PM

Hold on here, since when were the Vac pump rebuild kits discontinued? Two of the three sites I just checked show rebuild kits in stock.....

cooljjay · #13 08-18-2014, 07:46 PM

I had a mechanic replace my vacuum pump on my euro, long before I knew much about these cars, it turned out the master cylinder was the issue. He replaced that at cost with out any addition labor charge....I was upset that I spent the monies at first, but then I was like....well I don't have to worry about the pump losing a barring or going south for another 30 years....

That price you quoted is exactly what I paid, he got the pump from the dealer. If that is all your car needs, I would spend it....I mean you've owned it for 17 years, know what has and hasn't been done...I would spring for the coin....to bad you didn't post a few weeks ago, when I was on my trip....I could have picked one up and installed it for you...

Zacharias · #14 08-18-2014, 11:33 PM

The kit seems to be available, but it is called a "repair kit"... if you search for "rebuild kit" nothing seems to return.

The part number for the genuine Mercedes item is 0005861723.

Pelican lists it at $178 or $195 (seems to be duplicate listings).

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I also have chronic back problems and can sympathize with your frustration 110 percent. The way I have got around it is to pay my neighbour by the hour to do the hands on while I supervise and assist. This is a must when my back is acting up, or when the job is going to require extended bending (water pump, for example).

I am 6ft 4ins, so most everything means bending.

Maybe there is someone in your area who will do the work for cash on the side. Just a thought.

BillGrissom · #15 08-18-2014, 11:45 PM

If a 1-tube vacuum pump (piston) like my 84 & 85 300D, rebuild kit is ~$100 on ebay. If the earlier 2-tube pump (rubber diaphragm), a rebuild kit is ~$15. Easy to rebuild once you remove the pump, which is same work if a new pump. Or for $50 (ebay used) you could rig an electric pump from a recent VW or Audi diesel.

Fix the vacuum and your power brakes will again work, then your "brake problems" should disappear like magic.