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'99 Range Rover ~ '01 Land Rover ~ '06 Mercedes e350 ~ '76 Mercedes 280C
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Discussion Starter #1
I'm considering buy a neighbors '95 E300 diesel. It's a very nice car, higher mileage at 270k but well taken care of. The most recent repair was an injector service, intake gasket,etc....

Last Friday night he was traveling 70+ MPH and when he went to hit the brakes, they were very hard. He noticed the RPM's dropping and got it off the road. It still ran but barely and would not shut off. He attempted to move forward and it had little power and little throttle response and the trans was shifting poorly.

I know all these symptoms are vacuum related but I'm concerned just how involved it might be. I've looked up vacuum pumps but I only find the electric ones for under the rear seat that control the central locks.

What should I look for? He's just ready to get rid of it, said he's spent enough and would take $2000 for it. Can someone give me an idea of where to start looking into the vacuum?

Thanks!
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,667 Posts
Check the brake booster vacuum line. It is a large, black line that goes from the brake booster to the manifold. Over time, they become hard and brittle. The line also contains a check valve that goes. Not expensive ($50-$60) and very, very easy to change.

Good Luck,

Jayare
 

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'99 Range Rover ~ '01 Land Rover ~ '06 Mercedes e350 ~ '76 Mercedes 280C
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Discussion Starter #3
Thanks! I did check the brake booster vac line yesterday. I removed the smaller line at the T and checked for vacuum and there is none. Since he very recently had the manifold off to service the injectors and glow plugs I'm thinking it could just be a connection under there. I guess for $2000 I'll roll the dice and see if I can get it going.
 

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1996 e300 diesel 127,000
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9 Posts
Just so you know if you do not already , diesels make no vacum, they have pump , your madel has it on front of engine by injector pump , disconect there see if any vacum,
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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Sounds like the vanes in the vacuum pump have failed. I'm not sure if the OM606 pumps are rebuildable like the vane pumps used in VWs...but, they're really expensive
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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OM606 vacuum pumps are NOT rebuildable like the old OM617 or OM616 series. If the pump is known to be bad, replace with a new unit despite the cost.

A failed vacuum pump can cause the timing chain to break instantly, which is usually a fatal issue for the car and way more expensive than a new vacuum pump.
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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The failure mode should be significantly different than earlier versions, since rather than having a ramp and roller drive, the OM606 pump is driven straight off of the injection timer. The failure to make vacuum no doubt is due to the vanes wearing out inside the sealed mechanism. Here's the pump off of my OM606 turbo:

 

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'99 Range Rover ~ '01 Land Rover ~ '06 Mercedes e350 ~ '76 Mercedes 280C
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Discussion Starter #8
Thanks for the info guys. I've been dealing with this huge wildfire issue here in Myrtle Beach for the past couple days and have been unable to get away to further evaluate the E300 prior to purchase. I've done some research too and have come to the conclusion that the vacuum pump is likely the issue. I've seen prices from $175 to right at $300 for a new vacuum pump so it's not an expensive repair at all. I'm certain with the vacuum pump replaced [or if it's a line disconnected], the car will run and perform fine. All the current issues relate to vacuum. I've called him and expressed my intentions to purchase and he completely understands the circumstances at current with the wildfires. We're in no danger unless it refuels itself and the winds push the flames westward but there's dense smoke everywhere. I appreciate the info!
 

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W210
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OM606 vacuum pumps are NOT rebuildable like the old OM617 or OM616 series. If the pump is known to be bad, replace with a new unit despite the cost.

A failed vacuum pump can cause the timing chain to break instantly, which is usually a fatal issue for the car and way more expensive than a new vacuum pump.
Make sure you understand this. It happened to me! I had bought a brand new remanufactured engine for my 70 300D and didn't know that I had to use a brand new pump and so the shop installed the old pump. 4000 miles later my vacuum pump broke and some parts went into the engine and broke the chain which totally killed the engine. The warranty didn't help and it was voided. I cost me $6,000+ . I ended up selling the car for $500. This was back in 1995. A vacuum issue isn't just a vacuum issue. It can be a very expensive issue. I don't know if this also applies to the 95 model but if there are parts that have gone into the engine, then I believe the only way to make sure is to tear the engine apart and check if I'm not mistaken. Fixing it without knowing if any pieces have been sucked in would be like playing Russian Roulette. You could put the vacuum pump back on and within 2 miles you could have a catastrophic engine failure.
Tell the owner of the car this. With almost 300K miles and the car not running, it is not worth $2000 IMO. Get it to $1000, and spend the other thousand to have some professional make sure it doesn't have any parts of the vacuum pump in it.
I would walk away from it. Remember, a cheap Mercedes is actually the most expensive Mercedes.
Secondly, without this problem fixed, you can't really take it out for spin and test drive it. You also can't take his word for it that "it drives great." What be be "great" for him according to his standards, may actually suck.;)
Most importantly, if he does not have documentation on the head gasket every having been replace or the wiring harness, then offer him $500 if you must buy it, otherwise walk away!
 

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Would a faulty vacuum pump also case the engine to run/idle roughly?
No, but a faulty vacuum shutoff valve could inhibit fuel flow at idle. Another prime candidate would be leaky fuel delivery valves on the injection pump.
 

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No, but a faulty vacuum shutoff valve could inhibit fuel flow at idle. Another prime candidate would be leaky fuel delivery valves on the injection pump.
Ok, I understand sort off but now I'm confused also.:D If there was a faulty vacuum pump giving you zero vacuum, would it also affect the vacuum shutoff valve inhibiting fuel flow at idle?:confused: If there is no vacuum production to begin with.............:confused:

Also Z, my above post regarding catastrophic vacuum pump failure like the kind I had with my 79 300D which broke the timing chain and killed the engine; could this also happen with the 606 engine or is the vacuum pump much safer in these to prevent such engine failures?
 

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Ok, I understand sort off but now I'm confused also.:D If there was a faulty vacuum pump giving you zero vacuum, would it also affect the vacuum shutoff valve inhibiting fuel flow at idle?:confused: If there is no vacuum production to begin with.............:confused:

Also Z, my above post regarding catastrophic vacuum pump failure like the kind I had with my 79 300D which broke the timing chain and killed the engine; could this also happen with the 606 engine or is the vacuum pump much safer in these to prevent such engine failures?
If there's zero vacuum, the engine wouldn't shut off via the ignition switch--just the opposite of what you described...and the brake pedal would be hard as rocks.

The OM606 pump shouldn't be prone to those catastrophic failures, 'cause the pump mechanism is entirely enclosed, unlike the early models. I had a pump mechanically fail on my '73 220D, but luckily it didn't take out the timing chain.
 

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If there's zero vacuum, the engine wouldn't shut off via the ignition switch--just the opposite of what you described...and the brake pedal would be hard as rocks.

The OM606 pump shouldn't be prone to those catastrophic failures, 'cause the pump mechanism is entirely enclosed, unlike the early models. I had a pump mechanically fail on my '73 220D, but luckily it didn't take out the timing chain.
Thanks, I understand. So with no vacuum, the engine would still idle perfectly, right?
Now what if all the above happened as said in the original post and the guy states that after this event the engine is idling rough and that it ran fine before? This rough idling couldn't be due to vacuum leak/failure, right? Must be something else?
 

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Well, I think the early 606 engines used vacuum for the intake cross-over flaps and other emissions related gadgets, so it's conceivable that those items could be detrimentally impacted. I honestly don't know that much about the non-turbo versions of the engine, so that's all I have to work with.
 

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Well, I think the early 606 engines used vacuum for the intake cross-over flaps and other emissions related gadgets, so it's conceivable that those items could be detrimentally impacted. I honestly don't know that much about the non-turbo versions of the engine, so that's all I have to work with.
Thanks Z, I appreciate your help:)
 

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In the '95 E300D...is there any trick to getting the vacuum pump cover off? I removed the four bolts and attempted to pry the cover off. Any pointers?
 

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The cover is not intended to be removed. You need to remove the entire pump from the engine for an inspection.

And just for the record, my earlier posts were in error. The OM606 engine in question uses the same diaphram-type pump as the other 124 diesels. It's the later 606 engines found in the 210 chassis that have the vane-type pumps.
 

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The cover is not intended to be removed. You need to remove the entire pump from the engine for an inspection.

And just for the record, my earlier posts were in error. The OM606 engine in question uses the same diaphram-type pump as the other 124 diesels. It's the later 606 engines found in the 210 chassis that have the vane-type pumps.
Ah...that solves that then.:surrender: Thank you.
 

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230te
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vacuum pump

Is it enough to test the vacuum from the pump by pulling a pipe and putting a finger over the hole?

With my 300d OM606 engine running and the pipe removed from the pump I cannot feel any suck at all.
the barkes are hard, engine will not turn off at the key and auto shifts are violent.
All these effects happened suddenly on heavy traffic so something broke.

I am off outside to try to fix it now.
ill be asking;
Can you remove the pump with the radiator in place.
Is the pump available outside the Mercedes franchisers?
 
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