About to replace my vacuum pump
 

Anyone out there ever replace the vacuum pump on the 603 ('87 300D turbo) engine? I'm planning to do it this weekend, mine is leaking oil and making me nervous since I've heard these can go bad and take the engine with them. My question is that Phil got me the pump and gasket and I discovered there is another, different gasket that comes packed with the pump. The gasket with the pump is a metal compression gasket that looks like it also will allow the oil to pool up behind it and help lubricate the pump. The gasket from the parts book Phil sent is a typical fiber type that looks like it will make a much better seal than the metal one. My guess is that I'll need to use them both and I'll likely find out when I remove the old pump. If I'm going to need an additional part or gasket I'd love to know that before I tear into this. Phil could only tell me that the book lists one gasket only but that the book has been wrong before. Anyone out there have any experience with this? Thanks.
Randy

By the way, looking at this pump I can see how if it fails it could throw some nasty parts into the engine. Yuckkkkk!

Project completed! For the benefit of those who may need to do this job in the future, I managed to replace my vacuum pump in about 2 hours, and that was going at it slowly and carefully. As mentioned above, I had two gaskets but only used the fiber gasket Phil sent me, not the additional metal one that came with the pump, because the original only had the fiber type installed. The instructions that came with the pump were very good and I was able to make the change without removing the radiator or fan. You need only loosen the fan shroud and completely loosen the drivebelt. The rest is pretty intuitive. My old pump still looked pretty good but was leaking oil from the front so it seemed prudent to replace it. The metal gasket that came with the new pump is "filled in" at the bottom which I think is designed to create a kind of resevoir for oil and help keep the pump lubricated. Based upon the amount of oil leaking out of my old pump it was getting plenty of oil. That plus the fact I got 100K+ miles out of the old pump I guess I'm not too worried about not using the newer design gasket. Also, I was concerned that the metal compression gasket supplied with the new pump wouldn't seal as well. I couldn't find a torque spec for the pump housing bolts but they were not on really tight. If I get another 100K+ miles I'll be happy. Hope this is useful to somebody.

thanks for the writeup
 

I need to get a parts order in, so I will probably get a vac pump for my SDL with 126Kmiles.

The writeup was helpful.

See you around town.

alec (near lake street)

Alec,
Go for it. It's actually kind of a fun job. I used a 1/4" driver mostly because it gave me a bit more room. The hardest part was trying to keep the gasket clean when I put it back together so I wouldn't get an oil leak. It should be pretty much the same job as on my W124.

Randy (Cow Hollow)

My understanding on the gaskets for these pumps (from talking to my mechanic yesterday) was that the metal gasket was the original design, and is superceded by the paper/fiber one. As I understand it, the reason for the change in material was that the (later) thinner gasket allows the piston to travel a bit farther, thereby generating a bit more vacuum than the original one. It sounded reasonable on the surface. Perhaps there is a tech. bulletin that addresses this issue.

He said to make sure to get the paper/fiber one and that you must use a gasket sealant (they use hylomar) to make it seal correctly.

I am planning on doing this job on my 92 300D was investigating the price of this pump at the dealer - list is about $550, but he would sell it to me for about $440. Yikes.

This is the type of part that I would typically purchase from the dealer as this part is going to be on there a long time, but I will see who else can get me this part in the aftermarket.

Anybody know who is the OE supplier for these????

Chris

Hey,

Anyone have more specific directions on changing the pump on the 92 300D 2.5 Turbo? I got a new pump and will be changing it tomorrow. Would also like to not take the fan/radiator apart if possible.

Thanks much!

-m

I'm not sure about later models but my '87 124 didn't require removal of the fan or radiator. The rad shroud got in the way but I found that I could get by just loosening it and moving it aside. I put some cardboard on the inside of the radiator to protect from damaging it. I did need to remove the the serpentine belt but that was an easy matter of just taking pressure off the tensioner and removing the belt. Used a 1/4" wrench since it it smaller and the bolts, at least in my case, were not very tight. The metal gasket I have since discovered is appropriate for the very early OM603 engines that don't have a drilling that sprays oil on the pump (I believe it's engines built prior to late '86 but I may be wrong). The metal gasket has a "dam" that allows oil to collect against the pump. Later engines are fine with the regular fiber gasket without the oil dam. You almost don't need instructions to remove the pump. As I recall there are about 5 bolts around the pump that you unscrew and just remove the pump. (Don't forget to remove the vacuum hoses on top first) The new pump goes right back like the old one came off. Keep the gaskets clean so they seal properly. My biggest PITA was scraping the mating surfaces clean of the old gasket. Try not to let the bits of old gasket get into the engine. When you get the new pump in position snug up the bolts, reassemble the belt and rad shroud and you are done. It's not a hard job, just take your time and keep everything as clean as you can. Good Luck!

What is the Mercedeshop price for the updated vaccum pump?

I have been trying to locate an oil leak on my 91 350SDL ... thought it was the gasket on the bottom access plate on the IP, but after removing a/c compressor (blown bearing on the clutch ...) it looks more like the oil is dripping from the bottom of the pressed on (with "tabs") access plate on the front of the pump ... does this sound like what you guys are seeing on yours that were leaking?

It does not look like the leak is from the gasket area, but it could be ... is there anything in the pump, like a seal that separates engine oil and the access cover that could leak into the access plate area and get to the outside? Is it more likely the gasket (mine is fiber looks like) ...?

Email response would be wonder in addition as I will have Blackberry with me, but won't be able to log back in for awhile.

Thanks!

Me, again ...

I got rid of part of the noise from my 603.970 engine ... replaced A/C compressor and clutch (bearings bad in clutch) ... still have an odd sound that is at about 1/4 the rotation of the engine ...

If the vacuum pump is going bad does it make any noise ... I have a leak that appears to start with drips at the bottom of the (pressed on) access plate on the front of the pump?

My noise is sort of a light, near front of engine, "thud ..tick.. tick" and repeating ... squealing went away with A/C clutch replacement ... does not appear to be coming from other accessories on the belt, like the generator (coming from center or driver side ... listened carefully) or waterpump (relatively new) ... I also replaced the tensioner shock and the tensioner itself about 6 months ago ... all was utterly silent for a month or two, then started getting noises ... approaching 150K so some failures are normal, I guess.

Help!