where should one look at for this stamp?

Front side of the pump, on the lower portion. It is difficult to read with the pump on the car, and may be hidden behind years of dirt/grease/crud that must be cleaned off first.

:scooter:

I replaced the pump like 2 years ago, I saved the blown up pump as a testament to my car surviving. I need to dig it up. It is the earlier pump, it is a flat cover.

Failure seems to be random, I wonder if it has to do with how hard the pump is worked....like a lot of braking/city driving or vacuum usage/leaks vs. all freeway with a non-leaking system. My 601 has 232k and the pump I removed "seems" to be in perfect shape....but who knows...it was an original from '84. I much prefer having the new one with closed bearings installed!

How many miles were showing on the car on the one the pump came apart in?

Answer
 

235000 miles.



.

You guys are scaring me, my 300D 2.5 has 270,000 on the original pump.

You know the path to peace of mind, grasshopper :)

Sixto
87 300D

I think I'd be replacing it soon unless you like taking chances. :eek:

I take it you're a gamblin' man.

:chinese2:

I swapped mine out at around 230k. The plastic bearing cage was still in one piece, but you just cannot chance it with these engines.

Scary stuff. Perhaps I should step up my efforts to fit these two Pierburg pumps onto my 602. Electric vacuum with built in redundancy, and no internal grenading.

https://lh5.googleusercontent.com/-b...0/DSCN1822.JPG

No Im not a gambling man, just have no money. But I guess I should be looking for one.

Pretty sure Jeemu and others overseas with huge hp 60X cars run electronic vacuum pumps, I remember seeing the block off plate on his car. Might be worth sending him a PM or getting on hevosoima and having a look around.

Much ado about vacuum
 

I just replaced the vacuum pump on my '96 E300; the original had 193,000 miles, a date code of 1994, Torx screws on the cover and an enclosed bearing inside, and in appearance was perfect (but who knows?). My '96 E300 also has its original vacuum pump at 285,000 miles. I plan to replace it this year as a precaution.

As to the wear question, I don't think driving style affects the pump but probably, like all things with moving parts, it is sensitive to how clean the oil is. There's probably a random factor having to do with manufacturing tolerances and whether the bearing was made on a "good" day at the bearing factory.

It's a pity the forum can't hire a lab to do failure analysis on some "exploded" vacuum pumps. It would be interesting to learn what fails and why.

Jeremy