What in particular causes vacuum pump failure? - PeachParts Mercedes-Benz Forum

Stevo · #1 08-05-2012, 12:19 PM

Yah, its an automatic that was owned by a woman in my neighborhood. She drove home from work, parked in front of the house, heard a buzzing sound coming from under the dash. She came out next morning and it must have looked to her like someone had come during the night and tinted the windows. I guess the lesson is DONT IGNORE STRANGE NOISES.

pgringo · #2 04-12-2013, 09:46 PM

what vac output should a om617 have? my pump is cranking about 8 inches of vac.

Diesel911 · #3 04-12-2013, 11:53 PM

Quote:

Originally Posted by pgringo

what vac output should a om617 have? my pump is cranking about 8 inches of vac.

A good Vacuum Pump should put out 22-24 in Hg.

I don't think My Vacuum was that Low but I was having Hard breaking. And I removed and sprayed out the Vacuum Pump Check Valve that is right under where the Main Line Attaches to the Vacuum Pump and it restored My Vacuum.

Some have found the internal parts of the Check Valve Broken or even missing.

Don't use Brake Cleaner as part of the Valve is Plastic and the Brake Cleaner may soften the Valve.

This is a barrowed pic. All of the parts you see are not supposed to be loose like they are. They are supposed to be inside of the vlave.

vstech · #4 04-13-2013, 06:34 AM

Quote:

Originally Posted by pgringo

what vac output should a om617 have? my pump is cranking about 8 inches of vac.

I would not start your car again until you have pulled the vacuum pump and inspected it.
mine started having low vacuum, and then it took out the chain at 40mph...
pull the pump and inspect it. also inspect the pump cam ramp that drives the pump for wear, also measure any play in the timing device the ramp is mounted to. if all checks out, then put it back together, and find your vacuum leak. 8 is far too low.

barry12345 · #5 04-13-2013, 11:03 AM

A few random thoughts. I see no reason the end play of the ramp component cannot be checked with the chain on. Using a dial gauge.

Also never having a 603 type pump apart but looking at a picture. Could not the bearing shaft be pressed out and an open bearing just replaced with a caged or sealed one? Should be far less than 15.00 for a decent one at a bearing supply place. The shaft diameter is critical but a small outside diameter diferance not so much if this turns out to be a real oddball size. I doubt it would though.

Just from the posted picture unless I am missing something the bearing change looks doable. If this is true the choice of a replacement bearing must be considered.

Also does lifespan of the pump depend partially on vaccum leaks? The pump would experience more work and wear possibly with vacuum leaks. I
posted this last item a long time ago as a possible good reason to get rid of vacuum leaks besides the operational considerations of having them.

There must be some reason people have not been changing the bearing out. Perhaps just because after failure it is not possible usually and the mind is preoccupied with the damage.

Pre emtive strikes are another thing though. I could see people missing that. The swiveling yoke could be rebushed if there is enough meat to do it as well. I suspect it has no bushings but again have not looked at them. If bushed again a bearing supply house should have suitable replacements if required. In otherwords is an at home pre emptive partial rebuild of the parts that may cause serious issues possible? The 603 pump is far from cheap new.

glenlloyd · #6 07-05-2013, 01:25 PM

Quote:

Originally Posted by barry12345

A few random thoughts. I see no reason the end play of the ramp component cannot be checked with the chain on. Using a dial gauge.

Also never having a 603 type pump apart but looking at a picture. Could not the bearing shaft be pressed out and an open bearing just replaced with a caged or sealed one? Should be far less than 15.00 for a decent one at a bearing supply place. The shaft diameter is critical but a small outside diameter diferance not so much if this turns out to be a real oddball size. I doubt it would though.

Just from the posted picture unless I am missing something the bearing change looks doable. If this is true the choice of a replacement bearing must be considered.

Also does lifespan of the pump depend partially on vaccum leaks? The pump would experience more work and wear possibly with vacuum leaks. I
posted this last item a long time ago as a possible good reason to get rid of vacuum leaks besides the operational considerations of having them.

There must be some reason people have not been changing the bearing out. Perhaps just because after failure it is not possible usually and the mind is preoccupied with the damage.

Pre emtive strikes are another thing though. I could see people missing that. The swiveling yoke could be rebushed if there is enough meat to do it as well. I suspect it has no bushings but again have not looked at them. If bushed again a bearing supply house should have suitable replacements if required. In otherwords is an at home pre emptive partial rebuild of the parts that may cause serious issues possible? The 603 pump is far from cheap new.

There is a third design to the OM603 VP that is not shown. I would classify it as intermediate because it incorporates the cage and setup of the early design with sealed bearings.

The pump I have built this way is Pierburg but unfortunately I haven't taken a photograph of it yet. It was a replacement on an 87 SDL.

Stevo · #7 07-05-2013, 04:25 PM

So they went back to a diaphragm pump then, after using the piston type in the "later" 123? I like the diaphragm one better as the rebuild is a lot cheaper and easier.