Idiot Q on OM617 Vacuum Pump - PeachParts Mercedes-Benz Forum

koldstart · #1 12-08-2014, 05:27 PM

I'm looking in to retrofit a OM617 into something that does not use the typical vacuum assisted brakes. I'd still like to use vacuum to shut off the car so I don't want to eliminate the pump. I'm not sure what the best way to go about putting a system together so I can still use a electronic valve to open and shut off the engine.

I'm not sure if I should run a filter on the end of the hose coming off the vacuum pump, or run it to some kind of a canister reservoir to hold vacuum.. But I'm not sure how the pump operates... would it stress it if I plumbed the pump to a closed reservoir and used it for holding enough vacuum to shut the car off. Would this cause it to pull too much vacuum and collaspe the hoses, or does the vacuum pump have way to "releif itsself" once a certain vacuum measurement is reached?

leathermang · #2 12-08-2014, 05:37 PM

Some of these cars use an electrical pump ..... I think .... to produce vacuum.... have you checked that out ?

Why are you trying to take the vacuum out of the brake system ?

koldstart · #3 12-08-2014, 05:50 PM

I haven't looked into using a electrical pump yet, I guess it would be an option, I was hoping not to have to.

Im not wanting to take the vacuum system away from the brakes, its more so that the car I'm looking to transplant into does not use a booster. I'm just wondering how to deal with only needing a small bit of vacuum that the pump produces. I don't know or understand the principals behind the booster in conventional.. if the diaphragm fills and then bleeds? or if the pump reaches a certain vacuum and holds it stead (at whatever vacuum its designed for)

I just don't want to suck anything into the pump

leathermang · #4 12-08-2014, 05:54 PM

You are thinking and worried that you will have too much vacuum when you have a car which does not need vacuum for the brake booster system ?

engatwork · #5 12-08-2014, 05:58 PM

interzonearts · #6 12-08-2014, 05:59 PM

i ended up getting rid of the vacuum pump, got a nice stainless steel syringe instead.

koldstart · #7 12-08-2014, 06:05 PM

Im not afraid to admit I just don't understand the theory of how the vacuum pump and booster system work in a normal relationship. So thank you for your patience. If I was to take the one and only line coming off my vacuum pump, and plumb in a small closed reservoir, would there be any ill effects on the pump?

I guess what I'm saying is I can see the reservoir filling with vacuum, but at some point, it will be full and as the engine runs will still produce vacuum. Would that reservoir need to have a implement that would allow it to vent at a certain vacuum pressure, or, will the vacuum pump just relieve itself keeping a constant pressure inside the reservoir?

I know Im not explaining this clearly, could one plug the vacuum port off the pump completely and suffer no consequence?

koldstart · #8 12-08-2014, 06:07 PM

Quote:

Originally Posted by interzonearts

i ended up getting rid of the vacuum pump, got a nice stainless steel syringe instead.

I've seen it done, and is effective, I was just hoping to make this a factory as possible swap. Considering all options though

leathermang · #9 12-08-2014, 06:14 PM

Quote:

Originally Posted by koldstart

Im not afraid to admit I just don't understand the theory of how the vacuum pump and booster system work in a normal relationship. So thank you for your patience. If I was to take the one and only line coming off my vacuum pump, and plumb in a small closed reservoir, would there be any ill effects on the pump?

I guess what I'm saying is I can see the reservoir filling with vacuum, but at some point, it will be full and as the engine runs will still produce vacuum. Would that reservoir need to have a implement that would allow it to vent at a certain vacuum pressure, or, will the vacuum pump just relieve itself keeping a constant pressure inside the reservoir?

I know Im not explaining this clearly, could one plug the vacuum port off the pump completely and suffer no consequence?

Our cars have a nice strong vacuum reservoir .. made of plastic... you need something strong or you get one of those science lab demonstrations of the power of ambient air pressure.... 14.7 lbs per square inch can mash a lot of things....
I do not think you have to worry ... the system will only ' pull' a certain amount of vacuum .... It will not pull one of your door locking mechanisms into the engine compartment...
I am still worried about the car you are ' going to'.... does it have disc brakes ? Only old fashioned drum brakes are ' self energizing' ... if you have discs you need the extra boost ....

engatwork · #10 12-08-2014, 06:16 PM

You could put a pipe with a manual valve on the vacuum line coming off the pump, shut the valve and run the pump as long as you want and it won't hurt the "vacuum side" of the vacuum pump.

uberwasser · #11 12-08-2014, 06:19 PM

Quote:

Originally Posted by koldstart

Im not afraid to admit I just don't understand the theory of how the vacuum pump and booster system work in a normal relationship. So thank you for your patience. If I was to take the one and only line coming off my vacuum pump, and plumb in a small closed reservoir, would there be any ill effects on the pump?

I guess what I'm saying is I can see the reservoir filling with vacuum, but at some point, it will be full and as the engine runs will still produce vacuum. Would that reservoir need to have a implement that would allow it to vent at a certain vacuum pressure, or, will the vacuum pump just relieve itself keeping a constant pressure inside the reservoir?

I know Im not explaining this clearly, could one plug the vacuum port off the pump completely and suffer no consequence?

While I don't think it would be an issue, you could consider installing a small "vent" line that would allow the pump to continue to "suck" once the reservoir is full. Put a particular filter on that to keep junk from getting sucked in to the vacuum pump. Then you can install a check valve to prevent air from getting in to the reservoir, similar to how the door lock system reservoir on a W123 has a check valve to keep it under vacuum even after turning the car off.

koldstart · #12 12-08-2014, 06:29 PM

The car uses a hydraulic pump for assisting the brakes, it does not use vacuum. I would likely use a plastic reservoir you are talking about for holding the small vacuum needed to stop the engine. I just wanted to be sure that the vacuum pump would not be working against the reservoir trying to pull and pull more air from a closed system. I don't know if it needs to vent or if it regulates itself internally. (ie if the pump operates normally at 22hg, would it maintain itself at 22hg until the engine is stopped or reservoir is evacuated, or will that 22hg compound itself and compound itself?)

koldstart · #13 12-08-2014, 06:40 PM

Quote:

Originally Posted by engatwork

You could put a pipe with a manual valve on the vacuum line coming off the pump, shut the valve and run the pump as long as you want and it won't hurt the "vacuum side" of the vacuum pump.

I think that is what I wanted to see, if I blocked off the vacuum line from the pump it wouldn't hurt the internals of the pump trying to fight against it.

engatwork · #14 12-08-2014, 06:42 PM

That is correct.

vstech · #15 12-08-2014, 07:18 PM

The pump has a mechanism that retracts the lever when max vacuum is produced. Actually, when there is a vacuum leak, the pump runs continuously, and rapidly fails.