Electrical Vacuum Pump Conversion Project - Page 2 - PeachParts Mercedes-Benz Forum

Mölyapina · #16 12-20-2013, 11:55 AM

om617 Vacuum Drive Plate-Necessary?
Vacuum Pump Delete question

Simpler=Better, do you have a picture of what you did?

mach4 · #17 12-20-2013, 12:33 PM

Quote:

Originally Posted by funola

Thanks for posting this. I'll be following your progress. Does the car you took the vac pump from have a vac reservoir and vac switch? Have you looked into whether removing the cam driven vac pump will cause any issues with what drives it (the timing device)?

I'm not touching anything on the side of the IP. All I'm going to do with the VP is remove the piston. Then the vacuum pump housing will become the functional equivalent of a block off plate. I'll weld the check valve to seal up the unit.

I'm not sure if there is a reservoir on the VW. There is no vacuum switch as the pump is controlled by the ECU as shown here.

For the technically inquisitive, here it an extensive write up - http://www.volkspage.net/technik/ssp/ssp/SSP_257.pdf I found the section on open-loop systems particularly interesting as there is no pressure sensor used in these designs, rather they use indirect measurements of load, rpm, throttle position and brake light switch to calculate whether the pump needs to be on. This can be done because in a gas engine, vacuum will be low at idle (if there is a big cam), and at lower rpms when the throttle plate is in the open position, and of course if the brake light is on there is demand for vacuum by the booster.

cho · #18 12-20-2013, 01:00 PM

Quote:

Originally Posted by Jooseppi Luna

Some folks over at STD have eliminated the vac pump, I think. I'll see if I can find that...

if I m not wrong that guy used belt driven vac pump...

.

Diesel911 · #19 12-20-2013, 03:46 PM

Quote:

Originally Posted by cho

.

another cool project I might consider...out of curiosity...why do we
need to control vacuum pump?

edit: is it just a on/off so it is not runnin' all the time...lot of folks converting to ecars use similar solutions fwiw..
also good switch and relay 24+18 bucks

thanks

cheers
ChO

.

I used the same Electric Vacuum Pump (it is a Rotary Vane type Pump and there is no lube inside of it) and if it runs a long time it gets hot enough to blister your Finger.
A Vacuum Shutoff Valve may or may not keep it from Heating up. When the OP is done with his project and has tested it well will have the answer.
My thread on an Electric Brake Booster Pump 12 volt Electric Vacuum Pump
http://www.peachparts.com/shopforum/diesel-discussion/296397-electric-vacuum-brake-booster-pump-tested.html

The other problem is that if you have a Mercedes Diesel with an Automatic Transmission there is always some Vacuum leaking out of the Transmission Vacuum Valve on the Fuel Injection Pump so it is possible your Vacuum Pump may never turn off or only be off for a short time.

OM617YOTA · #20 12-20-2013, 03:49 PM

I have the EXACT same pump on my conversion. It handles all the vacuum requirements for the whole vehicle, and works just fine without heating up beyond design limits.

Diesel911 · #21 12-20-2013, 03:58 PM

Quote:

Originally Posted by pawoSD

211k? The VP in my 300sd has 321k and works fine....I'm not worried. I had it off around 280k and it was in perfect shape inside. We have several 617's with original pumps and high miles with 0 issues.

I think there's a lot of VP paranoia around here, how many have actually had one fail? I replaced the one on my OM601 with a new engine mounted one because the original had 250k on it and was the exposed bearing variety. The new one has closed bearings and has been working great for 6k so far...

One of Our Members installed 2 New Vacuum Pumps and ruined both of the. The reason was the Timer Bushing was worn and when the Piston and Arm of the Vacuum Pump came down it evidently did not get stopped by the Timer Cam but hung on the Piston and cracked the Piston.

The Bushing issue seems to be the more common reason for the VP Failure on the 617.952.
There is no clear answer why the Bushing seems to were faster on some Cars then others. I suspect it has to do with the past owners Oil Change record.

Another issue one of our Members mentioned is that if you have been driving your Car a long time and have not fixed your Vacuum Leaks the Vacuum Pump is working more then it would if you leaks were cured. That might increase wear on the Timer Bushing.

I think the Oil Change issues is also why some people have a not of Timing Chain Strecth compared to others with the same milage.
But, thoses are guesses.

My question What in particular causes vacuum pump failure?
What in particular causes vacuum pump failure?

Diesel911 · #22 12-20-2013, 04:06 PM

Quote:

Originally Posted by mach4

If you only need a shutoff solution, this is gross overkill. Use a vacuum pump from a Benz that is used for locking and unlocking. Dirt cheap readily available and low enough draw you shouldn't even need a relay.

There are no vacuum switches used on these pumps in their native installation. There is a vacuum sensor that is tied into the ECU that activates a relay when needed. Same exact operation as the electronic controller in post 1.

Yes for only the shutoff there is also a lot of electric Small Vacuum Pumps on eBay that are used for the Crusie Control. Lots of Ford ones available.
I did the below and it worked but I finally got around to fixing the leaks in the locking system and I left it in the Engine Compartment but disconnected it.
Electric Vacuum Pump for the Door Locks
Add On Electric Vacuum Pump for W123 Locking System

Unfotunately the Power Brake Booster needs; If there is such a thing the Vacuum Pump has to created enough Vacuum Volume/displacement to keep the Booster Functioning even after repeated Brake Pedal applications.
A tiny Vacuum Pump is not going to do that.

Diesel911 · #23 12-20-2013, 04:23 PM

Quote:

Originally Posted by funola

Thanks for posting this. I'll be following your progress. Does the car you took the vac pump from have a vac reservoir and vac switch? Have you looked into whether removing the cam driven vac pump will cause any issues with what drives it (the timing device)?

If you have acces to the 617.952 Manual look up the diagram of the Intermediate Shaft and the Bushings.
There is bushings on both sides of the shaft and Washer were needed to take up the thrust from either direction.

I suppose if the same Timer/Intermediate Shaft Bushing is worn out that causes Vacuum Pump Failure it is possible for the timer to go in and out to the limit of the clearances.

However, in normal use the Timer is likely already doing that. If you Vacuum system is seald normally one of the Members said the Vacuum Pump Piston is held foward with the Spring Compressed and the Arm and Bearing pulled away from the Timer.

If that is true no part of the Vacuum Pump makes contact with the Timer until Vacuum is bleed off. This means that for a period of time the Timer is operating as if there was no Vacuum Pump there.

None of the above seems to have a notiable effect on the IP timing advance.

mach4 · #24 12-20-2013, 06:39 PM

Got the bracket for the vacuum pump fabricated and installed. Turned out pretty decent.

In it's final configuration the vacuum line will just swing a few degrees left to hook up with the vacuum inlet on the electric pump.

I was able to use two existing captive nuts in the wheel well to attach the bracket, so no new holes needed to be drilled.

pgringo · #25 12-20-2013, 06:42 PM

I have the same vw vac pump I set up with a vac switch (22hg adjustable off eBay) and relay. With a Volvo 240 vac reservoir (fits perfect between firewalls next to master cylinder). It works great except I have a 300sd so the trans has a constant vac bleed. I was pizzed!

mach4 · #26 12-20-2013, 06:47 PM

Quote:

Originally Posted by Diesel911

The other problem is that if you have a Mercedes Diesel with an Automatic Transmission there is always some Vacuum leaking out of the Transmission Vacuum Valve on the Fuel Injection Pump so it is possible your Vacuum Pump may never turn off or only be off for a short time.

During the testing phase I will wire in a light that will tell when the pump is on as a way to determine what the actual duty cycle is in normal operation. This is one of the unknowns that needs to be tested.

I intend to carry a spare pump at least until the concept is proven. The way it's installed I should be able to swap it in about 10 minutes with just a wrench, a torx driver and a screw driver.

mach4 · #27 12-20-2013, 06:50 PM

Quote:

Originally Posted by pgringo

I have the same vw vac pump I set up with a vac switch (22hg adjustable off eBay) and relay. With a Volvo 240 vac reservoir (fits perfect between firewalls next to master cylinder). It works great except I have a 300sd so the trans has a constant vac bleed. I was pizzed!

Are you saying that because of the transmission bleed, the electric vacuum pump works too hard to be a viable solution?