OM617 vacuum pump disabling
 

Howdy friends-

Please bear with me for a bit of back story.

I've swapped an OM617.95x out of an '83 300SD into a 1990 Toyota pickup. Before purchasing the engine, I started it and drove the car it was in around the junk yard. No unusual noises or anything. During install in the truck I removed the vacuum pump, and after reinstallation and restarting the engine, the pump knocked badly. Yanked the pump, started engine, no noise. Discovered excessive intermediate shaft play and replaced intermediate shaft bearing, bringing play back into spec. Replaced vacuum pump bearings, reinstalled pump, STILL KNOCKING. Argh.

I already have an electric vacuum pump and control switch on the way. I'm going to rip the guts out of the stock MBZ pump and use the case as just a cover to keep oil in and dirt out.

What could have I boogered up during removal and reinstallation to cause the VP to knock like that? Does anyone want the innards? Cover shipping and they're yours.

Edit: Thought I'd add, the electric vacuum pump(Audi OEM brake booster pump) and switch came to less than $100, much less than a new OEM MBZ vacuum pump would cost. It also will eliminate a failure point for this motor and still give me power assist for the brakes even if the engine should turn off.

Thanks for the info, I have my pump gutted & cutdown for looks/clearance.

Do you have a part number for the Audi pump? Or what year/model/trim is came from?

I have considered an electric pump as well. Are you adding a reserve tank for vacuum? Does the Audi pump cycle, or run continuously? Sounds like a neat mod!

Getting rid of the vacuum pump on the engine is one of the best things you could do. I have pondered it for years, but never did anything in furtherance of the thought...

How big an electric pump (i.e. how many CFM per minute) would we need on our cars (mine is and 83 300D)

I'm using a Pierburg electric vacuum pump off a late 90s Saab 93 turbo. I still need to gut the internal out of the stock vac pump. Right now its just capped.
http://i.imgur.com/T4GZv.jpg

When you do pull it, make sure those hex heads are clean and you have 100% engagement. I had the motor on a stand and I still had to drill 3 out

If you have an Automatic Transmission the Vacuum Valve for the Transmission is a continuous leak. Even with a Vacuum Shutoff Switch the Vacuum may never shutoff unless the Vacuum Switch is set to go on at a lower Vacuum; and that could be below what is useful for the Brake Booster.
If you have a Manual Transmission I think an Electric Vacuum Pump would be able to shutoff.

If the Audi Vacuum Pump is the same as the one below it May get really hot.
My thread on an Electric Brake Booster Pump 12 volt Electric Vacuum Pump
http://www.peachparts.com/shopforum/showthread.php?t=296397

Thanks 911, that looks a lot like the one I bought. I will have a shutoff at a certain vacuum level and the only thing it will be running is the brake booster. Duty cycle intermittent.

After it is installed give us some feed back.
Are you going to use the stock Toyota Check Valve?

One of the American Car companies is using a Similar Vacuum Pump but instead of being made in Europe it is made in Mexico.

My Volvo Diesel occasionally exhibits some Vacuum Pump deficiency.
I was thinking about T-ing in the Electric Vacuum Pump with a Check Valve (I have that already) and hooking the Vacuum Pump to a Switch so that when I apply the Brakes Pedal it turns the Vacuum Pump on and releasing the Brake Pedal turns the Vacuum Pump off.

Yup, stock Yota check valve. Current plan is to wire/plumb it all up and run it and see how she does, and add a vacuum reservoir later if needed. I'll definitely report back and let everyone know how it goes. Might be a couple weeks or a month, this is an ongoing project and while I'm very close to getting it on the road under diesel power, life has a way of throwing curve balls.

This entire project has been 5 steps forward, 4 steps back, which makes for 9 steps to make one step forward progress. This vacuum system has been no exception.

Edit: Might wire in an indicator light in the cab that comes on with the vacuum pump. Being able to monitor how often and how long the pump is running might give me some indicator of a small leak or other impending problem that hasn't shown up in braking performance yet, and an indicator light will take up a lot less room on the dash than a vacuum gauge.

I've made a stab at guessing that here

http://www.peachparts.com/shopforum/3158423-post10.html

83.4 cm^3 per second at 750 rpm based on an 85% efficiency of an OM61X piston vacuum pump

Bearings worn?

Copper PTFE piston ring deed?

Did you use a gasket between the pump body and the block / did you RTV it?

Bearings were replaced, both the intermediate shaft bearing and the bearings in the pump. Made no difference.

Copper PTFE piston ring might be toast, though it wasn't knocking before I removed it and I didn't remove it from the vacuum pump when I removed the VP from the engine, just removed the pump and reinstalled. I did R&R it when I replaced the VP bearings. No difference in knocking.

I did use a gasket between the block and pump. Figured the thickness of the gap between block and pump was pretty critical for clearance inside the pump and drive mechanism and wanted to get it right.

I wish most people's guesses were as vague as your "guess" about necessary cfm for an electric vacuum pump to replace our mechanical one. :D

That distance is important - but I can't remember if there's a maximum distance the timing device can stick out of the block {specified in the FSM (I'll check)}...

...what's the condition of the roller coaster track on the timing device?



Err yeah sorry about the number it has a decimal point which gives the impression of precision - but - if you follow the link you can see how I got there => it is a guess I've just used numbers. If someone can measure this it will be a much better way.