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-   -   Electric vacuum pump- conversion? (http://www.peachparts.com/shopforum/diesel-discussion/134162-electric-vacuum-pump-conversion.html)

yago 09-14-2005 11:15 AM

Electric vacuum pump- conversion?
 
Has anyone done this? I have a1981 300D. The vacuum pump is gone. We use to put an electric vacuum pump in cars that had a high duration cam. They coul;d not keep 15 pounds of vacuum for the brake booster. So a electric vacuum pump was installed. Could this be done on a mercedes diesel?

boneheaddoctor 09-14-2005 11:27 AM

Quote:

Originally Posted by yago
Has anyone done this? I have a1981 300D. The vacuum pump is gone. We use to put an electric vacuum pump in cars that had a high duration cam. They coul;d not keep 15 pounds of vacuum for the brake booster. So a electric vacuum pump was installed. Could this be done on a mercedes diesel?

Try a search...yes it has been done and discussed many times...

SD Blue 09-14-2005 11:34 AM

vacuum pump is gone???
 
Where did it go? :D

You did not say what you meant by gone .

If the mechanical portion is in good working order, there is a rebuild kit available which includes the "rubber" portions.

Why do you want to go to the trouble and excess $$'s to redesign this?

burndup 09-14-2005 11:37 AM

Pardon my diesel ignorance, but why do our engines have these? To run the brake booster/door locks?

"Normal" manifold vacuum is insufficent for that purpose on these engines? I'd think with mad-crazy compression ratios, the opposite would be true... What gives?

Thanks!
-J

boneheaddoctor 09-14-2005 11:39 AM

Quote:

Originally Posted by burndup
Pardon my diesel ignorance, but why do our engines have these? To run the brake booster/door locks?

"Normal" manifold vacuum is insufficent for that purpose on these engines? I'd think with mad-crazy compression ratios, the opposite would be true... What gives?

Thanks!
-J

Diesels are not throttled and therefore generate no manifold vacuum.

burndup 09-14-2005 11:44 AM

Ahhh, sooo...

So why do we have throttle bodies, then? Kinda like a choke? Or just to help keep bugs out?

Craig 09-14-2005 11:57 AM

Quote:

Originally Posted by SD Blue
Where did it go? :D

You have to watch these things every second. Last week my water pump tried to run off. :sun_smile

boneheaddoctor 09-14-2005 12:21 PM

Quote:

Originally Posted by burndup
Ahhh, sooo...

So why do we have throttle bodies, then? Kinda like a choke? Or just to help keep bugs out?


Only newer ones have them...its has to do with measuring air flow so the fuel system can meter out the correct fuel for the situation for economy and emmissions reasons....

its not a throttle in the sense of a gasser where it creats an obstruction that allows a vacuum to build.

Craig 09-14-2005 12:30 PM

Quote:

Originally Posted by boneheaddoctor
Only newer ones have them...its has to do with measuring air flow so the fuel system can meter out the correct fuel for the situation for economy and emmissions reasons....

its not a throttle in the sense of a gasser where it creats an obstruction that allows a vacuum to build.

I think he's referring to the "throttle" damper located in the air inlet of the 240D.

boneheaddoctor 09-14-2005 12:43 PM

Quote:

Originally Posted by Craig
I think he's referring to the "throttle" damper located in the air inlet of the 240D.

Possible....but the newer diesels have what to the non-technical person might be wrongly assued to be a throtle...

but the fact is...remove the trottle on a gasser and wait for the parts to fly as it self destructs over reving.....

the diesel will only run as fast as the amount of diesel its fed allows...

rg2098 09-14-2005 03:08 PM

With ties to OEM diesel engineers. Modern diesels have a throttle plate in them to create vac for the sole reason to pull exhaust through the EGR for emissions. There is not enough vac to power everything else so they still have an electric pump.

Pete Burton 09-14-2005 04:53 PM

On the SD the central locking system IS powered by an electric vacuum pump. The mechanical pump is used for the climate control, brake booster, transmission modulator, engine shutoff and even the :pukeface: EGR.

MBeige 09-14-2005 11:50 PM

Which vacuum reservoirs usually yield to wear and tear first? I remember the W123 has one inside the driver fender and under the rear shelf. I can lock/unlock my car 5 times but the 5th time is really slow. Manual says 10 times! (of course, engine OFF :D )

Craig 09-15-2005 12:01 AM

Quote:

Originally Posted by MBeige
Which vacuum reservoirs usually yield to wear and tear first? I remember the W123 has one inside the driver fender and under the rear shelf. I can lock/unlock my car 5 times but the 5th time is really slow. Manual says 10 times! (of course, engine OFF :D )

I doubt it's the reservoirs that are reducing the capacity, they are just tanks. If you are losing vacuum, you may have a very small leak someplace. How long will the system hold vacuum if you let it sit without running the car (hours, days, weeks)? I have left my 300D for over a week and had it unlock.

MBeige 09-15-2005 12:07 AM

Last I remember, after 2 days one door was open. I don't think anybody opened the car. But the locks go up and down quickly, not like before when I knew I had a leak--it was kinda sluggish. Quite hesitant if I may say so.

Won't the tanks crack with age?


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