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  #16  
Old 04-02-2018, 07:54 PM
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Quote:
Originally Posted by Diesel911 View Post
Gassers use manifold vacuum. I believe your Engine has a similar butterfly valve that creates manifold vacuum used for the Pneumatic Governor. That could also be used with the power brake booster if the manifold vacuum is high enough.

It is also possible that that Engine did not come with the Car. The pictures in my book are from 190Ds. Did 190Ds have power brakes?
I mentioned this in a post recently - there's no way to have high vacuum in a diesel and have it still have enough air to compress to run - if there was we wouldn't need VPs in the first place.

I do suspect either the engine was one which never came with a VP originally or the timing device.

You have a good point. After an extensive google search I can't find any references for a 1966 W110 200D having a brake booster. There is the possibility one was swapped in?

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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

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  #17  
Old 04-02-2018, 11:30 PM
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From the EPC diagram below, it looks like the vaccum pump is driven by a bushing that acts in concert with two springs.

Sorry I don't have any more info for you.
Attached Thumbnails
Om621 still no vacuum after pump rebuild-110.110-1966-w110-200d-vacuum-pump.jpg  
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  #18  
Old 04-02-2018, 11:38 PM
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See if this helps. Looked up the same thing that Alec did, sometimes you have to look under weird things in the EPC to find what you want. Part numbers are shown on the left side. It looks like there are 2 different timing devices available.

Last edited by Diseasel300; 06-19-2021 at 10:06 PM.
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  #19  
Old 04-03-2018, 12:24 AM
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Is there a way to use the vehicles VIN Number to find what Engine Number range is supposed to be in his vehicle?
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  #20  
Old 04-03-2018, 12:48 AM
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ipernity: Throttle and venturi of a Mercedes-Benz diesel engine - by Michiel 2005

"From 1936 to 1979 Mercedes-Benz used a pneumatic governor on its diesel engines for passenger cars. The pneumatic governor used a throttle and a venturi in the air intake to govern the speed of the diesel engine."

If you look at the pic if the site you will see the Venturi in the Intake Manifold. However, if you look at the pic in the site you see the Venturi and the Butterfly Valve.

The Governor actually runs off of the Venturi Vacuum. However, it is hard to believe that with the Butterfly Vlave partly blocking the air way there is no vacuum in the Intake Maiflod beyond the Venturi Vacuum.

Also you can have a partial vacuum and still have Air Flow. But, I have not ever read anything one way or another on how the vacuum effects compression in Diesel Engines.
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  #21  
Old 04-03-2018, 01:34 AM
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Quote:
Originally Posted by Ryancoolwind View Post
I tracked down a rebuild kit and rebuilt my vacuum pump on my 66 200D. It seemed pretty straightforward, diaphragm was torn, replaced that and the 2 check valves! Easy, but still no vacuum. I'm wondering if my driver plate is worn or the roller lifter is worn down? I included photos and hope someone has any experience with this!
Just a random thought, could you have inadvertently installed a check valve (or two) backwards?
That's something I could see myself acomplishing.
It could account for your symptoms of no vacuum after a rebuild of a previously working vacuum pump.
Do you know if the pump ever produced vacuum before you rebuilt it?
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  #22  
Old 04-03-2018, 04:28 AM
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Quote:
Originally Posted by Diesel911 View Post
Also you can have a partial vacuum and still have Air Flow. But, I have not ever read anything one way or another on how the vacuum effects compression in Diesel Engines.
I really don't know what " of mercury etc they use to work. But no way a diesel which relies on compressing air to ~1/21(th?) of its original volume would work with a throttle plate blocking most air getting in.

Quote:
Originally Posted by Alec300SD View Post
Just a random thought, could you have inadvertently installed a check valve (or two) backwards?
That's something I could see myself acomplishing.
It could account for your symptoms of no vacuum after a rebuild of a previously working vacuum pump.
Do you know if the pump ever produced vacuum before you rebuilt it?
We already worked out why he has no vacuum Next mystery is why there's no ramp on the timing device....
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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

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  #23  
Old 04-03-2018, 11:06 AM
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Quote:
Originally Posted by NZScott View Post
I really don't know what " of mercury etc they use to work. But no way a diesel which relies on compressing air to ~1/21(th?) of its original volume would work with a throttle plate blocking most air getting in.


We already worked out why he has no vacuum Next mystery is why there's no ramp on the timing device....
There is a Butterfly Valve/Throttle Plate in the manifold of this particular Diesel.

It also takes X amount of heat to ingited the injected Fuel. However, that heat does not have to come entirly from the heat of compression the compressed Air.

I don't have the specific starting instructions for a 200D. But, I somewhat remember what people said and last night I read the instructions from another Diesel Car that has a Pneumatic Governor and the instructions were the same as people on the Forum have said.

You pre-glow then you step on the Accelerator Pedal (that would open the Butterfly Valve/Throttle allowing plenty of air to pass buy) and crank the Engine.

So we have the Glow Plugs and plenty of Air for Compression. At the same time the Pneumatic Governor in the face of no venturi vacuum (because of the wide open throttle) is going to go to full fuel so that you have plenty of Fuel.

When the Engine is going good you can take your foot off of the Accelerator Pedal and the Throttle Plate obviously partly closes to some idle position. Even though the Throttle Plate is mostly closed there is apparently enough Air and therefore enough compression to keep the Engine going at idle.

When you accelerate you open the Throttle Valve and remove the restriction to the Flow so you have plenty of Air for compression.

Once combustion starts in the Precombustion Chamber I bet that Ball Pin that the Injector Sprays down on gets hot really fast (and stays hot as there is limited area for heat to conduct away from it). That means once that Ball Pin is hot if any raw Fuel sprays on it the Ball Pin itself is sufficient to ignite the Fuel. If the compression was for some reason low once the Ball Pin is hot enough the Fuel is still going to ignite.

So that is my understanding on the above stuff.

In the past someone also mentioned that direct injection Engines have about a 17 to one compression ration and that the mercedes had a 20+ to one compression ratio. That would seem to indicate that 17 to one compration is sufficient to ignite the Diesel Fuel and if the Mercedes suffered some compression loss it could drop some and still work.

Maybe someone with a 200D or 240D that has a Penumatic Governor on it can disconnect the Vacuum Pump Connection at the Intake Maifold and connect a Vacuum Gauge to that port and we can find out for sure if there is any Vacuum in the Manifold of those particular Engines that have a Throttle Plate in the Intake.
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  #24  
Old 04-03-2018, 11:16 AM
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I a curious to know that since this particular Engine does not seem to be setup for a Vacuum Pump if the Intake Manual has the port open where intake hose on the Vacuum Pump attaches.
If there is no open port on the Intake Manifold I would belive that that patricular Engine was not made to have a Vacuum Pump.
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  #25  
Old 04-03-2018, 11:23 AM
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When looking up the 621 and 636's, it seems that they were very common in watercraft, probably more common there than in automotive applications and obviously have no vacuum pump. The timing device is different for the various uses, it would be interesting to know if this car has a watercraft engine or timing device fitted. Would certainly explain a lot...
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  #26  
Old 04-03-2018, 08:00 PM
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Wow this thread really blew up! Awesome information for me, the more technical the better. I specialize in repairing modern European cars and diesel trucks so I'm basically figuring out the mechanical operations that modern cars accomplish by computer systems. Let's give an update, I ordered a injector pump gear with vacuum pump cam actuator online. Once it gets here I will scrutinize the 2 parts to confirm they are similar in design.

As a side note, I shipped my brake Booster out to pwrbrakes.com and they are just about done rebuilding that.
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  #27  
Old 04-03-2018, 08:03 PM
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Originally Posted by Diseasel300 View Post
When looking up the 621 and 636's, it seems that they were very common in watercraft, probably more common there than in automotive applications and obviously have no vacuum pump. The timing device is different for the various uses, it would be interesting to know if this car has a watercraft engine or timing device fitted. Would certainly explain a lot...
Where could I find any identifying casting numbers?
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  #28  
Old 04-04-2018, 04:14 AM
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Originally Posted by Diesel911 View Post
There is a Butterfly Valve/Throttle Plate in the manifold of this particular Diesel.
---cut out---
Maybe someone with a 200D or 240D that has a Penumatic Governor on it can disconnect the Vacuum Pump Connection at the Intake Maifold and connect a Vacuum Gauge to that port and we can find out for sure if there is any Vacuum in the Manifold of those particular Engines that have a Throttle Plate in the Intake.
If there's a venturi, that will provide the vacuum required without having to cut flow off dramatically. Remember if you cut 1/2 the airflow essentially you're cutting the CR down to 10:1. Now if these engines started and ran with 10:1 compression with working glow plugs yadda yadda they wouldn't build them with 21:1.... that's my understanding of it anyway.

Only trouble with disconnecting the injection pump pipe from the manifold is that it will run away once started, so would have to be a Tee. I might try it one day on my Granddads '75 HJ45...


Block casting number is likely to be behind the IP. Should be 621 918 apparently
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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

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  #29  
Old 04-04-2018, 06:37 AM
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I think you guys are mixing up compression ratios and air fuel mixtures. The compression ratio isn't a dynamic number (except the new Nissan variable compression engine). When you momentarily block off an intake, the engine will only run richer due to the remaining air being used up faster then it is replaced. The engine will then stall once the rotating inertia isn't enough to overcome the vacuum in the manifold, or when the mixture is too rich and is unable to burn. Modern diesels have throttle bodies on them for emissions reasons, in certain drive cycles the TB will partially close to better have egr gasses pushed into the intake
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  #30  
Old 04-04-2018, 04:48 PM
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Quote:
Originally Posted by NZScott View Post
If there's a venturi, that will provide the vacuum required without having to cut flow off dramatically. Remember if you cut 1/2 the airflow essentially you're cutting the CR down to 10:1. Now if these engines started and ran with 10:1 compression with working glow plugs yadda yadda they wouldn't build them with 21:1.... that's my understanding of it anyway.

Only trouble with disconnecting the injection pump pipe from the manifold is that it will run away once started, so would have to be a Tee. I might try it one day on my Granddads '75 HJ45...


Block casting number is likely to be behind the IP. Should be 621 918 apparently


I am wishing someone would actually hook a up vacuum gauge; just curiosity.

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