W109 3.5: distributor renovation

[werminghausen]

I have the distributor out and opened the 'door', took the lower level points out.
I wonder if someone can help me guide through renovation of this part.
is there anything I should take apart and check. Is there a manual and testing procedure.
For instance
1) how is the axle lubricated? Do I need to take it apart and check
2) the lubrication of the cams seems very old and grease is old in the felt.
What kind of grease was use by Bosch here. Is it wise to clean the old grease out and put new one on?
3) new points: I have new points for the top points which control the injection timing. is there any need to take care of the lower point ..(which are for D-jet injection volume?)
4) Anything to test for the mechanism of injection timing/retard/advance for upper points
5) replace upper points

Any input is greatly appreciated. Martin

[JMela]

Good photo essay here:

http://www.glenn-ring.com/010/index2.html

Benz Dr. of this board rebuilds these units and supplies rebuild kits, I'm sure he'll chime in sooner or later.

[werminghausen]

Originally Posted by JMela

Good photo essay here:

http://www.glenn-ring.com/010/index2.html

Benz Dr. of this board rebuilds these units and supplies rebuild kits, I'm sure he'll chime in sooner or later.

Thanks. My distributor seems to be more complicated than the one in the pictures. I have a set of points (I think 4 points) in the lower portion of the distributor housing.

[Graham]

I R&R'd my 72 SL distributor a while ago and posted a description here:

http://www.benzworld.org/forums/r-c107-sl-slc-class/1374600-d-jet-distributor-removal-injectiontrigger-points.html#post2858839

If you wish to lube the trigger points, I would use a minimum and maybe use same Bosch or equivalent grease as is used for ignition points.

To test the trigger points, I used an ohmmeter to determine the angle that they remained closed. I posted some info here about this. A search for my name & trigger points should bring up the discussions. As the points wear, they can stay closed for too long.

here is one post, there may be others:
Trigger Points on old D-Jets

[Benz Dr.]

I looked at all of the pictures with descriptions and it looks OK but it really doesn't tell you very much. Glenn used a very simple distributor as an example, it has no vaccum advance system so there are a lot of things which are very different on later units.

The units that contain trigger points are used on all EFI systems that Benz made. The most I ever do with trigger points is hose them down with some contact cleaner and blow them dry with compressed air. The contacts have to be perfectly clean in order to work properly. Often, blow by gasses will travel up into the distributor housing along side the main shaft and settle out in the trigger point housing. An oily film will settle on everything including the tigger points. This film is what you would be cleaning off.
The cam lobes that open and close the trigger points are very smooth without the normal '' bump '' you would find for ignition points so wear is greatly reduced. I have a feeling that a lot of trigger points get thrown out that may be good and they are quite exspensive to simply throw away.

The ignition portion of the distributor is similar to any other unit. The main shaft bearings can wear as well as the advance plate and the top shaft that has the cam lobes. Some of these things can be repaired and some can be made to work better but not like new unless better parts can be found.
This system uses vacuum retard which I've already recently described on another thread. Part of making the distributor function properly is to have a clean throttle body. Remove it and clean the bore and throttle plate. The plate should just have a very slight grab to it when closed. Adjust the stop screw with lock nut to suit. There could be one or two vaccum ports, make sure both are clear and not plugged up with carbon. If there are two ports one is for vacuum retard and the other is for vacuum advance. The port below the throttle plate is vacuum retard and the one above is vacuum advance.

The actual distributor is beyond the average DIY guy. You need a distributor tester as shown in the pictures. I have a Sun '' 604 '' which is probably newer and towards the last ones made. BY 1974 most cars had some type of electronic ignition system and distributor testers became something that took up valuable shop space. Only vintage operations have them today. It's next to imposible to set up and calibrate a distrbutor without one.

[JPMOSE]

Dan..my '70 280SE 3.5 Cabrio has the same distributor. It seems to work perfect! But I've noticed that a lot of parts for the W111 and D-Jetronic are starting to be NLA (like the Throttle Valve Sensor). Would it be worth obtaining a new set of Injector Trigger Points for a future date? In other words, if mine fails a few years from now and they become NLA, are they able to be rebuilt? Same applies to the distributor...are all the parts readily available? Thanks for your time!

[Benz Dr.]

There are a lot of things going on that I really don't understand but the basic jist is that Bosch is no longer making a lot of these parts. Whatever they are making is going directly to MB and not to WD's so this is where most of the hefty price increases are coming from.
Once something becomes '' Classic '' the price doubles or triples over night. Case in point:
107's are now pretty close to going classic if they aren't already there. I priced out a fender today. Last year or last avaliable price was $770.00 in Canada. Today's price - $ 1,199.00 Same thing for a rear muffler: last price 507.00 - today it's $715.00 - that's a 40% increase in one jump.
The list price for a euro 113 head light is just shy of 2K here more than double in a year or more.

Now, there may be places where you can find them for less but if you walked into the dealer that's what you would pay. That's what insurance would pay if your car got smashed up. Hit very hard and it would be a write off.

So, yeah. Maybe it would be a good idea to pick up certain parts that you might need in the future. I never know what will become NLA or so over priced that it's beyond crazy. Exchange rates aside someone is making a butt load of money. Little of this can be justified. If it wasn't for used, repro, or after market parts, a lot of these cars would all be razor blades.

[werminghausen]

Originally Posted by Graham

I R&R'd my 72 SL distributor a while ago and posted a description here:

http://www.benzworld.org/forums/r-c107-sl-slc-class/1374600-d-jet-distributor-removal-injectiontrigger-points.html#post2858839

If you wish to lube the trigger points, I would use a minimum and maybe use same Bosch or equivalent grease as is used for ignition points.

To test the trigger points, I used an ohmmeter to determine the angle that they remained closed. I posted some info here about this. A search for my name & trigger points should bring up the discussions. As the points wear, they can stay closed for too long.

here is one post, there may be others:
Trigger Points on old D-Jets

Thanks Graham. This is what I was looking for. Martin

[Graham]

Originally Posted by werminghausen

Thanks Graham. This is what I was looking for. Martin

Good Luck - I installed a Pertronix 1885 as a replacement for the ignition points. Inexpensive and effective.

I luckily obtained a good used set of trigger points from a low mileage junker. There are new or rebuilt ones available from Bosch, but they are very expensive.

[werminghausen]

Originally Posted by Graham

Good Luck - I installed a Pertronix 1885 as a replacement for the ignition points. Inexpensive and effective.

I luckily obtained a good used set of trigger points from a low mileage junker. There are new or rebuilt ones available from Bosch, but they are very expensive.

Hi Graham, thanks.
I can't tell about the condition of my lower trigger points (I guess these are the 4 points sitting in the lower 'rack'? )
But from the outside they look amazingly good. If they are 40 years old- wow.
Is there anything to test? I attached 2 pics.
The other question is the lubrication of the cam itself. How does the system work? Does lubrucation rely on one time grease...like a wheel brearing? Or is there a connection to the engine oil?

[bwostosh]

Martin, Blow the trigger point assembly with Berryman's or equivalent and re-apply Bosch Cam grease to a cleaned lobed shaft. Look for grooves on the lobes. I clean the shaft with scotch-brite or 500-600 and flush. A drop of oil to the bushing below the trigger point chamber. Spin it without any points and listen for the cleaned weights.

Thinking about the trigger points themselves, some suggest against this. I draw a folded over strip of 600 grit between the points, after all they are either tungsten or silver, and those metals do clean up without significantly changing the dimensions. A distributor machine will tell all.

[JPMOSE]

The trigger points (pulse generator) are NLA at the dealer. However, Bosch is issuing a repair kit, starting this month!

Follow the Bosch link in the site below and there are a lot of Vintage Bosch goodies in it's news letter and website:

http://forum.w116.org/mechanicals/news-from-bosch-automotive-tradition-centre-re-d-jetronic/

[bwostosh]

"Maybe it would be a good idea to pick up certain parts that you might need in the future."

I've been pulling and stashing these parts for 15 years, some think it is a little wacko to be doing this instead of a normal hobby. Fooled them, this hobby will be a service to the Benz community someday. What does golfing contribute?

I was priced out of the old BMW R69S motorcycle market and learned from that. Loved that bike, couldn't afford the parts.

[Graham]

Originally Posted by JPMOSE

The trigger points (pulse generator) are NLA at the dealer. However, Bosch is issuing a repair kit, starting this month!

Follow the Bosch link in the site below and there are a lot of Vintage Bosch goodies in it's news letter and website:

http://forum.w116.org/mechanicals/news-from-bosch-automotive-tradition-centre-re-d-jetronic/

That is good news. Hope the cost is not ridiculous as it is for some other old parts.

[Graham]

Originally Posted by werminghausen

Hi Graham, thanks.
I can't tell about the condition of my lower trigger points (I guess these are the 4 points sitting in the lower 'rack'? )
But from the outside they look amazingly good. If they are 40 years old- wow.
Is there anything to test? I attached 2 pics.
The other question is the lubrication of the cam itself. How does the system work? Does lubrucation rely on one time grease...like a wheel brearing? Or is there a connection to the engine oil?

Your points are enclosed and I don't think you can get at them without destroying the covers. Those points never burn out - they just sometimes get an oil coating. Don't use any kind of abrasive on them. At most, if you can get at the contacts, slide something like a thin piece of a business card back & forth a few times and see if it picks up any grease or oil. If you can't get at them, try spraying them thoroughly with some electrical contact cleaner in hope that this will remove any oil.

Regarding testing the trigger points. What actually wears on these points, is the fibre rubbing block that contacts the cams. In one of the earlier links I gave you, I may have provided the distance between the rubbing blocks for my two sets. If I recall correctly, one set was worn more than the other.

To test the points, I set them up in a vice. I connected an ohmmeter between the centre connector pin and each of the other pins in turn. For each pair, I rotated the distributor (using the rotor) and noted the angle that that pair of points stayed closed. From the design, you can see that this angle should be roughly 100deg. I had one set of points that were bad in that they stayed closed for almost 180deg. This caused the ecu to inject fuel incorrectly and I had a very rich mixture. The points can't really be adjusted. Some (including me) have tried bending the mounting bracket but it would be much better to try an get one of the new repair kits when they become available. But only if tests show you need them.

I am running on my spare used set and have a brand new set still in the box!

Regarding lubrication, the felt pads on trigger and regular points are just lubed once in a while. The distributor itself has a hollow double concentric shaft. There is a small felt plug near the top (under the rotor) You are supposed to add a drop of oil once in a while. I seem to recall that not all cars have that felt plug, but my '72 SL does.