Big technical problem, help needed!

[Cortez-Campos]

Last week my oilpressure disappared, I went to my local mechanic,  but he is not a MB expert, not even Mercedes know anything about these cars ( found out last year when they replaced my exhaust )

I have now located the problem to a verticle timing gear

Download Attachment: billed af gear.jpg
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but as I only can buy the verticle and the horizontal gear together, I will ofcause replace both, but my question are :

Can my mechanic pull the horizontal gear out of the "front" of the engine, without separate the engine?

how many hours are we talking about???



280 SL 1969 anthracite 172, with red inteior.

[J. Huber]

Hi Christian. Sorry no answers -- the experts will hopefully chime in soon. My question for them, when its my turn, is: is this that worse case scenerio for a worn Tach thrust bushing that we have all learned about?

James
63 230SL

[ja17]

Hello Cortez,

Replacement of the both gears in a matched pair , is what the factory suggests. They are expensive!  I have replaced just the worn vertical gear with another good used gear and have had no problems. However repalcing the gears in factory matched sets is safest but costly.

The vertical gear comes out fairly easily, however the horizontal gear is much more difficult. Sadly the injection pump must be removed also! Review the photo to see what is involved in the process. The horizontal timing gear slides out the injection pump opening.

Remove the hood so you have good access to the front of the engine. Turn the engine to 20 degrees after top dead center "TDC" of number one cylinder. Remove the injection pump. Remove the distributor (noting which direction the rotor is pointing). Remove the aluminum distributor housing from the front of the engine block exposing the chain sprocket in the block. Remove the nut and washers, distributor drive gear and it's wood ruff key. Be careful not to drop any parts down into the engine. Remove the valve cover, and the upper chain rail on the front of the cylinder head. Split the timing chain and attach a wire to each end. Lower the chain down into engine so you can remove the chain sprocket in the block. You can tap shaft back into the block to aid removal of the sprocket. Be aware of a second woodruff key under the chain sprocket.Do not allow this to fall into the engine.  Once the chain sprocket and it's woodruff key is removed  the "horizontal timing gear can be be pushed out through tbe injection pump opening in the block.

Download Attachment: The whole picture.jpg
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If your engine timing chain has never been changed, It will be a good time to do it. Quite a project!

Keep in touch, sorry for the bad luck.

Joe Alexander
Blacklick, Ohio

[Naj ✝︎]

Hello Cortez,

 

quote:I have now located the problem to a verticle timing gear

Can you post pictures of the damaged/worn parts please?

naj

68 280SL

[ja17]

James,
Worn gears are the long term result of a worn thrust bushing. Examine  the gears during trust bushing replacement. Usually the gears are fine with only some minor wear and they can be left in use.

Joe Alexander
Blacklick, Ohio

[mulrik]

Hej Christian
Sorry to hear about your problem. To do what Joe suggests is not that difficult. I did it myself this winter. I would actually estimate that you can do it all yourself relativly easy. I'd say 3-5 hours work should do it. You don't have to take the hood of, however, taking the black grill out behind the mercedes star in the front will be a great help in this procedure.

But I don't understand how this could affect your oil pressure, could you explain that?
BR,
Ulrik


'67 250 SL Papyrus White 113043-10-000023

[Cortez-Campos]

Arr sorry, it is in this topic NAJ asked for a picture.

As you can see the bushing is very worn at the bottom, I guess 5-7 mm, so the verticle gear could "jump" up and not run together with the horizontal gear, without damage the gearwheel.

As I have understand it those gears drive the oilpump, and when the verticle gear "jump" up, the oilpressure disappear

The horizontal gear is not bad damaged, but you can't buy only the verticle gear, you have to buy verticle and horizontal gear together, I bought them from SLS - Germany, and paid 860 euros!!




Download Attachment: WORN GEAR.JPG
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280 SL 1969 anthracite 172, with red inteior.

[ja17]

Hello,

Yes, a very worn bushing will allow  the vertical gear to raise and disconnect the oil pump!!!! Luckily you discovered the problem before the engine locked up from lack of lubrication.

It is a easy job to check for a worn bushing by measuring the play in the vertical gear, just unscrew the tach cable at the engine and use a screw to test up and down movement in the gear.

Download Attachment: checking bushing.JPG
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This simple procedure may save your engine some day.

Joe Alexander
Blacklick, Ohio

[Naj ✝︎]

Thanks for the picture Cortez.

Lucky you caught it in good time !!

naj

68 280SL

[hands_aus]

There was a very good discussion about replacing the thrust bush in this topic
http://index.php?topic=3097&whichpage=1

JoeA included pictures and a great description.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto