Loose ringgear on a MB280 SL 1069

[MBfreak]

I overhauled the 6 cyl 2,8 l straight six on a friends MB 280 SL 1969. Around 220.000 km ( ie app 140kmiles)
Also converted to Megasquirt and EDIS.
Engine as new after boring , grinding crank and flywheel, new cyl head. All new fasteners.
When tuning it suddenly stopped cranking. Starter spun, engine did not turn over.
Bought a new Bendix , replaced .
SAME PROBLEM.
Removed the bellhousing inspection cover. Cranked.
Ring gear turned, flywheel stationary.
After disassembly , measured the flywheel dia . Perfect, exactly in the middle of factory tolerance
Bought a new ringgear . Heated to 180 C and put on.
All well.
Talked with a guy who service and repair mostly modern MB diesel taxis.
Had never heard of that problem.

 

[Mr.N]

I want to know more on how you fit the copper to the O-rings for the fuel injectors.

 

[MBfreak]

Mr N.
Swedish standard copper tubes come in 15 mm OD. ID is 13,0 mm
Euro fuel injectors have a neck metal dia of 13,0 mm and a single O-ring seal with an OD of 13,4 mm
Factory fuel rails have a seating dia of 13,20 mm.
So I used a tool grinder machine to grind and polish each part to 13,2 ( thanks to friendly people at a
large company experimental workshop) . This was done after everything was soldered up.
The "nose" of the fuel injector has the same fit.
And the 280 SL engine has original fuel injector seats in the cylinder head just above the intake valve with standard 14-1,25
spark plug thread. Removed ceramics from spark plugs, soldered in a piece of OD 15 copper tube and machined to ID13,2.

All good. Car was done in around 2008.
Worked perfectly and just to stun the annual exhaust inspection we had a setting which performed reasonably well at 0,2 % CO2. However, not something to use for daily driving.
MB setting of the MB SE and SL 1960-s engine family is 4,1% CO2 at 750 rpm.
The combustion chamber is rather finnicky.
When owner passed 2018 the car was bought by a guy in Germany.

Ola

 

[MJD1]

Possibly in the past the ring gear was heated, removed and flipped over because it was worn on one side. I've done it a few times on certain vehicles, but I usually placed 3 evenly spaced short welds to insure it didn't move

 

[Mr.N]

Mr N.
Swedish standard copper tubes come in 15 mm OD. ID is 13,0 mm
Euro fuel injectors have a neck metal dia of 13,0 mm and a single O-ring seal with an OD of 13,4 mm
Factory fuel rails have a seating dia of 13,20 mm.
So I used a tool grinder machine to grind and polish each part to 13,2 ( thanks to friendly people at a
large company experimental workshop) . This was done after everything was soldered up.
The "nose" of the fuel injector has the same fit.
And the 280 SL engine has original fuel injector seats in the cylinder head just above the intake valve with standard 14-1,25
spark plug thread. Removed ceramics from spark plugs, soldered in a piece of OD 15 copper tube and machined to ID13,2.

All good. Car was done in around 2008.
Worked perfectly and just to stun the annual exhaust inspection we had a setting which performed reasonably well at 0,2 % CO2. However, not something to use for daily driving.
MB setting of the MB SE and SL 1960-s engine family is 4,1% CO2 at 750 rpm.
The combustion chamber is rather finnicky.
When owner passed 2018 the car was bought by a guy in Germany.

Ola

Thank you for the explanation! I am keeping this idea for the future.
I've some copper tubes ran instead of heater hose...