230SL 1966 engine rebuilt help needed

[balder]

Hi all,

I am rebuilding my 230SL 1966 engine and have a few questions:

1. When opened the engine, piston 1 was burnt (see photo). What can be the reason for that? Other 5 pistons are OK. Bad material or..?
2. The pistons are 83mm, 25mm pin, 3 rings. Can I replace them with mid 3 rings piston or even early 4 rings pistons? I must then replace conrods as well? Is 180 030 71 18 part no for this late 83mm piston?
3. What is the standard size of conrod and crankshaft bearings? 47mm and 59 mm respectively? Anyone knows part no for these?

Thanks a lot for help.
Srba 

[Sead]

I sent you email...
or contact me +387 61 528 220

[Harry]

Just finished my rebuild of same engine.  The Classic Center was super helpful with these types of questions.  I’d be happy to help as well.

[balder]

Thanks, guys.

I am a bit concerned about piston burn, have no clue how this might happen. If it's bad material structure, should I replace all 6 pistons?

Srba

[mnahon]

Looks to me like that cylinder was running too lean, also indicated by the color relative to the one next to it.

[ja17]

Yes, running too lean, spark plug much too hot or inhalation of foreign debris (any engine nuts or bolts missing)?

[balder]

Thanks a lot, Joe & Meyer.

No debris was found in cylinder, so I guess it was running too lean for some time. Need to check injection pump and nozzle. I assume this didn't happen instantly, more likely it was more gradual process?
Do you have any experience on con rod for this cylinder? It looks intact, could higher temperature make any structural not visible damage?

Srba

[Benz Dr.]

The whole engine should be gone through and since shards of metal circulated everywhere, all of the crank bearings with oil pump should be replaced. I'm not sure what the red stuff is on the top of the block but I would take a light cut off of the parting surface to true it up. I would also inspect the intake manifold to make sure that it's not warped. It's possible that you had a major vacuum leak.

[balder]

Will do all checks above. Red thing is a silicone sealer someone put on earlier, nothing serious.

Big thanks for your help and support.
Srba

[Esmo]

The Piston you have described is a generation 3 and yes 180 030 71 18 is the correct part number for the 83mm 3 ring 25mm bolt. I understand you cannot replace with a Generation 1 or 2 .