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6.9 Overheating

Started by ramiro, 26 July 2022, 10:20 AM


If I understand correctly the first photos are looking down super close into the water jacket.  If so - to me it is incredible that there could be this amount of layers of corrosion within an engine.   Makes one look again at the options for cleaning out a cooling system on a regular basis.
1973 350SE


I dont know if hot tanking the block would even get all that rust out. You would need to consult with a machine shop and see what they think.

This may be and idea:

You might need to soak it for a 3-7 days a few times and see how much rust it removes.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,


I had a german alternative to evapo rust already for serveral days in the engine after i manual cleaned the block(actually 2 times , first before i put the heads on and the after that i filled the whole engine again for serveral days) , the phots were from the worst spot and it was mostly loose rust , but all the small passages between the cylinder were blocked.
But i don't believe that it has to do with rust in block because the temperature didn't change at all after i put the heads back on , and it's definitly much much cleaner then before.