Never have heard of . . . .
so many tubes going 'open'. But if you look at the way the tubes are fabed, it's just a matter of time till they fail.
Although, my tech, whose been a Mercedes man for 30 yrs+, has never seen an open tube. In fact my car was the first he had seen. After mine, he had one other. Interesting??? I've had three (3) tubes fail: two on the right, one on the left.
The tubes in '92s (500SL) are metal with spring loaded end cap using a 'beebe'. Much better quality.
Where were open tubes? What side and cyclinders?
Regards . . . . JimF
'94 S500 Cpe
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