I'm new to this forum and it is very nice. (english is not my first language) I had my transmission rebilt this week and after the mecanic reinstalled the transmission, he started the engine and BANG! I dont have all the details but it look very bad.

My question: The mecanic told me on the phone that the only cause he can think of is the fact that he "turn the engine in the opposit sens" (rotation) while reinstalling the transm. He said that this way of proceding in "forbiden" on some recent performance engine but he doesn't know (now) if it is the case with that particular engine.

If he cause the "destruction" of my engine, his insurance will pay the bill. So I need to know if my engine can be manually "turn backward"

You are not suposed to turn them backwards because of how the timing chain tensioner works.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

Thank you very much.

This is exactly what I needed to know.

The starter only cranks in one direction...

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

The starter did crank in the right direction. The problem is that the mecanic manualy turn the engine backward in the process of installing the transmission. When he engaged the starter, I understand that the dammages to the engine were inevitable.

I dont know about the cost of rebuilding a 1987 420 engine, but I may have to look for another Mercedes... Mine had only 95 k!