The bolts holding the water components on the front of the engine are the worst for snapping off. If it was over torqued in the past you are in for a nasty surprise...

Maybe someone on the forum has a spare 617 tstat housing, and they would be willing to help a new member out....or there is always PNP.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech