If a hex head , it'll either be a 17 0r 13 MM . if an allen head , it'll be a 6MM IIRC .
Loking at the size of the threaded hole in the motor mount picture , should tip you to what to expect ~ 10MM theeads , 17 MM head bolt .
8MM threads , 13MM ATF or 5/6 MM allen headed bolt .
In either case ,_NOW_ , before you begin to work on them , is the time to get some coveralls or old clothes and at least four cans of de greaser and some brushes , a couple paint brushes and one long stiff bristle solvent brush and go to town cleaning the engine and the uniboby as believe me , there's going to be oil soaked road grime you cannot imagine , in every nook and cranny way up underneath .
DO THIS NOW so it'll be dry in a week or so when you attack it .
Expect to get beyond filthy your own self , don't dispair , just keep swirling the munge around with the various brushes , spraying ever more cleaner as you go , work the driveway stains with the brushes too and when you wash it all down with the garden hose (use a nozzle , dig) , it'll come splashing back into your face and hair , don't stop , quit or give up , keep flushing it until the water runs off clean no mtter how obscure the corner or crevice you point the nozzle into , then flush the pavement clean , _all_ that mess will dissolve & rinse away leaving you with a clean engine & under carriage plus a sparkling clean and fun to work on , driveway .
Guess how I know this ? .
Nate
Kevin wrote:
>
> I’m almost ready to do the motor mounts and tranny mount on my ‘77 240D. Still waiting for the center mount to come in. I can feel that it’s just behind the oil pan, but I can’t see what type of bolt it is to determine what tool are neded to remove it. I’ve done the side mounts on the first 300D I had, but this third mount behind the oil pan is new to me.
>
> Kevin in Hillsboro, Oregon
> 1977 240D 315Kmi, Liesel the Diesel
>
