The 1991 560SEL is getting brakes so is out of service; it appears it has the same 8mm motor mount bolts as the 1984 300DT so I should be able to use it.

That said, even with a two foot long breaker bar the motor mount bolt in the 1991 560SEL doesn't want to budge! Could I spray PB Blaster on it, wait, then clean the bolt up using brake cleaner? Thank you for any ideas or input......

Is it possible a local hardware store would stock this particular 8mm bolt for our motor mounts?

Yes, the hardware store has them. If you're talking the two small bolts on each mount they're M8x1.25x20 and for the larger center ones they're M10x1.5x40.

-Rog

Thank you thank you! I guess I need to put thread locker (blue perhaps?) on them when I reinstall?

As many as I've seen disappear, I would definitely do thread locker. It'll help keep them from getting corroded and stuck as well.

-Rog

YES ! What Rog said.

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

^ Sound advice. I always use thread locker on ALL bolts on the underside of the vehicle, any time I have them apart. Mainly because they seal the threads against water intrusion, and so I never have to worry about them being seized or rusted together. It sounds counter intuitive, but for this reason, using a thread locker product actually makes bolts *easier* to take apart later on.

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1998 E300 turbodiesel

America's Rights and Freedoms Are Not The Enemy!

Went to Home Depot, hardware man shared with me that hardware store bolts are generally not automotive grade. He said they need to be Grade A for motor mount use, otherwise they will snap off when you step on the gas!

12.9 or Grade A cap bolts are required for this application, I bought mine this morning at a local specialty fastener supply house.

I am using blue thread locker on them.

Most probably, the hardware man said "grade eight," which doesn't apply to metric fasteners in the first place. Where I live, Home Depot does indeed sell automotive grade fasteners.

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You want a 10.9 for the engine mount. Go to a real hardware store such as Ace.



SAE bolts are "graded". Metric bolts come in "classes".

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