What is this engine bay part?

[Rain]

See the photos below. It appears to be 1 of 2 guides for the big air box to slide into for alignment over the engine block. My driver’s side one is still firmly attached, but the passenger side one recently broke off, and looks like it had been super glued on by the previous owner. My mechanic noted that it should have a fastener on the bottom to attach it to the solid cast metal on the block

Anyone know the name and part number?

 

[liviu165]

That looks like a vibration isolator. The rubber separated from the stud. Maybe one of the m119 experts can advise on the part number.

 

[gerryvz]

A very good question, and thank you for observing and asking it.

Yes, as the @liviu165 says, that is one of the two rear vibration ("isolator") mounts for the rear airbox that screws into the top of the valve cover on each side.

You need to remove the broken off stud that is screed into the valve cover (it should have a round plate), per your photo above, by gripping it with a pair of pliers or a vise-grip and turning it.

Then, also remove the hexagonal piece that is screwed onto the piece that you showed in the photo above.

Get a few new parts (an extra or two is good as these do break) from your handy mail order MB parts place online (such as MB Annapolis or other online dealer). Part number is 103 988 01 11. Current MB list price is $6.50; discounted ~$4.60 each.

When you get the new mount, unscrew the hex piece from the old mount and screw it back onto the new one. Then screw the new mount into the intake manifold. Take care not to cross-thread anything, but it should go on just fine.

Good idea to do the other side as a proactive replacement at the same time. These mounts are cheap and get heat baked by engine heat back there.

These are also used on the M117 engine.

I just got a few spares a few weeks ago to join the two spares I already had in hand. Here they are and this is what they look like.

Cheers,
Gerry

 

[LWB250]

To add to Gerry's comments, I highly advise you buy some spares and keep them on hand, as these are prone to fail over time for the reasons stated. That, and they're used on decades worth of Mercedes models, so if you ever get another or more Mercedes', you'll use them, believe me.

Also, be sure to get the OE parts. These are cheap, relatively speaking, and aftermarket versions are typically made with low grade rubber that fails in a short time, often under a year.

Dan

 

[Rain]

Thanks so much, @liviu165, @gerryvz and @LWB250! I appreciate all the helpful info. I’ll order myself a few pairs today.

 

[dionphaneuf]

I suspect these are broken on ~90% of the cars that had them from the factory.

 

[Rain]

I suspect these are broken on ~90% of the cars that had them from the factory.

The way it’s metal attached to metal by way of fragile plastic seems so un-German.

 

[luckymike]

I suggest applying some anti-seize to the threads and to just turn these in finger tight.

 

[gerryvz]

I suspect these are broken on ~90% of the cars that had them from the factory.

Yes, they are very commonly broken off. It's a good proactive replacement to do for everyone. I did both of mine this summer when I did my top-end rebuild job.