Damn Air Cleaner Mounts - PeachParts Mercedes-Benz Forum

psaboic · #1 04-10-2019, 12:34 AM

Does anybody have a decent solution for making the W123 rubber air cleaner mounts last? My 83 300D breaks them on a fairly regular basis. The last set lasted a whopping 10 days.

BWhitmore · #2 04-10-2019, 12:58 AM

The genuine Mercedes mounts last a long time but are $22.75 each. Using the heat shields does help some. The mounts that are less than $3 each are junk.

Squiggle Dog · #3 04-10-2019, 01:27 AM

I did a permanent fix on my air cleaner mounts. The bolts tend to tear out or the rubber rips in the center, and then the air cleaner starts coming off. Mercedes diesel owners just replace these regularly and figure it's part of the hassle. I said no more and fabricated my own unbreakable mounts.

I bought six new mounts and cut the bolts off the ends, leaving just the rubber.

Then I ran the rubber on a belt sander to get them flat and the correct height.

Next I made some holders out of hardware. If I remember correctly, for each mount I used a 35mm M6 1.0 bolt and cut it down to about 33mm. I put a split washer and then a flat washer on it and threaded it up through the bottom of the air cleaner mounting bracket. Then I installed the heat shield, three 1/4 X 1" stainless fender washers (the lowest one needed to be filed around the edges until it fit down all the way). Then I threaded on an 11mm long M6 1.0 coupler nut (I couldn't find these locally and had to order them online) and secured it with blue threadlocker.

I drilled holes in the rubber and slid them down onto the holders. I think that the clearance between the air cleaner and bracket is supposed to be 18mm, so I probably made the lower rubber spacer 14mm tall as the total height of the heat shield and washers was about 4mm.

Squiggle Dog · #4 04-10-2019, 01:27 AM

I made more rubber spacers (about 11mm tall, I think) to go on top of the air cleaner after it was mounted, so it would be sandwiched and allow for vibration to be absorbed in both directions. I cut down some M6 1.0 joint connector nuts (which I had to order on eBay from Lithuania) to about 7mm tall to thread down over the rubber, until the ends of the bolts bottomed out inside of the nuts right after slightly compressing the rubber. Blue threadlocker was used to keep them from loosening.

It all fits together nicely and the new mounts I made cannot just rip apart in the center like the original design, yet they still absorb vibration just as well, if not better.

The stock air filter still fits.

Here is the air cleaner all put back together. I will have peace of mind knowing that I won't suddenly hear clunking, only to find that the air cleaner has broken loose from the engine again.

rocky raccoon · #5 04-10-2019, 05:59 AM

I simply drilled out the holes in the bottom of the can a little so there was no sideways shear stress on the rubber mounts. With the use of the heat shields, my URO mounts have been good for 4 years so far.

I like squig's idea of putting a rubber washer on the inside and will do that at next filter change.

It also helps to tune your engine to minimize vibration.

tyl604 · #6 04-10-2019, 08:12 AM

Or you can just remove the metal plate and screws on top and bottom and drill a hole through the rubber; then run a long screw with washer up from the bottom. That's what I did and they have lasted for years.

Squig's looks a lot more professional.

97 SL320 · #7 04-10-2019, 09:26 AM

This type of stud mount can be damaged during install if torsion is applied to the rubber. If the engine is worn out and shakes a lot, everything is going to fail at some point.

The bolt through mod will work, but it needs a spacer in the center so the bolt has something to tighten against otherwise the nuts will become loose / holes become worn / mount is now solid. ( One pic shows a washer spacer combo that solves the problem.)

For premmade bolt through mounts , have a look at Lord Rubber. https://www.lord.com/ Also look at McMaster Carr , they carry many mounts.

JimFreeh · #8 04-10-2019, 09:45 AM

I've had good luck with mine by wedging a piece of rubber between the cam cover and the filter housing.

Got another OM617 last year with some broken mounts, and after replacing the three mounts, took an old one and used that rubber to wedge. We'll see how long it lasts, but if memory serves, I didn't have much issue with the mounts back when I was running these as drivers using this hack.

I recall seeing this tip many years ago on another tech list, likely the Ritter-Easley list, before Ritter took it over.

Jim

SD Blue · #9 04-10-2019, 09:55 AM

Once I installed the heat shields and did a fine tuned valve job, I haven't had an issue in 5+ years.

Diesel911 · #10 04-10-2019, 11:06 AM

Before I fixed the issues that were causing the excessive vibration I found in an old thread you put like a 6 inch section of 3/4" or 1" heater hose (I can't remember which size) between the manifold/valve cover and the bottom of the Air Filter Hosing.

I believe fixing the vibration issue will increase the life of your Motor Mounts.

In the attached pic one of our members used what apparently is a piece of angle iron and a rubber bumper making contact with the valve cover side of the air filter housing.

Squiggle Dog · #11 04-10-2019, 01:07 PM

Sometimes these rubber mounts can last a few years if all conditions are correct. But, even then, surprises happen, and I didn't like how vulnerable it made me feel that they could break at any time.

The way I engineered them eliminates the possibility of them failing, as there is a bolt that goes all the way through. However, rubber is required on both sides of the air cleaner so vibration can be dampened on both ends. If one were to simply put a bolt through a rubber mount, it would dampen in one direction and be rigid in another, which would cause rattling and would also reduce the overall dampening effect by about half.

As 97 SL320 points out, the through bolt needs to be secured by more than just pressure from the rubber. What I used was a coupler nut so the bolt which threaded up from the bottom was secured on its own, and then the joint connector nut which secures down the air cleaner had to be the correct length so that it would tighten up snug against the coupler nut on the bolt and compress the rubber a little.

I like that you can buy rubber mounts that are pre-drilled for through bolts. I'll have to look them up. I thought of using hose, but finding the correct inner and outer diameter would have been difficult, and I wanted the same shore hardness that is specified for the original mounts (whatever it is). It was a pain cutting and drilling the mounts.

I had considered selling these as kits but it's difficult to gauge interest and to know how long it would take to get my investment back. I used to sell Viton O-ring kits for the OM603 engines, but it just took so long to get my investment back and I'm pretty broke. So, hopefully someone finds my idea helpful, even though it's kind of a lot of work initially, but it pays off in the long run because you don't have to fear your mounts shearing while you're on a long trip away from home.

Maximan1 · #12 04-10-2019, 01:08 PM

I did the direct mount mod on my 240D, and one of the studs I used broke off flush with the intake manifold and I wasn't able to get it out with an EZ out + heat.

Coincidentally, the engine never started again after I attempted to remove that broken off stud.

The rubber is there to isolate the vibration. The stud mount I used was only temporary (my air cleaner was bouncing around like crazy and parts were a paycheck away). I am spending the extra $$ on genuine Mercedes mounts for my rebuilt OM617.

Squiggle Dog · #13 04-10-2019, 01:12 PM

For what it's worth, I had my engine finely tuned, freshly replaced genuine Mercedes engine mounts and dampers, heat shields, and new air cleaner mounts, a hose wedged between the intake manifold and valve cover, and the mounts sheared off after only a few months. At that point I decided I was done playing this game.

Diesel911 · #14 04-10-2019, 03:11 PM

I have had the Air Filter Housing Mounts get loose but I have never had to replace them and I have owned my Mercedes since 2007.

h3ffe · #15 04-10-2019, 03:31 PM

Step 1: Go to 99 cent store
Step 2: Buy rubber door stop (they come in a 3 pack, so your friends can have shake-free air cleaners too!)
Step 3: Wedge and tap rubber door stop between air filter housing and valve cover using a block of wood and a hammer
Step 4: Enjoy your quiet ride.