2000 C280 w202 motor mounts

[glenmore]

I am past the easy part of doing these motor mounts. I have done the easier passenger side by removing the alternator and pulling the old mount thru the front. While I had the alternator out, I changed the voltage regulator. Top mount bolts were not too bad.

I have read 2 accounts on doing the driver side, one from the front by releasing the AC compressor and moving it aside and another from the rear by releasing an oil line and manipulating the tie rod/idler arm assembly. The rear removal looks awfully tight.

Can anyone confirm which way is easier? In releasing the compressor, just the 3 bolts and let it hang by the hoses?

Thanks,

glenmore
1991 300CE
1999, 2000 C280
2000 C230K

[glenmore]

Just did the motor mounts on my 2000 C280, 90k. I had the rough idle while stopped and it would almost go away when slipped into neutral. Car ran fine and the vibration was not noticeable at speed. The definitive test is to jack up the engine a little bit to see if the vibration goes away which it did in my case.

Here are a few things that might make it a little easier for you. All the usual caveats. Work safe!

You don't want to do this repair again anytime soon so buy good parts, OEM if possible, I used Corteco. Stay away from ebay parts!!!!!!

Put front of car up on jack stands (Important! not ramps, wheels need to be free to turn). Chock rear wheels.

Unlock steering wheel and THEN unhook battery.

Remove 13mm lower mount bolt both sides.

Passenger Mount:

Removal is to the front so alternator needs to come out, but check my later thoughts below.

Release fan belt at the idler pulley with E10 torx on the belt tensioner, CCW. Remove fan belt from around alternator pulley and rest on dip stick.

From below, remove splash guard to the right of alternator, 2x8mm washer bolts. (Alternator will not drop with the slash guard in place). Disconnect two wires to back of alternator. Remove lower E14 torx alternator bolt.

From above remove upper E14 torx alternator bolt. No chance of the alternator dropping as it is held tight by its bracket. From below, pry it loose, or you might get it started from above. If you have around 100k and haven't yet changed your voltage regulator, now is a good time. Three screws for the black cap and some clips, then gently pry off. Voltage regulator just 2 screws.

Top mount bolt is 16mm, kind of an odd size. SAE 5/8" works well. Lot of different tools that you can use here, stubby combo wrench, saltus wrench, low profile flex socket with short extension as a handle. Plenty of room to get both hands on the bolt. You may be strong enough to break the nut as is, if not, a good method is to pry against something solid and your wrench. All you need is one good pry to break the bolt free. I put the upper alternator bolt back in a few turns and that provided a nice slot for the pry bar. Remove the 16mm bolt and the heat shield. Then jack up the motor with a broad piece of wood under the oil pan. I do this in small increments, but this is probably not crucial as an old mount is about a 1/2" shorter than a new mount and you'll have to raise the motor the 1/2" and then some to get the new mount in. Remove old mount, sweep away grit in the mount seat. Note that the slot in the mount bracket (attached to the block) is facing away from the motor. Raise the motor until you can get the new mount in, locating pin of the new mount in the mount bracket, and the heat shield and put in the upper bolt finger tight and the lower bolt in a few turns.

Driver mount.

I read one version where the DIYer eased the AC compressor aside to remove this mount to the front like the passenger side mount and another DIYer who did it thru the rear by removing some hose brackets. I really didn't want to mess with the compressor, but it looked pretty tight from the rear. I had time so I decided to monkey with the rear removal. Release two metal hose brackets, one on the tranny pan and one on the oil pan. There is a heat shield to the left that you may be tempted to remove but the upper bolt is really tough so I didn't bother, and turns out it didn't need to be removed. Same as with the other side, easy access with both hands to the top mount bolt, use a short wrench and pry against something. Raise engine enough to get the mount out of its seat. Sweep out grit. To get the mount out, manipulate the left front wheel to move the idler rod and tie rod into the perfect position to let the old mount pop out. IIRC it came out tail end first. Work in the new mount the same way.

Button everything back up. Drivers side routine. The alternator is a real pill. Pay attention to the bushings in the brackets where the alternator is held. I started with the bottom bolt and with a stoke of luck the alternator slipped in for the lower bolt. Start with the side opposite the side with the bushing. There must be a reason those bushings are there. For a small pry bar? I then held the alternator aside and quickly put in the splash shield. This prevents the alternator from rolling down. I found it just about impossible to get the alternator into the top part of the bracket. I tried and tried but nothing worked. Finally in looking at the bracket I see the three bolts just to the left of the water pump pulley. I eased all three of them and the alternator slipped right in. I don't know if this is a good procedure as these bolts must hold some part of the water pump on, but I eased them as little as possible.

Additional thought: Book time is 2.5 hours so a tech could most certainly be able to do it in less time. I'm guessing that the correct procedure is to remove both mounts to the rear and the time consumed in removing and replacing the alternator is not necessary. On the passenger side there is just the heat shield for the o2 sensors with 2 easy bolts. I already had the alternator out, but I probably should have tried the same method of moving the right wheel around to allow the mount to slip thru as on the drivers side.

Either way, not too bad a repair and an easy way to save a little money.

[cgshawaii]

I tried getting it out the back but was not successful.

I had previously changed the compressor and was not happy to have to remove the bolts, but all in all it wasn't that bad- much better than the time I spent trying to remove from the rear.

My vote is to take it out the front after you unbolt the AC compressor.

[WilliamMcLean]

Apologies for resurrecting an ancient post, but this was extremely useful in working on my 2000 C280. Thanks, Glenmore!

I initially tried working on the drivers side by removing the ac compressor, and couldn’t get the mount out the front so I’ll be trying your approach tonight for the rear removal and will report back.

On the passenger side, one tip I found useful for replacing the alternator was to spray the bushings with penetrating oil, wait, and then grasp them with with pliers and ease them forward (towards the radiator) with a twisting back and forth motion. This was easy on the top bushing, though more of a challenge on the bottom one. It was much easier to pop the radiator back in, and the process of torquing down the bolts moved the bushings back into the right spot.

Fingers crossed I can finagle the mount out the rear - thanks so much for this great write-up.

[WilliamMcLean]

Full update, for any lingering 98-2000 c280 owners.

At about 230k miles, all three of my mounts were shot. The transmission mount is relatively easy 10 minute job.

The passenger (right) and drivers side (left) mounts were both replaced successfully. I highly recommend purchasing the Mercedes offset 16mm motor mount wrench, since access to the top bolts is a bit tricky from above on both mounts (the exhaust manifold sits directly over them).

Glenmore's approach to the drivers side mount worked perfectly, although the fit was tight. As I worked the old mount out and the new one in, moving the tire slightly back and forth allowed enough room to pop it through. I was working alone, and having the steering wheel unlocked with the battery disconnected made it an easy job to do from underneath.

I spent several hours working on the passenger side mount, since the alternator is a pain to free and replace (though much easier once the bushings are worked forward). The drivers side only took about an hour once I tried this approach. All told, it was pretty easy, and less work than the ac compressor approach. I had spent a few hours trying to work it past the unhooked ac compressor on a previous night, and it wasn't working.

Do one mount at a time, and it while it isn't an easy DIY, it's pretty doable. I used Lemforder, and definitely second the advice to avoid cheap parts. You really don't want to be doing this job again any time soon. I've heard horror stories of cheaper mounts giving out after 20-30k miles.

[Ferdman]

William, next time I recommend using a combination of a bolt, nut, washers and a short piece of plastic pipe that fits around the alternator mounting braket sleeves to slide each sleeve forward. It's much easier and less likely to damage the sleeves and/or mounting bracket than using pliers.

[WilliamMcLean]

Thanks, Fred! Great suggestion to make a little press for the bushings. I'll give that a try next time, and would recommend others take that approach too.

[sgoespp]

Originally Posted by WilliamMcLean

Full update, for any lingering 98-2000 c280 owners.

At about 230k miles, all three of my mounts were shot. The transmission mount is relatively easy 10 minute job.

The passenger (right) and drivers side (left) mounts were both replaced successfully. I highly recommend purchasing the Mercedes offset 16mm motor mount wrench, since access to the top bolts is a bit tricky from above on both mounts (the exhaust manifold sits directly over them).

Glenmore's approach to the drivers side mount worked perfectly, although the fit was tight. As I worked the old mount out and the new one in, moving the tire slightly back and forth allowed enough room to pop it through. I was working alone, and having the steering wheel unlocked with the battery disconnected made it an easy job to do from underneath.

I spent several hours working on the passenger side mount, since the alternator is a pain to free and replace (though much easier once the bushings are worked forward). The drivers side only took about an hour once I tried this approach. All told, it was pretty easy, and less work than the ac compressor approach. I had spent a few hours trying to work it past the unhooked ac compressor on a previous night, and it wasn't working.

Do one mount at a time, and it while it isn't an easy DIY, it's pretty doable. I used Lemforder, and definitely second the advice to avoid cheap parts. You really don't want to be doing this job again any time soon. I've heard horror stories of cheaper mounts giving out after 20-30k miles.

Hi WilliamMcLean,
I am planning to replace the mounts on my 99 C280 (M112 engine), same as yours. Could you please confirm the following? -
1) With the 16mm Mercedes offset wrench, did you loosen both mounts top bolt from the top or from the bottom of the engine?
2) So you had to unbolt and move the alternator and the AC compressor for doing both side mounts respectively?