Well, I did it! I replaced the 2 front engine mounts this evening. I just got finished cleaning up a few moments ago. Wow - that was a tough job! I never NEVER would have done it without the helpful, insightful info from Cees and Rodd. Thanx again guys.
There's a couple of things I'd like to add to Cees' post on this thread, which might make it even more straight forward for the next poor slob who attempts this. Here's the "Blair Wagner" version (revision) of the task:
Engine removal is not necesary. A good experienced technician can labor through the job in about an hour. That's with MASSIVE experience and the right tools and no unexpected difficulties. Plan to spend three or four hours if you are an intermediate mechanic. If you're a beginner, forget it! Take it to someone for help!!!
There are some important tips and basic tools you'll need. Make sure you have a 1/2" drive rachet-handle or breaker bar, a 12" or longer extension (also 1/2" drive), a 19mm swivel socket (built in universal) or use a swivel extension. If you don't have one, you might get away with a smaller 19mm socket and 3/8" rachet - if the bolts aren't too frozen.
You will also need a 6mm allen-socket (a socket with a 6mm allen sticking out the end, 3/8" drive is ok for this with extension and handle). You may want to have a traditional 6mm allen wrench on hand also. Some lubricating oil fo free up rusted bolts is VERY helpful, like WD-40 or Liquid wrench.
If you do not have a lift or hoist then a floor jack and a nice 10" section of board at least 4 inches wide will work for lifting the engine. Your neighborhood Sears or other tool store can supply these tools at an affordable price.
If possible, a day or two before you do the job, spray the lubricant (WD40, etc.) on the top 19mm bolt, and the two 6mm allen key bolts, and alow the penetrating oil to loosen up the rusted threads, if possible.
Step number one make sure you have the correct parts. If you are using the original round style there is a right and a left. Pay attention to the part number and be sure to install on the correct side. My Edition C dealer parts book gives # 127-223-12-04 as left and 127-223-11-04 as right. These numbers have probably changed. Kits were also available with some of the hardware and other minor parts. Kit # 110-586-02-22, I do not know if it is still supplied or if the number has changed. Maybe one of our other listers can help us here.
Plan on removing and unhooking one side at a time. If you unfasten both sides, the installation and alignment becomes more difficult.
Start with the driver side first. Begin by removing the Fuel filter housing (and filter). This will afford you a great deal of access space from underneath, up front.
Unbolt the large 19mm bolt in the top of the mount on one side. If you do not have a hoist, the floor jack with board will work nicely. Position the wood board on the bottom of the engine sub pan so that the jack does not damage the pan. Make sure that the jack and board are positioned to off center, toward teh driver side, so that you lift the driver side of the engine. Be gentle, take it slow as you raise the engine. You should be able to get about an inch or so above the old mount.
Next spend a little time cleaning out the grease and grit from the sockets of two allen bolt heads. If the heads of these allen bolts strip then the project becomes much more difficult so spend some time cleaning them out. Do not be tempted to use anything but a good grade allen tool. Now remove both 6mm allen bolts. The front most allen bolt is most easily accessed from underneath the car, in front of the tire, through the position where the fuel filter was. Try not to get dirt into the fuel filter head.
The rear bolt is actually easily accessed by leaning your belly (gently) on the brake booster, and reaching your right hand down, to the right of the brake booster, behind the injection pump, and then forward to the bolt. I know it sounds like a yoga exercise, but it's really pretty easy. Depending on the size of your 3/8" wrachet head and socket allen key, you may not be able to use them. A standard 90 degree bent allen key worked best for me. I used the little allen key to remove both bolts on the driver side. If an allen bolt head begins to strip, take a heavy drift or punch and smack it, the shock will loosen up the rusted threads. This really works!
After both 6mm allens are removed the mount can be lifted out. If your old mount still has the torque plate attached, you may need to lift the engine more than expected. There's a plate bolted to the underside of the engine mount. The plate and bolt that fastens it to the engine mount protrudes down and makes it difficult to extract the engine mount unit. Once extracted, remove the torque plate and install it on the new mount. It's juyst one large 19m bolt that attaches the torque plate to the mount.
Install the new mount by first inserting the two 6mm bolts, but do not tighten them securely yet. Lower the engine a bit and then install the 19mm bolt. You may need to "wiggle" the engine around to align the engine bracket to the hole in the engine mount. Don't get discouraged - it will happen. You may need to raise or lower the engine in small increments until the hole is lined up. Lastly tighten the 19mm and 6mm allen bolts.
Lower the engine and remove the jack. Move the jack and board to the passenger side of the pan, but don't lift the engine yet. This 19mm bolt is harder to get too, due to less access space under the intake manifold. I used a smaller 3/8" rachet and 19mm socket. With a little muscle, free the bolt and remove it. My car has a bracket bar for the A/C held down by this 19mm bolt. If you have it, you'll need to bend it up and to toward the fender (away from the engine) to get it out of the way. Don't worry, it will easily bend right back.
Raise the passenger side of the engine using the floor jack and board (or hoist). Now, remove the two 6mm bolts. The front most bolt is best accessed by leaning on your belly on the car fender, and reaching your right hand down in front of the manifold, and back toward the bolt. Your 3/8" rachet and 6mm allen socket will do fine. The rear bolt is easily accessed from under the car, behind the passenger tire (lay down under the passenger door). Again the rachet and socket allen key will work fine.
Note: you will have to raise the engine as far as it will go. I had to raise it so much, the engine cooling fan made contact with the shroud. There was no other way to get the old mount out and the new one in. Again, the torque plate bolted underneath the mount really makes it tough. Once you do wrestle it out, remove the torque plate from the old mount, and install it on the new one. Wrestle the new mount into place.
Again, install both 6mm allen bolts but do NOT tighten them. Lower the engine a little, and bend the A/C bracket bar back in place (if present). Insert the 19mm bolt and again "wiggle" the engine around to line up the hole. It may be necessary to lower the engine a little, in small increments until it lines up. Tighten the 19mm and 6 mm allen bolts. I just made them all hand tight. I have no idea what torque setting to tighten them to.
Reinstall the fuel filter and housing. Be sure everything is super clean! You don't want dirt getting into the injector pump!
One last thing, after cleaning up your tools, check the engine compartment carefully for any wires or hoses that may have come off their fitting, and reconnect as needed.
One side note; the later Mercedes 108 series square style sedan mounts fit and seem to work fine. They are a later design, are universal (both the same, no left or right), the torque plates do not seem to be necessary. They bolt up and installation is exactly the same.
The V-8 series 108 mounts are heavier duty and may be more suitable for competition in the 113 series possibly? They seem to be stronger and last longer also. They may be less expensive and easier to come by? I've done this change many times and it seems to work fine. This is just another option to consider. The part number for the 108 series 6 cyl. sedan was 108-223-01-12 (both sides) or the 108
8cyl sedans (280-SE 4.5) #116-223-01-12 (both sides)."
One last tip: unless you're really a DIY enthusiast, I'd recommend paying someone else to do this. This job was far more difficult than I expected. But, good luck, if you decide to do it yourself.
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William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
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