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1986 560SL
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Discussion Starter · #1 ·
Maybe a dumb question but how does one get to that allen bolt (10mm) from below in the subframe? I can't even see the head (because of the control arm and it being recessed) to determine how rusty,etc. I was able to get a socket/extension/swivel/wrench up in there but it always seems like it ends up at an angle-so I'm paranoid I'll round it off. Everything I have read here talks more about the difficulty with the two smaller bolts holding the mount to the subframe (including a special tool someone fabricated). Can someone point me to a thread that might explain this in more detail or offer advice on how they did it? Local indie I called during a frustrated moment quoted me $390 labor (including rear):eek:. My biggest concern is determining whether or not they really need replacing-how does one know? I purchased the three mounts for $40 from a guy who changed his mind-if I do it myself and they are not too bad...a little labor on my part -no harm no foul. If I pay someone $400 and they are in O.K. shape-expensive way to lose some weight (in the wallet that is). I replaced the front shocks a few weeks ago and didn't notice the difference I was expecting after 131,000 miles. Went back to the packet of receipts from the previous owner(s) and :crybaby2: must have missed the fact that they were replaced at 88,000. No record of subframe bushes having been replaced but when I replaced those they were not too bad-nothing like I've seen on some of threads here. I just don't have the discretionary cash to be replacing stuff that can wait when there is so much else to fix on this car.

Thanks

Bob
 

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US spec MB560SL 1986, Audi A4 and A6, Ford Taunus 1964 17M and 2.0 1975
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1,433 Posts
Use long stick

I used long wooden stick from front/above the engine and turned the whole motor mount counter clockwise an half turn - the small allen bolt head comes visible. The power steering pump was loosened and turned aside.

I have posted those pics before but I can not find the that thread with my ipad.

I will post later those engine mount assembly pics again from my PC.
 

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US spec MB560SL 1986, Audi A4 and A6, Ford Taunus 1964 17M and 2.0 1975
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1,433 Posts
Pics....

Here are the promised motor mount assembly pics. I did at the same time the subframe bushings. By memory I loosened front shocs, engine shocs and power steering pump before the assembly work. I did not open the brake hoses or front stabilizer bar.

The subframe ruber bushings are easy to change when the engine is supported up.

Hope the pics will help you.
 

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560SL,380SL,E350
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Making the tool or having a very mini tool is worthwhile, as is replacing the motor mounts. As I recall, my 560's were shot, one being broken and the other one flattened, at less than 100K mi. It is easier to do this while you are doing the subframe mounts.

IMO, rounding off the screw heads, which leads to the torture of the damned, can be avoided by:

0. Liquid wrench soaking first, and waiting.
1. Good tools.
2. CLEAN the inside of the hex thoroughly first, with liquid wrench, and Q-tip or stick/rag.
3. After you know it's "in", tap in with a mallet a little to be sure.

2 and 3 are especially important. A little time spent here will save a LOT of time if you round something out here.
 

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1986 560SL
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Discussion Starter · #6 ·
Thanks YKA for the pictures. They help me better understand but I was curious about how you said the left big bolt (driver's side) was easier to remove from the top? How is that possible if the head of the bolt is underneath? I laid under the car for a couple of hours trying to get an allen wrench up that tube in the subframe but never felt sure I had a good grip because you can't see very much with the control arm in the way. Even when I completely removed subframe bolts. Also, you did not remove the two smaller bolts that hold the mount to the subframe through the wheelwell but by moving the power steering pump out of the way did it from the top?
 

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1987 560SL, 2000 Kawasaki W650
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I just looked up the thread on my engine mount replacement. This was the way I handled it:

I bought a new 10mm 3/8"s hex socket, marinated the fastener in Kroil for several days, cleaned the inside of the head and put some valve grinding compound on the socket for extra grip. That bolt is torqued at 70 nM, and has built up 26 years of crud and rust.

I second the above advice to give the fastener a couple of whacks with a hammer to loosen up the threads. (Put the hex socket on an extension and hit the end of the extension.)

If I had to do it again, I would follow mach4's advice and filled the mounts with urethane to increase their lifespan:

http://www.benzworld.org/forums/r-c...-sorry-looking-motor-mount-2.html#post5592961
 

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1978 280slc
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Another tip if you use allen drivers is to grind the head of the allen driver flat, they are made with a chamfered edge which reduces the amount of contact between the allen driver and bolt. My old man has to do this with torx drivers at the test lab, some torx heads only have .125 or less of driver engagement.
 

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1987 560SL, 2000 Kawasaki W650
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grind the head of the allen driver flat, they are made with a chamfered edge which reduces the amount of contact between the allen driver and bolt.
Didn't know that. I'll take that advice next time I want to get my steering wheel off.

Oh, and buy the best quality socket you can. The cheaper ones from "Hazard Fraught" are fine for less critical, light torque stuff. You can get individual ones from Sears or any auto parts store.
 

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US spec MB560SL 1986, Audi A4 and A6, Ford Taunus 1964 17M and 2.0 1975
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Thanks YKA for the pictures. They help me better understand but I was curious about how you said the left big bolt (driver's side) was easier to remove from the top?
Sorry my inaccurate wording - the big engine fixing bolt shall be removed from the bottom side, first. Two small engine mount bolts are easier to remove from top side. When you have removed the "easier" engine mount fixing bolt you shall turn the engine mount by long stick counter clockwise => the "difficult" small engine mount bolt head will became visible from top side, as pictured.

Also, you did not remove the two smaller bolts that hold the mount to the subframe through the wheelwell but by moving the power steering pump out of the way did it from the top?
By memory, yes - I loosened the power steering pump from it´s place to get more working room/space. When the power steering pump was aside the small engine mount bolts are better visible. After removing the "easier" engine mount bolt I used the long wooden stick and hammer to turn the engine mount counter clockwise and make the "difficult" engine mount bolt visible.
 

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1986 560SL
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Discussion Starter · #11 ·
Thanks for the advice all. I think I'll give it another try when the weather cools off later in the week. Still haven't figured out what combination of extensions, swivel joints, etc will get me up past the control arm to remove the main bolt on the driver's side. May have to buy some additional different lengths. Let you know how it goes.

Bob
 

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Just did the motor mounts on my 1989 560SL when doing the subframe mounts. Found both motor mounts completely broken which explains why the air intake tube was always coming off I expect.
Thanks to the original submitter. I found it very helpful! My Tips:
1) You can get penetrating oil on the Big Bolts (M12X80s that go in through the bottom of the sub-frame and through the mounts) from inside the wheel wells. You will see the bolt coming up through the metal engine shock mount that has the nut attached to the top.
2) I used the "pivot the motor mount" technique above to get at the second small bolt holding the mount to the frame but executed the pivot through the wheel well with a crow bar vs broomstick. Reversed that when putting the bolt back in.
3) Tried removing one Big Bolt with an impact gun using an extension and 10mm allen socket. Immediately stripped the head. Had to take the bracket (aluminum one clearly seen on the left side of the photo posted above that has the caption "This bolt shall be removed first") off the side of the engine (4 bolts) and then took the broken mount, bracket and assorted attachments out through the front of the wheel well, onto the bench and drill out the head of the bolt. Once the head came off the bolt unscrewed from the nut with just my fingers so no corrosion. Got the other Big Bolt out with a 2 foot breaker bar.
 
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