Changed out the shredded strut boots on my 1991 300CE, 136m. While I was there, also changed out the strut mounts which were original. They looked OK from the top with minor cracking but after removing them, there were bigger cracks in the rubber on the underside. I also had new bumper stops ready but the originals looked pretty good so I left them in until I need new struts.

I was hoping to do this repair without completely removing the strut and it turns out you can. On the first side I took off the wheel but on the other side I didn't even do that and this adds to the safety margin. I was nervous about working around that spring, so I studied a lot of posts. This topic normally brings up two positions, 1) to have a jack stand under the control arm and the weight of the vehicle compressing the spring and 2) the car on jack stands and a jack under the control arm, compressing it a bit. I did it using method #2.

The repair calls for a deep offset 22mm box wrench. I made do with a 22mm Craftsman stubby that has a slight bend to it.

This is how I did it. Observe all safety precautions! Chock rear wheels. Jack up one side of the car at the jack pad and place jack stand under side rail just before it turns up. Place jack under control arm as close to the wheel as you can and jack up a few inches. I jacked until I could see the spring being compressed. The spring MUST stay compressed while you take off the three 13mm mount nuts and the big 22mm nut. Dry fit the boot to the underside of the new mount to see how it goes. It attaches to the smaller flanges. First break the 22mm nut with a socket. Hold the rod with a 7mm allen while you loosen the 22mm nut with a box wrench. Remove the three 13mm mount nuts. Check your jack again. I used a big screwdriver to compress the strut and then grabbing it from underneath, I slipped off the old mount. If you get tired wrestling with it, you can tilt the strut and let the rod expand part way until it hits the underside of the car where the mount goes. Compress it again and slip on the new boot and then the mount. You don't need to attach the boot to the mount at this time. I did this last. Torque for the three 13mm nuts is 20Nm. Again hold the rod with a 7mm allen while tightening the 22mm nut. Towards the end of the tightening, the rod will stop wanting to spin and you can then finish up with a socket and torque wrench, 60Nm. Lower the control arm, remove jack stand and do the other side. It will go even faster. I attached the boots to the mounts last. Mostly by feel. If you have them mostly on, spinning the boot helps seat them. Also you won't be able to attach them at the lower point until now anyways as they won't stretch all the way with the wheel dropped.

Looking forward to when the struts need replacing, I think I'll opt for using spring compressor. If the logic is you should never go under a car supported with just a jack, then you should never work around that spring (with the strut removed) with it being compressed just by the jack.

glenmore
1991 300CE
2000 C280
1990 LS400

I just jacked the car up on that side enough to get some room, leaving the tire firmly on the ground. Same procedure. Bit of a wrestle if the shocks are good.

Changing the strut is similar, just put a jack stand under the control arm and you will be fine -- leave the weight of the body sitting on the jackstand. I took the strut off to replace a ball joint. No problems.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!