Gl550 , bad engine mounts , procedure for replacement
08-31-2023, 06:34 PM
#26
i recently replaced both engine mounts in my garage, no lift, just a couple of jackstands and a jack. It’s a real pita but turned out fine. Wear gloves cause your hands will get torn up in those tight spaces.
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oldmangrimes (08-31-2023)
12-31-2023, 05:39 PM
#28
I just did the mounts on our 2017 GLS 550 with 52k miles. The passenger side was very, very difficult to remove. There's really not enough space to get it out, it took some use of a pry bar to move the engine to the side while it's on the jack and it took every millimeter of room to let me pry it out. The driver's side was a breeze in comparison. Came right out.
Couple notes:
The driver's side is the one that is going to go bad first because it's the one that is dealing with the engine's torque trying to lift away from the subframe. This is why we felt a "thump" every time we'd take off from a stop. I took a video of the old mount, it's completely shot, almost like it was about to completely pull apart. I'll post a video soon.
The mounts can be bolted in two ways, you can spin it 180 degrees and bolt it in either way, but they have two little tabs on top where the engine mount bracket would sit on them, and they tell you which way to orient the mount. They have to be pointing out towards the outside of the car, otherwise the engine bracket won't be allowed to sit fully on the mount, and then you can't get the large bolt through the mount and the mount bracket.
Tools I used:
3/8" e-torx bits sizes 10, 12 and 18. 10 for the downpipe to exhaust manifold and heat shield bolts. 12 for the downpipe to center exhaust clamps and lower engine mount bolts. 18 for the engine mount bolts. btw, the motor mount bolts are indeed VERY tight, it took me having to use a pipe on my 1/2" ratcheting socket wrench (along with some extensions, a reducer and a swivel) to break them loose. It calls for 85 nm when you re-torque them which is a lot when you don't have optimal room to work on them.
Ratcheting e-torx wrench with a 10 on one end and 12 on the other end for some of the heat shield bolts which are really close to the frame of the car (no room for a socket and socket wrench). I found it on Amazon and was here in a day.
22mm open end wrench for the O2 sensors.
3 of the 10" long 3/8" extensions, and a swivel.
Floor jack with a few blocks of 2x4 pieces of wood to fit on the lower oil pan.
8mm socket on my cordless driver to zip off all of the plastic splash shield bolts.
On the driver's side, it is impossible to remove the 3rd and final bolt for the heat shield that covers the engine mount and mount bolt. It's way up around and behind the mount, it'd only be accessible when the engine is completely out. All I did was bend the heat shield up and away enough to where I could get the bolt out and back in. Just bent it back in place with my fingers and got the other two bolts back in no problem.
I jacked up the engine as far as I could to where the back side of the engine is just touching the firewall. I was getting up and checking to see if the engine still wiggled when I pushed it around to make sure it was still free. As soon as I made contact, I stopped. Then back below, I used a crow bar to help rock the engine over to the driver's side to allow JUST enough room for me to pry the passenger side mount out and to get the new one back in.
I'm really surprised how bad the driver's side mount was. It's like they used a mount from a smaller engine car because I really don't think it should be that bad after only 50k miles. I've been working on cars for 30 years and never seen one this bad.after this many miles.
Couple notes:
The driver's side is the one that is going to go bad first because it's the one that is dealing with the engine's torque trying to lift away from the subframe. This is why we felt a "thump" every time we'd take off from a stop. I took a video of the old mount, it's completely shot, almost like it was about to completely pull apart. I'll post a video soon.
The mounts can be bolted in two ways, you can spin it 180 degrees and bolt it in either way, but they have two little tabs on top where the engine mount bracket would sit on them, and they tell you which way to orient the mount. They have to be pointing out towards the outside of the car, otherwise the engine bracket won't be allowed to sit fully on the mount, and then you can't get the large bolt through the mount and the mount bracket.
Tools I used:
3/8" e-torx bits sizes 10, 12 and 18. 10 for the downpipe to exhaust manifold and heat shield bolts. 12 for the downpipe to center exhaust clamps and lower engine mount bolts. 18 for the engine mount bolts. btw, the motor mount bolts are indeed VERY tight, it took me having to use a pipe on my 1/2" ratcheting socket wrench (along with some extensions, a reducer and a swivel) to break them loose. It calls for 85 nm when you re-torque them which is a lot when you don't have optimal room to work on them.
Ratcheting e-torx wrench with a 10 on one end and 12 on the other end for some of the heat shield bolts which are really close to the frame of the car (no room for a socket and socket wrench). I found it on Amazon and was here in a day.
22mm open end wrench for the O2 sensors.
3 of the 10" long 3/8" extensions, and a swivel.
Floor jack with a few blocks of 2x4 pieces of wood to fit on the lower oil pan.
8mm socket on my cordless driver to zip off all of the plastic splash shield bolts.
On the driver's side, it is impossible to remove the 3rd and final bolt for the heat shield that covers the engine mount and mount bolt. It's way up around and behind the mount, it'd only be accessible when the engine is completely out. All I did was bend the heat shield up and away enough to where I could get the bolt out and back in. Just bent it back in place with my fingers and got the other two bolts back in no problem.
I jacked up the engine as far as I could to where the back side of the engine is just touching the firewall. I was getting up and checking to see if the engine still wiggled when I pushed it around to make sure it was still free. As soon as I made contact, I stopped. Then back below, I used a crow bar to help rock the engine over to the driver's side to allow JUST enough room for me to pry the passenger side mount out and to get the new one back in.
I'm really surprised how bad the driver's side mount was. It's like they used a mount from a smaller engine car because I really don't think it should be that bad after only 50k miles. I've been working on cars for 30 years and never seen one this bad.after this many miles.
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FWP! (12-31-2023)
