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I'm hoping it can come out the bottom, but I'm guessing it has to come out from the top.
I haven't looked it up on WIS because it probably has the S550 not the S600. They are similar, with the ABC tandem pump sitting on top, but I'm guessing the V12 has far less room.
Done it before on a V12. It has to come out from the top. You’re right, the WIS won’t match perfectly because of the ABC pump.
You have to pull the radiator fans and the fan shroud first to get any kind of room. Then you can get to the compressor bolts. It's tight, but it beats dropping the subframe. Expect a lot of skinned knuckles.
I'm hoping it can come out the bottom, but I'm guessing it has to come out from the top.
I haven't looked it up on WIS because it probably has the S550 not the S600. They are similar, with the ABC tandem pump sitting on top, but I'm guessing the V12 has far less room.
Any advice welcomed. Regards... Mark
I got to do this in my 221 S-65. I pulled the fan and radiator. Is not fun but do-able in a day for a D-I-Yer the first time you do it. If you don't have a hoist; rent time on one. It comes out the top.
That's what I thought. No one mentioned the ABC pump. Does it have to come out? I'm hoping not... Alexie said just the fan and shroud. John said fan and rad. Is it worth taking out the rad, or can you work around it?
I have 77K miles. I'll take a look at everything when I'm in there. I'll have plenty of time to order parts, given the scope of this job, and how long it will take me...
My hat is off to Alexie and John, who actually did this replacement on the V-12. Here’s my story.
I got an aftermarket compressor and attempted the R&R. I removed the hoses and got the fan and shroud out. I even got the bottom bolt off the compressor. I could have gotten the top bolt off, but needed different tools. No big deal, but my brain told me, “you’re going to have to get to a bunch of sh** you can’t even see! And, do you really want to do this?”
My answer was, no. So, I called the nearest dealer.
Sidebar: I have never taken my car to the dealer, or anyone else for repairs. And I’ve done all my own repairs, including the ISM; a job I wouldn’t wish on my worst enemy. But, this one— compressor replacement— left me frustrated enough that I decided I’d pay whatever price the dealer wanted.
So, I put everything back together, and 39 days later (Yes, the car was at the dealer that long) and wallet $6100 lighter, I have new comp, belts and pulleys. Bright side: MB Roadside Assistance picked up the 50 mile flatbed fee (est $400) and the dealer delivered the car back to my house. I never set foot on their property, or had to leave my Island!
Tech Tip: If your AC compressor goes out, don’t think you can drive the car with the AC off.
The compressor pulley is not steel. It’s a composite, and will disintegrate, leaving you with no serpentine belt, i.e., no PS, alt, ABC, etc.
I was lucky, in that, I was only moving the car a short distance when mine blew apart.
Since these AC compressors are pretty much ubiquitous, I assume this Tip applies to everyone on this forum.
$6100.00 I'm thankful to be able to do such things. I didn't enjoy getting to pull the fan and radiator all the times that got to happen in 2020 and early 2021 to replace everything in front of the engine in whack-a-mole fashion due to not having the $$$ or sense via the clear lens of hindsight to do it all at once.
OP if you don't have equipment to evacuate and recharge the A/C DIY-ing the compressor only makes sense if you were to then tow it to someone who can as the compressor won't live long without refrigerant and lubricating oil doing its job to lubricate and cool the compressor.
The A/C compressor is the second worst job to do on the front of the engine. Worst being the Duo-Pump. There are fasteners for that one that I was cussing at with the engine out.
You can purchase a shorter belt to bypass the A/C compressor. I had to do this when the pulley bearing went bad during the winter, I drove all winter and part of spring with a shorter belt that bypassed the compressor. I wound up purchasing a used compressor and installed it over the course of two days. I purchased some A/C manifold gauges and vacuum kit to service the A/C. Note this wasn't a V12, regular m273.
John-- Yes, I had the HVAC equipment to evacuate and refill the system. There are a few other things that made me reconsider whether I wanted to do this.
1. I didn't want to damage the evaporator coils or crack the elbows, and wind up with a larger job.
2. I bought a presumably Chinese knockoff compressor, and had read elsewhere that these may not hold up. So I did want to do it twice…
3. Even though I was close to removing the compressor bolts, I couldn't see how to get the high and low lines off the top of the compressor, since they're right under the duo pump. And, there's just no room in there. I'm guessing you can pull the compressor out enough to get to those fasteners. Is that how it's done?
The breakdown of the $6100 was about $4000 labor and $2000 parts, including MB compressor, idler pulleys, tensioner and belt. So, I shouldn't need to go back in there for a while.
Also, I looked at WIS for the S550. IRRC, the instruction is to take off the front end of the car?? I’m not sure how the dealer did it, but they told me they put their best tech on it. Did I mention it took 39 days? Anyway, they didn’t charge me for any extra parts, so I assume they didn’t break anything, and did a professional job.
Phil-- That's a good tip on the shorter belt. Especially if it's not the hot time of year. I'm in the tropics, so it's always the hot time of the year. But, yes, if you need to use the car, that's pretty much the only option without replacing the compressor. Even if the pulley on the compressor is turning, it's my experience, it will break after only very a few miles. So, be forewarned.
Besides noise, a telltale that it IS the compressor, and not just a leak, is an electrical burn smell. At least that was so in my case. Also, in my case, I caught it early enough that, I was able to hear the refrigerant leaking out at the compressor clutch. I was surprised that the composite pulley came apart; I didn’t see that one coming, and I assumed it was okay to continue to drive the car without AC. It’s not, and from what I’ve read, I’m not the first to have this happen. Bottomline: driving with a bad compressor is a risky proposition.
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