2005 Mercedes-Benz CL65 AMG: Back in the Shop
July 24, 2014
The problem started about a week back. I texted Mr. Takahashi at some point mid-morning on a Saturday with concerns about an intermittent noise at full throttle (weee!) from our CL. We checked out the car, he made pastrami sandwiches (pretzel bread, lots of mustard) and then we took a test drive. The noise happened once every 3-4 pulls and neither of us had any idea what it could be.
It sounded a bit like a blender with the blade disconnected was sitting just in from the driver, glued to the firewall and happened during acceleration and for a second when you let off. Belt? Turbos? Transmission? Someone said if it had a speedometer cable, it could be that.
In any case, Mark and I couldn't figure it out. So instead of taking it to the Mercedes dealer again, we took it to an indie shop around here that comes well regarded. During the test drive, the shop owner made one of those faces that says "that's crazy" when the noise happened. I asked, "Is that a 'I know this problem well!' or a 'I've never heard that before' face?" He said he'd never heard it before and we headed back to the shop.
Upon popping the hood, we found the metal engine cover had lost a grommet and was rattling against some metal bits on top of the engine. Sure enough, when jiggled by hand, it was a close approximation. Amplify that by 4K revs and we're talkin!
He said he'd order the grommet and I went off to get that blasted tire replaced. Once it got back from Stokes, I ripped off the engine cover and took it for a drive. Sure enough, the noise persisted.
Back to our indie shop.
Our guy had already refused to address the noise damper (ABC pump) because it "isn't bad yet. Next year, maybe. Four years" and was reluctant to take it for another drive, when the noise didn't happen because he never gave it the spurs, he doubled-down on his grommet theory and said he'd call next week. I'm not 100-percent sure I ever gave him my phone number. His shop is full of classic old Benz's and a handful of new stuff, I can't blame him for not wanting to tackle the hyper-complex CL65, but I'd rather he just say that.
So, without a diagnosis from our indie specialist, I set out Saturday to figure out a sure-fire way to make the car perform this noise when we took it to a dealership. I wasn't leaving with a "could not duplicate."
I let the CL warm up in the garage a bit and then hit the streets. 0.7 miles later, accelerating onto the highway the rattle/squeal/screech struck again. This time accompanied by a check-engine light and a fun new rough idle!
Simonson Mercedes service center was on my way back to the office so I dumped it there, told them to call me with a diagnosis and walked back to the office.
Mike Magrath, Features Editor @ 65,631miles