High mileage W166s (80k+)?




Then, I had my annual maintenance service this past winter when the SUV had a little over 95,000 miles on the odometer. Tire Rack had their end of year deal on Pirelli Scorpion Weatheractive tires into early January, so I had picked up a set of them to replace the Bridgestone Dueler H/L Alenza Plus tires installed at the dealership by the previous owner. Each of these old tires had a different date code (early 2018, late 2018, early 2019, and one from late 2020, which had been installed months prior to our purchase of the vehicle). The three oldest tires were already experiencing significant dry rot. As an example, this was the tire with the late 2018 date code:
The tire with the late 2020 date code did not exhibit any serious dry rot yet, and it still had a bit of tread left, so I decided to keep it as a full-size spare together with the rim, as it was also the only rim to have any curb rash:
I was able to find a brand-new replacement rim from the wheel business run out of the Auto Adriatique Garage center in Montreal. Total cost about 265 USD (and they threw in for free a set of 4 brand-new OE TPMS sensors, which matched the old ones installed by Mercedes under the SUV's previous ownership but a newer revision, of course):
The old TPMS sensors:
The new TPMS sensors:
One of the new Pirelli tires mounted and installed:
As for the TPMS code C159916 (i.e., "The battery of the tire pressure sensor has a malfunction. The limit value for electrical voltage has not been attained.") that I have been experiencing since last year, I cleared the stored code, and it didn't come back after the new TPMS sensors had been installed. It was just a battery/batteries getting low in one or more of the old TPMS sensors. There are also no new codes reported after performing a full scan of all of the SUV's modules.
While inspecting the vehicle, the techs noticed the corrosion on the brake pads, and one of the inner ones was delaminating. They showed it to me when the vehicle was up on the lift, and it was really separating. The pads were also getting worn down. According to the service records, the rotors had been resurfaced when the brake pads were replaced under the previous ownership at the dealer, so they were also getting thin. The brakes were due, and I wanted to replace the Genuine Mercedes brake pads (the OE manufacturer was TRW, I believe) with the Akebono Euro pads, which were on sale (the complete set of front and rear pads was on clearance and cost less than $85 in total). For the rear pads, the SUV takes Akebono EUR1630A (corresponds to brake kit Mercedes Benz part#: 007-420-83-20, which has been replaced by 000-420-99-04), and, for the front pads, it takes Akebono EUR1629 (corresponds to brake kit Mercedes Benz part#: 007-420-81-20, which has been replaced by 000-420-13-05). The Akebono rear pad kit comes with wear sensors and anti-rattle springs. The Akebono front pad kit comes with just the wear sensors. When I was looking up parts, I checked the Mercedes parts catalog, but it seems that the rear anti-rattle springs are not available separately from the Genuine Mercedes kit (I couldn't even find separate part #s from Mercedes). None of the U.S.-based parts suppliers had any either, but I think one might be able to find compatible aftermarket ones from vendors in Europe (or on eBay). Had to clean and reuse the old ones, since the ones that come with the Akebono rear pad kit don't fit correctly.
The spring clips for the front brake pads are available separately from Mercedes (possibly the same as those used on other makes and models), so I picked up a set from a dealership to replace the rusty ones on my vehicle (we're in coastal northern New England...).
The coating on the Genuine Mercedes rotors that came with the vehicle had held up well in our salty environment, and we were OK with their braking performance, so I decided to just get the coated rotors from Brembo, the OE manufacturer for the Genuine Mercedes rotors (both manufactured in the U.S.).
The Genuine Mercedes front rotors.
I purchased the Brembo coated front rotors, which are the OE equivalent.
The Genuine Mercedes rear rotors.
I purchased the Brembo coated rear rotors, which are the OE equivalent.
The parts prices with the sales discounts applied were pretty reasonable, I'd say:
The only other issue found was that two of the exhaust clamps were getting badly corroded, so I picked up a set from a dealership (they were $15 ea.).
There wasn't any significant corrosion or cracking of the exhaust pipes occurring at the clamps yet, so the local exhaust shop just cut the old ones out and installed the new hardware for 50 USD.
Other than having to address these common maintenance items, I haven't experienced any issues with the vehicle over the previous year.
There's a simple step to make your brakes work twice as good for normal driving.
crazy-strong stock SPRING jams caliper...
That anti-rattle caliper spring is responsible for poor braking. It keeps the caliper torqued 90° perpendicular to sliders with too much force...
caliper is unable to center over rotor on lubed slide pins as they should.
Only inner piston pad wears out while outer does nothing.
Tweak the spring tension to allow caliper to slide normally - Better than new firm brakes will result with a nice short pedal... not spongy long stock pedal.
Last edited by CaliBenzDriver; May 31, 2025 at 09:03 PM.




There's a simple step to make your brakes work twice as good for normal driving.
crazy-strong stock SPRING jams caliper...
That anti-rattle caliper spring is responsible for poor braking. It keeps the caliper torqued 90° perpendicular to sliders with too much force...
caliper is unable to center over rotor on lubed slide pins as they should.
Only inner piston pad wears out while outer does nothing.
Tweak the spring tension to allow caliper to slide normally - Better than new firm brakes will result with a nice short pedal... not spongy long stock pedal.
Last edited by Œuvre; May 31, 2025 at 11:34 PM.




I confirm the radiator leaks on schedule... mine certainly does:
VALEO radiator designed to leak
When we add everything up... the only question is what else is next ??
The heatsoak feature is designed around the engine storing extreme piston heat. They have been known to self-ignite aka. LSPI.
After engine stop, block boils up engine coolant, forcing pressure relief at the weakest seal.
The best way is not to seal leaky relief parts, it's to disable heat accumulation.
Exact same deal with oil hoosing out of engine: prevent pressure blow-by.
As you can imagine, disabling these buggy features is experimental.
Last edited by CaliBenzDriver; Jun 1, 2025 at 01:13 AM.
I confirm the radiator leaks on schedule... mine certainly does:
VALEO radiator designed to leak
When we add everything up... the only question is what else is next ??
The heatsoak feature is designed around the engine storing extreme piston heat. They have been known to self-ignite aka. LSPI.
After engine stop, block boils up engine coolant, forcing pressure relief at the weakest seal.
The best way is not to seal leaky relief parts, it's to disable heat accumulation.
Exact same deal with oil hoosing out of engine: prevent pressure blow-by.
As you can imagine, disabling these buggy features is experimental.
It's fine to run an engine hard, but you ABSOLUTELY have to give it a moment to cool down by idling after a hard run, even if it's only for 10 or 30 seconds. This is especially true for a turbocharged engine (unless you like coke building up in the oil cooler passages of said turbo) but it also is absolutely necessary for ANY internal combustion engine be it a car, diesel truck, 4 wheeler, or chainsaw. The cooling system on liquid cooled engines is designed for this but - as is pointed out by CBD's post, is easy to overcome by going uphill at full bore then turning the engine off at the top without a moment to cool.
Last edited by rapidoxidation; Jun 1, 2025 at 10:59 PM.




