C63S Transmission Overheating?
Thread Starter
Newbie
Joined: Jan 2020
Posts: 5
Likes: 0
From: Napa
2016 C63S
C63S Transmission Overheating?
My 2016 W205 C63S Sedan has been great in the three years since I've owned it. Only minor issues with no major mechanicals--only going through too many sets of brakes.
For the past ~6 months however, the transmission oil temp has been elevated. It gets up to about 230F in basic highway driving over the course of an hour. Approaching 60k miles, I took it in for a transmission oil / filter replacement. Immediately it felt better, even seemed to shift more smoothly.
Fast forward to this weekend - I take my car to the track (I go about 2-3 times per year), and after about 1 hot lap, the transmission oil temperature gauge is maxed out at 280F. I slow down, take a few cool down laps, and it barely dips to 270F. After driving around the parking lot, idling it, and finally turning it off, the engine fan seemed to stay on full blast for a good 5 minutes. I'll note that this has never happened, even on hot track days previously - if anything, the brakes fading and the engine oil creeping up in temp prompted cool down laps, never the transmission.
Take it out again for the second session, and the trans oil goes from 200F to 280F in about 1.5 laps. I was being judicious with shifting -- going between 3 and 4 without much engine braking.
Anyone aware of issues related to transmission coolant? I'm unsure if this issue is related to additional friction from the trans having issues, or a cooling issue. Called my mechanic, and he hadn't heard of this issue but was going to do some research. Anyone had similar experiences? For what it's worth, about two years about the dealer gave the trans the latest firmware/software update.
For the past ~6 months however, the transmission oil temp has been elevated. It gets up to about 230F in basic highway driving over the course of an hour. Approaching 60k miles, I took it in for a transmission oil / filter replacement. Immediately it felt better, even seemed to shift more smoothly.
Fast forward to this weekend - I take my car to the track (I go about 2-3 times per year), and after about 1 hot lap, the transmission oil temperature gauge is maxed out at 280F. I slow down, take a few cool down laps, and it barely dips to 270F. After driving around the parking lot, idling it, and finally turning it off, the engine fan seemed to stay on full blast for a good 5 minutes. I'll note that this has never happened, even on hot track days previously - if anything, the brakes fading and the engine oil creeping up in temp prompted cool down laps, never the transmission.
Take it out again for the second session, and the trans oil goes from 200F to 280F in about 1.5 laps. I was being judicious with shifting -- going between 3 and 4 without much engine braking.
Anyone aware of issues related to transmission coolant? I'm unsure if this issue is related to additional friction from the trans having issues, or a cooling issue. Called my mechanic, and he hadn't heard of this issue but was going to do some research. Anyone had similar experiences? For what it's worth, about two years about the dealer gave the trans the latest firmware/software update.
Out Of Control!!
Joined: Nov 2018
Posts: 11,432
Likes: 5,342
From: San Francisco Bay Area
2019 C63CS
You most likely have a leak in the transmission radiator. Common issue on PFL. The radiators in the front are exposed and can get pierced by rocks. There are protective mesh that fit over them to avoid this. The FL has them installed from the factory.
MBWorld Fanatic!
Joined: Sep 2016
Posts: 1,720
Likes: 609
From: Australia
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
Your options: New factory coolers with oem mesh protectors, upgrade the radiators to aftermarket ones or if budget is tight just locate the leak and JB Weld it.
Where are you located? If Sydney pm me I've got an almost new set of factor coolers you can have (free) just pick up.
Thread Starter
Newbie
Joined: Jan 2020
Posts: 5
Likes: 0
From: Napa
2016 C63S
Thanks for the replies - I got ahold of my mechanic at a third party German shop in Northern CA, and he said it's likely a pierced heat exchanger leaking fluid, or the coolant pump has failed. I'll be taking it in next week to check for presence of coolant first, then if coolant seems good, pump replacement. I'll update the thread with the issue.
It's peculiar they would leave a part like that exposed on pre facelift W205s. Glad to hear it's fixed on subsequent models. I have a Carmax warranty on the vehicle - I'm hoping it covers what may be considered road damage (likely not) - almost hoping it's a pump failure as that's more likely to be covered. I'll ensure there's a mesh covering on the radiator/heat exchanger regardless of whether a rock strike is at issue.
It's peculiar they would leave a part like that exposed on pre facelift W205s. Glad to hear it's fixed on subsequent models. I have a Carmax warranty on the vehicle - I'm hoping it covers what may be considered road damage (likely not) - almost hoping it's a pump failure as that's more likely to be covered. I'll ensure there's a mesh covering on the radiator/heat exchanger regardless of whether a rock strike is at issue.
Out Of Control!!
Joined: Nov 2018
Posts: 11,432
Likes: 5,342
From: San Francisco Bay Area
2019 C63CS
It's peculiar they would leave a part like that exposed on pre facelift W205s. Glad to hear it's fixed on subsequent models. I have a Carmax warranty on the vehicle - I'm hoping it covers what may be considered road damage (likely not) - almost hoping it's a pump failure as that's more likely to be covered. I'll ensure there's a mesh covering on the radiator/heat exchanger regardless of whether a rock strike is at issue.
https://thelemonfirm.com/2021/03/09/...adiator-leaks/
Senior Member
Joined: Aug 2021
Posts: 398
Likes: 130
From: SoCal
16' C63s, 22' RAM 1500
Trending Topics
Senior Member
Joined: Aug 2021
Posts: 398
Likes: 130
From: SoCal
16' C63s, 22' RAM 1500
Thanks for the replies - I got ahold of my mechanic at a third party German shop in Northern CA, and he said it's likely a pierced heat exchanger leaking fluid, or the coolant pump has failed. I'll be taking it in next week to check for presence of coolant first, then if coolant seems good, pump replacement. I'll update the thread with the issue.
It's peculiar they would leave a part like that exposed on pre facelift W205s. Glad to hear it's fixed on subsequent models. I have a Carmax warranty on the vehicle - I'm hoping it covers what may be considered road damage (likely not) - almost hoping it's a pump failure as that's more likely to be covered. I'll ensure there's a mesh covering on the radiator/heat exchanger regardless of whether a rock strike is at issue.
It's peculiar they would leave a part like that exposed on pre facelift W205s. Glad to hear it's fixed on subsequent models. I have a Carmax warranty on the vehicle - I'm hoping it covers what may be considered road damage (likely not) - almost hoping it's a pump failure as that's more likely to be covered. I'll ensure there's a mesh covering on the radiator/heat exchanger regardless of whether a rock strike is at issue.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Thread Starter
Newbie
Joined: Jan 2020
Posts: 5
Likes: 0
From: Napa
2016 C63S
There is a class action against AMG for the missing protective mesh. Supposedly they were there prior to 2016, but then left out for some reason in subsequent years and then brought back probably due to the lawsuit. There is a service campaign, but it only seems to the cover the E and GLC. Not sure what the status is of the lawsuit, but clearly they started to install the mesh again. Probably some bean counter wanted to save a couple of dollars.
https://thelemonfirm.com/2021/03/09/...adiator-leaks/
https://thelemonfirm.com/2021/03/09/...adiator-leaks/
Thread Starter
Newbie
Joined: Jan 2020
Posts: 5
Likes: 0
From: Napa
2016 C63S
I'm in NorCal. Would definitely love to meet up! I typically go to Thunderhill for track days. The AMG's are few and far between, though there was a GT-R last time I tracked it... Where are you tracking your car? And anything unique about your setup for tracking?
Out Of Control!!
Joined: Nov 2018
Posts: 11,432
Likes: 5,342
From: San Francisco Bay Area
2019 C63CS
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
