racenut

I drove a fully stock C63 on track for the first time last weekend and sorry to say, the fun lasted for only 2 laps.

I was using the manual mode on Sport ESP. After 2 flying laps the car converted back to FULL AUTO and before that lap was done, I could not rev past 4000rpm.

Immediately I suspected transmission overheating. So I took it easy for a lap and gunned it the second time around. The car was back to full power but no manual mode, for less than a lap...

Before I could completed the lap the engine went limp again and would not let me go past 4000rpm.

Coming back home on the highway about 2 hours later all is back to normal, including the manual mode.

I don't know if there was anything wrong with this car's transmission as the only other paddle shifted car I have taken to track was an F430 Scud and that car did not encounter problems even after close to 2 sessions of more than 10 laps each (did not count the exact number of laps). Then again, the Scud's is no auto tranny but full manual transmission.

Has anyone experienced the same?

Infamouz

Without a doubt, a stock C63 is no track car. I personally have had experience this as well.. as I'm sure many others have. Considering I hardly track at all, I never thought about doing it ... although, if you plan on tracking more, I recommend doing some cooling mods such as a larger transmission oil cooler.

MikeS54

I personally had totally opposite experience as u and the OP. I have tracked my car four times already, with the car totally stock. For each track day i ran i had four-five 20-25min sessions and my car is totally fine. Never overheated and brake never give up(there were some minor brake fade though).

Don't think i am not hard on the car either, i brake quiet late and pushed the car to the limits. Also the road course i tracked on is a tighter course which is known to be very hard on brakes so.....its interesting how the op has very opposite experience.

racenut

Hi Infamouz, thanks for your feedback. I learned somewhere that the CLK63 Black has an ADDITIONAL tranny oil cooler. I'll have a look if this could be retrofitted to fit the new W204 body.

racenut

Hi MikeS54.

I drove the C63 pretty hard as we were trying to get the fastest lap time for this car. There was also serious brake fade after the 4th lap.

I agree with Infamouz, from how the tranny 'overheated' and how early the brake faded, in stock form the C63 is definitely designed for the street not track.

Cheers.

Infamouz

I believe it's location is on the underside of the vehicle, close to the rear bumper. It's a heat sink... although relatively simple, it's very effective.

Unless of course this is something else, than my mistake. I don't own a CLKBS..

--
And MikeS54, although I experienced the same symptoms as the OP, I forgot to mention that I had done 10 laps; 5 times that of his before I experienced the same thing. This could all be relative to our locations in the world... weather/climate plays a huge part.

racenut

Hi again MikeS54,

Just realized maybe the difference is on the track layout. I drove my C63 on a pretty high speed layout where we could reach a top speed of 130mph on 5th and flowing 3rd or 4th gear corners. There was only one 2nd gear chicane in the 12-turn lap.

Maybe, just maybe, that the transmission works harder if you exposed it to higher speeds.

racenut

Infamouz, could it be that you are referring to the differential cooler fins? A tranny oil cooler would normally be found up front.

Infamouz

Now that you mentioned you were hitting 130mph, at what I assume was nothing less than WOT, you are definately making the transmission work to it's full potential.

The use of additional/larger coolers will definitely improve lap times and longevity on the track.


Edit; Yes, sorry. I forgot about that, my mistake!

SMP

The oil cooler (not heat sink) covered by the carbon fiber diffuser in the rear is for the differential. The CLK63 BS has also additional oil coolers for engine, transmission and power steering.

Infamouz

Learn something new everyday...

Thanks for the info.

jvanbrecht

I ran mine stock at Summit Point, I had no real issues that you described.. but (I bow my head in shame), I ran the laps in sport mode with ESP in sport mode as well. Only having the car for a month or so, I was not comfortable running it in manual on a track where I could impede other cars...

I did note that towards the end of the track session 2 (20 to 25 minutes per session), I was losing power in WOT, but I did not take note of the rpm at the time. Also it was 100+ weather, and high humidity that day.

emericr

I guess it seems to depend on the car or situation because two other members were recently at Sebring (check threads) and believe me, they ran the car really hard and temperature were very hot (Summer in Florida). They did not have any limp mode issues. Both were tuned so I wonder if that has anything to do with it.

chief63

I have ran my car extremely hard at Mosport all day (140MPH) and it was about 90 degrees farenheit. No problems except brake fade, same thing at other tracks.

I'm thinking now that some guys may be downshifting way too early into braking, putting a lot of stress on the transmission, is that possible?

I just find it weird some people can make 200 laps without any issues and some can't even do 2... weak cars maybe?

hhughes1

During two sessions my oil temp reached 280 and the car got sluggish(limp mode?). I usually track in sport mode but the theory about manually downshifting at high speed has merit. The tranny should never be used an engine brake especially at track speeds.

1st amg

I agree with Chief, the track days I have completed with my car and other C63 with PPP have never given me that problem, except once when I did down shifted early continually for two laps as I was enjoying the loud exhaust pops and crackles, then only did it revert to auto mode until the tranny cooled off then it was back to normal...as well, this same situation happened to me in May as I was tracking and lapping a brand new 2010 E63 with the new tranny and it also went into auto mode from manual as we were downshifting very early in the corners which if you were to lap properly was unneccesary to do.

Questions

Yes, this is strange. There can't be that much of a difference between cars...can there?

I know it's not the tranny, but if I'm tooling around town in a spirited manner, downshifting early to hear the throttle blips, my oil temps will get up into the 235, 242 range.

SonnyakaPig

I admit I'm not a transmission expert, but I'm not sure I would agree that the "tranny should never be used as an engine brake..."

I don't see a problem with downshifting as a means to slow the car down when you're driving around town at less than 55 mph. As long as you give yourself enough distance to slow down gradually (by that I mean allowing the car to lose speed by not pressing on the throttle) and then downshift when you are confidant that the rpms will not jump too high the trans should probably be safe.

I do, however, conceded that allowing the car to slow down by releasing the throttle as a precursor to downshifting is in effect preventing the trans from acting as an "engine brake" all by itself.

That said, I can see how the trans would take a beating if people were tracking the car and downshifting at too high of speeds.

SonnyakaPig

Those temps seem pretty hot for these cars for around-town driving; even "spirited" driving."

I do not push my car when the weather is very hot. I live in a desert and the temps throughout summer range between 100-115+ consistently. But sometimes I will mash the gas and play around for short durations when it's hot (how can you not? ), and I haven't seen my oil temps exceed 227*F yet.

Even though I don't have any proof for this: I fear shifting my car in manual when the weather is in the 100's*F. Even before purchasing this car, my last car had a "TapShift" mode and was a sporty type car with some good power and I chose not to shift aggressively when it was hot out.

I guess if the weather is very hot where you live, I can see how your temps get that high if you are driving hard.

I was under the impression that C63's have trans and oil coolers. I don't know what the trans temps are for our cars as I don't have a sensor and gauge for that measurement but because I have not seen my engine oil temps and my coolant temps exceed a certain number, I assumed there were coolers on the car and they were doing a good job keeping my car at a consistent temp?

Can anyone confirm if C63's have trans and oil coolers? Seems like there are some heat exchangers up front but it's not easy to see what they are.

Questions

If there was a problem...besides non-functioning oil coolers, what could it be? If an oil cooler isn't working, there should be some kind of code or message or light, right?

SonnyakaPig

Absolutely. If our cars in fact have an oil cooler and it wasn't functioning correctly, I'm positive a CEL of some kind would show.

Even though I think the temps you are seeing are slightly high, they are not in the danger zone.

I have been told that engine oil temps are often 30 or so degrees higher than ECT's. What makes me think C63's have engine oil coolers is that my car typically runs at 195*F (ECT) and 210-217 (engine oil temp). And because my engine oil temps have only reached 227*F and then fall quickly back down to 217*F when I back off the throttle for a minute or so, I assumed there was an oil cooler doing it's job.

Granted, I haven't tracked my car and realistically, I haven't driven my car that hard on city streets or the highway, so I haven't really pushed my car.

I'm sure if I really pushed my car the engine oil temps would rise above 227*F. But I think I would have to drive it very hard around town to reach those higher temps. And where I live, that would be very hard to do, even though, we don't have a lot of traffic compared to the bigger cities.

So, that's why I commented on the temps that you are seeing. It just seems like you would have to drive the car pretty hard to get those temps.

How fast do the temps drop when you back off the throttle for a bit?

I really would love to know what our trans temps look like. That would probably give a lot of information.

ATL_MB

I was told (by the chief tech at AMG Academy) that the transmission shares a cooler with the engine coolant and also has a separate cooler. There are certainly two oil coolers, one along the bottom middle of the car and the other in front of the right wheel, behind the fog light. The one on the side even has its own dedicated electric fan with venting into the wheel well and out of the side slats.

I have seen engine oils temp near 250 F range for extended periods with no issues. I had a E63 that shut down on me when the oil reached 280 F. I saw no warning messages, so I don't know if it was transmission temps or something else that caused the issue - I am sure it is temperature related, though, as the car sat for 30 minutes or so and then was fine.

Like others, I am perplexed why some people have had problems on track and others have not. It just can't be build variations from car to car.

I would say, though, that I have not seen anything to prove that it is transmission temps that are causing these issues. It does seem that those that use manual mode tend to have this issue more often (lending some weight to the trans temp theory), although without trans temp measurements, it is really hard to say. I have used manual mode at the track without any issue (in 100 heat), but generally use sport mode. My only problem has been steering fluid boiling over, which a dealer tech told me is pretty common on the track, although I haven't heard of anyone on the boards with the same issue.

SonnyakaPig

ATL MB,

It's good to know that we have these extra coolers. Thanks for letting us know.

Questions

I've heard of this happening...how did you deal with it?

racenut

Downshifting early (engine braking) causing excessive heat in transmission (and engine) is something that I am fully aware of. In any car, when on track I rely exclusively on the brakes for deceleration not the transmission. I am an experienced race driving coach so I am quite certain the problem was not driving error.

The ambient temp when I took the car out on track was about 100F, which is hot but still not over the top.

Infamouz, yes the car was almost always at WOT except when I was braking/turning in or balancing the car with the throttle mid corner.

From how easily the brake faded (which we all agreed on) and the weak transmission in some of the cars, I can only conclude that Mercedes focused the C63 for the street more than I anticipated.