Weird - intermittent CEL and coolant overflow
Thread Starter
MBWorld Fanatic!
Joined: Jun 2008
Posts: 8,074
Likes: 2,867
From: Los Angeles
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Weird - intermittent CEL and coolant overflow
Ok. So my car had been sitting for about a week while I installed my new ModeCarbon parts on the car. I didn't do anything to the engine, it was just a bumpers off job. I headed to Island Dragway last night for a couple more runs stock, and have encountered a few problems...
1. As soon as I turned the car on, I had a CEL light. Car sounded fine, and I got in and drove it easy for the 60mi or so from the city to Island. I figured if something went/felt wrong, I'd just watch my buddy run. No problems getting there whatsoever.
2. At the track, when I turned the car back on, the CEL was gone. I tried plugging in my MyGenius to see if it would read codes (have NOT flashed yet), but apparently it doesn't.
3. Made 2 passes. No traction at all from my bald rear Conti's (18" Nitto 555R's are getting put on Monday morning- thanks for the info superlubricity). MPH was very barely fractionally down (1mph). Hit 240deg oil temp at the end of my first run, and 250deg after my second. Fairly normal, maybe a little high but the runs were back-to-back.
4. Started looking around, and noticed that there was some white smoke coming out of the DRIVER SIDE TAILPIPE ONLY. Smelled like condensation - no coolant, no oil - although there was zero coming out of the passenger side tailpipe (dripping water condensation). Sounded like MAYBE the car was missing slightly at idle but I could be imagining that.
5. Started to snoop around a bit more, and found this under the hood:
Looks like my coolant overflow reservoir puked all over my engine bay at some point in either this drive or the last. I know this is brand new because my engine bay is spotless.
Driving home late last night, oil temps stayed around 217deg cruising on the highway, while water temps were anywhere from 180deg (which is the coolest I have ever seen so far), up to a not un-normal 200deg. It fluctuated back and forth up and down the whole drive - seemingly more than usual. When I got to the city and slowed down, oil temps went to 240deg, and stabilized at 230deg - 10deg higher than usual. Water temp was normal at 197deg.
So we have a CEL turning on and off, an overflowing coolant reservoir, and somewhat erratic temps.
SO... the question is does this sound like a head gasket or a misfire in the drivers side bank? Would the car throw codes for either or both? And what is the best thing I can get to read codes within reason? Many thanks guys, this one has me a little stumped...
1. As soon as I turned the car on, I had a CEL light. Car sounded fine, and I got in and drove it easy for the 60mi or so from the city to Island. I figured if something went/felt wrong, I'd just watch my buddy run. No problems getting there whatsoever.
2. At the track, when I turned the car back on, the CEL was gone. I tried plugging in my MyGenius to see if it would read codes (have NOT flashed yet), but apparently it doesn't.
3. Made 2 passes. No traction at all from my bald rear Conti's (18" Nitto 555R's are getting put on Monday morning- thanks for the info superlubricity). MPH was very barely fractionally down (1mph). Hit 240deg oil temp at the end of my first run, and 250deg after my second. Fairly normal, maybe a little high but the runs were back-to-back.
4. Started looking around, and noticed that there was some white smoke coming out of the DRIVER SIDE TAILPIPE ONLY. Smelled like condensation - no coolant, no oil - although there was zero coming out of the passenger side tailpipe (dripping water condensation). Sounded like MAYBE the car was missing slightly at idle but I could be imagining that.
5. Started to snoop around a bit more, and found this under the hood:
Looks like my coolant overflow reservoir puked all over my engine bay at some point in either this drive or the last. I know this is brand new because my engine bay is spotless.
Driving home late last night, oil temps stayed around 217deg cruising on the highway, while water temps were anywhere from 180deg (which is the coolest I have ever seen so far), up to a not un-normal 200deg. It fluctuated back and forth up and down the whole drive - seemingly more than usual. When I got to the city and slowed down, oil temps went to 240deg, and stabilized at 230deg - 10deg higher than usual. Water temp was normal at 197deg.
So we have a CEL turning on and off, an overflowing coolant reservoir, and somewhat erratic temps.
SO... the question is does this sound like a head gasket or a misfire in the drivers side bank? Would the car throw codes for either or both? And what is the best thing I can get to read codes within reason? Many thanks guys, this one has me a little stumped...
Thread Starter
MBWorld Fanatic!
Joined: Jun 2008
Posts: 8,074
Likes: 2,867
From: Los Angeles
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Just to add two things - the car was at the dealer last Wednesday for an oil change as I need to find a reasonable dealer around here and figured that'd be a good way to check out their operations. I asked them to pull any codes and just give it a thorough once-over as I drove it 8k miles so far this summer. Everything came back fine, clean bill of health. They changed the oil and added some sort of fuel additive - I assume it was just injector cleaner. That was the last time I drove the car. The CEL light went off at the track after I added 5gal of Sunocco race gas.
Thread Starter
MBWorld Fanatic!
Joined: Jun 2008
Posts: 8,074
Likes: 2,867
From: Los Angeles
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Yeah, I'm at my car now and the coolant res cap was loose. However the cap doesn't 'click' or catch like I'm normally used to. Is that normal? Could be a bad cap throwing the CEL? Smoke was maybe just condensation (on startup after the track session after sitting for 2hrs). Then heat issues would be caused by too low coolant maybe. Hmm will go get some distilled water and top it off then. Thx for the suggestion.
MBWorld Fanatic!
Joined: Sep 2005
Posts: 3,165
Likes: 59
C63 AMG P30 *EuroCharged*| Porsche Cayenne | Buell XB9SX
Yeah, I'm at my car now and the coolant res cap was loose. However the cap doesn't 'click' or catch like I'm normally used to. Is that normal? Could be a bad cap throwing the CEL? Smoke was maybe just condensation (on startup after the track session after sitting for 2hrs). Then heat issues would be caused by too low coolant maybe. Hmm will go get some distilled water and top it off then. Thx for the suggestion.
