MPG Plummeting For C350
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From: Los Angeles, CA
2015 C400 Tenorite Gray
MPG Plummeting For 2009 C350 at 122K
Here's the overview. I have 122,000 miles on the car. No CELs.
EPA Says 17 City. Highway 25
The manifold was repaired at 81,000.
Tire pressure is not an issue.
I did replace the plugs some 20,000 miles past service. I know.... Everything else has been done on time.
MPG has taken a dive to 13.7 (from start). I would think at a min that 15 to 16 should be the average.
Recently replaced the fuel injection hose as it was seeping.
I am doing a lot of city driving but that's been the case for some time.
Current Symptoms
Q. Manual states Fuel filter at 150,000 miles. That seems high. I would have thought sooner....
If anyone has some thoughts or actual experience at this mileage point, please comment below. Thanks!
EPA Says 17 City. Highway 25
The manifold was repaired at 81,000.
Tire pressure is not an issue.
I did replace the plugs some 20,000 miles past service. I know.... Everything else has been done on time.
MPG has taken a dive to 13.7 (from start). I would think at a min that 15 to 16 should be the average.
Recently replaced the fuel injection hose as it was seeping.
I am doing a lot of city driving but that's been the case for some time.
Current Symptoms
- Odd noise when doing turn around in driveway
- Consuming 1 quart or more between oil changes
Q. Manual states Fuel filter at 150,000 miles. That seems high. I would have thought sooner....
If anyone has some thoughts or actual experience at this mileage point, please comment below. Thanks!
Last edited by Nicholi2007; Jun 10, 2019 at 01:27 PM.
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Posts: 604
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From: SA
2008 C350-Sport-AMG-Active Agility Pack(Not reliable) +Izuzu KB6 3L(It seems Reliable)+Mazda
They told me the feulpump & filter is one unit to be replaced.
When you touch up oil, is it same oil as spec, or how do you know if correct oil spec was used-?
What do you mean by turn around, going forward left or right, or reverse involved-?
When you touch up oil, is it same oil as spec, or how do you know if correct oil spec was used-?
What do you mean by turn around, going forward left or right, or reverse involved-?
Last edited by Moto_Guzzi; Jun 10, 2019 at 09:44 AM.
Thread Starter
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From: Los Angeles, CA
2015 C400 Tenorite Gray
2. Turnaround on side street into some one's driveways and turning around.
Q. At what mileage did you change the fuel filter and fuel pump?
I have Your Mechanic (mobile mechanic) coming to do an inspection on wed.
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Joined: Sep 2015
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From: Milwaukee, WI USA
2012 C300 4Matic
That 13.7mpg, what was it before? And over what kind of distance was that? If it was like 10 miles as opposed to 200 miles that would make a big difference. If you do a lot of short trips and do a lot of stop and go driving, that mileage might not be unusual. Has anything changed recently with your driving habits?
Thread Starter
MBWorld Fanatic!
Joined: Jun 2007
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From: Los Angeles, CA
2015 C400 Tenorite Gray
That 13.7mpg, what was it before? And over what kind of distance was that? If it was like 10 miles as opposed to 200 miles that would make a big difference. If you do a lot of short trips and do a lot of stop and go driving, that mileage might not be unusual. Has anything changed recently with your driving habits?
I'm specifically looking to hear from others who had a loss in fuel economy with this model car, what was identified, and done.
Obviously this will vary.
I'll see what the 75-point inspection reveals.
Last edited by Nicholi2007; Jun 10, 2019 at 01:20 PM.
Super Member
Joined: Nov 2008
Posts: 604
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From: SA
2008 C350-Sport-AMG-Active Agility Pack(Not reliable) +Izuzu KB6 3L(It seems Reliable)+Mazda
Hi, They told me it lasts very long, I don't have to worry about it, so I did not change the pump/filter combo.
Car at 143 000Km no problems in that regard.
My car developed noise in front shortly after new, they replaced bushes, it also chewed up one tyre on the inside wall, I was lucky to spot it looking underneath from the front, if you walk around the tyres looked ok.
Car at 143 000Km no problems in that regard.
My car developed noise in front shortly after new, they replaced bushes, it also chewed up one tyre on the inside wall, I was lucky to spot it looking underneath from the front, if you walk around the tyres looked ok.
Last edited by Moto_Guzzi; Jun 10, 2019 at 05:47 PM.
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From: Los Angeles, CA
2015 C400 Tenorite Gray
The inspection found warped rear rotors and my front shocks are almost gone.
I'm thinking of replacing with a Bilstein with a slightly firmer ones. Just not sure....
Probably time to clean the MAF and throttle body....
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Thread Starter
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Joined: Jun 2007
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From: Los Angeles, CA
2015 C400 Tenorite Gray
UPDATE: Fuel Smell Still A Problem
UPDATE:
I've had the front struts and the rear shocks replaced this past week. I will be going in for alignment.
Fuel smell outside of car is still there. I can only smell it above a half tank of gas. Below a half tank, no smell. It seems strongest when tank is full.
Any ideas?
I've had the front struts and the rear shocks replaced this past week. I will be going in for alignment.
Fuel smell outside of car is still there. I can only smell it above a half tank of gas. Below a half tank, no smell. It seems strongest when tank is full.
Any ideas?
Member
Joined: Oct 2018
Posts: 108
Likes: 7
From: Canada
2017 C300 Coupe
Here's the overview. I have 122,000 miles on the car. No CELs.
EPA Says 17 City. Highway 25
The manifold was repaired at 81,000.
Tire pressure is not an issue.
I did replace the plugs some 20,000 miles past service. I know.... Everything else has been done on time.
MPG has taken a dive to 13.7 (from start). I would think at a min that 15 to 16 should be the average.
Recently replaced the fuel injection hose as it was seeping.
I am doing a lot of city driving but that's been the case for some time.
Current Symptoms
Q. Manual states Fuel filter at 150,000 miles. That seems high. I would have thought sooner....
If anyone has some thoughts or actual experience at this mileage point, please comment below. Thanks!
EPA Says 17 City. Highway 25
The manifold was repaired at 81,000.
Tire pressure is not an issue.
I did replace the plugs some 20,000 miles past service. I know.... Everything else has been done on time.
MPG has taken a dive to 13.7 (from start). I would think at a min that 15 to 16 should be the average.
Recently replaced the fuel injection hose as it was seeping.
I am doing a lot of city driving but that's been the case for some time.
Current Symptoms
- Odd noise when doing turn around in driveway
- Consuming 1 quart or more between oil changes
Q. Manual states Fuel filter at 150,000 miles. That seems high. I would have thought sooner....
If anyone has some thoughts or actual experience at this mileage point, please comment below. Thanks!
Thread Starter
MBWorld Fanatic!
Joined: Jun 2007
Posts: 1,022
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From: Los Angeles, CA
2015 C400 Tenorite Gray
Can't say for sure if that's what it is in your case, but my noise/vibration when turning the steering wheel all the way was caused by a faulty planetary gear in the transfer case. Had it fixed by the MB dealer along with a blower motor replacement for 1100$ CAD total and haven't had the issue since.
Thread Starter
MBWorld Fanatic!
Joined: Jun 2007
Posts: 1,022
Likes: 44
From: Los Angeles, CA
2015 C400 Tenorite Gray
Thread Starter
MBWorld Fanatic!
Joined: Jun 2007
Posts: 1,022
Likes: 44
From: Los Angeles, CA
2015 C400 Tenorite Gray
Joined: Nov 2016
Posts: 7,847
Likes: 3,498
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
What caused the warped rear rotors? Did they overheat? Could you have stuck calipers, causing additional drag?
Thread Starter
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From: Los Angeles, CA
2015 C400 Tenorite Gray
I think I'll start stuff a little earlier to lessen the blow.
Last edited by Nicholi2007; Sep 20, 2019 at 10:06 PM.
Joined: Nov 2016
Posts: 7,847
Likes: 3,498
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
That's the thing about maintenance...do it before it becomes repairs.
It is very possible that you have stuck calipers now that are causing the additional drag. Or even a stuck parking brake. The warping is due to excessive heat; something had to cause it. You can always drive the car a little while and then feel if there is a lot of heat coming off the rear wheels. I once had a stuck caliper on my truck that got the entire wheel so hot that it melted the valve stem cap.
It is very possible that you have stuck calipers now that are causing the additional drag. Or even a stuck parking brake. The warping is due to excessive heat; something had to cause it. You can always drive the car a little while and then feel if there is a lot of heat coming off the rear wheels. I once had a stuck caliper on my truck that got the entire wheel so hot that it melted the valve stem cap.
Thread Starter
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From: Los Angeles, CA
2015 C400 Tenorite Gray
UPDATE: Rear Differential Fluid Change
So evidently the rear differential needs to be done every 4 years or 40,000 miles. Mine was done at 56,00 and I have 129,000.
No one ever suggested I do it so I did not know.
Car feels more responsive. MPG numbers appear to be climbing.
Hopefully that was the fuel economy issue.
No one ever suggested I do it so I did not know.
Car feels more responsive. MPG numbers appear to be climbing.
Hopefully that was the fuel economy issue.
MBWorld Fanatic!
Joined: Aug 2013
Posts: 1,364
Likes: 149
2012 C300 4MATIC Sport
So evidently the rear differential needs to be done every 4 years or 40,000 miles. Mine was done at 56,00 and I have 129,000.
No one ever suggested I do it so I did not know.
Car feels more responsive. MPG numbers appear to be climbing.
Hopefully that was the fuel economy issue.
No one ever suggested I do it so I did not know.
Car feels more responsive. MPG numbers appear to be climbing.
Hopefully that was the fuel economy issue.
Thread Starter
MBWorld Fanatic!
Joined: Jun 2007
Posts: 1,022
Likes: 44
From: Los Angeles, CA
2015 C400 Tenorite Gray
The W204 maintenance booklet says that the rear differential fluids needs to be changed every 4 years or 40k miles ONLY for the C63. As for 4MATIC models and based on all the reading and research I've done, it's only a mileage interval and it's 100k miles. Obviously I am not going to wait that long, but definitely not changing it at 40k miles or 4 years. Maybe 60k miles.
I could not find it in the maintenance booklet. Pelican Parts says 80,000 which is the transmission change interval.
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2012 C300 4MATIC Sport
Not a bad idea at all to change it along with the transmission fluid and filter but for the 7G+, it's 70k miles as per MB not 80k miles.
Thread Starter
MBWorld Fanatic!
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From: Los Angeles, CA
2015 C400 Tenorite Gray
Thread Starter
MBWorld Fanatic!
Joined: Jun 2007
Posts: 1,022
Likes: 44
From: Los Angeles, CA
2015 C400 Tenorite Gray
The seal seemed ok. No cracks. The cover was actually black not white.
I could not see any cracks. I wonder if they are hairline and tough to spot?
