1996 W140 S280 M/T: BAD FUEL CONSUMPTION, BAD FUEL ODOR, LOW POWER, ETC.
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Joined: Jan 2014
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'84 w123 300D M/T and '96 w140 S280 M/T
1996 W140 S280 M/T: BAD FUEL CONSUMPTION, BAD FUEL ODOR, LOW POWER, ETC.
Yes, that's right. I own a super entry-level w140 S280 that comes with a manual transmission, non-leather seats, non-power seats, non-moon roof and pretty much non-everything.
I'm new here so please be gentle.
I've been looking around for a while now but still can't come up with a concrete answer...
Bought the car from my friend last year and still haven't had the time to take it to the shop due to some life issues that I need to sort out first. For the mean time, I've been researching thoroughly online on different sources and the 'best' error that I've come up with is the faulty engine wiring harness. The reason why I've finally decided to post on this forum is to get validation from the alleged fault and further possible errors that I think I'm missing. Big time.
Before I proceed, I would like to share a little history of the car: It was a diplomatic vehicle which was pretty much taken for granted after having the last Mercedes dealership PMS at 30,000km. My diplomatic friend acquired the car and it had 60,000km ODO reading after being parked and exposed to sunlight in the embassy parking lot for 2 years. He was basically saying that the embassy did not have the car fixed appropriately from 30k to 60k and just abandoned the poor thing after years in service. He spent around $2,000 to have it running (at an independent shop) and it ran well but with a horrible fuel consumption which was never fixed (3km/liter or 7mpg city driving).
According to my research, M104 engines built in the 90s had a biodegradable housing wrapped around the engine wire harness which eventually breaks down when exposed to heat. Makes sense given the car's facts: 2 years exposure to sunlight (I live in a tropical country) and my friend abused it for a year after that. The black housing inside the instrument cluster have been reduced to dust and the leather shift knob ****ing MELTED. But despite the torture the car went through, the paint is still in good condition. :bowdown:
The symptoms I'm about to write happened a year after my friend's $2,000 fix.
Without any further ado, the MAJOR faults in my car are:
1.) LOW POWER: Engine runs very weak. Idle RPM reading is around 500-600. It sometimes die on its own if the gas pedal isn't pressed. Moreover, the car won't run on first gear if the gas pedal isn't revved 'til 2,000-3,000 RPM while the clutch is half-way pressed so the car won't nudge and die. Every time I shift gears, the car would have an awkward nudge before the transmission is firmly shifted on the selected gear. Reverse gear acts the same way.
2.) CAR DIES WHEN AC IS TURNED ON: If the car was running idly and the AC is turned on, it will inevitably die. BUT the AC runs fine when the car is running around 60kph or more.
3.) BAD FUEL SCENT: Exhaust smells like rich, unburned unleaded. No visible smoke coming from the exhaust but the smell is too horrible, a few seconds of exposure to it will cause nausea.
4.) RANDOM ENGINE KNOCK: Revving the engine while on idle or on any gear will result to a random engine knock. Very disturbing as it gives me the impression that it could break at any moment.
5.) FAULTY OIL PRESSURE: Sometimes, the oil pressure gauge reads at 0 while running. The most it read was at 2.
6.) FREQUENT OIL DRIPS: Before I've acquired the car, my friend had to put a bottle of synthetic oil every damn month as he used it as a daily work horse. This is definitely not normal. Although since I don't use the car to avoid further damage, there is no visible oil drip in my garage. The car is parked on a slight decline around 5 degrees.
The MINOR faults in my car are:
1.) DAILY RADIATOR WATER REFILLING: Before the car is used, the reservoir needs to be filled with water. Nothing major really but it's become quite annoying.
2.) BROKEN SIDE MIRRORS: The power switch of the side mirrors don't work. Although an electrical kind of hum can be heard from the side mirrors.
3.) BROKEN REAR VIEW MIRROR: It's loose and the power switch does not work anymore.
4.) BROKEN POWER WINDOWS: Only the two front power windows work. The back parts have long been useless. Doesn't work regardless of which switch is pressed.
5.) BROKEN TRUNK THING: I forgot what it's really called but it's the metal chrome thing that pops out when the trunk button is pressed. It's now perpetually exposed and it's kind of annoying. The trunk button inside the car doesn't work as well. The trunk needs to be manually locked or unlocked using the keys.
6.) BROKEN ALARM SYSTEM: Not alarming now since everything is pretty much broken, eh? Doors need to be manually unlocked using the keys.
7.) BROKEN LIGHT SWITCH: I literally have to put a folded piece of paper in between the switch when the rear fog lamp is pulled to be turned on. This is very annoying as the switch bounces back flat if no paper is jammed. Also, the low beam and fog lights sometimes don't turn on despite the switch being turned to position.
8.) FAULTY BASS: The sound system is fine and bearable but when the bass drops, all hell breaks loose.
I've tried my best to identify the issues that are known to me thus far. I can upload actual photos and videos of the car if need to. Thanks heaps, everybody!
I'm new here so please be gentle.
I've been looking around for a while now but still can't come up with a concrete answer...
Bought the car from my friend last year and still haven't had the time to take it to the shop due to some life issues that I need to sort out first. For the mean time, I've been researching thoroughly online on different sources and the 'best' error that I've come up with is the faulty engine wiring harness. The reason why I've finally decided to post on this forum is to get validation from the alleged fault and further possible errors that I think I'm missing. Big time.
Before I proceed, I would like to share a little history of the car: It was a diplomatic vehicle which was pretty much taken for granted after having the last Mercedes dealership PMS at 30,000km. My diplomatic friend acquired the car and it had 60,000km ODO reading after being parked and exposed to sunlight in the embassy parking lot for 2 years. He was basically saying that the embassy did not have the car fixed appropriately from 30k to 60k and just abandoned the poor thing after years in service. He spent around $2,000 to have it running (at an independent shop) and it ran well but with a horrible fuel consumption which was never fixed (3km/liter or 7mpg city driving).
According to my research, M104 engines built in the 90s had a biodegradable housing wrapped around the engine wire harness which eventually breaks down when exposed to heat. Makes sense given the car's facts: 2 years exposure to sunlight (I live in a tropical country) and my friend abused it for a year after that. The black housing inside the instrument cluster have been reduced to dust and the leather shift knob ****ing MELTED. But despite the torture the car went through, the paint is still in good condition. :bowdown:
The symptoms I'm about to write happened a year after my friend's $2,000 fix.
Without any further ado, the MAJOR faults in my car are:
1.) LOW POWER: Engine runs very weak. Idle RPM reading is around 500-600. It sometimes die on its own if the gas pedal isn't pressed. Moreover, the car won't run on first gear if the gas pedal isn't revved 'til 2,000-3,000 RPM while the clutch is half-way pressed so the car won't nudge and die. Every time I shift gears, the car would have an awkward nudge before the transmission is firmly shifted on the selected gear. Reverse gear acts the same way.
2.) CAR DIES WHEN AC IS TURNED ON: If the car was running idly and the AC is turned on, it will inevitably die. BUT the AC runs fine when the car is running around 60kph or more.
3.) BAD FUEL SCENT: Exhaust smells like rich, unburned unleaded. No visible smoke coming from the exhaust but the smell is too horrible, a few seconds of exposure to it will cause nausea.
4.) RANDOM ENGINE KNOCK: Revving the engine while on idle or on any gear will result to a random engine knock. Very disturbing as it gives me the impression that it could break at any moment.
5.) FAULTY OIL PRESSURE: Sometimes, the oil pressure gauge reads at 0 while running. The most it read was at 2.
6.) FREQUENT OIL DRIPS: Before I've acquired the car, my friend had to put a bottle of synthetic oil every damn month as he used it as a daily work horse. This is definitely not normal. Although since I don't use the car to avoid further damage, there is no visible oil drip in my garage. The car is parked on a slight decline around 5 degrees.
The MINOR faults in my car are:
1.) DAILY RADIATOR WATER REFILLING: Before the car is used, the reservoir needs to be filled with water. Nothing major really but it's become quite annoying.
2.) BROKEN SIDE MIRRORS: The power switch of the side mirrors don't work. Although an electrical kind of hum can be heard from the side mirrors.
3.) BROKEN REAR VIEW MIRROR: It's loose and the power switch does not work anymore.
4.) BROKEN POWER WINDOWS: Only the two front power windows work. The back parts have long been useless. Doesn't work regardless of which switch is pressed.
5.) BROKEN TRUNK THING: I forgot what it's really called but it's the metal chrome thing that pops out when the trunk button is pressed. It's now perpetually exposed and it's kind of annoying. The trunk button inside the car doesn't work as well. The trunk needs to be manually locked or unlocked using the keys.
6.) BROKEN ALARM SYSTEM: Not alarming now since everything is pretty much broken, eh? Doors need to be manually unlocked using the keys.
7.) BROKEN LIGHT SWITCH: I literally have to put a folded piece of paper in between the switch when the rear fog lamp is pulled to be turned on. This is very annoying as the switch bounces back flat if no paper is jammed. Also, the low beam and fog lights sometimes don't turn on despite the switch being turned to position.
8.) FAULTY BASS: The sound system is fine and bearable but when the bass drops, all hell breaks loose.
I've tried my best to identify the issues that are known to me thus far. I can upload actual photos and videos of the car if need to. Thanks heaps, everybody!
Last edited by yourstrulyjoey; Aug 13, 2014 at 06:25 PM.
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Joined: Jun 2010
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From: tennessee
s320
I'd check fuel pressure then compression test,as you say it missing coolant.Thoose are two tools you can rent.Check condition of harness too.If all thoose are ok,look at the plugs while you have them out.They can tell you if antifreeze is on them,or oil from burnt piston.They also can tell if coil is not firing.Proceed and check every plug in under the hood.Wires from transmission can get ATF to computers.
Thread Starter
Newbie
Joined: Jan 2014
Posts: 3
Likes: 0
'84 w123 300D M/T and '96 w140 S280 M/T
I'd check fuel pressure then compression test,as you say it missing coolant.Thoose are two tools you can rent.Check condition of harness too.If all thoose are ok,look at the plugs while you have them out.They can tell you if antifreeze is on them,or oil from burnt piston.They also can tell if coil is not firing.Proceed and check every plug in under the hood.Wires from transmission can get ATF to computers.
