JohnOS
Active Member
- Joined
- Aug 27, 2020
- Messages
- 35
- Reaction score
- 28
- Location
- Malvern
- Your Mercedes
- 2012 E500 Cab 4.7 TT V8
Just posted in the Brakes, Suspension forum about the resolution to my braking issue, so thought I'd follow up here with some detail on a recent High Pressure Fuel Pump issue. I had an engine warning light, and ignition was slow to catch on turning the key. Plugging in my iCarsoft I got these codes...
P008700: fuel pressure in system too low
P008992: pressure regulating valve malfunction
P008792: fuel pressure too low
...which made sense; engine isn't going to fire readily on start if there's not enough fuel. Researching this led me down a terrifying youtube rabbit hole on direct injection problems. Especially this video:
Yeah, the guy works for an oil company, so he's talking his own book on frequent oil changes. Anyway, since my E500 is a summer car, not a daily, it doesn't do sub 15min shop runs, and I always warm up properly and never go above 2K revs until temperature is up. Not that I need revs with 800nm torque at 2K from a stage 1! The comments on chain wear are highly relevant for anyone driving a DI Merc, especially 1st gen TT like M157, M278, M276, and 2nd gen hot V M177 et al. My 2012 M278 has the old chains. Everything post 2014 has the new chain tensioner. I'll have that installed in my M278, when I start to hear a hint of chain rattle on start. Timing errors can cause incomplete combustion, leaving soot in the cylinder, and oil, which aggravateds the chains. So what was the fix?
I use the excellent indie specialist ACMS Walsall for servicing. But this time I was busy in London, and needed a local specialist. Merc Care Enfield has good online reviews. They plugged the E500 into their Merc diagnostics, and confirmed the iCarsoft diagnosis. Merc diagnostics showed it was the right HPFP. A couple of days later I had the car back with a new HPFP installed. Engine now catches cleanly. I've been running this E500 since Sep 2020; I bought it on the back of a heads up post here at mercedesclub.org.uk! Previously I had a 99 CLK230 Cab. So I've had 3.5 years of just service & MOT until the last few months, when the car has needed a brake line fix as well as the HPFP. So I feel I'm still ahead of the game; Maserati, Jag, Audi or BMW four seater convertible V8s would surely be more expensive to run.
So I guess I'm here to say that DI V8s are more fragile than the M113 series V8s. Yes, they're more powerful, torquey and efficient. But you have to look after them. My plan going forward is...
1. Annual oil changes regardless as this is a low mileage car that only gets serviced every other year.
2. Continued regular premium fuel for the added cleaners.
3. Continued proper warm ups before using revs.
4. Listen for timing chain rattle on startup and replace with improved post 2014 chain & tensioner set when necessary.
I believe the official schedule is timing chains as 80K. Everyone I've asked has said "do not put new timing chain in until you hear the rattle". Merc Care advise they can fit the new chains without lifting the engine out. They charged 738 inc VAT and parts for fitting the new HPFP, which I thought very fair given part cost and the time it takes to get at the HPFP. So I'll need to budget for a four figure spend on the chains at some point. Given that I've run this car for nearly four years, I'm quite happy with only ~1300 non service/MOT costs from the brake line and fuel pump fixes I've had to do this year. I used to run a Land Rover Disco3, so I know how much a real lemon can cost!
P008700: fuel pressure in system too low
P008992: pressure regulating valve malfunction
P008792: fuel pressure too low
...which made sense; engine isn't going to fire readily on start if there's not enough fuel. Researching this led me down a terrifying youtube rabbit hole on direct injection problems. Especially this video:
I use the excellent indie specialist ACMS Walsall for servicing. But this time I was busy in London, and needed a local specialist. Merc Care Enfield has good online reviews. They plugged the E500 into their Merc diagnostics, and confirmed the iCarsoft diagnosis. Merc diagnostics showed it was the right HPFP. A couple of days later I had the car back with a new HPFP installed. Engine now catches cleanly. I've been running this E500 since Sep 2020; I bought it on the back of a heads up post here at mercedesclub.org.uk! Previously I had a 99 CLK230 Cab. So I've had 3.5 years of just service & MOT until the last few months, when the car has needed a brake line fix as well as the HPFP. So I feel I'm still ahead of the game; Maserati, Jag, Audi or BMW four seater convertible V8s would surely be more expensive to run.
So I guess I'm here to say that DI V8s are more fragile than the M113 series V8s. Yes, they're more powerful, torquey and efficient. But you have to look after them. My plan going forward is...
1. Annual oil changes regardless as this is a low mileage car that only gets serviced every other year.
2. Continued regular premium fuel for the added cleaners.
3. Continued proper warm ups before using revs.
4. Listen for timing chain rattle on startup and replace with improved post 2014 chain & tensioner set when necessary.
I believe the official schedule is timing chains as 80K. Everyone I've asked has said "do not put new timing chain in until you hear the rattle". Merc Care advise they can fit the new chains without lifting the engine out. They charged 738 inc VAT and parts for fitting the new HPFP, which I thought very fair given part cost and the time it takes to get at the HPFP. So I'll need to budget for a four figure spend on the chains at some point. Given that I've run this car for nearly four years, I'm quite happy with only ~1300 non service/MOT costs from the brake line and fuel pump fixes I've had to do this year. I used to run a Land Rover Disco3, so I know how much a real lemon can cost!
