270 CDI Starting issues

[Wearethesound]

Ok so my CDI has been having some issues starting randomly. Now I just went through the "Black Death" and removed and cleaned all the injectors, replaced #3 due to it being cracked, replaced the copper seals and got it running good again. Now it seems to be having trouble starting, randomly. Sometimes it's the first start of the day, sometimes it just after being shutoff. Now it seems like it's a fuel feed issue and I've read that it could be due to the fact I put a non-merc fuel filter in it, and I've heard it's probably the o-rings between the fuel filter and the high pressure pump. Also been told crank and cam shaft sensors along with the fuel pressure regulator. Am I on the right path with replacing the filter and o-rings?

The only add on I have is some days it idles rough but runs smooth others, and the last time it would start I nearly drained the battery cranking before "jumping" it and it immediately fired up. So would I be right to assume it could be the battery? Or battery is just another issue along with a fuel feed one? Any help or suggestions are much appreciated. Thanks in adavance.

 

[GadgetBoy]

Glow Plug Relay

 

[Wearethesound]

I'll add that to the list. First time I've heard that but seems like a cheap part to throw at it if the filter and o-rings don't do it. Thanks!

 

[MOZ]

I Might be wrong, but assuming you have used a reasonable quality aftermarket fuel filter like Mann etc, I would be very surprised if its that (unless the hole for the plug in fuel pipe is outside tolerance and letting air in).

My guess would be either worn O'rings on the fuel lines, or possibly a broken retaining clip on one of the fuel lines. I had this issue on my ML270 where the retaining clip on the fuel filter connecting hose had one tab broken. The car ran fine and started fine some times then others it would take 30 seconds or more of cranking to get going (but then run fine). I put it down to vibration allowing the hose to move slightly (as only one retaining tab holding it in place. It may even be a crack in the brittle fuel pipe or plastic connectors. Air in the fuel lines on these 270's are very common and at the age of yours and mine.

I replaced that pipe and not had any trouble since - by the way I'm using a Mann aftermarket fuel filter rather than the Merc OEM one (probably manufactured by Mann anyway?)

I have had a number of issues with my fuel lines as they are prone to aging and get brittle and the plastic ends can break, but hopefully its just the O'rings that you need (O rings are about a quid each from Merc so worth trying first (careful around the bottom of the High pressure pump connections as this area is a bit fiddly - especially with big hands) and as I say the lines get brittle with age so you may break the pipe or plastic connector while trying to remove them to replace the Orings, so just go with care (I would avoid trying to use a flat bladed screwdriver to prize them out and just use some gentle force by hand as experience has shown the screwdriver approach can crack the plastic, not trying to teach you to suck eggs but just a heads up (been there done that ).

The fuel pipes are about £35 each from Merc (molded shape) so not too expensive if you need to replace them, but hopefully not.

Re battery- if you are having to crank it a lot to get going and only doing short journeys then you may find the battery is struggling. If you get teh fuel feed sorted and do a good long run in it, the battery may well be OK (could get it tested at a garage for peace of mind). mine was teh same when I had my issues and had to jump lead it a couple of times, but it was OK after that. I did change it subsequently for a number of reasons but I suspect its struggling due to being hammered on the starting so much. If you do change the battery - make sure you read the correct procedure for changing it as reconnecting it in the wrong order can put surges through various systems and kill them (eg, AAM, SAM etc. so worth double checking the correct battery re connection procedure before doing it).

Good luck.
Moz.

 

[219]

Before you throw too many parts at it , have you read the codes ?

Even a cheap generic EOBD code reader , £10 or £15 , can often point you in the right direction .

 

[Wearethesound]

First thank you for all the replies. Don't worry about offending me by giving beginner pointers. I'm use to working in much older vehicles where force with a flat tip is common, so thanks. I went ahead and ordered the o-rings and before I swapped them I started her up and watched the fuel lines to see which one had air bubbles in it, sure enough it was the line coming from the fuel filter so I replaced the o-rings and gave her a go again. Still had air bubbles after letting her run for about 5 mins or so (should I run it longer? Not sure how long it needs to bleed.) I looked at the line just after the fuel filter next to the connector and didn't see any bubbles I also looked in the middle where the chaff wrap had a break in it, no bubbles but when I looked near the connector that goes into the pump I saw bubbles in an almost continuous stream. Now a few of my connectors have cracked clips on them. Not completely broken but just cracked. Could this be the issue? (although the o-rings where bad and squared off) Also I removed the fuel line to check for a crack or split I can't see one but if the clips are a possible cause then I should just replace the whole assembly anyway.

 

[MOZ]

Sounds like you are on the right track, is it still playing up? for a while after I did mine I could see some small bubbles in the pipe near the pump end but the starting problem was fine, and then eventually after a day or so no evidence of bubbles. If you have a big bubble gap due to flow back to the fuel filter then maybe a crack is letting air in.

Up to you if you change the whole pipe, as I say its about £35 and I did both mine (from fuel filter to pump, and the one from the HP pump to the LP pump - due to the fact that I damaged it while changing the thermostat - another common issue). the only one I havent replaced is the return from the injector rail back.

Again another tip - if you need to change the pipes going underneath the HP pump, there are 2 retaining clips mounted on the front of the engine to hold the pipes away from the perilously close auxiliary belt. These tend to break when you try to open them to free the pipe so worth getting a couple of those too before attempting the job (again only a couple of quid from Merc) but it sounds like yours is the pipe from the fuel filter to the LP pump so may not need to do those under the HP pump.

more info in this thread if it helps

ML270 diesel unidentified T bleed contraption - MBWorld.org Forums


All the best.
Moz

 

[Wearethesound]

Found bubbles coming from the line that feeds into the fuel filter re-sealed it and still air bubbles. Are there more connectors that I can reseal? Or should I replace the component it plugs into, heat exchanger maybe? Not sure what it is as I said before my knowledge of cars is much older models and Diesel engines are with tractors/heavy machinery only. Thanks for any help you have to offer. .

 

[handyandyspark]

Im also having intermittent trouble starting on my 2007 E class, keep getting the engine management light coming up after accelerating following use of the cruise control through roadworks. Everytime i can reset it by starting 3 times. Had it into my Indy at xmas and they had Over pressure on the rail fault codes but couldnt find why. Fuel filter and some pipes were changed. Id say it does it every other month but just recently it refused to start until after several attempts then had engine management light on for a while as I darednt stop but it did reset after a while. had it into indy again today same overpressure codes and also cam belt sensor fault codes have been coming up, all reset fine and it started every time they tried it. Typically they said if it happens again bring it straight back so they can see which code has come up and within 10 mins i was back when it refused to fire first time, the same 2 codes were up. Indy is going to price up a fuel regulator as a starting point but they cant understand how im getting over pressure.

 

[MOZ]

Hi wearethesound,
Check the rubber pipe from the back of the fuel filter (inlet) to the black unit about 100mm away (I think this is a fuel heater) as that pipe may be perished and leaking (a brand new one is quite expensive for what it is - I bought one and changed it when I changed my fuel filter as mine looked old and I was worried it would disintegrate half way through the job - the old one turned out to be OK and just perrished at the cut end sections so would have been fine but changed it for peace of mind anway) but when I heard the price I was pretty peeved and should have just bought some standard rubber fuel hose from a motor factors (worth thinking about if you change it as it is expensive for what it is).

If there is no leak there then I would question whether there is some leak back on the injectors, I notice from your original post that you have done some work on those, it may be worth having a leak back test done on those by an indy (unless you can do it your self).
Have a look at the following link as this might help.

Air in fuel lines ML270 2000 - Mercedes-Benz Owners' Forums


All the best.

MOZ

 

[Wearethesound]

Got her book in at a local shop for an injector leak test. Will post the findings, hopefully she gets fixed!

 

[tec]

When I had the inlet manifold replaced on my 270CDi by Mercland they recommended I had the fuel pipes replaced, which I did have done.

I think the pipes get brittle and hard with age, so just replacing the o-rings seems like a false economy, but will be interesting to hear what your garage finds.

 

[Wearethesound]

Yeah, she's been starting right up since replacing the o-rings but then today just after driving it to work (20 mins) I tried to start it and she wouldn't fire, I noticed a lot of air in the fuel lines tried to start her for 20-30 mins (had to have it jumped) and she just wouldn't start. Been sitting all day and just tried it and first crank she started. So from what I'm gathering seems like injector leak off maybe the cause. Maybe?..... Shop quoted me at£135 for the test, and to reseal and cut a new seat for the #1 injector as it is leaking again. (I attempted to cut the seat myself but was easy on it as I've never done it and didn't want to go too deep.)

 

[MOZ]

Hi again,
Been having more of a look in detail about this as I may need the info myself in the future and found this interesting thread

mL270 2003 failed to start - Page 5 - Mercedes-Benz Owners' Forums

where the problem turned out to be cracked high pressure return seals inside the injector, that were fixed in situ!!.

Thought it was worth passing on for anyone whos interested.

Let us know how you get on.

Moz

 

[Windybrow]

I have just experienced intermittent cutting out and non start on my 2004 ML270 after I have re sealed 2 injectors and replaced a third, The exhaust gas had caused the plastic solenoid block connectors to become brittle and the connectors became dislodged. I discovered that cleaning re fixing them cured the problem. New connectors on order from E-bay and plastic zip clips are keeping them is place until I repair properly. I have a code reader , but no fault codes were recorded when problem occurred.

 

[Wearethesound]

Just got her back after 2 days in the shop, they re-sealed a valve on the back side of the fuel rail, resealed my #1 injector and cut a new seat for the seal (5.5mm) also the did a injector leak off test. All checked good and within spec. They test drove it and started it over 30 times without a fault. So I picked her up, paid my £200 and she was running just fine, got her home and out of curiosity I popped the hood to look at the fuel lines, still had air bubbles but I will say not nearly as many as it had before, so I took her for a drive to run some errands and see if I could get her to fail. 4 different stops and starts all at different time intervals all different engine temps and she started everytime much stronger then before, but the disaster! On my way home as it was getting dark I turned on the lights and about 3 mins later she died, didn't sputter, didn't lurch, just straight cut out like I had turned off the key. But, she started right up after I got stopped. Resumed my drive home with lights on and immediately she died yet again in the same fashion. Pulled over and stopped went for a crank and she cranked but no start and then something strange happened...... When I let off the key it keep cranking on its own for about 6 seconds. After that I recycled the key off and back to go for a crank and "click" nothing, all lights on dash out. So it looks like I have a bad battery? Or maybe an issue with the alternator? Tomorrow is a new day and I will keep updating you all with my findings...... This is becoming quite frustrating.

 

[Wearethesound]

Battery showed 11.4v so I Put the it on a trickle charger and this morning. No change. So Today ill be getting a new battery fitted and see if my problem is indeed solved or just another side issue.

 

[MOZ]

Nightmare!!
Hopefully its just the battery now and fingers crossed the fuel delivery is fixed.
I guess lots of cranking over the past few weeks with teh fuel issue may well have taken its toll on your battery.

Fingers crossed for you.
Let us know how you get on.

Make sure you read up on correct disconnect and reconnect procedure (you might even be better off keeping your old battery connected via jump leads while swapping so as not to lose volts and create a surge once the new battery is installed.

if not doing the bypass method as I mention at least read up on correct instalation sequence as i know a wrong sequence of +ve or -ve first (cant off the top of my head remember which way round it needs to be) can cause an inrush surge that can take out various modules. I think the correct procedure is in the manual but if not do a search and I'm sure you will find it.

Good luck.
Moz

 

[Wearethesound]

Thanks mate, new battery fitted and all seemed good to go, then the starting issue came back, but as I was watching the fuel lines while my wife cranked I noticed something. Air bubbles coming out of the fuel filter but none going in so I popped off the lines and boom, fuel filter bowl was empty, like barely any fuel in it at all, so I topped it off and presto she started. Now I'm trying to figure out how the filter bowl is allowing air into the system, maybe a bad seal after the filter change? While it's running I can rev it up and get tons of air coming out with none coming in and when I shut it off the "in" line fills with air as the fuel heads back towards the tank..... Is there some component I'm missing? Maybe a lift pump is going bad? If there is one...... All I know is I can't find where it's leaking from but I'm about to cover the whole lid area with some epoxy and put it back together to see if that fixes it (temp) till I can order a replacement if it is the cause, thoughts?

 

[MOZ]

I may be wrong but I don't believe there is any lift pump in the tank or on route. As far as I'm aware the low pressure pump at the front of the engine ( where the fuel pipe from the filter goes) pulls the fuel from the tank through the filter when the engine turns ( as isay I may be wrong).
It sounds like you have some leak allowing air in around that filter area.
How long ago did you change the filter and was it a reasonable brand? I know you checked the rubber pipe from the filter inlet to the bullhead fuel heater, have another look around that area and check there are no iffy pipes or leaks.

You may find it is the fuel filter itself ( although I would be surprised if it's a reasonable brand).

Good luck, and am really sorry your having so much frustration with it.
Good luck.
Moz