Diesel spluttering

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The W124 E250D I got recently had never missed a beat - until today .

Passed the MOT last Saturday , and between a run to Dundee and back , plus some local mileage , had covered almost 500 miles without any problems .

This afternoon , we went up to Glasgow , but on the way back - amidst torrential rain - the car just started to lose power , then spluttered to a halt .

On trying to restart , at first it would turn over but would not fire , then it would splutter without catching ; after a couple of minutes , when I kept cranking and gave it some throttle the engine sprung back into life . All went well for a couple of miles , then the same thing happened again ; as before the first few tries to restart were fruitless , then I got her going again . This time , we made it the five miles or so home .

The fuel guage showed a little over 1/4 tank remaining ; it had previously ran fine with less showing . The car has stood for three years before I got it - so I'm thinking new fuel filter is the first thing to try .

Having perused the Haynes manual ( I know my way round petrol Mercs reasonably well , but this being my first ever Diesel I must admit to being somewhat lost ) I see no mention of an electric fuel pump - so no fuel pump relay to troubleshoot ? There apparently is a mechanical lift pump and a fuel pre-filter in there somewhere ?

I can guess that , having sat for sometime , there could be water and/or some cr@p in the fuel system - so a filter change seems an obvious place to start ?

Can anyone suggest anything else to troubleshoot this problem ?
 
If it's been sat for 3 years I'd be having the Tank & lines emptied and flushed with a new Fuel filter as a first port of call.

500 miles of recent use may well have stirred up all sorts of shyte in the Tank.
 
It had been run to empty by the previous owner when he trailered it down from the Black Isle - to keep the tail lights on .

I then put £20 worth of Diesel in before towing it the 50 miles home from my mum's , where it was delivered to . After that , I put another £30 in before taking it for the MOT and then filled the tank before the last week's running around .

I suspect that anything in the tank may well have worked its way through to the filters , so will change these tomorrow and see what happens . If the problem happens again , I will drain the tank and blow the lines through to see what comes out .
 
The fuel filters live in the aluminium casting at the front of the engine, just in front of the manifold.

There is a small pre-filter where the single pipe comes from the fuel heater and the main filter which is bolted on using a banjo bolt.

It will be either the fuel filter or a air leak into the clear plastic pipes.

When changing the main filter ensure you fill it with diesel first otherwise you run the risk of a flat battery before the engine fires.

The tank strainer could be blocked, access is from below.
 
Thanks .

I know the big canister filter right at the front of the engine , which looks easy enough to change , and will look for the pre filter this morning . I will change these , then run the tank as low as I dare before dropping the filter out of the bottom of the tank .
( after I get a new one from MB and make sure I have a socket to fit it ! ) .

This will be the sort of fault that I won't really know if it is fixed until I have run the car for a month or two without it happening again - unless I pull out an obviously and totally gunged up filter with a load of cr@p inside .
 
Make sure the shutoff valve is opening properly

Nick Froome
 
There are a number of plastic pipes behind the fuel filter.
These were not MB's finest idea.
The many seals at both ends of the pipes may well have deteriorated, and the system could be drawing air.
As DM says - These cars will self-bleed, but it sometimes takes a bit of cranking to achieve this, once air has got into the system..
The pre-filter is just beside the main fuel filter.
The O-ring seal for this is large-diameter and can sometimes get a bit leaky.
If you change the pre-filter, be sure to fit a new O ring seal and make sure that the housing is clean where the O ring fits.
 
Silver Saloon (who I am sure you know) offers a full set of VITON seals for the plastic pipes and the shut-off valve (at a very good price)
These are a better quality seal kit than you can buy from MB.
I renewed all mine recently, using these seals, as I had a number of leaks in this area.

If you access the Russian site, there are some good diagrams of all the components around the injector pump.
I have found these most-helpful in sorting out what does what.
 
Having had a look around earlier today , during which I closely watched the plastic pipes for any signs of bubbles while the engine was idling , of which there were none , I then had a look on the EPC and drew up a list of part numbers .

I am now just back from MB Glasgow , where I managed to get both the main fuel filter , the prefilter and seal ring , which they had in stock , and have also ordered the tank strainer , seal ring and flexible hose , along with both seal rings for the fuel pump .

I'll fit the filters I now have tonight and see if it makes any difference ; I took the car a mile up the road earlier today and could still feel a hesitancy when asking it to pull hard , so I'm fairly sure there is some blockage restricting fuel flow somewhere . Hopefully , it will be fairly obvious when it is sorted .

I will speak to Derek about his seals and give them a try ( presumably they are useful for veg oil conversions ? ) . I may look at alternative fuels later , but for now I just want to get the car running properly on regular Diesel until I know everything is OK .

Once I get everything sorted with the fuel system , I will be looking at the brakes ( which are working fine and passed the MOT last week ) but certainly need new pads and adjustment of the parking brake .

I had intended spending this holiday fortnight catching up with jobs on my W126 too :doh:
 
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There is nothing difficult about refitting pads and discs on these cars.
If the car has been sitting around for 3 years, the parking brake may be partially-siezed.
I had the same when I bought the E430, which had been parked for a while.
 
Hi Dereck,

can't remember how to post but while I'm here I thought I'd ask if as anyone had their car leave a puddle of fuel in the garage only to be told by a dealer there was no fault to be found?

Had my beloved r129 out again recently and noticed a puddle while it was ticking over outside. It smelt like fuel and went up in flames like fuel but the guys couldn't find fault with it. A week later the suns out for a rare appearence so I drag the old girl again only to find she had gone potty while it was tucked away. There was a fast drip from under the drivers seat but 3 miles down the road at work the drips have gone and no leaks?? Wondering if condensation is somehow the cause?

Untill i figure out how to post again I'd appreciate any thoughts.

Cheers

Ed
 
There is nothing difficult about refitting pads and discs on these cars.
If the car has been sitting around for 3 years, the parking brake may be partially-siezed.
I had the same when I bought the E430, which had been parked for a while.

The parking brake is holding and releasing fine ; there is just a bit more travel in the pedal than there ought to be . I think I still have a spare set of shoes , left over from one of my previous 124's , kicking around somewhere , so replacement and proper adjustment will be in order . As for the pads , I noticed they were all fairly well down when I had the wheels off to have the tyres replaced - not desperately urgent , but on the 'to-do' list along with changing the brake fluid to eliminate the slightly spongy feel the pedal currently has . I will have a better look at the discs and decide whether or not to replace those as well .
 
Having had a look around earlier today , during which I closely watched the plastic pipes for any signs of bubbles while the engine was idling , of which there were none ,

Try revving it hard from idle.
 
Earlier tonight I replaced both the pre filter and the main filter . The pre filter was badly clogged up with what looked like the mess you get in a chip fryer ! With the two new filters in place I took the car for a drive and it seemed much better . The engine would rev freely from idle without any difficulty ; I dont remember any problems doing this before changing the filters either - I will do this when looking at the pipes tomorrow to see if it provokes sny bubbles . I then took it for a longer drive and it seemed that the hesitancy which was apparent earlier had gone ; even accelerating hard uphill , which was earlier causing the engine to feel as though it was struggling , was now smooth and effortless . Having taken the car for an extended run , without straying too far from home , it now seems to be running fine .

Although the tank strainer is due in on Saturday , I have refuelled the car and worked out the consumption at a whisker over 40 mpg . This was for about 200 miles of dual carriageway on the run to Dundee and back , with a further 300 miles of mixed town and open road driving , mainly short runs . I'm not sure if this is good , bad or indifferent for the model , but I will see if I can better it as I gradually get the car sorted out .

I will replace the tank strainer in a week or two , once I have run the tank low again .

I also have to replace the tensioner for the poly drive belt , which is rattling quite badly at idle - the new parts came with the car and I will do this next week .

If I can get the bugs ironed out of this car , maybe I can spend some time on my W 126 .
 
If the pre-filter was full of gunge, it's likely that the tank strainer will be similar.

I have always added Millers diesel additive to my two E300TDs and run them on ordinary diesel fuel.
I change the pre-filter every two years (which for me is 40k to 50k miles).
I never seen any build-up of sludge or anything in the pre-filter.

Regarding mpg.
Around 40 mpg seems pretty-average for one of these cars.

I've just been on holiday and measured the E300TD over 1600 miles.
It returned 36.4 miles to the gallon ... Which I found a bit disappointing ... Especially as around 1000 miles of this was motorway or dual-carriageway driving.

I assume your car has a new(ish) air filter.
This is obviously important with a diesel, as they draw in a lot of air, and the air filter condition will get blocked if neglected.
 
The air filter is something I haven't yet looked at , but I will look at it and replace as neccessary .

We're back in Dundee , meeting the outlaws again , with 111 trouble free miles behind us on the trip counter since refuelling ( and changing those filters ) .
 
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hi Derek.

dying at 1/4 but if you refill it works again, deffo the tank strainer. This can be cleaned out rather than replaced as its just plastic mesh
 
It was only a tenner for a new one , which will be in tomorrow , along with a new seal ring and flexible hose , so I will change them over when I run the tank back down .

I'll take a few photos when doing it , for the benefit of others .

Are these seal rings , mentioned earlier , that you have for use with veg oil/biodiesel ?
 
As an update , the car has now covered a further 250 miles without any recurrence of the problem . I still have to go up to Glasgow to pick up the tank strainer , but no great rush since I need to run the tank low again before changing it , which will probably be around the end of the week .

I have kept the gunged up prefilter , and will take photos of this along with the strainer at that point .

Meantime , here are a few photos I took the other day .

The engine bay is reasonably tidy
31IMG_3272.jpg

33IMG_3274.jpg


albeit a slight leak from the oil filler cap , either due to excess pressure or a worn seal ... I had wiped this clean , only for it to return after a couple of hundred miles .

18IMG_3259.jpg


New fuel filter fitted
20IMG_3261.jpg


genuine MB item this time , in place of Mann filter which was there before
21IMG_3262.jpg


I'll post some general pics of the car in the 'Late 124' thread
 

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