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Injection/Vacuum Pump Ramp Gear Injection Timing E300D W124

Discussion in 'Engine' started by superleggera, Jul 25, 2011.

  1. superleggera

    superleggera New Member

    Messages:
    13
    Joined:
    Jun 12, 2011
    Location:
    North Staffs, England
    Car:
    1990 190E 2.6 Manual
    Hello all!

    My car is still in and out of the local indy specialist- the vacuum pump went and took the ramp gear that drives it with it. All been replaced but now it's got timing issues. The guys have put everything back according to the specs in the Mercedes manuals, for an OM606 engine it's 15deg +-1deg but it now suffers massive diesel knock/valve clatter rolling on to the throttle with virtually zero engine load.

    The guys think that the gear, which is made of two parts that extend via centrifugal force/weights (bit like an old starter motor) according to engine speed, perhaps might need to be installed with some amount of compensation taken into account for the final timing etc. They don't want to keep taking it out and changing it because it's a big job and they haven't got the manpower. They have over 20 years Merc main dealer experience, they've called other dealers and no-one seems to know, there's a bit of a blackout of info as far as these E300D W124s go.

    Does anybody know what this might be? Is there some sort of compensation or does it just go in at 15 degrees?

    Any help would be much appreciated, it's my only car and I need it back asap!
     
  2. Number_Cruncher

    Number_Cruncher Hardcore MB Enthusiast

    Messages:
    987
    Joined:
    Jan 14, 2008
    Location:
    Midlands
    Car:
    1995 E300D
    Yes, there is a timing device - it gives the injection pump a centrifugal advance - the pump timing is advanced as the engine speed rises.

    However, if you're timing by checking the position of the pip in the governor flyweight (by removing the bung at the rear end of the pump) you are including the centrifugal mechanism in the setting.
     
  3. OP
    OP
    superleggera

    superleggera New Member

    Messages:
    13
    Joined:
    Jun 12, 2011
    Location:
    North Staffs, England
    Car:
    1990 190E 2.6 Manual
    Hi, thanks for the reply. I probably haven't made my request particularly clear. We know about the timing advance mechanism etc and the Inj Timing is being checked via the pip at the the flyweight etc.

    Basically, the engine runs well and very quiet/economical, if a little underpowered at 19deg BUT I can hear light tinkling when the engine is under load, escpecially in warm weather- classic ign advance/lean mixture pinking. They set it at this as a rough guestimate by ear until they could get the official hyper-accurate tool from Germany, after which they measured it and found out it was 19 degrees.

    With the timing set at the official 15, or 14 deg the engine suffers from this very loud valve clatter/knock that kicks in at around 1500, even if the engine has no load, ie in Neutral or Park at standstill.

    To their credit, the guys don't want to leave the job half right, there must be one correct answer/method.

    We can't find any other info related to this apart from the Mercedes own workshop stuff, which at the moment seems to be incorrect. Could they have installed the gear incorrectly? It only seemed as though there was one possible way to go in, but maybe there was another way, this is what I'm asking I guess. Has anyone else changed one of these ramp drive gears or had anything like this on their Merc? The fuel lines are good, no air at all in them, pump seals just been changed to make sure etc.
     
  4. Dieselman

    Dieselman Banned

    Messages:
    34,206
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    Car:
    Peugeot 403 Convertible
    They are setting the timing at 15 deg AFTER TDC, aren't they, not 15 deg BTDC?
     
  5. OP
    OP
    superleggera

    superleggera New Member

    Messages:
    13
    Joined:
    Jun 12, 2011
    Location:
    North Staffs, England
    Car:
    1990 190E 2.6 Manual
    Hello, yes they are, it wouldn't run at all if it was that far out. It has been set exactly as the factory settigns dictate.

    I've been doing a bit of Googling research and I'm starting to think that the one thing they might not have taken into account is the timing chain stretch.

    Apparently the chains on the OM60x engines are pretty good but even so they can stretch up to 4degrees worth of retardation at high mileages. One guy reckoned that once they hit 4deg they needed changing, which could be at as little as 150k miles, which is about my kind of mileage. After fitting a new timing chain, the injection timing must be checked after 1200miles due to initial stretch. Could it be that the difference between what the flywheel says is TDC, what the pump says is TDC and what the valve gear thinks is TDC add up to the symptoms we're getting?

    All thoughts much appreciated :)
     
  6. Number_Cruncher

    Number_Cruncher Hardcore MB Enthusiast

    Messages:
    987
    Joined:
    Jan 14, 2008
    Location:
    Midlands
    Car:
    1995 E300D
    Checking chain stretch is worth doing - after the vac pump has failed, are you sure there is absolutely no chain damage?

    I wouldn't get too worried about being accurate - there's no guarantee the pointer on the timing cover is really in the correct place, and I ceetainly wouldn't trust it to the last degree unless I checked where TDC was by measuring piston height.

    Personally, I wouldn't worry too much about what the (dubiously accurate) timing figure is, but, would simply set the pump so that the car drove properly.
     
  7. Ian B Walker

    Ian B Walker Hardcore MB Enthusiast

    Messages:
    7,672
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    Jun 7, 2003
    Location:
    Freckleton
    Car:
    300-24, saloon and coupe, E300 24 valve diesel estate
    Set at 15degrees BTDC then time the pump using the proper Mb tool (costs £11). We struggled with Christine trying to time her correctly. (Hi Rob :D)
     
    1 person likes this.
  8. bolide

    bolide Hardcore MB Enthusiast

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    Oct 8, 2005
    Location:
    Brighton
    Car:
    BMW E39 525 Diesel Touring
    Roll another E300 Diesel in there and check the two side-by-side

    Are you sure that the timing is wrong? Maybe it's right and the fault is elsewhere. Hence my suggestion above...

    Nick Froome
    the independent Mercedes Estate specialists
     
  9. Rob77

    Rob77 Hardcore MB Enthusiast

    Messages:
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    Location:
    Bolton
    Car:
    '90 W201 2.6 Sportline; '96 S124 E300D; '94 Aprilia Pegaso 650
    Hi Ian, took her down to Leicester and back last weekend. Running sweetly, thanks :)
     
    1 person likes this.
  10. OP
    OP
    superleggera

    superleggera New Member

    Messages:
    13
    Joined:
    Jun 12, 2011
    Location:
    North Staffs, England
    Car:
    1990 190E 2.6 Manual
    The timing had been set to 14deg so I said to the guys put it to exactly 15deg and then at least we know where we are starting from etc. I've driven it around for a week or so and the difference between 14 and 15deg is quite noticeable, even though common sense tells us that 1deg won't make a difference.

    The guys' main concern was that they had inadvertendly installed the wrong timing gear/device- one that looked the same and fitted but meant for a different engine and perhaps had different weights or springs in it that would result in different, more advanced timing for a given engine speed.

    Having driven it for a week I reckon it's the right gear and for whatever reason previously the timing was more retarded than it should have been. Part of what makes the clatter so noticeable is that at idle it's a very quiet engine, the quietest this garage has ever heard (most people think it's a petrol engine car when I park up) and so when the clack/rasp does kick in it's very noticeable. I've been listening for that noise on my van, which has absolutely perfect timing and a similar noise is there especially when the oil is cold but it's a much noisier engine so it's more difficult to distinguish at first.

    Driving around, the car has good throttle response, the rasping/klack/clatter does kick in when I punch it hard, in kickdown or when the revs start to get around 2500-3000 rpm. I'm going to go back in a week or so and we'll try it at 16deg, even though supposedly 1deg won't make any difference.... At motorway/freeway speeds the noise is quite intrusive and if I can manage to get the same driveability but lower cabin levels of noise at 85mph ish then I'll be happy- I don't mind the rasping/clack at other times. The guys at the garage think the timing is too advanced still and reckon by sound it should be retarded further.

    They reckon they can adjust the timing in about half an hour so it's no sweat for them to play with it a little when I take it back. This is my first Merc, had quite a VW diesels before (still got a Mk2 Golf GTD and a T4 TDI) and I have to say that Merc diesels don't seem to sound like any other which throws me out a little. My Dad also pointed out to me that I rev engines a bit harder than the average driver (habit from owning/riding motorbikes for years maybe) so things like this if they are going to be noticeable are more likely to be noticed by me than someone who cruises sedately etc.

    Thanks for all your help and suggestions on this one. If anyone else would find it useful, here's what we have deduced so far:

    1- The new (used part, MB doesn't sell them seperately anymore) timing ramp gear/device that was fitted had a slightly longer collar but in all other respects it appeared to be the same. Apparently there was a later revision to the design which may have accounted for the fact that it didn't just simply go back in the way it came out as regards to timing, so either they fitted the newer one or the newer one was originally fitted and swapped for an older one.....

    2- Despite what we and everyone here thought, 1deg of timing does seem to make more of a difference on these 24v 3L OM606 engines then you might imagine. If you're having to time one in the future might be useful to bear that in mind. Maybe it's a combination of the timing, cam profile etc but it seems there is a relatively narrow, non-linear 'window' of where the timing needs to be rather than a gradual getting better/getting worse kind of thing.

    3- The point at which the garage has ceased to make a profit on this job has long passed, the guy who owns it is a real stickler for getting everything exactly right (time served factory trained MB tech) and will keep trying and trying until everything is spot on, where most garages would call it a day he keeps plugging at it. If you have a Merc that needs some attention for whatever reason, you could do a lot worse than take it to Merx in Stoke-on-Trent.
     
    1 person likes this.
  11. trapperjohn

    trapperjohn Hardcore MB Enthusiast

    Messages:
    7,314
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    Nov 19, 2008
    Location:
    Lancashire
    Car:
    124 300D 24V Estate
    If you are ever up Preston way. Give me a shout. You can have a cabby in my 300D Saloon. Its the same engine as yours 24v 3L OM606. 195K on it so its getting near to its "run in" point.
    Ian and his team at 124 Works look after it for me and, if I do so say myself, its just about "Bob On" Perhaps to be de-cated in the future and a decent exhaust system put on it. It currently runs on an exhaust system of various makes (It was like that when I bought it) But still runs sweet.
     
    1 person likes this.
  12. OP
    OP
    superleggera

    superleggera New Member

    Messages:
    13
    Joined:
    Jun 12, 2011
    Location:
    North Staffs, England
    Car:
    1990 190E 2.6 Manual
    Thanks for the invite although I won't be going past Preston for a while, not in the Merc anyway maybe in my van though....

    The timing is now set at 15 deg ATDC, runs sweet until 2k rpm no load/ 2750 rpm with load when the really harsh clack/clatter/knock kicks in. I've just done 500 motorway miles and the noise was doing my head in- it's REALLY loud.

    Going to try it at 17 deg, to see what sort of difference it makes. I've also just bought a timing light and a diesel pulse adapter, so I can measure the timing when the engine is running etc. Does anyone know what the DYNAMIC TIMING for the Injection/Start of Fuel Delivery should be for the OM606.910/E300D W124 should be according to Mercedes? I've looked everywhere- static is easy, 15 deg but I can't find the running/dynamic figures..... I reckon comparing the advance curve on my mine to what it should be by using a timing light is the easiest way of working out whether there is a problem with the timing device on the pump.

    Any thoughts much appreciated....
     
  13. Number_Cruncher

    Number_Cruncher Hardcore MB Enthusiast

    Messages:
    987
    Joined:
    Jan 14, 2008
    Location:
    Midlands
    Car:
    1995 E300D
    When the vac pump failed, what, exactly, did the garage replace?

    timing chain?
    crankshaft chainwheel?
    they have replaced the IP chainwheel and advance mechanism
    timing chain guides?
    timing chain tensioner? - did they bleed this properly?
    oil pump chain?
    did they have the front cover off?
    has the TDC pointer been removed / moved?
    did you get ALL the debris out of the sump?
    did you account for everything? is the engine using oil?
     
  14. OP
    OP
    superleggera

    superleggera New Member

    Messages:
    13
    Joined:
    Jun 12, 2011
    Location:
    North Staffs, England
    Car:
    1990 190E 2.6 Manual
    Thanks for replying, sorry for my tardy reply, been really busy this week.

    They replaced the timing device and gear with a good used item as they can't be purchased from MB anymore, you have to buy the whole pump etc, at around £600 for just the part it was a no-no. Apparently I was lucky and nothing else needed replacing, they accounted for all of the bits of pump etc, as far as we know nothing went into the sump. The engine uses no oil at all!

    They retarded it down to 17deg ATDC the other day, it's quietened it down a lot, idles better, less 'popping' (I think these Mercs pop like popcorn rather than knocking at idle like my VWs for instance).... The clatter/knock still kicks in but at around 2500-3000 rpm and it's much quieter, not the noisiest thing in the car anymore, the wind noise is louder. If it was any other car you would probably not notice it because plenty of other diesels I've driven sound much worse (Mk5 Golf TDI for example) however it is a Merc E class and they are not just any diesel are they? The car still has good power, no discernable smoke even at hard acceleration unless it's at night and someone's behind me, then I can see a haze in their headlights. The low pitched rumbling/drone has come back now at motorway speeds which is more of a Merc noise I think (sounds similar to being on a Virgin Pendolino train)- it seemed to have disappeared at the more advanced apparent timings of 14 and 15 deg.

    I can also induce the noise at very light engine load situations, at around 75mph on the motorway by just tapping the throttle on and off etc or when accelerating in first gear when the revs increase to the point of the box changing up- if it was a petrol engine I'd be inclined to think that that this issue has been caused by wrong timing and some issue with the vacuum advance and now the timing is okay just the vacuum advance to fix but the diesel doesn't have a vacuum advance or does it?

    After the car was first fixed it was running with 19 deg, which is what they set it to by ear before they got hold of the MB tool to set it accurately (when they got it they measured what they had set it to previously)- the car ran very smoothly but it was a little sluggish and it sounded like it was pinking up hills and on hot days- I don't mind the extra clattering/rasping noise if I get a bit more poke, all modern diesels and petrols are re-timed each engine cycle to be as near to the point of knocking as they can get away with using knock sensors etc so maybe setting it to 17deg is replicating this. Maybe from the factory MB tune the engine for refinement rather than the extra few bhp? As long as this knock/clatter isn't going to cause any extra wear and tear through higher cylinder pressures etc then I'm not too worried about it now. I may change it to 18 deg at the next service.

    I'm also wondering that maybe it could be running a little lean, I don't know the history of the car really and maybe somebody fiddled with it to get better economy. That would explain why I don't seem to ever see any smoke, even when it was running at 19 deg. When I first bought it I was getting up to 40mpg, at 14 & 15 deg it's been around 30 mpg. I still haven't had a chance to use my new timing light and pulse adapter which finally turned up yesterday, maybe that will shed some light on it.....will do it tomorrow weather permitting!
     
    Last edited: Aug 28, 2011
    1 person likes this.
  15. bigshineybike

    bigshineybike New Member

    Messages:
    26
    Joined:
    Mar 27, 2008
    Location:
    based Surrey UK
    Car:
    W124 estate
    Hi all, I thought I had followed everything in the rebuild of engine following my smashed timing pulley and vacuum pump
    I have put everything back together but the car will not fire or start.
    (OM606 300 D 1996)
    While I was taking stuff apart the timing chain was wired to the top cam pulley.
    I fear though that the chain may have jumped on the crankshaft sprocket.
    I want to check the relationship between all the components driven by the chain.
    when setting everything I was assuming.

    The twin cams are pinned with the 6 mm rod with the two spots aligned.
    (Or is this wrong?)
    The injection pump is locked with the special tool.
    the crank damper pulley is marked before and after tdc. I think this should be set at 15 degrees before top dead center for injection timing but should the cams still be pinned?

    I am confused here as I expected that the cams when locked in position should be at top dead or does this 6mm pin set the cams 15 degrees off top dead.

    I am beginning to think that the cams pins are tdc and the pin should be pulled out and the engine turned to 15 degrees after top dead centre. then the pump locked with the special tool is fitted to the cam chain.
    was it locking th cam shafts that threw me?
     
  16. bigshineybike

    bigshineybike New Member

    Messages:
    26
    Joined:
    Mar 27, 2008
    Location:
    based Surrey UK
    Car:
    W124 estate
    Sorry repost since I dont seem to be able to edit that rubbish I wrote above.
    Hi all, I thought I had followed everything correctly in the refitting of timing pulley and vacuum pump.
    I have put everything back together but the car will not fire or start.
    (OM606 300 D 1996)
    While I was taking stuff apart the timing chain was wired to the top cam pulley as suggested .
    I fear though that the chain may have jumped on the crankshaft sprocket. (is this possible?)
    I want to check the relationship between all the components driven by the cam chain.

    When setting everything I was assuming that the twin cams should be pinned with the 6 mm rod while the two spots are aligned.
    I think this is here i went wrong, should that pin only be used to check top dead centre alignment?

    With the 6mm cam locking pin removed should I now turn the crank (taking the cams with it) to 15 deg after top dead centre.
    With the injection pump locked with the special tool.
    I am guessing now its time to re fix the timing device sprocket onto the pump splines.
    finally refix the top sprocket to the twin cams, re-tension and reassemble ready to try again?

    All the Mercedes guides I have concentrate on taking apart

    Thanks for all the help.
     
  17. Number_Cruncher

    Number_Cruncher Hardcore MB Enthusiast

    Messages:
    987
    Joined:
    Jan 14, 2008
    Location:
    Midlands
    Car:
    1995 E300D
    It might be worth removing the inlet manifold, and checking to see if it's obstructed.

    From your symtoms and description of the work that has been done, I also suggest that you check the compressions, and, while the injectors are out, check them for:

    - opening pressure
    - leakage
    - spray pattern
     

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