´87 300D W124 6 months in, some "imperfections" remain

Discussion in 'General Discussion' started by bennycb, Jun 1, 2015.

  1. bennycb

    bennycb New Member

    Oct 23, 2007
    ´87 W124 300D
    Hey guys,

    Bought myself a very cheap ´87 W124 300D manual which i´ve now owned for exactly 6 months. Having not been used for 2 years and not having paperwork things didn´t start off to well...but after new engine mounts, prop shaft couplings, prop shaft bearing, rear diff mounts, 4 new tyres, complete service, tie rod end and tracking things are looking up and all the electrics have fixed themselves and the car runs sweeter than ever. Cruises very nicely and 50mpg is possible when driving on a roads at sensible speed. It still has the following problems which I´m living with but would be interested to know how important they are to fix and what can be done...

    1) thermostat always open. Planning to swap this before winter

    2) when starting cold takes 5 seconds to get oil pressure/fire on all cylinders. idles at 600rpm when cold and gets proportionally more when engine gets hotter, when it idles at 1000rpm. If in neutral going round a roundabout turning a sharp left increases it momentarily to 1200rpm. No idea why. not a sticking throttle cable as revs literally go up automatically as engine warms up in traffic. Exhaust smells a little of diesel when idling but car never makes any visible smoke. Still retruns excellent mpg.

    3) clutch has no bite until last 20%. then comes in very quickly making clutch control an "art" to drive smoothly. Still lots of bite on the clutch and hillstarts no problem so im assuming no reason to replace it pre emptively. Might be exaggerated by gearbox mount that i think needs replacing (vibrations through car when pointing uphill)

    4) Differential whine (worse when turning right) at certain gears/speeds. Not really noticeable with stereo on and less so when car has warmed up a bit.

    5) play in steering made a bit better by replacing clonking tie rod end and adjusting the wheel bearings. The bottom balljoints are apparently recent and have no play but the other 4 tie rod joints are said to be a little warn but don´t make any clonks. Is there anything else to check for in the steering?

    6) front left wheel sits a tiny bit lower than the others if you look really carefully, broken spring? doesn´t seem to affect handling or ride though.

    7) strange noise from brake pedal like compressing air (very quiet though, you have to listen for it). Brakes all checked and plenty of life and easily passed MOT requirements like this. Should I change brake fluid or bleed system or is it just normal and how the servo works?

    The car has MOT until March and seems perfectly servicable so I really don´t want to spend endless amounts of money on it as I´ve spent about 1,000GBP on it already on top of the 250GBP purchase price...i´ll be interested to hear how important these things are too address?

    Thanks in Advance, Ben
    Last edited: Jun 1, 2015
  2. bolide

    bolide Hardcore MB Enthusiast

    Oct 8, 2005
    BMW E39 525 Diesel Touring
    These are exactly the things that wear out on W124s and this points to a prior lack of maintenance

    The engine should idle at the same rpm at all times. I don't remember if the early diesels have an idle stabilisation setup - the late cars have a system that controls the fuel rack at idle. I'd look at the path of the throttle cable and also see how much friction there is in it. A new throttle cable can make a real improvement

    If you still have play in the steering check for loose front wheel bearings, worn track rod ends and worn steering idler. Replacing the idler can make a surprising difference

    Also look at the rear suspension arms that set toe, the leading rear subframe mounts & body mounts

    Nick Froome
  3. Ted

    Ted MB Club Veteran

    Feb 26, 2004
    Bourton on Dunsmore
    SLC 250D AMG Line, Yamaha XVS 1100, Jeep Renegade
    4) Differential whine (worse when turning right) at certain gears/speeds. Not really noticeable with stereo on and less so when car has warmed up a bit.

    I've had this on several Mercedes without it getting worse. I swear that on my W210 it actually got quieter over time.

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