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Here's one for the 202 experts........

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by CRH71, Oct 23, 2012.

  1. CRH71

    CRH71 Senior Member

    Likes Received:
    Jun 11, 2012
    Your Mercedes:
    C250 TD
    So, for my sins (which appear numerous) I have a C250TD Estate, 1998 (S), auto, now 169,000 miles.

    Lovely car but being spoiled by very un-Benz-like vibrations and noises at times.

    I suspect (and it is only suspect) that an engine mount is less than good, as when she's cold, there is a fairly significant "vibration" that travels throughout the car - BUT it can be considerably lessened (to the point of not noticing it) by easing off on the loud pedal - to me, it feels like the trans mount COULD be a bit "iffy" and is allowing the trans to rest on the crossmember transmitting the engine vibration to the car.

    Second little issue (and, probably linked with the above) is the sound of a "bearing" noise at anything over about 25-30mph - at 70 it's pretty loud (reminds me of a wheel bearing fault, but it doesn't worsen with left or right-hand turns) and can be revved through (bring her up to 80-85, or drop back to 65 and the noise all-but disappears - it's still faintly audible, but it is tolerable for one with a modicum of mechanical sympathy). Bear in mind that I rarely have the radio/CD on - hearing issues make it better for me to listen to the 'car sounds' rather than music or radio.

    This has come at probably THE worst time that it could. MOT's due (and I'm pretty sure she'll fail) and I left work three months ago to become a full-time carer which has impacted on our cashflow somewhat.

    I'm semi-handy with a set of sockets (OK, confession time, I'm a buffoon with a shiny tool set...) and could nip down to my mate's, 20 miles away and borrow his well-equipped garage with engine crane etc., but obviously don't want to do this until I'm certain of the problem and what it's likely to cost me.

    I did have a local indy quote me for replacing engine and gearbox mounts (they did the coolant and thermostat for me a couple of weeks back) but when the potential bill was mentioned at around £450 my wallet curled up in fright.

    I'd thought at first that the axle was causing the issue (she's got 169,000 on the clock and I suspect she's been used for a lot of towing by the last two POs) so I got the indy to check it over - they confirmed that it is leaking, very slightly, from the two side seals and the level was fractionally low so they topped it up for me FOC and confirmed that the leakage seemed acceptable for the age and mileage of the car.

    Tyres are Vreidstein (sp?) all round and about half-worn. No visible abnormal wear patterns.

    Any clues, anyone?
  2. toby1

    toby1 Senior Member

    Likes Received:
    Mar 13, 2007
    West Berkshire
    Your Mercedes:
    1998 CL420 C140
    Propshaft possibly? Or prop coupling?
  3. grober

    grober Senior Member

    Likes Received:
    May 15, 2002
    Your Mercedes:
    W204 C200cdi estate
    My thoughts too. Possibly the centre bearing or the flexiblerubber mounting its held in? You will possibly have to remove an exhaust heat shield to see it up on a ramp.
  4. wireman

    wireman Senior Member

    Likes Received:
    Sep 20, 2005
    Your Mercedes:
    nice 201 2.5D 1993 & very nice 129 SL500 1994
    I think you are on the right track with the diff for the bearing type noise, probably the pinion bearing is at fault, a droning/humming with no real connection to what power is being delivered, a pig of a job which calls for dismantling the diff and some care/precision to get it right, I'd wait until it wails like a banshee, expect a long wait and get a second hand unit when you can't take any more.

    The engine and transmission mounts are an easy to do fix that does not cost the earth, and since the car has many miles (enough to have eaten them) on its clock why not give it a treat. Lots of posts about changing mounts, fronts:-undo top & bottom bolts, jack off the engine's weight and swap, tranny;-support tranny, unbolt cross member and tranny nut, and lower and remove/swap mount, an hour or so for all three. If you use non MB mounts it will cost <£100, MB a shade more, at £450 he's having a laugh.
    If you can pull and push the engine or transmissions tail any amount the the mounts are most likely dead. Engine judder as it stops is another indicator. The front mounts are hydraulic and they do eventually leak their fluid (glycol) making them shrink about 10-15mm.
    Not sure about your 202 but on my 124&201 the fans are dead central to the cowls now they have good engine mounts, dead front mounts sag making a larger gap at the top than at the bottom.

    Do give the propshaft a looking at as the others have suggested, push and pull the rubber mounted centre bearing to check for slop.

    Neither of these conditions is an MOT fail, brakes, suspension and steering are the ones to have right.

    If you intend to get your tools dirty make sure a decent set of axle stands and wheel chocks are part of it, never ever work without them in place.
    Don't let it being a Merc put you off, its not complicated, its well engineered and there are few jobs that you can't do for yourself using ordinary tools, easier to work on than a great many other (lesser) cars, and much more rewarding to drive.
    Last edited: Oct 23, 2012

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