1. 'bant

    'bant Loyal Comrade

    A droning sound has appeared starting at around 60km/h in top, it reduces as the car passes 80km/h. It started as a patter 2x a second and within 20km has changed to a continuous drone. Letting the freewheel kick in or pressing the clutch at 60km/h makes the noise go away. Rev the engine up to a similar engine speed with the clutch disengaged and the sound is does not appear.

    I checked the drive shafts which both have a small amount of vertical play at both ends which I presume is not as they should be. However, driving round a car park full lock in both directions does not produce any drive shaft noise.

    I have not checked the gearbox oil since buying the car, I will try and do this tomorrow. I plan to swap the drive shaft oil seals at the gearbox end and then replace the oil. There seems to be oil covering the drivers side drive shaft boot at the gearbox end. The inner drive shaft joints were greased shortly after buying the car.

    If it was crankshaft and bearings why does the droning sound appear at 60km/h over halfway up the rev range? Why is all smooth at lower engine speeds?

    I have fitted winter tyres on the car this weekend, all the wheel nuts are tight.

    I am not sure if this droning is the engine, crank/bearings or gearbox/final drive or even drive shafts. Or if it is normal and acceptable. My main concern is that the noise has appeared in the last couple of days. Any suggestions for possible causes and/or diagnosing the problem further?
    Last edited: Sep 28, 2015
  2. Austinpowers

    Austinpowers Loyal Comrade

    Silly question but are you sure it's not the tread on your winter tyres. I have had tyres that make noise at a certain speed.
  3. Ron

    Ron Premium Member Forum Donor

    Without hearing it first hand it is difficult to tell... I think you're right to be checking the oil level and quality (try to catch it in something you can look at it in, see if it's full of metal?!!). It should be up to the level plug on the side, 1.3 litres I think. That would be my first check, let us know what you find, and don't drive it any more!

    There are some very knowledgeable gearbox people on here, so you're in the right place, and any new noise is worth investigation. By the way, my driveshafts also have a wee bit of play, doesn't seem to cause any problems, but I suppose if they were bad enough it could set up vibration(s) at certain rpms...

    Good luck with it, let us know how you get on.
  4. Ron

    Ron Premium Member Forum Donor

    Just another thought, your exhaust/manifold/heater pipe is all tight and secure? You can get all sorts of weird noises if any of this is loose...
  5. 'bant

    'bant Loyal Comrade

    Perhaps not so silly - I did notice in the English language manual on this site that the toe-in is different for crossply and radial tyres. I will check to see if there is any obvious scrubbing on the tyres.
  6. 'bant

    'bant Loyal Comrade

    The same goes for a loose cylinder or damaged cylinder foot gasket I take it?

    I noticed that the interior of the car has started smelling of petrol whilst the engine bay doesn't. Would that be a symptom of a loose cylinder or cylinder head or gasket problems? I guess it is worth checking that the spark plugs are tightened too.
  7. Austinpowers

    Austinpowers Loyal Comrade

    I had the petrol smell as well. It turned out to be the filter cover on the fuel tap. The rubber o ring had some small splits in it. I changed the plastic filter body for one that's made of aluminium. As the old plastic one would not tighten up properly and just spin around and around.
  8. 'bant

    'bant Loyal Comrade

    @Austinpowers I checked the filter cover. It tightens up OK but I didn't check the O-ring.I have read that the aluminum covers are better so will order one when I get round to placing that (ever increasing) order with Trabantwelt.

    I checked the front tyres, no obvious signs of scrubbing.
  9. Ron

    Ron Premium Member Forum Donor

    I suppose so, 'bant, but I would expect worse noise and power loss if the cylinder gaskets were failing... I don't know for certain, mind, it's never happened to me! What I did notice though is that my (very faint petrol) smell disappeared when I replaced the exhaust. I think the heat exchanger was rusted/broken down inside and allowing exhaust into the cabin. Is yours old/rusty/crumbling?! Could be the source of the noise too...

    How did the gearbox oil look?
  10. Austinpowers

    Austinpowers Loyal Comrade

    When I lost power in my Trabi I thought that the head gasgets had blown again. So whipped the heads of only to find that they were good. It was as I was putting everything back together that I spotted that the expansion pipe had become quite rusty. And on closer inspection there was small holes developing. I fited a new sports expansion pipe and it was transformed from no power to a nippy little beast.
  11. 'bant

    'bant Loyal Comrade

    @Austinpowers Is this part what you mean by expansion pipe? I'd call it the heat exchanger.It looks OK from the outside, I would expect to smell exhaust fumes when driving it that was at fault.

    @Ron I haven't had the chance to check the gearbox oil.

    It looks like I will have to devote some time to checking over various things asap, which means dismantling stuff.
  12. 'bant

    'bant Loyal Comrade

    I think I have identified the source of the 'petrol' smell. The insides of the rear window pillars and other metal parts in the same area have a layer of waxy rust proofing on them. It is still sticky so it is still giving off vapours. That explains why there is no petrol smell on the floor of the car but plenty at head height as it is not petrol vapour I smell. Plus it explains why there is no trace of a petrol smell in the engine bay or outside or under the car but the interior smells strongly.

    Now I can concentrate finding the source of the droning noise :)
  13. Austinpowers

    Austinpowers Loyal Comrade

    Yes Bant that is the part. I had no smells coming in to the car,as the bit that was leaking was around the joint to the pipe. And also on the welded seems around the edges of the box. It was only when I removed the box and started to clean it up with a brush that the true extent of rot was revealed.
  14. turbofiat124

    turbofiat124 Loyal Comrade

    I don't know if this is the same thing or not but when I had the freewheel device replaced, the guy said the input shaft bearings were bad. They did not have any play in them but made a noise when spun. Afterwards this noise I was hearing went away.

    What's weird was the noise intensified if I pressed in the clutch but quieted down in gear. I thought the release bearing was bad but there are no "bearings" in the release bearing. Just a large piece of graphite!

    My Trabant makes a weird uneven thumping sound at low speeds. This issue seemed to start after installing new brake shoes but not resurfacing the drums. With the front end off the ground there is a noticeably uneven sound coming from the driver's side from wheel when rotated.
  15. 'bant

    'bant Loyal Comrade

    I've not taken the cooling shroud apart as yet but the back and underside of the engine is covered in oil. So are the bottoms of the cylinders or at least the bits I could see looking up the cooling shroud from underneath the engine. A case of leaking cylinder to crankcase gaskets?
    Last edited: Oct 5, 2015
  16. 'bant

    'bant Loyal Comrade

    Hmmm. The droning sound, now accompanied by a slow frequency thrum is appearing in other gears now. The frequency of the thrum is much lower than the engine speed. I checked the gearbox oil level and it seems to be overfilled. The car was ever so slightly nose down so I will check again where it is completely flat. In addition, there is now a slight putt-putt coming from the front exhaust damper. Time to place another order for spare parts.

    I will jack up the front of the car at the weekend and check for hub/driveshaft noise.
  17. 'bant

    'bant Loyal Comrade

    I think that the clutch is on the way out, I adjust the cable, gear change gets easier, then the next time I drive the car the gear changing is harder again. I am now experiencing a lot of clutch judder. Could a dodgy clutch cause droning sounds and vibration?
  18. 'bant

    'bant Loyal Comrade

    The problem is the tyres and rims, some rather low quality out of true reconditioned rims to be precise. I have just put the old crossplies on again and the problem has mostly disappeard. There is some low key residual thrumming which I am fairly certain is worn driveshafts.

    When the garage put the tyres on they had a lot of trouble balancing the tyres. I will ask them to check again and then get them to check the toe in just before the winter season starts. If they can't get the rims to balance then I think I will try to get some other rims.
  19. RogerDerSchrauber

    RogerDerSchrauber Loyal Comrade

    Sounds like the stop nut on the clutch cable is slipping out of adjustment.
  20. RogerDerSchrauber

    RogerDerSchrauber Loyal Comrade

    Hey, nobody ever answered this question for you. Yes, your engine needs new head and foot gaskets for the cylinder heads. It will run without them, but you lose a lot of power and waste fuel. It's not all that hard to do, but you will need a torque wrench.
    Keri and 'bant like this.

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