£1850

Nice one, mate.

Me's now pissed off ... re-fitted everything, including a complete new exhaust system and we still get a bloody knocking noise. Not masked by the exhaust blowing now, so we can hear a definite 'clonk' every (sort of) wheel revolution, and in reverse ... dunno what to do now.

So, we're going to try Injectors, then clutch, but I don't think it's either of them and I'm bloody stumped!

Won't be at Tong this Sunday, unless we get it sorted.

You talk about the noise being present in reverse - does this mean that the noise only occurs when the vehicle is moving? ... or is this a static test with the transfer 'box in neutral?

Netiher of those are going to give a low frequency knock. To save me trawling back through the group, does this happen when stationery or only when on the move?

Wasn't it the diff then?

You haven't got a loose wheel have you? (I've got the T-shirt)

Lee D

When stood the engine sounds brilliant.

The clonking only occurs when it's moving. It isn't the CV joint, it doesn't get worse or start when turning, it isn't UJ's, it isn't diff output shaft or bearings, half-shafts and all splines look fine, wheel bearings have been done up. Wheels have been checked, discs, calipers, indeed all the bloody running gear has been looked at so closely that I must be missing the wood for the trees.

Haven't been able to check the clutch, or the gearboxes, haven't got an engine hoist to help split cases etc

Been out in the dark with a torch just sat there, under the thing, looking to see if I can see any 'scratch' marks or obvious signs of knocking somewhere.

Going to get drunk now.

Only on the move. We thought it was turbo related as we only heard it at higher revs or under heavy load, but now we've fixed the exhaust and manifold blowing it's definitely a knock or clonk at either wheel revolution or propshaft rev rate. Tonight, possibly 'cos all other 'odd' noises have been removed, was the first time we've heard it in reverse. So I've been looking at the rear end since ... dunno why ... ;)

Nope, good suggestion, but they both look fine.

Nope. After loosing a wheel a short time ago this is one area I am now paranoid about ...

Is it actually wheel or propshaft frequency related? Put a chalk mark on a tyre and get a helper to sort out which it is.

If it's wheel frequency related it MUST be somewhere between the crownwheel and the tyre at one end or other. Ignoring your "I've checked everything and all is ok" statements it's got to be on of the below:

- chipped crownwheel (unlikely as it happens in both directions).

- diff side bearings

- CV joint (unlikely as it happens in both directions)

- wheel bearings

- brake rotor or drum

- loose wheel

My educated guess (and I'll buy you a beer if it's wrong) is a wheel bearing that has lost the hardening off it's inner race. You won't see it even when disassembled (unless you dismember the bearing totally) so it's hard to confirm visually.

I don't supose its brake pads "clonking" in the caliper..or carbunkle on a tyre...I had both.

John

That is a very big statement man, I'll find out & if yer wrong, you can buy me the beer!

What makes you say it isn't a U/J? You haven't said positively that it happens every wheel revolution or prop, there's a hell of a difference between them, you should be able to ascertain that. Or are you just rolling on a bumpy bit of road with knackered shocker bushes? Have you double checked every single thing that you've done?

Martin

Experience says I'll probably be right - took me a long time to find said problem on one of my vehicles.

We've driven it with rear and front prop off ( at different times) and the noise still occurs. Just confirmed it again, front prop off, driven, rear prop off, driven, noise still there.

So .. stripping front hubs now, having a looksee at the wheel bearings, ordered new ones all round 'just in case', and the discs/calipers/pads etc. Currently it's up on ramps and axle stands so I can take the front off .. the noise does appear to be from the front, but we all know how sounds travel ... ;)

In that case it's pretty much got to be wheel bearing noise.

That's what I'm thinking, hence us ordering new ones. Just also took handbrake drum off to check shoes again 'just in case' and all is well, nothing loose, lots of material left and none of it moving about.

Getting really pissed off now, thobut. ;) If it _is_ the wheel bearings I'll buy you a bloody crate of beer ... ;)

How have you eliminated this? It'll still clunk with the prop off. On my 101 It could be heard clunk with wheels off the deck and spining the one wheel. I've a video clip of it somewhere but dammed if I can find it now.

Lee D

Both props on, both axles off ground on axle stands, spinning wheels forwards then backwards, then one wheel only, then the other etc, in gear, out of gear, diff-lock engaged and not, low/Hi boxes, clutch in/out ...Then same again without wheels .... All 'feels' fine, no play in any bearings. Only thing we can see is very, and I mean minimal, wear that allows some backlash between wheels of about 2" movement at the tyre tread ... which seems f. all to meand pretty normal!

Next trick we're going to try as it only seems to happen when we're actually running, is to lift it back onto axle stands and run the thing, nice and steadily, with swmbo inside, going up the gears to see f I can hear _exactly_ where it is from from the outside. (We're going to do this with the front bumper chained up against the gate supportsl, so any torque reaction fore and aft should be compensated for and it won't (in theory .. heheheh) fall off the stands.

The clunk does seem to be at the same speed/cadence as the props/diff turning, but we still haven't definitely found if it's front or rear ... though it's sounding more towards the rear when we're on the road, now that we've eliminated the other noises from the exhaust and manifold area.

We've also wondered if it's just something loose on the body, but I've pulled prodded and poked everything from boot floor to body panels and there's nothing more loose than it should be and nothing loose that's anywhere near enough mass to make a clunk rather than a clatter, or close to the drive-train iyswim. ;) We also reckon if it was something loose it wouldn't happen at _exactly_ the same rhythm/cadence as this is.

Phew, what a feckin' palaver ... It's the rear diff! After all the feckin'about, new wheel bearings, new UJ's, new allsorts of stuff including front discs (had a spare set as we knew of a developing problem ... ;)

Dunno which part of the diff yet as we haven't had it apart. Can't hear anything at all when turning the wheels by hand, but when all jacked up and running in third to about 1500 rpm there's a definite noise from the rear diff. So went to the local 4x4 garage, up on their ramps, dropped the wheels, started up and listened with a stethoscope .. definitely rear diff, definitely a loud, sharp clunk, so it seems it might be a chipped tooth or teeth.

So, anyone got a 300 Tdi rear axle they don't need/want for a reasonable price?

I don't want to buy a diff alone as it sounds a bit 'gritty' with the stethoscope so I'm suspecting more than one chip/broken bit and I haven't had time to drop it out yet.

Going to chance going away tomoorrow night, towing the caravan ... the diff's fecked anyway so as long as it doesn't lock up totally I'm hoping we'll be OK ... ;)

Take some tools with you just in case so that you can remove rear prop and halfshafts to avoid being stuck if it does lock up, Murphy's law says it will if you don't want it to! :-)

Martin