Hi
As i was slowing down i heared a loud bang and crunching noise from the rear, I decided to turn back home as i was close, at this point the noise is more of a scraping noise.

I curently have the up on axle stands, when turning the wheel by hand i hear an intermittent scraping noise with the odd crunch, the sound seems to come from the diff but hard to pinpoint.

any ideas would be appreciated

Regards
Phil

 

Phil,

My first idea is to get your question in front of XJ40 owning members. I've moved it to XJ40 forum and left a re-direct here.

I had a rear hub collapse on an XJ40 in the outside lane of the A1(M) a few years ago - that was exciting!

Graham

 

I lost a left front wheel on a high bridge nr. Stafford on the M1, saw it rolling down the road, all was well til I hit the anchors....not in an XJ40 though, a loaded lorry.

Apologies for the thread hijack Phil

Larry

 

Meanwhile, back on topic.

157 Views and 0 suggestions. Extraordinary!

A failed diff is usually quite dramatic and leaves a lot of broken teeth rattling around in the casing. The "intermittent scraping noise" makes me think more likely a bearing (diff output or hub) or a failed UJ on the drive shaft.

You are going to need an assistant to rotate the wheel while you can get up close see what's happening at both ends of the drive shaft.

Graham

 

I saw this and had started a reply. However, as I re-read and retyped what I had written, I realized that it made absolutely No Sense. So rather than muddy the waters with useless claptrap I deleted it.
In any case, the gist of my comment was this- I recently had a pinion bearing fail in the Moneyfunnel. As I pondered my ability on the repair side of this I came across a complete (minus motor) xj12 which luckily had a good diff in it. I have never opened one of these diffs, but I have had to replace both of mine.
My "diagnostic process" was to lift the rear to crawl under it and see where the side play is. My removed pinion bearing has about 1/8" side play. It was very loud. If your side bearings are bad I presume you would be able to wiggle them side to side also. I would also check the hub bearings on the outer ends of the axles and the 4 u-joints too. Its odd to me that you would get a bang in the drivetrain without some "loss of forward momentum."
A scraping noise could also be a problem with the brakes. Did you notice any odd feeling in the brake pedal? If nothing is obviously wrong maybe part of the parking brake mechanism came loose.
Sorry to delay. I still dont think it makes much sense... Good luck.

 

Hi Phil,

I'm sorry to hear your XJ40 is unhappy.

Since you have it on jack stands and can rotate the rear wheels, I would suggest you acquire an inexpensive mechanic's stethoscope, available at most auto parts stores. With the stethoscope, you can probe the differential and rear hubs to see if you can isolate the source of the sound. You can also use a long screwdriver, socket extension, wooden dowel, etc., but the stethoscope has a metal diaphragm that amplifies sounds and makes it easier to dial in the source of a sound. Just take care not to touch any rotating parts with the probe.

I'm not going to hazard a guess at the source of your sound, but add to the list of suspects the parking brake mechanisms inside the "drum" portions of your rear rotors. Those tend to get very little attention ever, so if something rusted to the point of breaking, that could lead to your symptoms. It is also not impossible for the friction material of a disc brake pad to disintegrate, so check your pads.

As far as the differential goes, it would be rare to have internal failure without significant audible warnings. The pinion bearings, when worn, tend to whine like a jet turbine on off-throttle. The output shaft bearings tend to growl and their seals leak oil when they are failing.

Looking forward to your next update.

Cheers,

Don

 

Had a neighbours mechanic look as it and discovered a worn UJ on the drive shaft, fortunately my late father had a spare shaft, so swapped it out. Car now runs great, now to repair the old one as a spare.

Next Job new exhaust to fit.