Ticking/tapping sound

[JCS]

John

You are quite correct; it is possible to view the carbon release clutch bearing thickness through the bottom of the bell housing. To do so it is not necessary to use a remote stick flash light, a normal flash light will suffice.

Jaguarmg

As Glyn has suggested, I would also suggest checking the crankshaft end float initially, because it can lead to gearbox problems. However, I would suggest doing so as follows:-

1. With the engine stationary remove the tin shield, (four UNC set screws) at the front of the flywheel. Using a large screwdriver prise the flywheel fore and aft and measure the crankshaft end float.

2. Run the engine at idle speed with the flywheel tin shield removed and if you can measure the flywheel rotation deviation with a dial indicator on the rim of the flywheel. Expect the flywheel to deviate or wobble at the rim by 0.020 inch, anything less is good.

3. Repeat No 2 above at 2500 rpm.

I notice the car has the full synchromesh gearbox and from memory when that gearbox design was fitted in other BMC /Leyland models the end facing of the reverse idler tapping the case was an issue. I THINK that problem is potentially possible on the Jaguar synchro version.
Another problem that arose was fan belt noise when damage to the inside section of the belt resulted in a noise similar to a Tick or Tapping sound, quite unlike a belt problem. This type of noise is also damped when the clutch is disengaged as the crankshaft moves forward. Don’t discount this fault, I know a main agent (not Jaguar) who took out an engine for that fault, 28 hours out and 34 hours back in, an expensive fan belt.

[jaguar&mg]

I notice the car has the full synchromesh gearbox and from memory when that gearbox design was fitted in other BMC /Leyland models the end facing of the reverse idler tapping the case was an issue. I THINK that problem is potentially possible on the Jaguar synchro version.

I think this may be it. What now?!

[Glyn Ruck]

I notice the car has the full synchromesh gearbox and from memory when that gearbox design was fitted in other BMC /Leyland models the end facing of the reverse idler tapping the case was an issue. I THINK that problem is potentially possible on the Jaguar synchro version.

I think this may be it. What now?!

If it were me and it's not driving you nuts I would live with it until you had a good reason to remove the engine & gearbox. Increasing/changing the idle speed slightly might help.

[JCS]

Jaguar&mg

I am of a similar opinion as Glyn on this issue but before assuming anything you need to check out the issues I mentioned. Perhaps you might also advise us of any recent history of the clutch slave cylinder. Don’t forget the engine idle speeds were raised across the product ranges when these 4 speed synchromesh gearboxes were fitted, predominately to suppress gear chatter.

After the suggested checks, your next step might be to remove the gearbox centre floor pan and gearbox lid. However, I personally will stop at this point until I have chance of considering some of your results, without knowing some firm answers it becomes impossible to advise.

Norman

[Glyn Ruck]

Norman & I are in agreement. Do as suggested. Report back. Increase idle speed.

After that monitor for change. No change no worry.

If you want to suppress remove console & gearbox tunnel cover which is just fibreglass & cover it & surrounds with Dynamat Xtreme.

[jaguar&mg]

Norman, Glyn

Thank you. Some of these instructions have pushed me to my technical limit (!) but my conclusion, with some help, is that changing the idle speed has made no difference because the 'chatter' speeds up with engine revs (and sometimes gets left behind, meaning that it slows down slower than the engine revs die). Clutch was redone about three years ago.

I can live with this because it is clearly an engine-out job and that won't be happening any time soon (no need).

[John Quilter]

I notice the car has the full synchromesh gearbox and from memory when that gearbox design was fitted in other BMC /Leyland models the end facing of the reverse idler tapping the case was an issue. I THINK that problem is potentially possible on the Jaguar synchro version.

You may be referring to the Rover designed 5 speed gearbox used in the Rover SD1, Triumph TR8, and later TR7 in the late seventies. This box known as the 77mm box was used in some Jaguars, circa 1980(?) when the older Jaguar full syncho four speed was phased out. I think these would have been Series III XJ6 cars. The 77mm designation refers to the distance between the layshaft and main shaft. Interestingly it has a pump for lubrication in the rear on the mainshaft. From my warranty experience in the USA I do not recall any issues with this box except for hard shifting in cold ambient temperatures which we solved with a bulletin recommending a change to automatic transmission fluid.

[Glyn Ruck]

Your memory regarding the Rover box hard change when cold is spot on. We made a special product for them with clever viscometrics & containing Potassium Borate.