Hi all,
I’ve fixed nearly all of the problems I knew about, but have not yet alleviated the tapping from the engine bay…! I’m now stumped. Let me describe the symptons and see if ANYONE has a clue…
fast tick, tick, tick noise (about 8/9 a second)
does not vary in frequency - i.e. it’s the same rate regardless of revs - just gets louder
only occurs under acceleration, even cruising at 60 it’s not apparent
revving in the garage leads me to think it’s coming from passenger side / middle at front
I’m certain it’s not the servo (as someone previously suggested)
Maybe - might only be 1 blade per revolution that touches something though. It should be obvious as you will most likely have a corner missing from the blade(s). It fits with the position if not the “only under acceleration” bit (unless the engine twisting on it’s mounts is pulling something into contact) It’s hard to think of anything else which has a rotational frequency independent of the engine revs.
Kevin
My main mechanic suggested a work tappet bucket top (the tapping occuring when as the bucket rotated increasing clearance). But it only happens at decelation…or fast return to idle.
James,
Is it the vacuum non return valve for the servo. This can cause a ticking sound if it is attached to or touching the bulkhead. As standard it is situated in the middle of the bulkhead just above the rear of the head.
Cheers
John
I know you would think that this would have to increase with engine speed…but have you thought of the timing chain hitting the top of the valve cover. Easy to check by taking off the valve cover and looking at it.
James,
Pic of vac valve. It’s the alloy bit in the middle that joins the rubber tube to the steel tube. Mine is attached to the bulkhead, otherwise it flops about in the breeze.
Cheers
John
I don’t think it’s the fan, as tweaking the throttle standing in the garage causes the sound but the electric fan is not spinning… however, I can’t find the vac valve! is it close to the vacuum-ball-cock?
If so the rotor disk in the dizzy (don’t know its technical name) can raise the height of the rotor arm and cause it to touch the contacts in the cap. Check the wear on the contacts for any signs of rubbing. It will give a light, hollow but annoying knock.
On mine with Lumination ignition I had to file a few thou off the rotor arm so it sat back at its original height to stop it catching, after ruining the cap and annoying me for weeks.