Clutch knocking noise

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zigzagsky
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#21 Re: Clutch knocking noise

Post by zigzagsky » Sat Oct 14, 2017 10:42 am

One more thing to clarify after my post just now...

It's definitely a regular knocking (or heavy ticking) noise rather than a rattle that you get when something is loose or rattling around.

Cannot really hear it through the stethoscope when pressed against the starter motor so I'm pretty sure it's not that. 95% sure it's within the bell housing and not the engine block.

It also seems to be worse when the car is cold (or maybe my ears just get used to it).
Brian
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#22 Re: Clutch knocking noise

Post by Hugo » Sat Oct 14, 2017 11:01 am

This is getting weirder. The fact that you can feel the release arm vibrate when you hold it against the pressure plate tells us that the release fingers are slightly uneven. Not really a problem, although if excessive it can cause clutch judder.
This might also cause the release bearing to rattle against the face of the pressure plate when lightly in contact with it. Resting your foot on the pedal should shut it up though, and you say it doesn't?
But you say the noise only disappears when the pedal is fully depressed - is that correct? In which case it pretty much has to be the gearbox. A bit of end-float in the layshaft - that kind of thing.
But then you say the noise is coming from the engine side of the bellhousing?
Everything seems to contradict everything else! Have I got it right so far with everything I've said above?
I think if it were my car, I'd be reluctant to start ripping things apart until I had a clearer idea what I was looking for. Otherwise what do you do? Replace the clutch and hope for the best? I'd be peeved if I did all that work & the noise was still there! I think I'd keep driving it till something goes bang, or at least until it manifests itself unambiguously.
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#23 Re: Clutch knocking noise

Post by Hugo » Sat Oct 14, 2017 11:02 am

zigzagsky wrote:One more thing to clarify after my post just now...
It's definitely a regular knocking (or heavy ticking) noise rather than a rattle that you get when something is loose or rattling around..
This comment crossed with my last - seems to rule out pretty much everything I said!
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#24 Re: Clutch knocking noise

Post by zigzagsky » Sat Oct 14, 2017 12:47 pm

I agree Hugo that it is strange and difficult to pinpoint the exact cause and that it's driving me nuts.

To be honest, I was at a rally last weekend and a recognised E Type expert did suggest that I just f*****g drive it!

The idea behind taking her apart is that hopefully I will see marks where the contact is taking place and that should show what the problem is. I also thought that maybe I just give her to a specialist garage and see what they come up with. This may be a good idea in the long run as I've only had her for a few months so they could do a full service, sort out a few other minor issues I have and then I would be driving a car with known mechanical state.

As an alternative though, maybe it would be interesting to go on a bit of a drive for a few miles and see what happens, AA card in hand...
Brian
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#25 Re: Clutch knocking noise

Post by Hugo » Sat Oct 14, 2017 3:09 pm

If this has only just developed, it may not have left enough evidence. If it were my car, I would definitely just keep driving it. Buy some earplugs if need be. Kill or cure.
There is simply nothing that suggests itself from the contradictory combination of symptoms you have listed. It will either get worse and therefore become easier to pinpoint, or it might disappear on its own. What you don't want to do, of course, is wreck something else in the process, but I think that is unlikely. If the problem is in the clutch, for example, and you end up damaging the clutch further, you've lost nothing.
That's what I would do if it were mine I think. Don't sue me if it all goes horribly wrong though!
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#26 Re: Clutch knocking noise

Post by christopher storey » Sat Oct 14, 2017 4:44 pm

Brian : I have an impression ( forgive me if I am wrong ) that you do not realise just what a major undertaking it is to split the engine and box. It is bonnet off ; all ancillaries off ; suspension ball joints dismantled ; reaction plate off ; every linkage disconnected and ditto all pipework, propshaft , gear lever etc . Even for someone well practised in this job you are talking 5 man hours at the very least ,( more realistically 8 - 10 man hours ) and more to get it back in . It is not in the remotest way something you just add on to a few service tasks , and to have it done professionally I would say that you are talking a minimum of £1000 + VAT

Before you get involved in that I suggest you get hold of a borescope and have a look inside the bellhousing for either foreign objects, or some broken metal such as a chipping off the flywheel ring . In addition, I would remove the starter motor and examine that carefully for signs of damage/misalignment etc, because if for example the pre-engagement solenoid is not withdrawing properly it could account for your noise; that is always assuming ( and I hate to tell you this ) that someone has not bodged up an inertia starter and shimmed it to fit, as has happened to me with one car. Failing that, I think the advice you were given to drive it and see whether the noise changes, is not bad advice at all

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#27 Re: Clutch knocking noise

Post by Hugo » Sat Oct 14, 2017 5:11 pm

I just had a thought - you said the slave cylinder "let go' I believe. That is pretty unusual. Normally they just leak quietly away till they run out of fluid. Is it possible that what you experienced was not a hydraulic but a mechanical failure in the clutch? Clutching at straws here I grant you. Did the slave cylinder dump all its fluid, or did you just lose the pedal? If one of the release fingers had broken or worn through that might give a similar symptom (and would account for the wobble on the lever), although it is unlikely that you would now have a clutch that works perfectly (or does it?).
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#28 Re: Clutch knocking noise

Post by PeterCrespin » Sat Oct 14, 2017 5:26 pm

Hugo wrote:If one of the release fingers had broken or worn through that might give a similar symptom (and would account for the wobble on the lever).
It's a Series 2. The diaphragm clutches don't have 'fingers', unless a DPO poked one into an inspection hole while the engine was running.
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#29 Re: Clutch knocking noise

Post by Hugo » Sat Oct 14, 2017 7:00 pm

I don't know what clutch it has fitted - I don't know what you call those things on diaphragm clutches - I thought the term 'fingers' would cover all eventualities :wink:
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#30 Re: Clutch knocking noise

Post by phil.dobson@mac.com » Sun Oct 15, 2017 3:38 pm

Can you see the face of the release bearing?

the only other thing I can suggest is to jack the rear wheels off the ground and rotate the wheels put the car in in top gear. if you get the noise remove the starter. if it goes away....... etc.
If not then its time to take the lot out.

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#31 Re: Clutch knocking noise

Post by E600 » Sun Oct 15, 2017 10:13 pm

Hi
I pm'd you yesterday. We live close And I have a free 2 post ramp. If you wish we could make use of this and investigate further. Details in the PM.

Regards
Pat

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#32 Re: Clutch knocking noise

Post by zigzagsky » Mon Oct 16, 2017 9:12 am

Gentlemen,

I really appreciate all the help and advice so far.

To answer the recent questions.

The slave cylinder did have a slight leak which is why I had already purchased a replacement. When it 'let go' when reversing the car out of the garage to position her properly to do the work, it suddenly dumped all the fluid so the seal just went. As mentioned in the beginning, I pulled the car the short distance back into the garage on the starter.

I have taken the starter out (it's a high torque replacement - Edge Performance from Cambridge Motorsport) and nothing seemed to be amiss. Rotating the wheels with the starter removed is something I hadn't tried so maybe I'll take it out again.

Or just do what is suggested by Hugo and drive her for a bit to see it it gets better or worse.

I do appreciate the work involved in taking the engine and gearbox out of her, hence the need to exhaust any possibility of fixing the problem with the engine in situ. If it does have to come out and I pluck up the courage to do it myself, I have heard that dropping it is a bit easier than taking it out the top. Otherwise I have been given details of a reasonably close specialist who did the clutch on a fellow forum members car at a reasonable cost. I would then 'add' some servicing requests to the job if they are happy to do the work.

Pat has kindly offered to let me use his 2 post lift to get a better look. Although I have a small scissor lift, it only raises the car 3 feet or so and it is still a bit difficult to work underneath.
Brian
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#33 Re: Clutch knocking noise

Post by Hugo » Mon Oct 16, 2017 1:38 pm

How bad is the noise? Would you call it a ticking or a knocking noise? Can you tell if it's engine speed? I will wager that if you strip it down at this stage you won't find anything!
The starter might be a candidate, since you used the starter to wind it back into the garage. That shouldn't normally cause any damage, but as it's a non-standard starter you never know - might have bent the shaft or something? At least it's in the right place. You might try hooking it up to a battery & see if the pinion wobbles?
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#34 Re: Clutch knocking noise

Post by zigzagsky » Tue Oct 17, 2017 1:42 pm

It's definitely a knocking noise rather than a ticking noise.

Your idea of running the starter out of the car is a good one. Failing that, I might see if I can borrow a replacement to try.
Brian
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#35 Re: Clutch knocking noise

Post by zigzagsky » Wed Oct 18, 2017 5:38 am

Ok, so following on from a few miles driving (making no difference) I have managed to notice one thing which might give a clue.

As mentioned before, depressing the clutch makes the sound disappear. Last night I tried depressing it slowly. About halfway down, the knocking stopped but when it did, it slowed briefly slightly just before - like a rotating part which stops under inertia once the driving force is removed. It was late and I didn't manage to do much more and I'm away on business until Friday. Pat has kindly offered to let me get her up on a 2 post lift on Friday and has a proper horoscope so maybe we'll see something.

Had a quote from a specialist to take the engine and gearbox out. Assuming it's just the clutch the cost is still way over £2K as it's a 4-5 day job to complete the whole out, fix, repair job.
Brian
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#36 Re: Clutch knocking noise

Post by christopher storey » Wed Oct 18, 2017 8:43 am

Right, well that narrows the field a bit. I would expect that it is something which stops revolving when the clutch is disengaged, and that suggests it is either something on the driven plate, or on the first motion shaft of the gearbox. What it could be, I have no idea,because if it were on the driven plate, then you would expect the noise to disappear also once the clutch was fully engaged, ( because driven plate, pressure plate and clutch cover would all be rotating together with no relative motion between them) so the most likely explanation is that something - perhaps a piece of debris - is rotating with the first motion shaft

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#37 Re: Clutch knocking noise

Post by Hugo » Wed Oct 18, 2017 10:50 am

The plot thickens, huh? I'm with Christopher - almost - except that if it is in the gearbox it can't be confined to the input (first-motion) shaft. Everything except the output shaft will be rotating till you depress the clutch.
I also cannot see a way in which the clutch centre plate would make a knocking noise when the clutch assembly is all locked together (i.e. foot off). And you now seem to have ruled out anything to do with the release bearing or mechanism.
Which only leaves the gearbox. But I find it almost inconceivable that a gearbox capable of handling that kind of power could be damaged by winding the car on the starter motor. In any case, what kind of damage would make a knocking noise in neutral when there's no load on anything? Unless you've knocked a tooth clean off. Is that even possible?
Next question - is the noise at engine speed? When you drive the car, does the noise vary when you apply or release power?
Of one thing I am pretty certain - if you strip the car down you won't find the cause. Ok, you can replace the clutch, but while the gearbox is out you will need to strip that. And when everything in there looks ok what do you do? This is the sort of thing that can eat up thousands in garage bills. Whatever damage is probably already done & you won't make it worse by driving the car till you flush it out. You never know - the noise might disappear and remain a mystery for ever more - I have seen stranger things happen!
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#38 Re: Clutch knocking noise

Post by E600 » Wed Oct 18, 2017 2:07 pm

Brian
If you have a laptop can you please bring it. Its for the scope.

Regards
Pat

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#39 Re: Clutch knocking noise

Post by zigzagsky » Thu Oct 19, 2017 9:46 am

Will do Pat.

Does it matter if it's a PC or Mac?
Brian
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#40 Re: Clutch knocking noise

Post by zigzagsky » Thu Oct 19, 2017 9:51 am

I think that what Christophe and Hugo says makes sense to me.

So it's either something in the gearbox or... maybe... the clutch hitting something in or around the bell housing?

I may have sourced a spare starter so may try replacing the existing one just to finally rule it out 100%.

I will also do some test drives at the weekend when I'm back from my business trip to see if it varies with engine and/or road speed. I'm 95% certain it does vary with engine speed and I can hear it when driving in 1st gear but need to listen carefully to see if it occurs in all gears.

As you rightly point out Hugo, I could spend a bundle of money on getting the drivetrain removed and split and still be none the wiser and just be a LOT poorer.
Brian
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