The 'E' Type Forum

Hi all,

I've just been reading Alan Cochrane's recent post re noisy tappets. My 3.8 has a clatter at idle that builds then disappears repeatedly. When the engine is started cold it is silent but gets noisy as it warms up. When cruising I can here this clatter on a trailing throttle (it is a more constant clatter at higher revs) and it is less obvious when accelerating. I am running Penrite 20W60 oil. I had the tappets shimmed and upper timing chain adjusted about 2,000 miles ago by an experienced independent Jaguar mechanic as he had access to a shim kit. This quietened the constant chatter down but this noise that cycles in and out is still there. In his opinion it is a loose tappet guide. I am going to remove the cam covers for inspection and will recheck the clearances and chain adjustment. I assume if a guide is loose there will be obvious signs. Perhaps I should invest in a stethoscope to try and pinpoint the noise before dismantling. As always any advise would be appreciated.

Cheers
Pete

Pete, this does sound like a loose tappet guide, and a stethoscope (or wooden dowel) will identify the culprit if this is the problem. If you haven't already done so, I highly recommend installing a tappet guide hold-down kit.

Hey Moe,

Definitely no hold-down kit fitted so will do that regardless.
I think your right, from what I have researched so far the noise sounds like a tappet guide. I think timing chain or tappets would be more consistent.

Cheers
Pete

peters3103 wrote:Hey Moe,

Definitely no hold-down kit fitted so will do that regardless.
I think your right, from what I have researched so far the noise sounds like a tappet guide. I think timing chain or tappets would be more consistent.

Cheers
Pete

Why would the noise go away if it was a tappet guide working its way up?

Pete

Pete

I'm just feeling my way at the moment. I've owned quite a number of XK powered Jaguars but never experienced this type of noise before.
Have you any other suggestions. I will remove the cam covers tomorrow (after a listen with a stethoscope) and see if there is anything obvious.

Pete

The engine expands when it gets warmer. On full-alloy engines this is even more the case then on the XK. When the engine expands, the chains become a bit tighter. (Thats what my Citroen SM expert, London-based, told me regarding chain noise, and this very engine has 3 chains...)

Carsten

peters3103 wrote:Pete

I'm just feeling my way at the moment....
Have you any other suggestions. I will remove the cam covers tomorrow (after a listen with a stethoscope) and see if there is anything obvious.

Pete

Sounds like a plan. Diagnosing noises definitively without hearing them is above my pay grade but so long as you're feeling your way you should track it down. It's just you sounded a bit sure after your researches and I was wondering what you'd read. I would expect a rising tappet to get very loud and not go away, or if it went away one time, not to do it repeatedly. Stethoscopes are wonderful things. Good luck.

Pete

My theory--which is admittedly more guesswork because I'm not physically there--is that the tappet guide loosens via expansion of the alloy cylinder head as the engine warms up. If this is the case--more guesswork here--the problem is most likely in its early stages and the guide hasn't really started to work its way out significantly.

I had the same problem in my 3.8, it was sporadic but occurred mostly on startup/cold engine. Installed the stakedown kit on exhaust side and no more tappet noise. Did not bother the inlet side. Before installation I inspected the tappets and I thought I could see very, very small marks on two or three of the tappets.

Thanks all for the replies - what a great forum this is. I haven't yet had the time to tinker (Father's Day yesterday so no garage time!) Assuming I need a stake down kit which is best - the self tapper or threaded type and who is the preferred supplier of these kits?

Pete

Interestingly looking closely at the "valley" of the head there are faint marks which at a glance could be holes drilled externally at corresponding intervals to accommodate fixing screws for the tappet guides. I've seen this on some other XK engines. If this has been done perhaps guides aren't the cause.
Watch this space...

Pete

I bought the kit from XKS, as far as I can tell the quality was very good. Very good finish and heavy for the size ("machine steel").

http://xks.com/i-6917479-17-1580-hold-d ... uides.html



Here is how I installed the kit in my '61.
http://etypeuk.com/forum/viewtopic.php?t=5517

Durango2k wrote:The engine expands when it gets warmer. On full-alloy engines this is even more the case then on the XK. When the engine expands, the chains become a bit tighter. (Thats what my Citroen SM expert, London-based, told me regarding chain noise, and this very engine has 3 chains...)

So my engine gets noisy as it warms up so probably not chain noise then. Was the installation of the tappet guide hold-down kit successful in that your engine is now quiet in the cam/tappet area?

Pete

My engine is quiet! Well, almost, I did not have a complete shim kit when I did the valves last winter and I had to compromise a little.

Ordered the shim kit from same XKS company this summer and want to readjust in the winter. Nothing like a silent XK engine.

The harsh tappet noise is history though.

A great result
Hoping to achieve the same :)

Cheers
Pete

I removed the cam covers today. The exhaust side tappet guides 1, 2 & 3 have a very light mark on the inside edge at about the 11 o'clock position. Certainly not consistent with being hit by the camshaft many times in my opinion. The inlet side guides are unmarked. The tappet clearances are as follows, 1 thru 6

Exhaust: .006, .006, .007, .007, .006, .005
Inlet: .006, .004, .006, .004, .004, .002

Apart from inlet number 6 these seem within range.
I have checked the upper timing chain tension and by levering the chain with a screwdriver inwards at the halfway point between cam sprockets
and intermediate sprocket it flexes approx 5/16" both sides. Is this excessive and would it make a noise?

Pete

I'm still trying to determine the source of my tapping engine. It was suggested to me to over-tighten the upper timing chain temporarily to eliminate this which I have done - no change. It sounds to me by going over the cam covers and centre of the head with a stethoscope that the tapping is loudest beside the exhaust valves 2, 3 and 4 although the clearances are correct. I think it's safe to say that the tappet guides are locked in place by screws inserted through the inner side of the head. There is no visible damage to the guides. The question is, why the tapping when the clearances are correct? Can worn/damaged shims be the cause.

Pete

The buckets can rock in the guides, making noise.

G'day Andrew,
Can you explain this in a bit more detail if you wouldn't mind.

Cheers

Lateral Play. When They moove sideways it makes a clonk.

Carsten