Tapping on start up from cold

[toolsisme]

My 2001 4.0 XKR is making a slight tapping noise on start up for about 30 seconds and has got slowly louder over the las t 2 years (i don't do many miles)
I removed cam covers in 2012 to check things and found it has later aluminium secondary tensioners and duplex primary chains and was told this is a "Hybrid Engine " with 4.2 fittings .
If this is the case do i need to worry about tensioners or do the latter type give problems too?
Any advise would be greatly appreciated.

Rob

[mike020150]

The chances are that on a 2001 car, you are hearing a noise caused by wear in a VVT (variable valve timing unit). Until oil pressure builds in the unit, it is not uncommon for worn units to make a noise after a cold start. As VVT wear increases, engine performance will be affected, so the problem does need correcting although failures are not normally catastrophic, unlike timing tensioner failures. Mike.

[toolsisme]

HI Mike
Thanks for the fast reply but its an XKR supercharged it doesn't have VVT .
By the way its done 69,000 miles

Thanks Rob

[mike020150]

Early XKRs didn't have VVTs, later ones did which is why I mentioned it as a known possibility where VVTs are fitted. Nothing mechanical is perfect so, although the later tensioners are very reliable, they can still fail, albeit rarely. It might be worth using a 'proper' independent oil pressure gauge to see if the tapping noise really does coincide with a pattern of low oil pressure or is merely coincidental and it is not oil pressure related. Or, could it be a restricted oil feed to a tappet? A thorough oil flush and regular oil & filter changes might help the latter situation. The sources of noises are notoriously difficult to pin down so it's best to carry out as many diagnostic and other simple procedures as possible before resorting to stripping components to search for worn items. Mike.

[aaj]

Hi Rob
You have been misinformed regarding your engine being a 'Hybrid Engine'
Engines after 0108122359 (MY2002) have the 4.2 Timing Chain System (Tensioners & Morse Primary Chain, but not the improved Water Pump) fitted at Factory so if you have metal tensioners they have been retro fitted. Most people only replaced the upper tensioners.
Regards
AllanJ

[toolsisme]

Hi Mike and Allen.
Thanks for your replies.
Ive owned this car since it was 34 months old and 35,00 miles and change the oil and filter every year regardless so i don't think it should need flushing but a good idea to use an oil gauge Mike.
Allan the term "Hybrid" was quoted to me by an ex coordinator on here but he was vague about time periods so your information on engine numbers is interesting.
My engine code is 0110261521 so am i right in thinking all chains and tensioners will be later type?

Thanks again for all your help

Rob

[aaj]

Hi Rob

Yes, in theory, you should have the 4.2 Valve Timing System. But the alarm bells rang when you quoted that you have duplex chains. I've attached a photo of a Morse Chain.
I had a MY2002 XK8 from 2005 (NB0112071801) until it was written off in 2019 and I removed a Cam Cover to be sure that my engine had the 4.2 Timing Chain System
I hope this is of help
Regards
AllanJ

[toolsisme]

Hi Allan
Sorry for my poor terminology. Yes i have the HY-VO type chain.
So this regular tapping i have ( sounds like a tappet or piston slap)that goes after about 30 seconds, do you have any more thoughts as to what you think it could be.

Thanks again

Rob

[aaj]

Hi Rob

A Good independent Jaguar Workshop who has extensive knowledge of the Jaguar Supercharged V8 engine may recognise the noise your engine makes at startup. If you have such a garage local to you I would try there.
Good luck
AllanJ

[toolsisme]

HI Allan
OK thanks for all the help

Rob