highest mileage on original timing tensioners and chains

[ROSSYSTEVE]

Hi all I'm a newcomer to the this forum and so by way of introducing myself I thought I would ask the above Question.
My 1997 convertible has done 105K.
I bought it Feb this year with last ten years of service history @2002 it had 62K on the clock. I contacted the previous dealership who confirmed thay had not been changed.
I will be doing them in a couple of weeks and will post their condition then. But in the mean time I was wondering if there are any out ther running with a higher mileage ? .

Cheers Steve Ross.

[J44EAG]

You might be living on borrowed time if your tensioners are plastic. Mine were badly cracked at 44k miles. At such high mileage, I would be lifting the cam covers to have a look to see what is in there. If they break, it will cost you an engine rebuild.

One thing is certain. Plastic tensioners will let go.The problem is knowing when they will go.....

[mike020150]

Unfortunately, the original design of 'plastic' tensioner is totally unpredictable. Some let go at incredibly low mileages (less than 20K) whereas others have soldiered on to more acceptable figures (150K is unusual but not unheard of). It is this wide unpredictability coupled with a lack of any warning noises that condemn this design. If you are lucky, when they fail, the engine will bend a few valves. However, it's just as likely that the engine could suffer a catastrophic failure costing thousands to correct. Hence, the only sensible course of action is to replace at least the upper tensioners with the robust, metal bodied versions fitted to the 4.2 litre engines. At 100k+ miles, it would probably be advisable to opt for the more involved task of replacing the chains and stripping out the lower tensioners and guide too. Whilst failures of the latter are generally not as frequent or as catastrophic, the guides have been known to crack. The standard 4.2 litre guides won't interchange directly but some suppliers are now able to supply modified versions to beef up this area of the engine. Good luck with the job. Mike

[Nik]

Hi Guy's ,
I suspect that the longevity of the Mk1 tensioners may be dependant on the engine temperature , with the well known issues of early water pumps loosing their vanes the engine temperature could exceed the design parameters without the driver noticing anything or perhaps a slightly higher reading on the gauge

This would cause the plastic tensioners to become quite brittle .

One upper tensioner failed on my 1998 XK8 causing the chain to break on the R/H bank Luckily upon stripping the engine all was well so the engine was reassembled with MK2 tensioners and new chains , when I became it's second custodian I ran her for some three years before the paranoia set in
I had the timing gear stripped and inspected , all chains and tensioners were as new with no signs of wear whatsoever but as a precaution and piece of mind MK3 all metal tensioners were fitted , I can take some photo's of the MK2 tensioners if anyone is interested (if I can find them )

My advice would be to inspect them ASAP and replace all tensioners , chains and guides for the latest versions , while it's apart also change the water pump , thermostat and preferably replace the plastic thermostat housing with the cast alloy version (SNG Barratt do them at a very reasonable price)

Hope this helps ,

Nik

[ROSSYSTEVE]

Feedback on the tensioner and chain replacement. 105K miles
The secondary tensioners; original plastic where present, one had lost its plastic top and was thus metal to chain, the other had a crack through its mid section.
Primary tensioners where fine but both slippers had the commonly seen cracks through the mid sections.

So, I'm VERY glad I chose to do them on what was sounding like a sweet engine

My advice if your driving a high mileage xk8 on original tensioners, get them changed, the piece of mind and confidence to floor the pedal is very very satisfying.
cheers Steve Ross.

[J44EAG]

Wise words indeed.

Neville Anderson`s kit kicks the problem into touch once and for all. For £250 not doing the uprate is a no brainer.

http://www.ebay.co.uk/itm/JAGUAR-V8-TIM ... 2a10d57ff0

Mike K

[ROSSYSTEVE]

I used this kit http://www.ebay.co.uk/itm/JAGUAR-V8-TIM ... 2a10882af7

a few bob, more but it included all the gaskets needed.
Also many thanks to the club specialist tools shelf for posting the required tools to do the job.

All good stuff !!

Steve.