I have read all sorts of threads about replacing chain tensioners and guides. My 04 XK8 has just about 180,000km on it. It runs really well and the engine is very smooth and quiet. But because of the high mileage , I am thinking that during winter storage I will pull off the chain covers and inspect , and probably replace the tensioners and guides.

No one ever mentions replacing the timing chains themselves though. Are they so robust that they don't wear out ? Again I go back to my rallying Mini-Cooper days when it was common practice to replace the timing chain every 50-60000 km.

Have any of you folks replaced your timing chains ? Or an I just being paranoid and the tensioners and guides would be all I need ?

 

I don't recall timing chains being a major source of problems, e.g., breaking or expanding; however, given the amount of work involved in removing the front covers to gain access to the tensioners, it was my thinking that replacing the chains at the same time was a prudent investment of time and money. Likewise for changing out the water pump and thermostat.

 

The secondary timing chain tensioners were not a high failure item on the 4.2 litre units as they were on the 4.0 litre.

Unless there is evidence to the contrary, save yourself the time and expense of replacing the primary and secondary chains, guides and tensioners.

The water pump has not been a high failure item on the 4.2 litre, but the water outlet should be replaced each time the coolant is changed as it can only undergo a finite number of hot and cold cycles before leaking. The replacement water outlet comes with a new thermostat in situ.

 

The main failure items are guides and tensioners but if you buy these items piecemeal I don't think it would be cheaper than a full kit so why skimp? when I did mine there were the ones who said just do the secondary tensioners and nothing else but when I took everything apart a quick look with a boroscope at the primary guides showed cracks and bits missing. Don't ever do part of this job, it just aint worth it.

 

You may have "pre-answered" another of my questions Is there is a "kit" available with tensioners, guides, chains , gaskets etc ? and if so ( besides the dealership ) where ?

I tend to agree that if I have the front off the motor anyway it seems jsut as well to replace the chains I replaced the thermostat and housing when I bought the car

 

SNG Barratt a forum sponsor has an excellent and reasonably priced kit with everything you need.

 

there is no track record of any problems with the 4.2 l .engines. 4.0 only.

 

So does that imply that there is no need to be concerned about the chains , even in such a high mileage vehicle ?

 

Kindly reread post 3.

Unless there is evidence of noise, or other condition, there is no need to replace the primary or secondary timing chains and associated parts.

 

High mileage? Where? What did I miss? Surely you are not suggesting that 180,000Km (a little over 100,000 miles) is high?

Take a look at the old Mk1 in my avatar . . . when I acquired it, she had 120,000 miles on it. That XK engine was stripped and miked all over . . . the crank was found to be unmarked and still within factory specs on all journals and big end pins; same with camshafts, sprockets and chains. The only measurable wear was about 2 thou of thrust side taper wear in the bores, with corresponding wear of piston rings.

It was always destined to be bored, sleeved and high comp pistons fitted. It was carefully re-built with all new standard bearings on crank and cams and new rings fitted after "gapping to spec" (too often overlooked). That engine, after reset of valve bucket clearances after 1,000 miles, ran for a further 250,000 miles (400,000Km) with no work other than plugs, points and regular maintenance of fluids & filters.

Now, I know that the intervening 50 years have brought us better materials and far more accuracy in manufacturing. Provided owners apply the same rigour in their maintenance, these newer Jaguar engines, especially the silky smooth 4.2L V8 coupled to the superb ZF 6HP26 box, should last equally as long.

Across the breadth of our family, one adage reigns supreme when speaking of any well maintained Jaguar that crosses into 6 figure territory . . . "Oh, great, so, it's run in then???" Sub-text? "If it ain't broke, don't fix it!"

Best wishes,

Ken

 

+1. The 4.2 is not at risk like the early 4.0. Save your money for a fuel pump, especially if you lay it up for the winter.

 

Yep . . . and also a smart multi-stage charger or battery tender . . . as well as a low cost WiFi or Bluetooth ELM327 code reader which you can use with the Torque app. These cars are almost on a par with their contemporary sibling, the S-Type . . . rewarding being unloved for even just a fortnight by throwing all sorts of spurious faults once started on a sagging battery.

The fuel pump is not cheap and my suggestions here will add another $50-$80 but all 3 are wisely spent.

Best wishes,

Ken

 

The fuel pump was replaced by the Jag dealer about a month before I bought it I replaced the thermostat and housing because of a small leak right after I bought it..so I guess I'm good

Thanks to all for the input !