Howdy folks,

Looks like I've landed myself a money pit. Only had the car a few weeks, on the first day of ownership the water pump failed and now, today at my mechanics on other business, he tells me my timing chain needs attention.

I've purchased a reconditioned water pump, (no new ones available in Adelaide Australia apparently), so will do that job myself.

Is the timing chain a job for the home mechanic, or do I need to sell some real estate to afford a Jag specialist to do it?

Any advise appreciated.

Car is a 1983 XJ6 Vanden Plas.

The Wife thinks this is hugely hilarious by the way, looking to prove her wrong!!

 

You wouldn't be the first person to be burned for a timing chain when all it needed was adjustment. As these engines are quite an old design they actually employ a system that you can manually adjust the timing chain with, not like today's 'sealed for life' attitude towards stuff. to do this you remove the breather off the front of the timing cover. i think you need some sort of tool that can be improvised. if you dont feel up to the task im sure a jag savvy mechanic could do it in five minutes.

there is a chance that its not simply the adjustment i suppose but ide certainly get a second opinion first. these are pretty sturdy engines and i havent herd of many mechanical problems like timing chains. otherwise its a pretty involved job. requires stripping most of the front of the engine away so its certainly nothing to sneeze at. ive dont plenty on fords and the like but not the jag so best wait for someone who knows the procedure to give you the run down.

Regards ,
Jay

 

There are two timing chains on these engines, a lower and an upper. The lower one is automatically tensioned by a tensioner that is worked by oil pressure off the main oil gallery. The upper one is tensioned manually as explained above, and there is a timing chain adjustment tool available to make it easy. Tensioning the upper is theoretically easy, one just takes off the circular cover (where the crankcase breather comes out), loosens off the nut and turn the adjuster using the tool. It does help to take off a cam cover to check the tension. Sometimes one finds that the adjuster wont turn and then it gets interesting.

The chains last a very long time, but will wear out eventually as will the sprockets. Jaguar fitted endless chains, but some people fit chains with split links, although that is something I would not contemplate, frankly, but fitting endless chains means the head has to come off, and for the lower chain, the timing chain cover and sump. Sometimes only the lower tensioner needs replacing because its hard rubber wearing surface has worn away. Other thing that can happen is the gauze filter in the oil pressure supply hole gets blocked reducing the pressure to the tensioner so it doesn't tension the chain properly.

So you get the message - replacing/working on these chains is a PITA and generally only done at engine overhaul time. They should last that long, but how many miles on the car ?

 

Car has done over 360,000 km's, but engine was rebuilt by previous owner in 2006. Looking at the invoice, it says that both chains were replaced.

Previous owner had an independent assessment done by the RAA, and they said the valve train noise, at all engine speeds, was considered abnormal. Only way to find the cause was to dismantle. That was at 327,000 km's.

Bloke I bought the car from said it needed re-shimming, whatever that means, and he'd had a quote of $2,000 Aussie dollars.

Looks like I'll have to revert back to my trusty 1974 Ford Fairlane while I attempt to fix this problem.

Thanks for your replies.

Cheers.

 

Re-shimming is referring to the tappet clearances. There are little pucks under each valve bucket, ground to give a precise thickness. There is a range of thicknesses available. These are sometimes called shims but they're much thicker than shim steel. If the clearances are wrong you can get noisy tappets, (or too silent ones if the clearances are too small). Re-shimming means the cams have to come off.

If the chains have been replaced, it is likely the lower tensioner was done too. So adjustment of the top chain sounds necessary. Have you tried the mechanics stethoscope trick with a long-shaft screwdriver to find out where the noise in coming from ?

Other thing that causes noise is tappet guides coming loose and needing staking down. There are kits available for this.