Hi there.
My 2000 XJ8 X308 74000 miles is causing me some problems.
Last year it failed a uk MOT (Ministry of Transport) test on emissions and has now developed what I think is a timing chain knock/rattle. I am intending to get the timing chains done but wondered if it may have been the cause of the emissions problem in the 1st place. If the timing chains need replacing could it throw the emissions out ?
I have replaced O2 sensors, air flow sensor and done leak tests on the exhaust and had some marginal success with emissions but now on cold start up there is a knock/rattle for a few seconds and the 'restricted performance' warning has come on.
I would be grateful for any suggestions any of the members may have.
Best
Pete

 

You should hang obd reader on and look at what is exactly failing, is it running rich or lean and if there are any stored errors, without it it is just a guess party
If you are sure it is timing rattle don't start engine at all, until you inspect what is happening there

 

If the secondary timing chain has slipped, your vehicle will be out of time and this will upset emissions.

 

Listen to xjack. You need to let the car tell you what to do. Yes get the tensions/chains and all that replaced first.
Yes DON'T start the engine again until it's torn down and inspected. When things let go you will destroy the engine and bend valves at the minimum.
Sounds like your engine is right on the edge of coming apart.
Catch it BEFORE it does!
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if you pop the cam covers off & turn the engine by hand you'll be able to see if the flats on the sprocket end of the cams line up correctly or not. If they don't it's proof your secondary chain has slipped on that side.

have a search on here for timing chains etc & there's loads of pics of what to look for when checking the cam timing.

 

The 'RESTRICTED PERFORMANCE' - this will be the ECU's camshaft vs crankshaft sensor signals being way off.
"Interference engine" valves meet pistons and new engine required once the tensioners fail.

As the other erudite members have suggested - don't start it until you've confirmed the issue. Hopefully its parked were it can be worked on.
The car being an early AJ27 engine 3.2 no VVT, steel lined, but will have plastic tensioners and guides, a new set can be readily bought chains too.

The replacement - loads of "how to" threads on this forum, what to look for to diagnose and how to go about fixing it.
Specialist tools
OBD II Reader
Crank damper puller to remove pulley for timing cover removal. Replace the bolt and cone and inner face seal once timing is renewed.
Cam lock + starter ring gear locator, this to put the motor in service position of 45 after TDC and all camshaft 'flats' level. These can be bought cheaply
The rest is standard tools.
To pay a specialist? Call Tom Lenthall, he'll give you an honest breakdown.

 

read the dtcs. cam crank correlation doesn’t put it into restricted performance

 

One of the easiest ways to check your primary timing chain guides is to drain the oil out, remove all the 8mm headed bolts on the oil pan and drop it down. The plastic chunks that can be in the bottom of the pan is an indication that the guides have failed. Also ***throughly*** check inside the oil pickup for any plastic debris as this can starve the engine of oil pressure and volume which of course can prematurely ruin your engine.

 

Great suggestion to look for plastic in the pan. That has been reported many, many times.
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The place I'm booking my XJR in for chains later this year said they always drop the sump & clean it out for that reason as part of the job.

 

I would like to thank everyone for their input. I have had the car towed to the excellent North London Jaguars for further diagnosis and timing chain replacement. Far too big a job for me to handle. It's one of those jobs that make you think "do I keep the car ?". Up to now the answer has always been .."Yes" . I just couldn't contemplate anything else frankly. In for a penny, in for a pound

 

Keeping these ladies on the road can be a daunting yet rewarding task.
We are glad to hear you are working toward that end.