www.jec.org.uk

1998 XK8

I have have had the jag for just over a month and I am trying to determine if the tensioners have ever been replaced. One previous owner with FJSH. 2 main Jag dealers have done all the servicing.

From contacting them I know it has a new gearbox, throttle body replacement and the the pump has been changed. I'm hoping that if they would go to the trouble of doing the pump they would have looked at the tensioners but would like to verify.

I've heard from this and other forums about removing the valve cover to inspect and different opions about needing to replace the gasket.

My local jag dealer has quoted over 300 to do this check for me (including replacing gasket).

Is this a relatively simple job to do myself, i don't have a garage or much in the way of facilities?

Looks like it's time you were put in touch with a friendly local Jag specialist. Where do you live? Contact your local region too - help and advice are usually available and a few friendly faces - see the Club website which has a map with all info you need. Paul(Lincs. North).

the coolant pump on our V8 engines can easily be removed and replaced without the need to disturb the cam covers or front engine chain cover ,

so i doubt very much that they removed these items to ' look ' as a hell of a lot of work and new seals are required,

and to be honest, if you want to ' look ' you may as well get all the parts to replace while its all in bits

you may well see from my sticky post at the top of the forum that the condition of the secondary tensioners can not be fully determined by a non intrusive inspection, the only real way is to pull them, and at £40 each you might as well put in brand new modern ones

the primary tensioners can even be seen without taking the front of the engine off ,
get a local garage with experience with this job to do it for you, the cost will be sub £1000 , Jaguar want £1500 to do the full job.

the parts alone will come to around £300 , thats two primary , two secondary , new front seals, 4 x new secondary bolts ,new cam cover seals , new spark plug seals , new lower pulley oil seal and on an AJ27 engine new solenoid seals for the VVT

if you want to do it yourself ( like i did ) the special tools will cost around £400, but like i did , you can sell them after completion for very little loss ( if any ) , and the whole job should cost around the £300 once done by you

hope this is of some use

BB

Thanks Paul, I'm in SE London and have been looking through the list of independents the most local seem to be out in Kent so i think you are right about contacting the local region.

BB - Good advice. I agree that if i do a full inspection then yes then i might as well get the parts and do a full replacement.

What i don't want to do is pay for this and then find it has mk3 tensioners in there already. When i say inspection i am essentially asking is if there is an easy way to find out if the tensioners have already been replaced without taking the thing to bits.

If there is, is there a guide to this process? I have seen the guides for the whole replacement process but not for what i have seen described as "removing the valve cover" to see which version of tensioners are there.

if , once the valve covers have been removed, and you see tensioners with alloy bodies, rather than orange plastic, then yes, they will be the V8 4.2 Mk3 versions

however, the original white ( go orange with oil and heat ) went through several mods due to problems, and you may have had them changed at some point, but only to the latest plastic version and not the newest metal ones

as for a guide to removing the valve covers, well here goes

chose a nice day that isnt raining, or do it under cover, you dont want water getting in the heads !!!

the easiest side to remove is the drivers / right or off-side valve cover, as there is an oil dipstick in the way on the other side.....

remove the air intake tubing including the airbox to the throttle body , and put to one side

then remove the spark plug coil cover , under there are all the coils ( x4 ) for the spark plugs, remove the cable clips and bolts for the coils, and remove them and the wiring off the spark plugs, you wont get them mixed up as the wiring is cut to length ,

then with the loom out of the way undo all the bolts holding down the cam cover, if you have an AJ26 engine , then there is no VVT solenoid , an AJ27 engine has it sticking up through the top of the cam cover with a seal ,

carefully remove the cam cover in an upwards direction until its clear, and put to one side, you can now see the tensioner on the exhaust can sprocket with the chain going over it ( as in my pic ) http://www.talkphotography.co.uk/galler ... Small_.JPG

the orange unit under the chain is the secondary exhaust tensioner ,if it looks like my picture above, then it NEEDS changing,
if it looks like the one below, then it has the latest ones fitted
http://www.talkphotography.co.uk/galler ... Small_.JPG

now, i have heard that Jaguar have , in the past , only changed one tensioner , and not the pair, so its up to you if you want to check the other side, its 50/50 regards that


this will not cost you any money to check yourself, i would however recommend new cam cover and spark plug seals as a minimum , if when you take things apart there is oil in the spark plug well, you deffo need new seals on the cam cover......

lastly , this is a picture of the old knackered removed unit , along side the replacement one, you need shorter mounting bolts for the new ones
http://www.talkphotography.co.uk/galler ... Small_.JPG

i did all this work myself, and the car is running fine over two years and 30k miles later

BB

Thanks BB, exactly what i was after.

All I need now is a dry day.

Cheers,

Neil

Thanks BB, exactly what i was after.

All I need now is a dry day.

Cheers,

Neil

Great stuff.

Last week i took out all the coils and plugs.. half the plugs were platinum other have the iridium... today i will be replacing the plugs and coils but since i have half the bolts out i may take the cam cover off to inspect the tensioner.

a few of the bolts on bottom right side the difficult to get to look rusty.. i hope i can undo them else ill have a disaster.

i will update with pictures once i have the cover off.

Hi Tony here in Cornwall, my 1999 xk8 rattles terribly on start up then once revved goes quieter, I suspect tensioners
May well be the cause. I have read all the various threads on the methods of replacing them,one thing I can't understand is locking the flywheel in TDC. I understand the cam locking bar. But where do you lock the flywheel in place....or do you need to ?.....any advise please.

Strong advice here.

If the engine rattles badly on start up, you should immediately dis-continue to use this car until you have investigated further. This is a classic pre=failure symptom which inplies that secondary tensioner slipper plates have been torn off the mounting plates and in that condition can only lead to total tensioner failure within a VERY short time. Ensure the car is inspected as soon as possible and is preferably transported to a repair business on a recovery truck. Regret to say that unless this action is carried out, the engine may disintigrate when you next drive the car.

Ensure any replacement units are the later final aluminium units and that if damaged, secondary timing chains are also replaced at the same time. Given the age of the car, you would also do well to replace a third plastic tensioner and chains on the primary drive set up and possibly also the slipper plates which are part of the primary tensioner set up. This requires the further removal of drive belts, crank pulley and front tehsioner cover plate.

Actioning the above is cheaper than driving the car and having the engine explode on you. In the apst this has frequently happened and cost owners thousands to rectify. Most found it cheaper to replace the engine than repair a unit with disintigrated timing gear and smashed and bent valves and pistons.

As regards the flywheel locking, this may be found inboard of the starter ring gear on the drive flex plate. Look for an obling slot into which an appropriate locking peg is inserted to lock up engine rotation during tensioner renewal.

Sorry to be the bearer of bad news.

Mike K

Mike K may well be correct with his dire diagnosis but there is also another possibility which you should eliminate before blaming the tensioners. The XK8 has VVTs (variable valve timing units) which, when worn, allow oil to drain from them when left standing. A cold start can produce a lot of unpleasant noises until the engine is revved slightly when the VVTs refill with oil and quieten down. Both possibilities (tensioners and VVTs) require the front of the engine to be stripped allowing the tensioners to be checked. However, changing the tensioners without confirming the state of the VVTs only to have the same noises afterwards would be really annoying! Mike.

Thank you both for your replies, you have confirmed the conclusions I have come to researching and looking at some videos on YouTube.I intend to remove a cam cover firstly to confirm my assumption that the plastic tensioners are fitted to this engine ,if so will remove front cover and completely change the tensioners and chains,so will need to use a timing locking kit,and crankshaft pulley removal tool.And now I know where to look I can lock the crank.
Looks like it will cost about £450 for parts.
Is there a method of ruling out either vvt or tensioners ,do both go quiet when oil pressure builds up ?
I'd hate to put it all back together only to find out it was the vvt.
Tony

To be fair, most upper timing chain tensioner failures are catastrophic and occur without warning or noise. Lower tensioners are more reliable and can give warning noises. If the noises disappear when the engine is warm, I'd lean towards a VVT issue but nothing is certain without a proper examination of the components. Mike.

Thanks Mike, I am leaning toward VVT .I have just bought this car from a lady who told me it rattled on start up, but she had it for 10 months and it was like it when she bought it ! I Got it for the right money so thought I would risk it, I drove this car 70 miles last week in one go from Paignton to Cornwall , no rattles all the way. I stopped at home left it an hour then started it up again rattled until revved it then quiet again , I,m assuming the oil is draining back from the VVt unit.
Can the vvt unit be refurbished ? . I have another one a 1998, this one is 1999 , initially I bought it for spares but it is too good to Break, it passed the MOT last week !
one more question ...workshop manual ? is there a good download or book I can buy.
I find the JEC invaluable.
thanks Tony
PS went to the historic meeting at castle combe last week ....great day out.

Sounds like a two man diagnosis is called for, one to listen to the VVTs with a stethoscope while another starts the car from cold. I'm not aware of anything other than the obvious options of either new (expensive) or second hand (risky) VVTs, should your car require one or both. Mike.

My old 4 litre V8 S-type came back to me for service recently. The new owner noticed a "clack" on cold start up at 94k miles.

I knew it wasn`t tensioners as I`d fitted new ali units at 44k miles. The regular "clack" came from just the O/S tensioner. My fix on that car was two cans of Wynns Engine Flush, engine run for twenty minutes at idle followed by an oil drop, new filter and new oil. Result..."cold start clack" gone!

Broken tensioners are quite gutteral in sound when they go. It is very obvious something has given up. I can`t emphasis enough the importance of not starting or using a car if this symptom is present. If the chains were to jump a couple of sprockets, well thats enough to bend most of the 32 valves and bash up the pistons.

Mike K