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Discussion Starter · #1 ·
Hi all,

The lower - upper tensioners, chains and guides have been replaced by me. In fact not too complicated with the right tools. Everything worked out well. The engine started directly, no leakage so far so good. But the unpleasant noise I have written about earlier was still there. The noise starts after 15 sec and lasts for two minutes. Then it is gone as long as the engine is warm. Cold start and the same happens again.
To be able to exclude what could cause the noise I have disconnected the belt and then I have cranked the engine for a while. The noise was still there. Which means no problem with the power steering, water pump, AC or generator. I performed a test of the solenoids by using an external battery and I heard the characteristic clicking sound. No problem there either.
After all reading I have done I could think of bad performance of the VVT:s. Probably it take some time to get the right oil pressure to the VVT:s. The engine is the model A26 and I believe Jaguar upgraded the VVT:s in the engine A27. (I hope I am correct in this assumption). Maybe because of bad performance in the first generation.
Please give me a piece of advice.
1) Could this be the cause of the problem?
2) Have someone of you repaired the VVT:s? Take apart - clean - change o-rings etc. Any instruction available?

Any other piece of advice is more than Welcome.

best regards

Jaguar XK8 convert 1997

Lennart Åberg
 

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How old is your engine oil? Is the level ok? In certain other cars (errr cough BMW'S) the engine makes a tapping/rattly sound till it gets warm and the engine oil has circulated. Once warm it disappears until it has had time to settle off the working parts again.

Perhaps you could record the sound and put it up on Youtube then here so we can have a listen?
 

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VVT cams can make noise if there is insufficient oil pressure/flow and/or if they are gummed up with crap from lack of maintenace

i would flush the oil and renew with good quality synthetic stuff and see if the noise subsides.
 

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Discussion Starter · #5 ·
I changed the oil after replacing the tensioners. On this forum I have found a description how to repair/clean the VVT:s. https://www.jaguarforums.com/forum/xk8-xkr-x100-17/understanding-vvt-repair-pictures-writeup-54805/
If nothing else will do I will continue the hard work to find what causes the noise. However there could be a shortcut like you Henry_B suggests. Asked about this solution 50% Jag owners would go for it and 50% would not. I have in my garage FORTE motor flush. Would that do? Any other suggestions what to use?

Lennart

Jaguar XK8 Convert 1997
 

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My 4.2 s/c S Type used to have a rattle upon start up from cold which only lasted for a couple of seconds then disappeared. I changed the oil to Redline and the noise disappeared for a while then returned but not so badly. I have been well advised that it is the VVT unit which has a small spring and pin that should lock the camshaft when the engine stops and the oil pressure drops. This pin sometimes sticks.
One way to check is to try and hear which side of the engine sounds rattly then remove the appropriate cam cover and see if there is slack in the camshaft.
Seen this? http://www.jaguarforum.com/showthread.php?t=44536&page=3&highlight=rattle+start
 

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Hi Stagnite,

I am using Mobil 1 New Life 0W-40 oil for the engine. Maybe an oil change will do. What happened in the long run when you changed to REDLINE oil. Did the noise stay away?

Lennart

Jaguar XK8 Convert 1997
My 4.2 s/c S Type used to have a rattle upon stat up from cold which only lasted for a couple of seconds then disapeared. I changed the oil to Redline and the noise disapeared for a while then returned but not so badly. I have been well advised that it is the VVT unit which has a small spring and pin that should lock the camshaft when the engine stops and the oil pressure drops. This pin sometimes sticks.
One way to check is to try and hear which side of the engine sounds rattly then remove the appropriate cam cover and see if there is slack in the camshaft.
Seen this? http://www.jaguarforum.com/showthrea...t=rattle+start
It still does it a bit at startup but nowhere near as pronounced as it was. I understand its a common fault.

You say XK8 convert. Have you fitted a supercharger? They have a common rattle too. The coupling wears out and rattles. I recently changed one on a 5 litre s/c.
 

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Duplicate by mistake. How does one delete a post? Cant see how to do it.
 

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Discussion Starter · #10 ·
My jag is a convertible. Sorry for the misleading abbreviation. For the time being I am trying to bild up some energy to go into operation mood to do some surgery of the VVT:s. I will keep you all informed.

Lennart

Jaguar XK8 Converible 1997
 

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I had exactly the noise on startup you describe on my 1998 xk when using 5w/30 oil but have had no problems at all after changing to castrol magnatec 10w/40 which I believe is the correct grade for cars up to 1998. ..might be worth a try.
 

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It was difficult to capture the sound on camera but you can just make it out on this video at 1second in.

I removed the pipe and had someone tig weld up the crack and replaced it, a new pipe was about £150.

Dont know how long its supposed to be but I only get 3 seconds of video! Perhaps you can loop it then repost?
 
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