I changed the upper chains and plastic tensioners in my 1998 XK8 when I first got it last year. The car now has 96 K on it.

I just noticed that after a cold start, if you gun the engine, there is a metalic rattle for a split second. Car runs smooth and if you just start the car and drive off, no noise.

Could this be the lower chain tensioners have given up the ghost? They were plastic too correct? What on earth caused Jag enginers to use plastic? To many pints at the Pub? Plastic has no business inside an engine period!!

I am really concerned.

 

its called cheap..every thing we make in England now is mostly crap

 

I've got the same sound after a cold start, when gunning it a bit. Just lasts for a split second. Posted on it last year, with a short video that includes the sound. Most on the forum thought it was probably the VVT units.

I've had no issues other than that. You'll probably be fine, too.

 

Why on earth would you gun the engine at start up? Geez, give the engine some time to build oil pressure at all points and let it warm up with a few minutes easy driving before hammering on it. Would you treat a Ferrari or Lambo' that way? There's really to reason to ever gun an engine in park/neutral, warmed up or not. It is particularly hard on the chains and tensioners to snap all that torque against them.

 

When I say gun, I really mean just a slight blip. Nothing to hard just a quick very short RPM increase and only once or twice tops.

I would never race a cold engine. I heard what I thought was a rattle and gave the gas a quick blip and then heard it again and it did not sound like anything I have heard from this car before. My normal way is to start, put the car in gear and roll down the driveway and then slowly pull away. Nothing very harsh.

 

Hi Bigvettefreak,
I have the exact same noise from my 97XK8 when cold. i changed upper tensioners. but when cold a harsh single slap noise can be heard when accelerating from cold.

I believed the noise was primary timing chains. But I suppose the only way to find out will be to replace them.
Id be interested to understand why this noise could be VVT units.

thanks

Stephen

 

[QUOTE=steveeasy;588627]Hi Bigvettefreak,
I have the exact same noise from my 97XK8 when cold. i changed upper tensioners. but when cold a harsh single slap noise can be heard when accelerating from cold.

I believed the noise was primary timing chains. But I suppose the only way to find out will be to replace them.
Id be interested to understand why this noise could be VVT units.

thanks

My BMW makes a strange knocking noise at start up sometimes and it seems to be the Vanos system. alot of owners have it and to date it is only noise but no harm so I just ignore it because it doesn't happen all the time.

I guess the Jag could have a similar problem with their cam system. All I know is the engine never made that noise before. I really don't want to spend a grand just to see if it is the chain only to find out it isn't.

I am starting to think I made a mistake getting a Jag.

I should have stayed with the old fashion in the block cam design (It works.) and not have to deal with this kind of silly stuff. All because someone was stupid enough to use plastic for such an important part.

For anyone who wants to design a car or engine, remember NO PLASTIC!!!!!!!!!!!!

 

If you love the car you probably should bite the bullet and get new primary tensioners, guides and chains at some point. Also make sure they clean the broken plastic bits out of the oil sump screen.

I would not consider it a high risk situation (unlike the secondary tensioners), but something you can save for and plan to do in a few months.

 

I think I am just going to ignore the noise for now and chalk it up to vvt noise like my BMW and just drive the car.

If it is chains, it will get worse and then I'll decide what to do.

I am just getting tired of bitchy cars that need,need,need just like a gold digger girl friend. You love them, but they are a pain in the *** after a while.