just brought three weeks ago a 1998 xj8 3.2 v8 with 127000 miles with full jag/ indy dealer service history. so far its drives really well,gets good mpg and when doing a code check, i don't get any codes or warnings on the dash.

but when its warm and sitting at junctions/lights the engine at idle/ tickover is giving a small amount of vibration.
had the indy garage check it over on thu and they pointed out the bottom crankshaft pulley as movement like its loose,but when checked is very tight at the bolt.
new pulley is £800 pounds and fitting on top,

so is there any other areas to check ,replace parts etc before trying the pulley change. albeit with second hand pulley for a fraction of the cost.

thanks
mark

 

Is the A/C on or off when you feel the slight vibration? I have noticed that when the fans are running (with A/C on) the idle is slightly rougher.

But there are many possibilities for a rough idle:dirty throttle bore and plate, dirty MAF sensor, air leaks, worn plugs, leaking injectors, dirty idle bleed . . . . But lots of information on this forum on addressing each . . .

 

will try all of the above when out next,wife says its worse in neutral,so will try with a/c on as well.

 

still doing it and the car has been driven by three different drivers over the week end, all say it runs great but on tick over vibrates more when warm,less when cold.
any way off checking the idle side of things, where to look and what components to clean /check?

 

Now changed temp sender and thermostat, got the car running at correct temp and better mpg, but still got slight vibration on tick over.
Tried the engine mounts with bonnet up and no movement at all the lump was solid.
Short of doing the pulley, any other idea's to check/ try.

 

Reread number 2 for starters. What is the status of the secondary tensioners, if the timing is off, it will idle rough.

Search the forum for "rough idle."

 

Definitely check the status of the tensioners. There are many incidents on this forum where folks have had bad experiences due to failing secondary cam chain tensioners, and with a '98, it's walking on thin ice if they haven't been replaced. A one tooth jump of a chain will cause a rough idle, two teeth ...

 

Will check all above over the coming weeks,thanks everyone.

 

Have done the Maf and throttle body / flap clean, and still got it but a slight less every time something is changed / cleaned.
Won't get another chance to check tensioners till first week in Aug .
Not enough days in a week.

 

Doesn't matter.

The damper is a two piece affair with a rubber layer that
can separate.

If you put a chalk mark across both rings and there is separation,
you will see the chalk marks move in relation to each other.

If you need a damper, you might check with a breaker for a
used one.