Hello fellow xk8 owners

First of all, what a great forum it is and very helpfull. I would like to inntroduce myself, my name is Hani and live in UK, London. I am a proud owner of an xk8 and love this car so much.

I have recently been facing a problem with it so i will explain what happens in hope somebody out there may have come across it.

first thing as i switch the car on it makes a loud knocking or tapping noise in the middle of the engine at the top. this can be heard well in side the cockpit. I then rev it slightly the kncking goes away. the oil pressure is ok and oil level is fine from the start. the noise then comes back at idle. I drive off and as iam stuck in trafic i can hear the noise only at idle as when i drive it disapears so only on low revs it is heard. the car idles rough slightly too, however it drives fine.

just to note i have changes the tensioners and chains too. I have also change the oil.

I would be gratefull if anyone can guide me to what it can be and what is the cause as i really hate the fact the xk8 sounding like a diesel at the moment

any suggestions would be great.

thank you to all and speak to you soon.

Hani

 

The Variable Valve Timing (VVT) units can produce a diesel like clicking on higher mileage cars. Fix is to use a higher weight oil, try 10w40. You might also try an oil additive such as 'Restore' if you are not ready to change the oil.

 

Hi Hani, welcome. If you would either add the MY and conv/coupe in your signature line (see your control panel for the forum) or be forced to put that in every post you submit. It is very handy to know that info so misinformation is not given. Different years, engines, transmissions. thx!

 

I would have to second the VVT there are 2 types for the 4.0ltr engine and if you go full hog and have them replaced with new units expect to pay about £1000

I know a good independant based near Reading just off the M4 let me know if you are interested and I will PM his number, Jaguar trained and certainly knows his onions

 

Could this be the sound of the dreaded worn tensioners?

 

I have two videos on this page. See if you can play them and if the sound is the same.
http://www.gusglikas.com/AutoRepairBeltTensioner.htm Copy the link and paste if necessary.

 

Would it be possible to make a recording?

When did the noise started? Was it after you have changed the tensioners?

 

Hello everyone.
thanks for the replies. i will try to answer all the questions. the sound appeared about 6 months from changing the tensioners and also I have used 10w 40 semi synthetic oil but still makes noise. About the VVT units what could be possibley wrong with them? and how would I know which one is not working? i disconnected the wires from them and the car still makes the same noise. This is why i am feeling lost about it.
I have also plugged the car to a computer in a jaguar specialist and the results show no faults at all!

thanks

Hani

 

It may well be related to the work done if the noise started then. Possible causes could be not having used the shorter bolts for the new tensioners (both the primary and secondary ones), or the plate between the primary tensioner and the block was reused with the new tensioner (which you should not). I can’t say for sure what sort of noises this all could make, but it might be a possible cause.

 

I've found numerous sources for cold start "sounds or noises" on XK8s some changing by MYs too. Owners describe sounds like - Crickets, clicking, ticking, tapping, squeaking, squealing, grinding, etc. Most of these sounds can only be heard at idle and/or cold engines, with reports of the sounds going away after warmup and/or higher rpms. Here are most of the sources that can contribute to these sounds:

Serpentine belt (worn or cheap replacement belt, even new)
Idler pulley (dry bearing)
tensioner pulley (dry bearing)
Air compressor clutch (test by shutting off air con at cold idle)
VVTs
Bad alternator bearing
Noisy water pump (bearing - rare but often on new cheap non-OEM pumps)
Secondary tensioners going out - although more rare (old style plastic with missing slippers)

Belts usually contribute to the squeaking/squealing as the cold hard rubber belt warms up it quiets down.

Crickets or clicking is almost always the air con clutch - shut off air before cold start and listen for a change in sound.

Tensioner and idler pullys can cause a grinding or squeaking sound and often fades as the little bit of grease warms up and redistributes onto the ***** and races.

Just some places to check.

 

hi all.

well the noise started after changing the tensioners but after some time so if it is the tensioners wouldnt the noise apear stright afterwards if the unit wasnt installed properly? I find it strange to why suddenly it started doing that. I am thinking of opening it up and change the tensioners myself but i need to read up on how to do this. I am also going to change the spark plugs and clean the MAF sensor as its iddeling rough. when the car is warm the noise is still there and only goes when i hit gas a bit. so if i was in trafic i can put it on neutral and gas it a bit then the noise makes a click noise and goes then after 10seconds it comes back again. any ideas???

 

if its idling rough...that is not going to help your diagnostics on the noise. Assuming timing hasn't been affected, get the engine running smooth again and re-evaluate.

 

So you are sure the noise is internal to the engine and not a belt, belt tentioner, steering pump, water pump or A/C?

 

HI Gus
iam sure the noise is at the top of the engine and on the centre of the engine and it seems to come in from inside the engine block itself. I dont understand why it disapears when i rev it and comes back down. i used to get low oil pressure but i toped it up and now the pressure is fine.these are the two symptoms. I will try to make the engine run smoother and see if it still runs like this.

 

This does not sound good! Do you have a Stethoscope? http://www.harborfreight.com/mechani...ope-41966.html If not you can of the use a screwdriver or a hose or conduit and try to pinpoint the problem location. Old school is to put the car in gear apply the brake and accelerate a little and see if the knocking reappears or gets louder. If it does it is often an indication of a wrist-pin or a bearing. Another old school is to pull the plug wire for the cylinder you think it is and when you pull the right one it will stop the hammering; however, never used it with the newer engines and disconnecting the coil pack will set a code. Be sure you use caution in the process. I hope this helps!

 

Hi Hani,

My X300 AJ16 meets the same problem.
Could you suggest how you solved it finally?
Thank you very much.

 

Piston slap is what you are hearing.

 

I also have some moderate piston slap noise. Not too bad and once the motor is hot, it’s not noticeable.

Since it been widely reported by other X-100 owners I’m just going to call it normal for the amount of mileage my car has (177,000) and keep driving.


Z

 

I think you are right with that decision

 

There is a very faint noise when the engine is warm on my car. It's an XKR though so it doesn't have VVT, I figure it's one of the injectors if anything. It's sort of like a click or a noise would normally hear from a belt. Hard to describe it really and I doubt it would show up on a recording.