hi everyone, i have 2004 xj8 with 161k and i notice that every morning when i start the vehicle there is a knocking noise first 3 seconds only on first cold start,i replace the primary and secondary chain guides and all of the tensioners and i still receive that noise on every cold start. if there is any one had this kind of problem b4 pls give me a hand and help me take care of this problem. may be a spesific oil filter? or spesific oil?i really need this help.thank you all.

 

What is the oil you are using?

 

With this many miles, you might get the oil pressure checked, but it's likely that you have excessive clearance in a bearing on the crankshaft somewhere or you have some cylinder bore wear which translates into piston slap. When the oil pressure gets up, the sound of the loose parts hitting each other is muffled by the oil cushion filling the gap between the parts. My guess is the crank, piston slap usually contnues a little longer than 3 seconds.

 

I have a 2004 XJ8 with a very loud rattle . It started with a very slight ticking noise at idle the progressed over time to a louder rattle that would go away after just a few seconds now its constant loud rattle . The dealership said it was the intake manifold. I've replaced it with 2 different ones and the noise is still there. They say its because it used and a very common problem with the intakes. I removed the valve cover on the drivers side And started the engine the noise is VERY loud. and what an oil bath the car got. WOW Help

 

As for the knocking you need to use a stethoscope to pinpoint the noise. Yes it could be a bearing or piston or it could be your VVT or tensioner why Jaguar suggested it was an intake manifold is a bit puzzling to me. An old school procedure to identify a bearing or wrist pin you would put the car in gear and with one foot on the brake accelerate just a little bring the idle up and see if the noise appears. Note do not do this for an extended period of time. In order to better understand your issue we need to hear it so if you can record it and post it that would help.

 

You MIGHT try changing the oil. Many have commented that the engines running Castrol are quitter running. I use 0w-40 Castrol in mine. This is made in West Germany and is 22.00 for 5 quarts at Walmart.
I do not drive mine for long periods and it ticks on startup at 105,000 miles. The Auxillary and Supercharger belts and tensioner a are new. Squealed on startup when I purchased vehicle.

 

I don't know of any reason why the intake manifold itself would be rattling, unless the bolts are loose. But if they were loose enough to rattle that loudly, I don't think the car would start at all what with the giant air leak that would entail.

Also, did I read that right...you removed the valve cover and started the engine with it removed??