I have Jaguar 1998 XK8 with 65,000 miles and always ran smoothly.

Last week the main belt was shredded while driving. We replaced the shredded main belt and loss coolant. The coolant hose got knocked loose by the shredded belt. We replaced a new main belt and refilled the coolant. The first 40 miles after the fix the car ran smoothly and had no ticking sound. After 40 miles, the engine vibrated and had a clear ticking sound, the idle speed dropped to 600 rpm lower than usual. We thought due to the air trapped inside the cooling system. We purged for 4 hours with the purge valve open and the reservoir tank open. These did not work. We unplugged the battery to have the system reset itself. It did not work either.

Anyone can help me this issue. What is the problem? What should be done to get the engine sounds smooth like before

 

It's possible the coolant worked it's way under the coil covers, which are not sealed very well due to age, and have shorted a coil or two. They may not diplay a code or cause an engine light.

Remove the coil covers and inspect the coils, even remove them to look for coolant in the wells.

 

Did the car over heat? You say loss coolant...was this just from the cut hose or overheating?

 

The lost coolant light came on happened just after a short drive and right before reaching home, but for about 30 seconds and 500 ft before stopping at home. Did not look at the temp. The hose was whipped off but no damage to the hose. The temp was always at mid point after coolant was flushed and refilled

 

It's possible that it got too hot and you may have dropped one or more valve seats. Do a compression test if one or more cylinders have low compression then that is what likely happened. If these motors get hot you need to shut them off immediately. Your temp gauge might have not shown hot because there was no water in the system.

 

[QUOTE=Jandreu;1503647]Did the car over heat? You say loss coolant...was this just from the cut hose or overheating?

Here is the clip that recorded the ticking sound of the engine after refilling the coolant and main belt replacement:

[/IMG_3247.MOV

 

My bet is coolant in plug wells. If it ran smooth for any length of time after repair then the engine is OK. The tempt indicator will always be at neutral until coolant near 200 deg. Has a large dead zone so it always looks good. Do a search on that as you need to understand how it works.

Easy to check plug wells under coils.

 

Need a little more info.

How far did you drive it without a belt or with coolant hose disconnected? Or did you have it towed.

If you lost the belt the it wouldn't take very long for it to overheat. Hopefully you didn't drive it after belt lost.
What is pushing me towards valve seats is the ticking noise. Do the coils make a ticking sound if they are misfiring?
I bought a 01xjr with a ticking sound. It would come and go. When I took the heads off I found the dropped valve seats.
If it is the hose I think it is, yhe one going to the thermostat tower, the coolant would mainly go to the front of the engine and since the belt is gone it wouldn't be coming out very fast except for when it became disconnected.

If it was even driven a few minutes the car would get hot. That's why we need to know if it was ran at all after the belt failure.

I would still check the coils first.