Good Day, This may turn out to be a long note, so I'll ask questions first,
1. For the 1997 4.0 liter engine, is it true that valve train noise can be ignored (per another post discussing "tappet - like" noise)?
2. When putting tension on the secondary chain, how much is correct? I work from the idea that too much will cause wear and too little will make the valve timing late.
3. My mechanic refused to try 10W40 synthetic oil - recommended in the above mentioned post - is it frowned on by Jaguar specs?
4. I replaced one suspect secondary chain tensioner because when cold, at startup, it sits at the lowest travel of the spring for about 30 seconds allowing the chain to make noise as it collects at the input to the gear. The oiling system seems to work overtime till the spring activates. I discovered this by hearing the chain noise and then removing the valve cover. The replacement version was down level - all plastic and it does the same thing, but for less time. During regular driving there is no apparent chain noise - just the tappet noise that started this whole sequence.

Here is the story: I have owned the car for a year and a half. The previous owner claimed the timing chains had been changed. Eventually, that proved too be true. It did not make any valve train noise until I got it home. I started to address the noise this spring when the car came out of storage. We tried an oil change to 10W30 synthetic, with an stp additive. It ran quietly for 15 kilometers, then returned. I consulted two local mechanics - each said to ignore it, until they heard it. I obtained a stethoscope and attempted to find the source. I discovered that on bank two, cylinder two, there was a very loud (painful to the ear) noise centered on the screw that mounts the coil assembly.
Mistake number one - it did not occur to me two blame the coil.
I decided that the one of exhaust valves on this cylinder must be making the noise.
I took the time to remove both valve covers and measure all the valve clearances. Everything was within the specifications posted by Jaguar. I should have stopped there and consulted with my friend who owns a machine shop and has experience with this style of overhead cam engine. His comment at a later point was that in his opinion there was no need to change the cam followers in an attempt to quiet the engine.
I ordered a chain tool kit from a US supplier and two cam follower assemblies from a local dealership.
I was able to remove the exhaust cam with no unpleasant results, and found that cam follower removal worked well if a strong magnet was used (they are shaped like small drums with 5 thousands of an inch clearance to the channel walls.)
The next trouble came when it was time to remove the adjustment shim from the original follower. The shims sit in the top of the follower, held in place by a film of oil and just plain refused to be coaxed from their homes - I contacted the dealership that sold me the parts. A mechanic there claimed that the only way was to damage the small retaining wall on the top of the follower. Mistake number two was to believe him. I tried that and did get the first shim out, but concluded that the had to be a better way. It turns out that there is a tool available to remove said shims, but I found that careful positioning of finger nails on opposite sides of the circular shim coupled with patient spinning of the shim breaks the oil seal and allows removal.
So at this point I decided to install both new cam followers with the original shims (which were both of the same thickness - 2.5 mm).
The new followers have notches cut into their top retaining circle, which makes for speedy removal with a jewelers screwdriver.
Reassembly went acceptably, except for not knowing exactly how much to tighten the chain. I set it to have a slight play at he bottom guide. I remeasured the valve clearance on the cylinder and discovered that the new followers are thinner by quite a bit. Clearance with the old followers was .275 mm, but changed to .45 mm with the new parts.
I finally determined that the coil was bad. The quick test was to put the stethoscope on the mounting bolt and press on the coil assembly. At that point the coil noise went away. I consulted with the American supplier and ordered two coils and some shims (and a chain tensioner which was down level and on sale - thinking it would be nice to have a backup). The latest metal tensioners are quite expensive.
So I put it all together with the original metal tensioner and the new, thicker shims. The gap is still at .45 mm for both followers. Operation was smooth and acceptable. Even though the clearance is .15 mm out of spec I don't believe they are noisy.
None of this has affected the original tapping noise. I drove the car anyway with a general expectation that I would order the necessary shims and once again do the exchange; however, a new noise developed on days when the outside temperature gets below 50 degrees Fahrenheit or 10 Celsius. As mentioned above , the spring loaded tensioner allows the chain to bunch up at the input to the exhaust shaft cam. The powered oilers activate several times and within 30 seconds the tensioner fills with oil and begins to work. Needless to say this development causes worry.
My attempt to solve the latest problem is to order the next set of shims and a new level, metal bodied tensioner. The down level one is new from 2007 and had the spring compressor pin installed all that time, so I can only conclude that the spring is weak.
The downside to this long tale is that I consulted with the wrong folks, approached the problem from a North American perspective and failed to think outside the rut. The upside is that I found two problems unrelated to the original noise, one of which could have created a failing engine. Through the entire experience bank A has had no chain problems. The tapping noise has no apparent home and is still driving me nuts, because my experience with North American engines showed that valve train noise should always be addressed.
I consulted with one other repair shop which specializes in Jaguars. They had a 25 year veteran jaguar mechanic, now retired for the second time after helping to set up this independent shop. He is reported to have claimed that the dealership he worked for never bothered to address valve train noise.
I will appreciate your comments. Hopefully you will get useful information and one or two laughs at an amateur's efforts.

 

If anyone told me to ignore valve noise, or any unusual noises from my engine I'd delete them from my contact list.
I'm not sure the fact that the car made it "all the way home" before a noise resurfaced means anything as far as the timing chains being replaced.
I would pull the spark plugs and do a compression check because it's easy and it tells you a lot. If the reading on one cylinder is much lower than all the others, focus on that cylinder.
If all the cylinders have readings that are close, your valves are probably opening and closing OK and you might want to verify the timing chains were replaced rather than believe the guy who sold you the car. He might have had motives other than being completely honest. It happens.
Then you're probably tearing into the timing chains, at least enough to verify that everything is secure.

 

Thank you for your comment. I shall try the compression test. I verified that the chains are new by illuminating the guides for the long chains and determining that the original secondary chain tensioners are yellow plastic with a metal body. So far, the only irritating thing (aside from the noise) is that I'll have to remove the cam yet again to install a different set of shims. I considered using the undamaged old cam follower, but ultimately felt both new ones should be used as a pair. All of the other challenges offered by the car turned out to be 'regular' type issues, but this one is the toughest. The tappet like noise seems to have no home. My machine shop owner stated that I could have both heads rebuilt but there would be no guarantee that the noise would not return. I'm coming to the conclusion that the oil viscosity is too low.

 

This may not be of much help, but since the XK8 does not have hydraulic lifters, it doesn't seem plausible that the oil viscosity would cause the tapping noise. That would happen on engines with hydraulic lifters if the oil leaked down too quickly, especially with a hot engine (or if the oil level dropped too low). It sounds like a compression check might tell something. Good luck, and keep us posted.

 

Hi, this might be a long shot but does your engine have VVT fitted? this stands for variable valve timing and was an attempt to cancel out timing issues at high revs. I had a 1997 xk8 and, periodically I got a loud tappet-like noise after running for a few minutes at idle. When I blipped the accelerator a couple of times it stopped. When driving it was barely noticeable but at traffic lights it would come back, quick blip and gone again. It is impossible to trace it when it happens at idle speed. From the right side of the engine bay it sounds like it is definitely coming from the left side of the engine and vice versa if you stand on the left side of the engine bay. Just a thought you might check. If your engine has VVT you will see the solenoids on the font of each bank of cylinders, with a cable going to each.

 

Here is an update
The compression test is complete - here are the results in pounds per square inch
Radiator
left bank (driver's side) Right Bank

plug 1 170 plug 1 180

plug 2 175 plug 2 180

plug 3 175 plug 3 185

plug 4 170 plug 4 185

I finally received the new,,metal version chain tensioner and more shims. The interim tensioner that I tried turned out to have different dimensions which put extra force on the chain. It is a 2007 version.
I decided to remove both valve covers and re-check the valve clearance - in general some gaps shrank ( yes, I know that should not happen) - the replacement cam followers are now close to spec - .35 mm (spec is .25 to .30)
I removed the plugs this time - it made spinning the crank a little easier. The tightening sequence of the cam went acceptably. I finally decided to check the chains on the passenger side - the secondary chain turned out to be very loose - way too much free play. Yes, I should have checked sooner. I have spent too much time on the other bank. I got the cam bolt loose, but foolishly used my torque wrench, resulting in a broken wrench. The exhaust cam was not in perfect time, - late. The loose chain is the first indication of an actual problem The compression test suggested that there has been no internal damage.
It is obvious that whoever the previous owner got to change the chains was an inexperienced, entry level worker. He owns a restoration business for cars with accident damage, but did not change the chains himself, The car deserved better.
I'll be reassembling the parts tomorrow and will update this post soon.

 

Compression numbers look good as they are close enough to each other. That is great news.
When reading your early posts I was thinking that someone may have done something wrong when they replaced the timing chains such as not applying torque to the exhaust cam sprocket or VVT when torquing them, or not having the cams locked in place or something else. You really need to follow the steps in the manual.
So rather than being a positive, the fact that someone replaced the timing chains seems to be a point of concern.
I would go through this once and make sure everything is as it should be. You'll probably save yourself time and aggravation in the end.

 

So, the new torque wrench was acquired and the tension / timing steps appeared to go ok, until I removed the camshaft clamp and hand cranked the engine. The tension did not remain consistent. I redid the setting sequence,with the same result. I finally remembered another post where the owner had the same issue until he reinstalled the camshaft clamp. I did the same thing and got the tension back.
The right hand side adjustments are more difficult because the upper rad hose is in the way. It has to be removed from the rad input, so antifreeze enters the story line.
In summary, I wasted time, cash and effort replacing two cam followers. I discovered and eventually replaced a failing secondary chain tensioner. I corrected a poorly timed exhaust cam on the right hand side. It was about 7 degrees out of time in relation to the intake cam.
I checked with Jagbits.com and discovered that Jaguar has a connection with Castrol. Recommended oil is 5 W 30, but 5 W 40 is accepted. I'm switching to that in the spring.Why? Because the tapping noise is still there. It is a bit quieter. It seems to be roughly in the area of the left hand lower chain. I'll leave the 10 W 30 in the car over the winter and run it bi - weekly in an effort to prevent acid build up. I hope the different oil fixes the issue. I'm not prepared to rip the front of the motor part because of the apparent complexity and special tools required. I was able to drive only about 700 kilometers this season. I'd like to get more driving time when spring arrives. I have found a repair shop that has experience with this model, but am reluctant to start paying the big bucks.

 

I spent some time with the probe testing the oil pan area. I could still hear the tick, but not loud enough to indicate a bad rod bearing. I guess one possibility would be a loose wrist pin - a lousy thing to need fixing.
I re-thought the oil possibility, so had the oil changed to 5W-40. It made no difference. This noise is certainly elusive. Once again I am wondering if the primary chain assemblies were installed properly.

 

[QUOTE=Jpattr7;2315419
Once again I am wondering if the primary chain assemblies were installed properly.[/QUOTE]

Absolutely.
When I replaced my timing chains last year I did install one primary chain improperly until I came back the next day and noticed that it wasn't laying properly on the guide, instead it was laying on a ridge on the edge of the guide. Luckily at that point it only took 10 minutes to fix it. The chain would probably have worked its way off the ridge and I would have had a loose primary timing chain.

 

I was going to wait until spring to try a different oil, but impatience got the better of me. I had 5 W 40 installed, but the noise did not change.If anything it is louder. As well, the new bank two tensioner assembly has started collapsing overnight, just as the original one did. More poking with the probe near the exhaust manifold hints at the noise being louder on bank B, around cylinder one. I am considering getting the puller for the harmonic balancer and looking at the primary chains in detail. My garage is not heated, so I may have to wait till spring or call in a favour from a friend who has a heated space.

 

How many miles have you driven this car since you bought it?

How long did/has the car sat,,,, at any stretch of time,,, without being driven?

Are you able to post a YouTube video?

 

Hello, I bought the car in June of 2019. It was stored for last winter in an unheated warehouse. The tick developed this spring when it came out. I've put around 900 miles since bringing it home. This season I'll keep it in my unheated garage at home. I'll put it on trickle charge and try running it every couple of weeks. The noise sounds just like a bad lifter in an American V8. I'll investigate a you tube video.It sounds like meta on metal and is loud enough to be a problem.

 

For only one winter? Are you sure?

This is a pic of a cap I have in hand. Came off of the head removed when I bought the car. They do get gummy... Other things get gummy too. Like ports, chambers, journals galleries and

Did you say that you removed all of the caps on the side that you think is making the racket? How did they look? Any scoring around the barrels?

YOU DON'T HAVE TO FOLLOW THIS (of course)
I have a 34yo car with caps that sat for a long time, and a trusted jag and rennlist forum member both (he lives near me here) taught me about cycle heating the engine to git rid of it. I had a badly tapping valve(s) on my 928,,, sucked. Drained the oil, put half volume cheap NEW oil (new oil so I could see color change), filled the rest with cheap ATF and a pint of kerosene. Put a square of cardboard over the rad and cycled the engine to waaaay hot (not in the red) and then allowed it to cool using the cars coolant system and did it again x4 or 5. I could literally hear the engine sound changing as things smoothed out. Oil pressure dropped to almost ZERO... Tap gone. Later drained the oil and it was BLACK like jet black tar. Stank more than bad ATF. It's what I did.

These cars are OLD. There is gum... Thing is with the crappy temp gauge in these cars it's a scary-ER proposition.

 

Hello, The car has spent most of its life in a garage. Here is a short history
The original owner had it for 11 years - she lives in Toronto
She eventually had a minor front end collision - the air bags were set off and the insurance company sold it at auction
The second owner has a business where he buys late model damaged vehicles, which he repairs and sells.
He replaced the air bags, headlight assemblies, air conditioner pump, had the original hood straightened and the car painted.
He kept it for 11 years, using it sparingly, more like a valued toy than sports car
He claimed to have had the chain assemblies replaced at around 40000 miles. I think that is true because the secondary chain tensioners are version 3 metal centers.
I have changed -
the antenna assembly
the rear speakers,
the battery
two exhaust cam followers on Bank B cylinder 2 - completely not needed - the noise I was working on was caused by a bad ignition coil (now replaced)
the chain tensioner on exhaust chain for bank B - not necessary as apparently the tensioner relaxes when no oil pressure is applied. I thought the spring would hold the chain up even without oil.
The original cam followers show no build up. I'll try to get a picture installed here

 

Here is a youtube video link to the tapping noise. I ordered the secondary tool kit used to remove the harmonic balancer and will work on it in my unheated garage in an effort to verify correct tensioning on the primary chains