1998 XK8 at 95K and I recently had the original driver side or left bank secondary timing chain tensioner replaced. The lock down tool and tensioning wrench method were used. A new Jaguar tensioner was put in place keeping the original timing chain. After replacing, when starting the engine, it had a very pronounced clanking noise. I ask the shop to remove the covers again and using the same tools to lock down the cams, reset the sprocket bolt on the exhaust cam, while I observed. Everything looked to be in order, preloading the chain and tightening the cam sprocket bolt. We started up the engine again. It seem to be improved, but still the chain was clanking. After monitoring the engine for 15 mins or so we realized the noise would fade away almost completely and then come back. It seem to be louder after increasing the RPM's and returning to idle. The oil was removed and fresh replaced with a new filter. We also ran an oil wash prior to draining and replacing. Restarted the engine and after a few mins almost no noise. Now the noise will come and go and doesn't seem to relate to specific engine speeds. Everything runs fine no error codes, power seems okay too. The engine was running fine prior to replacing the tensioner. The valve gasket was leaking and while replacing the gasket thought it was a good chance to replace the original tensioner. The replacement tensioner looks identical to the photos I've seen here in the forum. The new one doesn't have the strong spring like the original one did though. I guess it relies only on the oil pressure. Anyone have a similar experience with new tensioner replacement using original secondary timing chains? Any suggestions appreciated.

 

"If a new problem appears after some work has been done, then revisit the work done"

I guess it's possible that the new tensioner unit is faulty they are spring-loaded:- the tech did remove the pin?:


At 98K you're taking a big risk with only addressing one bank. As a member here commented "Chancing it with the secondary tensioners is like playing Russian roulette with a fully loaded gun". I'd recommend NOT running the motor any more until you've found the cause, and replacing the other tensioner as the #1 priority.

 

Thanks for the reply Michael. That's a good quote too, my thoughts exactly. The reason for having them reopen the covers and readjust the sprocket was so I could put my eyes on it also. Yes, the pin was removed. The tensioner could be pushed from top to bottom with my thumb with little pressure. Should the spring on the new version be as strong as the one on the original? Or maybe even stronger since it's new? Somewhere along the way I was told the new tensioners were dependent on hydraulic pressure. If this is not correct, then it appears the tensioner is bad. Can you confirm the spring tension?

When I purchased the car it had a nice book of documented repairs. The secondary tensioner on the other side was replaced at 75K. Replacing the valve cover gasket, tensioner, a tune up and intake inspection were my first steps to evaluate what there is to work with. Good news is everything else looks good and it runs much smother, except for the chain rattle and that's a big problem. Thanks for your help.

 

From memory, my new top secondary chain tensioners weren’t that easy to compress by hand.

Maybe you’ve got a duff part.

 

Thanks David, if that's the case, this can be easily resolved. I think ordering a replacement will be the plan of action for next week. At least I can compare with a second one in hand.

 

You are right to be concerned - the tensioners are the main Achilles heel of these motors. The clattering you describe sounded like the pre-death warning that the gen #1 units apparently give.

I have to confess that I haven't done the job as my 2004 reman. came with metal-bodied ones, so thankfully David has chimed in to answer your question.

Good luck and do let us know how you get on.

 

It's been a while since I replaced any tensioners, but I believe the metal body unit has a ratchet action cam that prevents it collapsing once oil has extended the foot. They did replace it with a metal body one didn't they? The procedure also calls for removal of the injector solenoid of fuse and spinning the engine with the starter until the oil gauge registers pressure to avoid the chain jumping a tooth.

Is it possible the chain noise you here is from the primaries lower down in the front cover?

 

I am getting ready to start this process myself. I went and grabbed the NEW drivers side tensioner and pulled the pin on it. I was able to easily compress the spring with my hand and reinstall the pin. When playing with it like a stressball, I could most certainly hear a spring inside of it groaning a bit when I was compressing it. It didn't put up much of a fight, but it definitely had some pushback to it.

 

Thanks for the reply RJ. Interesting, I haven't heard about the procedure. Although, it makes sense to pump up the oil pressure first, if that is what extends the tensioner. I only saw everything static. You could move the tensioner down and it extended the other side. It didn't seem to apply enough tension as you would think needed, but I also didn't have the oil pressure up. Once the covers are off again, I'll test this to see if we have any additional movement when pressurized with oil.

The noise is definitely on top. I did look down at the primary chain and from everything I could see they are still intact. At least on this one side.

 

Thanks for the reply M.H.. I was reading your details, very well documented. I’m going to follow along as I will need to take the same path and replace everything up front. I’ll be taking notes.

It’s good to hear your observation on the tensioner. I didn’t think it was as strong as the one that came out. If you don’t mind, can you release the pin and measure the travel or extension? Do you think additional oil pressure will add to the travel?

 

Is there a link to an actual Jaguar technical instruction for replacing the secondary tensioner?
I have a PDF by D. Jensen from JagRepair.com - Jaguar Repair Information Resource that explains it well. It would be nice to look at the actual workshop instructions.

 

I was under the impression that these tensioners are a newer design utilizing a hydraulic assisted spring. Meaning that they will be fairly easy to compress by hand, with the engine off, without any hydraulic pressure to support the spring.
The older design was a spring only design that would need to be a much stiffer spring since it never had the help of hydraulic pressure to hold itself open.

The oil pressure is not going to add more maximum travel, just effectively stiffen the spring.


Is it possible that the chains have stretched enough that even a fully functioning tensioner is not capable of keeping the chain where it is supposed to be anymore?
Or the new tensioners were designed to be paired with a chain of very slightly different length?
Are your oil ports blocked or clogged?

Something I have been curious about myself, were the oil ports for these tensioners already in place where they mount from factory? If my car didn't come with hydraulic assisted tensioners from factory, why would I assume that the required oil ports are in fact in place? Why would they design the oil port for the tensioners, and then install spring only tensioners. That makes no sense haha.






Fully extended, different angle

Fully extended

Fully depressed

Oil port I imagine?

 

My understanding of the history of these is that the gen #1 plastic relied on oil pressure alone, and didn't have an 'assister' spring to help hold tension on the chain until oil pressure built up. These were the ones that gave some warning of impending death. Gen #2 had a spring to address this but still had plastic bodies. Gen #3 (the aluminium ones) also have the ratchet that RJ mentions.

I don't think there are specific workshop instructions but there are many threads on this - including the 'zip tie' method which obviates the need for the lockdown tools - although I'd not recommend that in your case unless you're 100% that all the timing is correct.

It may be worth dropping the engine sump to check for any leftover bits of plastic from the first job on the other bank. They can find their way to the oil pump strainer and cause a partial blockage.

 

Ahh that would explain why the oil ports would be in the heads already. That makes more sense than what my understanding was.

 

Wild guess - L & R are different. Could it have the wrong one installed?

Not sure if that's possible?

 

When these are labelled drivers and passengers sides. Do they mean LHD or RHD.

 

Thanks for all the photos M.H. much appreciated. It looks like there is only about 3/8 travel. I was thinking the same as you that maybe the chains have stretched. And the oil ports should be checked. I know it's possible to change tensioners alone. My engine has a newer tensioner in the other side, I'm just not sure which one. From the date of repair around 5 years ago my guess is it's the 3rd gen. At least now I have several items to cross check.

 

Most other threads have said that catastrophic failure would happen long before these chains would ever stretch. Maybe you are having some vvt woes?

 

Thanks Michael, good explanation of the design progression. The oil ports need to be looked at too and makes sense re RJ's procedure to pressurize the system.

I do have a PDF also on the zip tie method. We used the tools and followed the instructions that were available. Something just didn't go exactly as planned. Now for the discovery effort to find the missing piece. With M.H.'s help on the photos I have some measurements and understanding the design now I know it needs oil pressure.

It will be wise to look for plastic pieces in the sump. I'll keep you posted on my findings.

 

I was planning on bringing in a new tensioner and making the comparison just to be sure. Also, SNG Barratt shows several different part numbers all specific to the VIN #'s. May not have the oil port in the same place. The VVT is also interesting. Looking at the photos of a dismantled VVT it doesn't look to have breakable parts, but may need to be cleaned. Since it was working well prior and for what little I have run the engine it doesn't seem to have a timing issue. At this point I still think the tensioner is the problem. There are several things now to focus on. Hopefully next week it will be a simple solution. More to come, all the help is appreciated.