Troubleshooting 2000 v8 vanden plas tensioner failure
 

I am fully aware that I need to at some point very soon get the secondary plastic tensioners replaced on my Jag. In my ignorance, I figured I had many years before it was necessary (low miles) and had no engine noise. Now having read extensively on our site I know that preventive the preventative repair is way past overdue, assuming the owners before me had not done it previously. My problem is it is misfiring and going into the limp mode after it runs a short while. So far the suggestions here have been the battery health, the camshaft position sensor, and secondary tensioner failure. I know my new battery is good. The camshaft position sensor is in play but my big fear is that the tensioners have failed and are causing the misfire.

The car was in limp mode, running roughly. I cleared the codes and decided to crank it fearing the worst possible, having just read extensively about the dreaded plastic tensioners. I was out of the limp mode, it cranked and ran smoothly not showing the previous rough idle. I was surprised. This is my troubleshooting question. I want to be able to try to solve my problem with a running engine. If the tensioner was badly damaged or broken would it crank and run smoothly or at least way way more smooth than it did previously? In my previous testing after clearing the codes, it runs smoothly and had to run it up to 2500 rpm numerous time to get it to go into limp mode.
With these conditions do you think the tensioners are broken? To me, it seems they couldn't be broken but I want to be sure the car can be repaired and I'd like to be able the drive it so that my decision to repair the tensioners won't be throwing good money after bad. All opinions help.
I plan to make another post if appropriate after this question is answered, I'll drive and get my codes for a fresh start. To me, it's very disappointing that Jag who has had so many innovations in the auto industry and put so much art into that design would put our a powertrain with two fatal flaws like the A-drum in the transmission (fixed previously) and the plastic tensioners, just a shame. Will P

My worry would be that it has jumped one tooth. Another and the engine is trash.

Jag V8, could be but if so why smooth then rough, clear codes and smooth. If the timing is off even by one tooth would it always be off by one tooth and running consistently rough, that may be naive. Wouldn't there have to be tremendous slack in the timing chain? Now I've never even seen it except in pictures. Forgive my inexperience, please!

Are there any horrendous sounds coming from the engine? It sounds to me that there might be a coil going out. Have you had a scan done on the engine for any pending codes?

There are no odd engine sounds other than running and running roughly. I put my codes on my other post but some of them are left over from a 12 year old battery that went dead about twenty times and I've read that the low voltage can cause some sensors to give a warning. I planned on running through enough of the cycles that are required for a good reading as soon as I feel comfortable enough with it to drive. That is why I'm trying to troubleshoot the tensioner first so I can get new, good information on my misfire problem. It looks pretty in my driveway but I'd rather have it to drive occasionally. Will P

Are you able to remove cam cover and look? That to me is the only way be certain. Another check is to shut it off and disconnect the mafs plug when it's running rough, then restart.

I assisted in trouble shooting a Super V8 Daimler some months ago, which was perfectly drivable, sometimes threw a Camshaft position code, was lacking power, but was running smooth (although with a bit of ripple at idle sometimes).
Left bank was one tooth off though ..

What I want to say is, seems symptoms can come in various forms, don't gamble with tensioners.

The next few days here we have a big storm coming in from the Gulf, so a delay. I think I know where the mafs plug is located, does it just plug in so to say. I know it either has a sensor or is attached to one.

Also, what would I look for then after the jag is restarted?

A few years ago I was more able to do a lot more stuff but these days I'm having to pace myself more. Thanks, Will P.

All taken to heart. I know they are the number one killer for the jags of this time slot, I hope to work out having that done, after I do a lot more research and eventually try to find someone trustworthy with the knowledge to fix it I'll have to weight the pros and cons. For many of you that are knowledgeable, you would have this fixed in a snap. I never got to work on cars growing up and learned to do the little bit I can through books and now online.

Thanks, Will P

Should the time come I get that checked (taking off the cam cover) do I need a new gasket or something before the attempt? Will P.

New gaskets are a good idea, but not 100% necessary if just popping off the cam covers to do a check. I didn't install new gaskets the first time I removed the covers to see if I had the old-style tensioners (I did - and they were disintegrating).

Not necessarily, but you need to clean the surfaces and apply more RTV at the joint between the head and the timing case cover. When you replace the tensioners, which I suspect you will have to do, get new gaskets.


If you are well endowed financially, find a trusted Jag mechanic. If not, plan on maintaining the car with help from the forum.

Thanks, good to know. Will P

A bad battery can cause all manner of weird effects and it simply isn't worth having one.

E.g. coils can't fire properly. Result is bad running.

The list for a bad battery means first thing is get rid.

The current battery is new, just a couple of months. The codes were from before the new battery with the 12-year-old one up to two years ago. So all those accumulated low battery influenced codes. I had always driven older cars that ran good and didn't even know what the ODC codes were until I got the Jag five years ago. That is why I was asking if it was okay to run the engine now, after reading about the tensioners I was hoping I had some time to clear up the misfiring and get some running and driving codes to use to troubleshoot the girl. Thanks, Will P

(Hoping my symptoms indicated they were not so far gone that I shouldn't even drive and do the test!)

I am not sure why you had to start a new thread for the same problem. But, it is fairly easy to remove the cam cover on the right side. Just be careful with the tubing from the air filter housing to the throttle body. Unplug the MAF (might clean it); using a powered screwdriver and a 1/4" drive with a 6 or 8mm socket (memory is sliding south), undo the covers, undo the hold down straps to the coils, remove the coils (check for corrosion where they attach to the plug), lay the coils and wiring aside (carefully), remove the plugs (check for oil), undo the bolts to the cam cover using your electric screwdriver after breaking the tension with 1/4" ratchet, pull it off carefully, be careful of the bolt retainers and positioning of the gasket (I reused my gasket, no reason not to if your are careful) -- check the tensioners for breaks (lots of threads, with tons of pictures of what to look for). Using a 24mm socket on the crank, turn the engine to check the alignment of the cams (lots of threads and picture to show you what to look for). If they are split; quit, order new parts (Christopher), new plugs too. If you are lucky, you will find metal tensioners (as did a friend of mine a few years ago).

But lots of things can be causing your problem: it is just this issue and maybe a bad head gasket, that are terribly damaging. Later, new plugs, new fuel filter, new MAF, clean throttle, yada yada . . as time, body, and money permit. But bad secondary tensioners are fatal. One of the old timers on this forum used to note that the most important tool in your tool box is patience. This is an easy fix: with patience.

Jhartz, Jim thanks for this information with the details. It all makes sense as the “A” choice of action if possible for me taking all things into consideration. I'll have to live with the idea awhile and think out all the logistics and conditions, for instance in two days once this storm passes it will be 92 and 70% humidity (South Alabama). I will think it out and maybe I'll give it go, and if no maybe find someone that works on Jags (that I can afford, there are no dealers, and they would be too much anyway), I see older Jags all around so someone here must.

Right now, I won't try to crank it, I'll keep reading and build up some info. I appreciate yours and the other post I'm getting and will get. All opinions appreciated. I'm more patient these days and with this car, it's an indulgence like for many people on this site from what they say. An indulgence that I'd rather keep it's a viable choice. Will P

New info
 

Well, I did some reading and thinking. One of my main sources was the 21-page long post started by Brake buster about fixing his tensioner. Man if that article doesn't give you the message then nothing can. They are like a serious and eventfully deadly flaw that will eventually kill your Jag of our “ilk”. Jaguar should have recalled and fixed every car sold with that curse, period. Mine will eventually fail and to have peace of mind you have to get them replaced ASAP, period again.

When I started this post I did it to see if it was the tensioner causing my problems. But, after reading the shop manual and a lot of info on our site I decided that if I keep the car they must be replaced. After standing over my open hood for a half an hour and going through all the steps, I also decided that I couldn't do it my self. Up until a few years ago with the help of members here and the info compiled here, I somehow replaced the A drum in my transmission as it was broken. I had to remove completely twice and take it apart twice to re-do. And, back it off completely two more times and all the work that entails. So, the spirit was willing and with help, got it done. That same guy wanted to do the tensioners, but with my health and situation, I just know better.

So I decided to clear the codes and crank her up and see what happens. Cranked easily with absolutely no engine noise (loose chain or broken tensioner) and after a few minutes (the manual says two and a half minutes) the restricted light came on. It seemed a but rougher with a low idle, about 600 RPM or so. I cut her off and read the codes and they were

P301--- cyl A1 misfire
P304---cyl A4 misfire
P306--- cyl B2 misfire
P307--- cyl B3 misfire
P1316--- excessive emissions
P1000---all test not run

This is two cylinders on the driver's side and two on the passenger side, all of these are in the A bank. The B bank that controls cylinders B1, A2, A3 and B4 have again two on each side had no faults. With those codes and absolutely no engine rattle on startup, it's got to be something else, a least that seems logical to me. I will make the decision about the tensioners soon but I would like to convince myself that the car runs well, after just putting new tires on and one of those huge batteries in.

Any new ideas after seeing my new fresh info. Thanks, Will P

Will sorry to rain on it, but the codes you've posted are classic 'chain skip' codes, the cam position sensor and crank position sensor have reported an issue on the A bank, there's pretty much no doubt in my mind that's secondary tensioner failure.

Hate to say it but the next startup could be curtains - likened to Russian roulette...

Take your time finding a local shop that can work on these cars, a very similar engine is the Lincoln LS so a Ford tech experienced with those engines will be familiar with the Jag and probably way cheaper, so don't go 'it's a Jag' =$$$$

Well, Sean, that is exactly why I put it out there for you and others to hopefully give me some kind of consensus. Jhartz another opinion has told me the same thing. My only problem with that idea it seems wrong that it could skip a tooth or teeth and with that degree of looseness not make any engine noise and that the same four cylinders all in one electronic bank of the two can be misfiring on two sides of the engine at one time, did both sets of tensioners fail at the same time or if one side breaks does it throw the timing out on both sides. If that is so, that is correct then I bow to the knowledge here and my about me paying to get it fixed or selling it to someone who wants a nice jag as a project car. I know that either way, I will take a bath on the car moneywise. I just want to make a clear decision. And, I will not start it up again until I make the decision. Thanks, Sean. Will