After buying my first Jaguar, a 1997 XK8 with 50,000 miles, and reading up on the AJ26 4.0l V8 engine, I went into full timing chain tensioner panic, wondering what the heck I got myself into. So bad that I actually drove my $600 Saturn and left the Jaguar at home.

After doing a little more research, the panic subsided (at least a little). Here is what I learned so far:

- There are four timing chains and four timing chain tensioners in an AJ26 4.0l V8 engine. All chains are single chains vs. the duplex chains other car manufacturers use. I will refrain from commenting on this engine design (so I don't get beat).

- Overall, the probability of the timing chain tensioners failing is still rather low, depending on who you listen to. There are lots of opinions out there. Not every engine will have a failure and blow up. Still more reliable than driving a Chrysler Minivan (don't ask!) :-).

- The upper timing chain tensioners are more at risk of failing than the lower timing chain tensioners (and also easier to replace).

- Under normal circumstances, you will be able to clearly hear a timing chain running with a loose timing chain tensioner. Some crazy person even recorded the terrible sound on YouTube. Hence, listen to the engine before turning up the radio.

- A timing chain can skip a whole gear tooth and the valves and pistons will not hit each other. The engine will run terrible and sound terrible. Now would be a good time to shut it off and get it towed.

- If a timing chain skips two whole gear teeth, the valves and pistons will hit each other and one or both will loose. At a minimum the valves will be ruined. If a valve breaks off and busts a hole into a piston, anything can happen. Then it is time to tap into your emergency fund.

- A complete timing chain failure should be extremely rare.

- In case of an actual engine failure, a new $10,000 crate engine from Jaguar or a custom rebuild is only one possible solution. I can find a basic remanufactured AJ26 4.0l V8 engine from various engine builders starting at $2,750. So even if I get a better remanufactured engine, still less than $5,000 installed. That is still a lot more than a Saturn engine ($950), but only half of the $10,000 I saw mentioned a few times.

So, now I will enjoy my XK8 (and try to find out whether Jaguar has any maintenance records on it).

Andy

 

Or you could replace the upper tensioners and be done with
the crapshoot.

Under $250 as a diy.

 

If you're not certain, then get 'em checked...

M

 

Can I replace the upper timing chain tensioners myself? Or is there a lot I can screw up? I did rebuild a few VW Beetle engines before.

BTW: I live in Minnesota, so I only get to enjoy my XK8 for another four weeks this year before it goes into hibernation. I will not drive it in salty snow slush that eats metal. So I have several months to figure out the timing chain tensioners.

 

Andreas,
do a forum search on 'zip-tie method'. Mountains of guidance on here.

Lift the RHS cam cover to check; some kind soul may have done it for you.

You'll sleep better, knowing...

M

 

VW engine? Its about as difficult to change the secondary tensioners via the zip tie method as Pulling a 1600 or torquing heads and adjusting the valves on one.

 

Do the uppers (secondaries) yourself. Once you see the cracks in them you will be patting yourself on the back. Failure of the uppers has a much greater chance of causing damage to the engine. The forum search is your friend here.

 

dude, you just talked yourself out of doing a VERY important maint job on a XK8, a 97 model year at that!!
I had a 97, bout it with like 78k on it, drove it all the way home from Phoenix to Cincy. We drove it for a bit after that, mean time I learned of the TC issues and signs of them going out. Mine never ran like ****, no power loss. Pulled into grocery store for stuff, came back out and started it and CLAP CLAP CLAP went the chain at startup. Lucky I knew what is was and didn't start it again.
Most folks that come here with pre 02 cars that have went into the TC area that had no problems prior to opening her up all said to a person, CRACKS, THEY FELL APART IN MY HANDS, etc.
You do not want to put this off. Low miles does not mean low maint of your car. If anything you have many things headed your way as I think that you prob have all orig cooling system components? Never had the green shower from the hoses for the top, the ECM being an issue on 97's.
Anyway, do the TC repair now before you are going down the road at 50 MPH and one lets go on you and you are looking at a new motor.

 

The owner of this xk8 decided to wait:

 

like I said everyone that has came here with a car like yours, seemed fine, when they opened it up there was pending doom. Please don't wait.

 

My first XK8, a '00 MY, had the tensioners replaced at about 40k miles and again at about 80k miles both under warranty but both with the plastic second generation tensioners. I replaced them at 106k miles and both bodies had cracks half way up the front side that you cannot see without removal.

We are really not kidding about this issue being a terminal event. I cannot remember a forum contributor posting that they replaced the plastic tensioners and did not find a significant crack in the body if not the entire slipper missing.

It is not miles but time and temperature that causes the failures.

 

"It is not miles but time and temperature that causes the failures:

AMEN. Folks please don't get stuck in that LOW MILES if must be ALL GOOD frame of mind with these cars. They are been out there for years now, known for bad front end rubber components, aging cooling system components, and much more.

 

Here is the link with pictures as to how to DIY. I did this several years ago without any special tools. I used the zip tie method which worked just fine. The car at that time I believe had about 43,000 miles on it and now has 60,000. The primary ones will be done probably this winter. Just read all the details and study the pictures. Have fun.

https://www.jaguarforums.com/forum/x...ics-how-52653/

 

I did the ones on my XJ8 a while back using the zip tie method. It is not a terribly difficult job. You just need to take your time and be gentle with the camshafts making sure they are tightened down evenly. You might as well change the plugs while you are at it and of course the cam cover gaskets and seals. My old tensioners were falling apart but fortunately nothing fell down in the engine - oh yeah, definitely stuff a rag in there when you remove the old ones to prevent this if possible.

 

I have done a few timing chain jobs on the 4.0 V8s.



You know the risks. Here are the generations of secondary tensioners.



bob

 

Ouch!!

 

I just did all of them lower and uppers last year. They all were stretched. Car seems to run better with new chains and tensioners.

 

I had both upper and lower on mine done and in addition to the replacing fuel filter, I noticed immediate improvement in acceleration and responsiveness to small gas pedal pressure changes. Id recommend it also for performance improvement but not frying an engine should be the primary motivator. It was for me.

 

If you don't want to do it yourself there is a very good independent Jag mechanic in Minneapolis who did mine this spring at a reasonable price. Private Message me if you want more info.

 

Yeeehah! I finally scheduled an appointment to have all four timing chain tensioners replaced. Looking at my two left hands, handing over all my money to a Jaguar specialty shop seems to be the safer option.