My mechanic just delivered the bad news of a broken timing chain. Now what. What parts will I need? It is the left side exhaust chain. The valves are now stuck. The car is a 2000 XJ8 vandenplas 350,000kms., can I do the repairs easily at home?

 

Quick answer: easy repair . . . . if it doesn't extend beyond the chain.

Unfortunately, you have to do the chain and tensioners repair before you can determine if there has been other damage.

My car, I would rent the cam alignment tools, buy the Lincoln LS V8 parts (half the Jaguar cost and the same parts) and replace the chain and both tensioners (about $150 doing the work yourself). Then . . . you get to do the compression and leak down tests to determine if you have bent valves. The Jaguar V8 is an 'interference' engine, meaning that the valves and the pistons are capable of occupying the same space at the same time . . . but neither the valves nor the pistons enjoy the experience.

Some engines survive the experience, some are destroyed.

Here is a link to a pictorial of the chain/tensioner repair.

http://www.mediafire.com/?mijhydngtog

Good luck! Let us know.

 

I just re-read your post on the 350k km/217k mile engine.

Find a replacement, significantly lower mileage engine, to replace it with.

 

I tried that. Only engine I could find was in the U.S. with 125k miles on it. Too old an engine to be dropping in. Estimated $4500 to have the car back on the road. The car is in to nice condition to scrap out and I know what the issues are with it and what has been repaired.

Now for a different post.

 

You can determine if you have bent valves prior to replacing the chains and tensioners. Take the cams out and check leakage. Look for differences in tappet depth in head as well. No need to wing it and spend a bunch of $$ on parts if you don't have to.

 

You don't even need to pull both cams just the exhaust cam (and broken chain). Jagtech1 has the correct approach for a cylinder leakdown test. You can also do a compression test with the exhaust cam removed and just crank the engine with the intake cam rotating and it will give some sort of an indication of bent valves. A ZERO compression is BAD but positive readings might mean no damage to the valvetrain. I bought my 1999 XJ8L with a broken secondary chain and I got lucky that the exhaust cam stopped in a safe place (no bent valves). I would guess that 8 out of 10 broken secondary chains result in no damage to the engine. I think that it has to do with the engine speed when the chain breaks. Cranking, idling or shutdown is the ideal time and high revs is the worst case event.

Good luck and tell us what you find

bob gauff

 

So, if the timing chain breaks and it sounds worse than a tractor when you start it up, is that a good indicator the valves are bent?

 

Yep, and the the more you start it, the more $$$$ it costs to fix. The work to rectify is usually more than the total value of the car, many have been scrapped because of the timing chain tensioners failing, it's a common fault. This is why there are so many threads on the subject, and so many parked Jaguars.