I started up my XJ8 and it was running really rough for a few seconds and died.

I took the valve cover gaskets off to find broken upper timing chain and tensioner on the right side of the engine (see pictures)

Is this a death knell?

 

There is a very very slight chance to not have bent valves as chaing were broken at idle. But man that engine is dirty. Is it just a sun shinihng to the intake cam or does exhaust cam have burnt oil coating ? If it has burnt oil, then it is more likely frozen solid..

 

Well, it cranks, so it is not frozen solid.

 

Cams stopped but the other four cylinders plus some inertia would have kept the engine going for a few revs at least. And if you tried to start it afterwards, well then....... But not the end of the world. Pistons are probably OK (they're tougher than the valves) and only a few valves bent. Just go ahead, remove the head, take it to a machine shop, then put it all back together with a new chains, tensioners and guides, along with new seals and gaskets. Probably can DIY the minimum repair for under $1,500 in parts, the timing tool kit, and machine service. But as long as you're in that deep, you might want to consider spending more and doing a bunch of preventative maintenance while you've got access, like maybe go ahead and have both heads serviced at the machine shop (probably overdue to check shims anyway), replace a bunch of hoses and deep clean the engine bay.

 

slap an ebay quickfit chain and tensioner in there retime it hope for the best.

if it’s still broken it’s an NA car so just call the crusher

 

Are you saying the bent valves can not be replaced if the pistons are all right?

 

It appears that only the exhaust cam on the right engine bank stopped. If this is the case, then only some (possibly all) of the exhaust valves on this bank will be bent. There is most probably no serious damage to the pistons as the valves have very thin stems (just 5 mm) so they bend easily.

 

Pull the exhaust cam & chain then perform a cylinder leakdown or compression test!

 

All the valves can be replaced. You can order them from Eurospare, Partsgeek, etc. for around $9.00 each. Probably your machine shop would order them, but charge you $25 each. However you can't just install new valves yourself. You need the machine shop to grind/lap each valve to seal against the seat in the head and shave the stem to the exact length.

 

The quick and dirty way to solve is to just get a used engine, freshen up the timing set and just swap.

​​​​​Depending on your area you can get one from a local dismantler with an exchange warranty and it'll be the least amount of effort.

 

WAIT, wait: do what Bob suggested or have a machine shop equipped indy do it. This is not always a complete catastrophe: search back, you will find a few threads where just replacing the secondary tensioner and chain and everything was fine (my indy suggested maybe 25 % nothing broke inside).

 

I agree with Jhartz.

Man, I bet I can count on 2 hands how many times the oil has been changed in that engine over the course of 23 years. 🤦

 

Do you have a camera to lookin inside? Spark plug hole I was able to find my broken valves that way

 

As Bob suggested in post 8 above, remove the exhaust cam from bank 1, and perform a leak test. If air is escaping from the inlet manifold, the valves are bent.

Bear in mind if the exhaust cam has skipped 3 or more teeth, the exhaust valves are going to be bent.

Judging from the condition of the inside of the engine, it may be best to find a good used or remanufactured engine to install, or part the car out.