I need some insight. I drove then parked my XJ8, which has 101,000 miles on it. It ran great, as usual. The next day it would not start. I took to the mechanic. They said that on one bank of cylinders there is no compression. I know little about the engines but it sounds strange to me. I mean, is there a possibility of a single point of failure on compression, especially one that would only affect one side of the engine?

I someone on here can give me a little guidance.

Thanks

 

Tough to say without a few more tests but a head gasket failure would cause a drop. 2002 should have steel cylinder liners so no nikasil cylinder wall erosion and I have seem many X308s with 200K plus running on original piston rings, with regular oil changes of course.

Head gasket failure seems unlikely to affect all 4 cylinders but can be easily determined by examining the oil and coolant (If you are gaining oil you have a failure).

The other culprit would be bent valves/warped head. Has the engine ever overheated or had the timing chains changed? Overheating can warp the head or valves compromising the seal and off timing can cause the pistons to run into the valves. Either would be obvious as the engine would run rough if at all.

 

Sounds like classic bent valves from a secondary tensioner failure. Tho sometime in 2002 was when they switched from plastic to aluminum tensioner bodies I suppose you could have the earlier plastic tensioner if the engine was assembled in 2001, which would be a miracle it lasted this long. Each bank of cylinders has its own secondary chain tensioner so its not unusual that one side fails. If chain tension is lost, startup is prime conditions for the chain to slip. Simple to take the valve cover off and see if there's a big crack in the tensioner body, or worse, bits of tensioner scattered about.

Valves can also get tweaked from the build-up of carbon but you'd likely have noticed symptoms first, like getting harder to start on cold mornings. The tensioners by contrast sometimes give a death rattle, but often just let go all of a sudden without warning. If its just the tensioner on one side, then I would recommend having all the tensioners, primary and secondary along with the plastic chain guides replaced all at the same time to prevent any future issues. If the valves are compromised from carbon build-up, then you'll need to pull both heads as the valves on the other side will be near failure too. Lets hope its just the one secondary tensioner.

 

There almost has to be a code thrown...have they (or you) done a scan? I am finding it hard to believe all 4 cylinders went down at once without some type of indication...restricted performance, noticeable lack in performance, blowing white smoke out the exhaust, if it were a head gasket. This sounds like a CPS (Crank Position Sensor) either dirty or gone bad or a fuel pump going T up. But we need to know if any code(s) have been thrown?

2ndary tentioner is possible and as stated, easily checked by removing the OHC cover.

I'm with anduha, more tests for more info and pdupler on that cover removal.

 

The car has been babies since we bought it in 2005. Other than the typical occasional drip of oil on the garage floor it is been a great auto, well maintained. It has never been overheated, The last time I drove it was to back it out of the garage and put it back in an hour later. It always starts within a couple of seconds of the initial cranking. On Thursday it wouldn't fire off and didn't make any strange noises, either. I had it delivered to a local garage, where they tried to start it, they then checked compression. The left bank is at or near zero and the right bank is running 60-90 PSI. They did both a dry and a wet test. Their initial thought is that something happens with timing and that I do have bent valves. They don't want to tear into it, as they are just a general repair shop, no special expertise on Jaguars or other imports. I will have the car moved tomorrow to a garage with Jaguar experience.

I'll post back when I get the final results from the teardown, hopefully tomorrow.

Thanks,

 

See my reply to Adula. It ran well, with no indication of problems the last time it was driven (backed out of the garage and put back in an hour later. No noises, no strange exhaust, etc. The next time I tried to start it it wouldn't fire. My first thought was a bad fuel pump.

I'll post later once I get the teardown results. Yes the tensioner or something else to do with timing is the current suspect.

Thanks,
Von

 

Nope, no overheating. Loss of timing and bent valve stems are the current suspect. I'll know more after a partial tear down, hopefully tomorrow.