Long story short, helped my friend buy a very very cheap X308 XJR that had been rotting away behind a storage facility for years. I'm not new to Jags, I was daily driving an XJS until recently and have an X300 XJR as well. So I told him since the car was so cheap, it's worth a risk and I'll help him get it going.

We got the car home, cranked it over a couple of times to listen for timing chain noise, since i know it's a very very common problem on the early V8 Jags, car sounded quite healthy. The car did start and run while being fed ether through the intake, car has very little fuel pressure at the rail, so we determined the pump/pumps are probably bad from sitting for 8+ years.

However, we've run into a bit of an issue. Before calling it a night, we decided to crank it a couple more times before the battery completely died, and to check some electronics. On this final crank, the engined cranked slow (as expected with a nearly dead battery), then just seemed to stop all at once. We tried rotating the crank, it will nearly do a full 360 in either direction, but stop short of doing a full rotation like it's hitting something. I immediately suspected maybe the timing chain had jumped, even though it sounded okay. We pulled the valve covers, the chain is tight, no slop, top end is actually really clean for 160k miles, almost makes me think someone has done the timing chain/guides/tensioners at some point in the past. So, the timing chain looks good, I can't imagine it's the bottom end since it rotates fine until it hits that point, and we were cranking it rather slow so surely it wasn't under much stress. Only things that are coming to my mind are maybe a stuck valve or starter bendix? Anyone else have any ideas? Like I said, timing chain has no slop and the timing looks right from a quick glance, but I'm not too familiar with the early V8 Jaguars.

 

Since you could rotate the engine by hand, it is not the starter bendix. Another possibility is that the coolant has leaked into one of the cylinders (bad gasket or a crack in the head) causing a hydraulic lock. Remove all spark plugs and look inside with a borescope or just try to rotate the engine by hand again.

 

Removed all the plugs before pulling the valve covers, still the same situation. Chains feel fine, plugs didn't look that bad (just old), none were unusually clean or had rust like it had been sitting with a blown head gasket. I'll borrow a borescope from a friend and try and get a look in all the cylinders probably later this week. If it is a jumped timing chain, I'm not sure how, they sounded fine while cranking it and they feel nice and snug with no slop. My second guess was something similar to what you're suggesting with the blown head gasket idea, maybe a rust ring built up in one of the cylinders from sitting and once we cranked it and ran it for a few minutes maybe the rings freed up and are getting caught... I'll update when I can get a better look

 

Two things:

1. DO NOT rotate the engine in an anti clock direction when viewed from the front of the vehicle as damage to the main and rod bearings is the result.
2. Does the engine have the latest version upper timing chain tensioners with the metal bodies?

 

No, still has the plastic ones. No cracks in anything, they don't even feel brittle. Checked the chains in both banks and there is no play on anything at all, and the top end is super clean like someone been in there before.

 

Since you have the valve covers off try to rotate the engine to where the flats on the cams align. If they don't align you have jumped time.

 

If the one of the heads has a dropped valve seat (or bent valve) you should have a substantial clearance/gap at a lifter/cam.

Check 'cylinder leakdown'?

 

I'll check it tomorrow or day after tomorrow once I have some daylight

I'll check it tomorrow after making sure the timing is where it should be.

To be honest, the car was incredibly cheap (about $200), so if it turns out the engine needs a rebuild or some major internal work, I'll probably just use it for body parts for my X300 XJR6. However, I felt bad for him, so I bought the car back off of him for what he paid for it, going to bring it to my place in a couple of days and spend a week or so troubleshooting/fixing it before throwing in the towel and using it for parts for my car. Maybe I'll pull the head if it turns out to be something I can't fix without doing that, just for the experience on an AJ-V8 if nothing else, or try and get it back up and running if it doesn't take more than a week or so of my time.

 

I hope it can be saved, the more of these classics on the road the better. If worse comes to worse at least it can keep an even more rare XJR6 on the road. Check the boroscope and timing first but since this will be parted if you can't rotate the engine you may try pouring a bit of marvel mystery oil down the cylinders to see if that frees things up. I would then run a compression test to see if there is a dead cylinder(s) due to bad rings or busted valves. 2000 was steel sleeved not nikasil I believe so corrosion might not be as much of an issue.

 

Depends on when exactly in the year 2000 the car was produced. The first steel-lined AJ-V8 came off the production line in 2000 on August 18th at 10.43am so, if the engine number is lower than 0008181043, then it is Nikasil. "00" is the year (2000), "08 18" means 18th August and "1043" means time, 10:43.

 

My mistake, it's a 99 Model, produced 01/99, VIN#SAJPX1848XC865798.

 

I would worry more about the chains/tensioners before the Nikasil bore.

 

Went out and took some more pics today.Primary chain is tight as far as I can tell, as far as I can reach my hand down the timing cover. The engine is rotated in such a way that I can't get a look at the flats, but just feeling them with my finger they feel like they're in the same position.

Driver's side

Driver's side

Driver's side

Driver's side

Passenger side

Passenger side

Passenger side

I removed the starter, just to rule that out as being stuck, removed the serpentine belt as well to rule out a seized supercharger. Plugs are out, have the cylinders soaking in some oil to see if that does anything. What's the gap supposed to be like between the top of the valve bucket and the base circle on the cam?

 

It is a while since I did the top tensioners on my X308, but that one in the photo doesn't look right. It almost seems as though it is upside down. IIRC there is a pad on top which the chain runs on. That seems to be missing, and the chain cutting into the top of the tensioner. Maybe it has fallen down and is jamming the lower chain, preventing full rotation.

 

It would seem the timing cover must be removed to access the primary timing chains, guides and tensioners. If there's a bent valve or dropped valve seat, the primary timing chains must first be removed to alloy the cylinder head(s) to be taken off.

 

Have you taken the oil pan off? If any plastic or metal has fallen off it would be there or in the oil uptake screen. That would help determine engine health and eliminate a lot of possibilities for the seizing. Overall the tensioners don't look too bad but I would always upgrade to metal, if it runs first of course. Your plastic tensioners look like the ones that came off my '99. They didn't have an additional plastic pad, the metal replacements did to prevent metal on metal.

 

Well, looks like I'm pulling the head this weekend to get a more in depth look at the damage. My borescope arrived today so I could get a look down in the cylinders, and let's say it's... not good. Looks like 2 valves cleanly broken in #1 on the driver's bank, 1 valve broken and laying in #3 on the drivers bank, tiny valve mark on #4, and #2 is clean. I took some pictures with my borescope so you guys could see as well, Passenger side bank is 100% okay with no valve marks or anything, just a little bit of carbon like a normal engine.

 

yikes