Hi all, I'm new to this board but not new to cars. I've been a professional mechanic for 7 years now but have not really worked on jaguar engines extensively. We really do not get these cars in my shop besides the normal brakes/suspension/fluid exchange. Plus, Jags are not as common around here.

Well, here's the deal. I recently purchased an XJ8L with 78kknowing that the car was not running.(auction) After bringing it home, I put a new battery in it to get things going. After trying to start the car, it sounded like there was no compression. So I researched a little about the timing chain(s) and figured out that these were interference enigines. So then I did a compression test to see where I stood. Apparently the car has been sitting a while because of the sticks/leaves/stagnant water around the intake and like areas. As I pulled the coil packs I saw that the gaskets on the valve covers were shot, so oil has leaked onto the plugs and coil boots. (no big deal, its a very common problem on a lot of cars) So some cleaning and some new plugs are required.

Onto the compression test. I started on the passenger side bank and got absolutely 0 compression on those four cylinders. I thought that was extremely odd, so I thought maybe my compression tester was taking a dump(or possibly a bad schrader valve/o-ring) So I went to the drivers side bank compression numbers were 30,90,90,30. Very very low, but atleast I got a reading, so it wasn't my guage. This was yesterday. Last night I tried finding some info and came up here. Mitchell ondemand is absolutely no help and I wish I had Alldata back, but atleast I got some TSB info on the timing chain tensioners commonly failing. I ended up finding this forum, and saw some good information.

Today, I took the valve covers off to check the secondary chain tensioners and chains for anything out of the ordinary. It all seemed tight, but I noticed the passenger side bank primary chain had some slop in it opposed to the drivers side chain. I could move the chain and guide with my fingers. So I took the timing cover off to see what I could find. The only thing that I did find was that the primary chain tensioner on the passenger bank had failed hydraulicly and let the chain flop slightly loose. There is no way that it is loose enough to have jumped over the gear at all. Things came up so I had to stop for the day.

My question is, Why is there 0 compression across the board on that side of the engine. I could understand bending a few valves if it failed while driving, but I've never seen half of an engine taken out at once. It's just not possible the way I see it. Or, do the cams move enough to throw it so much out of time that compression gets all screwed up with it? Also, Why do I have such low numbers on the left bank? I can understand dirt or debris around the spark plug hole that may interfere with readings, so I'm not AS concerned with this problem YET.

Tomorrow, I'm going to replace the right bank tensioner and go from there (yes I have the cam lock down tool, my snap on guy actually had it on his truck lol). Any help or insight is much appreciated. I would like to get this car going soon and I have already factored in replacing the engine if I have too. It's a good thing I got the car super cheap, but I would like to keep it that way if I can.

Thanks alot!

 

Your 98 xj has the nikasil lined cylinders. I am not sure where you are located, but the nikasil wears off with no forgiveness if you are in the south?
With the compression issue, you have no way of knowing if car overheated. It may have dropped valve seats. I would do cylinder leakage test. Best way on yours is to unbolt the cams. Make sure you lock the cams down and put the tool in flywheel so itstays in time. Then unbolt cams and check cylinder leakage.
Likely it didnt damage pistons. You may have to pull heads and redo them if damaged, but that is much cheaper than engine replacement.
If you have cover off already most of the work is done. I do recommend replacing all tensioners and guides though. They are not great to begin with, and if you're like me you dont want to go back in for a second round.

Anyhow, let us know how cylinder leakage test goes.

 

Hmmmmmmmmmmm.......
Today I may just pull the heads as well. You're right about not knowing if it has overheated, and the 0 compression on all four still has me baffeled. The dropped valve seats or blown head gasket sound on par with overheating, but as I said before, that usually only takes out a couple cylinders. The only time that I have seen 0 compression on 4 cylinders is when a head lifted off the block. That was on a newer camry 4 cylinder and the guy drove it till it shut off. So do you think I should do a leakdown test first or go ahead and pull the heads off now to see where I stand.

I also wanted to add that I thought these engines were quite easy to work on and pretty well designed. I expected atleast a few stupid things that may require something else to be removed first. But if you think about, you only have the tensioner, idler pulley, and crank pulley to remove to get the timing cover off.

Thanks for the help and have you ever seen a car come into your shop with similar compression results? It's good to see you're a factory tech and have alot of experience with these engines.

 

Keep us posted!!! And welcome!!!

 

Greetings Roc,

Great screen name, by the way. I'm the sort who usuallynever dismantles anything before taking all possible steps to identify the fault first. You could pull the heads now, without knowing where the compression loss is going, and still not see anything wrong. Here's why I can say that:

I bought a '99 VDP parts car, 82K,drivetrain intact, that had been sitting for maybe six months. I had every reason to trust the seller, whosaid that it had been running fine when he parkedthe carand started stripping it.

So I pull the motor, and it sits a few more months in inventory. Then I get a call from an associate at a Jag dealer who is searching for an engine. We reached an agreement, and before I loaded it in the truck I decided to check compression. I bolted the starter back on and spun it over.I got garbage.

The last thing I'm going to do is sell somebody something that is going to come back, and the clock was ticking. So I pull the motor out of my 2000 VDP, since I know that one was running flawlessly, and into the truck it goes.

Returning home, I look at my gutted VDP and the '99 motor on the floor. I leak it down, and it's blowing everything into the crankcase. So I start squirting oil down the bores, cranking it, squirting it, and after a while the compression readings start creeping up from 25 to 55 to 95...
These Nikasil bores just aren't normal. They're supposed toprovide improved oil retention, but they behave exactly the opposite when they've been sitting for awhile. Fuel contaminated 5W30 doesn't help matters. What cast iron bore engine did you ever have to prime with oil to re-fire after it was flooded? Only Nikasil, and it happens all the time. And it happens when the bores are still fine, just washed clean from "can you move your car so I can get out, honey ?"

That engine went straight in my VDP, and fired straight up. No blowby out the full load breather, smooth and clean after it burned out all the "supplementary" lubrication I had provided. It's still fine after six months of daily use, and I didn't have to hold my breath about the one I sold either.

If you can't verify compression loss into the cooling jacket or past the valves first, don't pull the heads. You mightsee some leakage past the intake valves, they pit a little bit but mainly just have crud on them from sitting. The chain tensioner might even have come back to life once itsaw hot oil pressure too: I had another one like that, but I was reluctant to take a chance since it was out of the car so it got new timing components.

All of that is true, and Iwouldn't believe most of it either. It isn't going to cost you at all to start pumping the cylinders full of oil,which you might even want to try warming up first. See if the compression numbers start creeping up, you might be pleasantly surprised.

 

Wow, thank you for that information. Believe it or not, I once had a nissan 3.0 v6 that I had to prime with oil to bring compression up. Yesterday, I didn't do anything besides wash the car, so luckily I didn't pull the heads. Im going to be heading over to the car in about 45 mins. from now, so I'll try priming and trying to get some sort of numbers out of it. The car has been sitting for quite some time, I would even say over a year or two maybe. I have never heard of the nikasil cylinders before so I don't know how they work and what the advantage to the lining is. Or even the characteristics of the material itself. Im gonna clean up the engine today and see what I can get for numbers. Monday, I'll go get the primary chain tensioner that I need so I can atleast see if it will start. Thanks again, and I'll keep everyone posted.

 

Ok, I went down to the shop today to work on the car. I bumped the compression on the drivers side back up to normal using the oil priming/ring conditioning method by slowly adding a bit of oil down each spark plug hole, then turning the engine over. I got around 180-195 psi across the board. Pretty good imo, and it shows that it'll even out with regular gas and air in there. (just incase not everyone knows but liquid is not compressable lol, so the #'s will vary)

However, the passenger bank still remains the same. 0 compression. I lined the timing up and found that the exhaust cam is almost completely 180 out. I took some pics to show you guys both sides. Now remember, the primary chain tensioner failed and that chain is rather loose. I wanted to ask what my chances were of getting away with no damage to the exhaust valves. The clearance tolerances show there's alot more room for error than the intake valves , but something that far out, well, you know, not good. Im just a little hopeful. I've built many Honda engines for fun/hobby, and have broken a few too. Almost everytime there was a valvetrain failure (as in over-revving, slipping cam gears, failed tensioners, or broken belts) Its yhe intake valves that get hit first and shut the engine down.

Ok onto the pics. Atleast I now know my worst case scenario is only one head. Well Im gonna try to figure out the pic hosting. It's a little different than zeroforum's layout. Well, it doesn't seem to let me directly post the pics through the [img][/img] deal, so here are the links to them. Works the same I guess.

Passenger side bank, notice the exhaust cam not lining up. look for the flat spots where the lock down tool is supposed to hold them down.
http://i85.photobucket.com/albums/k7...8006Medium.jpg
Same basic pic here
http://i85.photobucket.com/albums/k7...8005Medium.jpg
Drivers side bank, notice how both cams line up. Both flat spots are pointing up, allowing the lock down tool to be installed.
http://i85.photobucket.com/albums/k7...8004Medium.jpg
Another of the drivers side bank
http://i85.photobucket.com/albums/k7...8003Medium.jpg
Passenger bank again
http://i85.photobucket.com/albums/k7...8002Medium.jpg
Passenger bank again
http://i85.photobucket.com/albums/k7...8001Medium.jpg

Hope you guys can help and see what I'm doing.

 

if the primary chain snapped, it is a tough call as to damage. Easiest way to see if it bent valves, is to unbolt the cams from that side. There is a tool to put in the flywheel to align motor in time. The 4 cams should have flats on top all the way across when in time with the tool in flywheel. I would take off the cams from the bad side as you are taking off cover anyway to do tensioner. I would after removing cams, set the other side in time Then all you got to do is bolt down the other side and not worry about damaging anything, as long as the flats are on top. The timing is of course paramount.
Anyway, if you unbolt the cams, obviously all the valves should be closed. Do cyl leakage test and it should hold within 3 - 5%. If valves are bent, you would be pulling head off anyway, so cams are already off.
Make sure you turn it over by hand before you start it....and if you are going after the tensioner, do them all. You are in there and you should replace all the tensioners and guides because the original ones are crap.

 

With regards to pics - that motor looks like it was cooked. Does it have the smell of death in it?

 

I know what you mean about the pics and the motor being cooked but it doesn't look like that in person. As I stated before, the chain did not snap. The primary tensioner has failed hydraulicly and let the chain have some slack. The motor doesn't have the definitive death smell. I know what you mean by that, you can smell those cars across the shop when they come in. The engine overall looks fairly clean, but you can tell it wasn't maintained meticulously, there is no sludge buildup, burnt smell, nasty coolant etc. The motor turns by hand, obviously I would have tried that first, but that doesn't mean that someone previously tried to start the car numerous times and bent the exhaust valves. Can you see where I said that the exhaust cam on the passenger side head is out almost 180. THE FLAT PART IS POINTING DOWN. How close is the tolerance for these.

 

Oh and briefly, about how much does the entire tensioner and guide kit cost? Im talking about cost, not list price. I'm not looking to replace the chains though.

 

I don't know about cost for that stuff, Ohio may know.

I have seen motors come in with snapped chains and never touched the piston. Depends I guess where it stopped rotating cam. Some get lucky.
How do you know the tensioner failed hydraulically? Do you already have the timing cover off?
Do the shoes look worn out on the guides? That is the more common problem. The plastic flys off and drops into oil pan. That is odd the the exhaust cam is 180 out if the chain didn't snap. I would make sure the tool is in the flywheel and set it all in time before you dismantle anything further.

 

Also, just wanted to say that the caps lock was not me "yelling" Just trying to make it more clear and standout.

 

Greetings FJT,

I know what you're saying about the pics, but alot of these engines are sludged like that from neglect...and it looks dry from sitting for solong (he said with the greatest optimism).

Rock, when you pick four out of eight in the lottery, they pat you on the back and say "better luck next time". That's got to have at least one pair of bent exhaust valves. Quick check is to run the valve clearances, you'll find them. FJT's way is always the best. But I can't make too much sense from the pic: if the right bank intake cam is flat side up with the flywheel locked in place, the primary chain didn't jump. If it did,the intake cam would take the exhaust came along with it.The secondary chain let the exhaust cam get 180 degrees out? Maybe if the sprocket bolt is loose...Anyway, you're on the right track . Make sure the V V T's are in the fully retarded position when you put it back together, you'll have to buy or make a tool for that. It's conceivable they're stuck on an engine that sludged up, the retractorspring inside the AJ27 V V T's is not very stout. Happy motoring!

 

FJT, I know it would be easier to pinpoint the problem with the leak down test performed and results posted but Im currently out of work and on Workers comp. So going to my shop to pick up the leak tester or other tools I need is a little hard. I haven't been released to go back to work yet, so technically I'm not supposed to be working on cars. When I say that I went down to the shop today to work on the car I was referring to my father's car lot and the garage he has there. I have some tools there but I sometimes have to get tools from My shop and I have one of my friends get them for me. So, I won't be able to get my leak down tester until monday. That's why I have gone about other ways of doing it.

 

That's what I was thinking. It's not possible for only one cam to jump like that if it's the primary chain that's limp. It's the only problem I've noticed though. None of the bolts on the cam caps look turned, so I don't see how maybe someone installed the cam backwards if you will. Nothing under the valve covers or timing cover looks as if it has been serviced. I don't understand how that cam is so far off. I'll host the large versions of those pictures to see if you can see the flat spots better.

 

Larger pics.

Passenger bank
http://i85.photobucket.com/albums/k7...6/98xj8001.jpg
Passenger bank2
http://i85.photobucket.com/albums/k7...6/98xj8002.jpg
Passenger bank3
http://i85.photobucket.com/albums/k7...6/98xj8005.jpg
Passenger bank4
http://i85.photobucket.com/albums/k7...6/98xj8006.jpg
Drivers bank1
http://i85.photobucket.com/albums/k7...6/98xj8003.jpg
Drivers bank2
http://i85.photobucket.com/albums/k7...6/98xj8004.jpg

Hope this is clearer, they are the only pics I have at the moment. I you look at the passenger side cams, you should be able to see the exhaust cam flat side down, all the other cams are flat side up

 

Yes, I removed the timing cover a couple days ago because I noticed the slack in the primary chain. I know the tensioner failed hydraulicly because I can move the piston slightly up and down with a pocket screwdriver. I also did notice on the guide where it sits on the tensioner that the plastic is missing there. So in between the chain and the tensioner piston, there is no material, but I never saw broken pieces and the rest of the guide is intact. Now that I read that, I never really paid much attention too it, but it makes perfect sense. I'll try to search around some more for prices, thanks for the help. And I guess I'll just do the leak down on Monday to see if I got lucky or not.

 

As Ohio stated, if you cannot get cyl leakage tester, (I am **** about doing things the most conclusive way) you can use feeler gauge. Rotate the cam until the lobes on a particular cyl are facing straight up. I forget spec. right now, but you can check that way too. Probably will be easier for you as far as access goes.

 

I'll see what I can get to tomorrow, I do know that I've seen the valve clearance specs on mitchell on demand, so I can use that as a source.

The exhaust valve clearance is .009-.010 in (.23-.27(mm))
The intake valve clearance is .007-.009 in (.18-.22(mm))

Just looked it up incase anyone else may need it. Anyway I guess we'll see how screwed up it is tomorrow. Are you located in the states FJT or in England?