Greetings all!

Sorry to be out of touch on the problems I have been having with my acquired 2001 XJ8 from about 3 months ago. I have been working on problems.

First, this link is the initial post but I don't think it needs to be referenced:

https://www.jaguarforums.com/forum/x...r-87491/page3/

Basically to review and bring you up to speed, I bought the car which showed not problems on three test drives when the engine was warmed up. On purchase of the car and the engine cooling overnight, it made a horrible tapping on start up that did not go away until the car was totally warmed up (15+ minutes of driving).

Consulted a Jag mechanic and he diagnosed that the right side tensioner failed years ago.

Redid the valves and the tapping went away. Also now the car will go in and out of restricted performance.

The Jag mechanic says that there was a slight scoring in cyl 2 but not bad.

I paid $4200 for the car and about $2600 for diagnosis and valve redo. So I am now into $ 6800 for a car that is not worth that much. The car is beautiful and I enjoy driving it but I can't keep driving it this way.

I am a modertely experienced person at mechanics but this engine is a little more than I know about. I wonder if it's something more complicated.

Along these lines my questions are:

1. Can the rods/pistons be removed and reinstalled from under the car without taking the head off?

2. What is the best way to find used parts as I understand Jag no longer supplies these parts. Aren't specific pistons/rings required for certain engine number runs?

3. What is the best way to support the engine while doing the work. Does somebody have the custom support to rent?

4. Are specialized tools required?

ANY comments will be appreciated.

BTW, I am leaving for a short trip tomorrow so if you don't see an immediate response please understand that I will be reading your posts.

Thanks!

Robert

 

I would want to be sure it is the rings before taking on a job like that. Did you squirt some oil down in the offending cylinders to see if the compression would come up ? That will usually confirm the rings not sealing as opposed to a bent or leaking valve.

 

No, mechanic said pressures were good except one cyl that was off a little but within tolerance. I am just speculating.

 

I don't have much experience with Jag engines but I'd have to say with 99.9% certainty that no, you can't remove the piston from the bottom. The head will have to be removed. I've owned my XJ8 for a little over 2 weeks now and I have been up and down that engine and it does not look hard to work on at all. The heads look easy to remove and the oil pan will drop right off giving you access to the connecting rod bolts. Remove the bolts and tap the pistol up out of the block enough to remove the rings. Replace the rings, compress them, and push piston back into the block. Connect back up to the crank shaft and replace the bolts (I'd use new bolts here and replace the bearings but whatever). My only concern would be to keep the timing aligned while removing the heads. If you re-install everything with the cams in the wrong position you could kill the motor.

I'm not a mechanic by trade but I work on cars as a hobby. Please don't take my advice as gospel. I know my skill level and I think I could swap out the rings in an 4-8 hours in my driveway.

EDIT: New gasket for the head and possibly the oil pan would also need to be replaced.

 

When you drop the pan you will not see the crankshaft and rod ends, you will see the windage tray, I believe it is called. And you can't get a piston past the crankshaft on any engine I know of. The heads have to come off.

 

Yes, the heads have to come off to take the pistons out of the block. I did this once on a BMW 6-cyl engine by dropping the sump pan, loosening the big-end cap bolts, removing the cylinder head & very carefully withdrawing the pistons & rods out of the tops of the cylinders-taking great care not to let the rods score the bores.

It's completely impossible to remove the pistons from the bottom of the block because you'd have to remove the crankshaft & then you still might find the block shape at the bottom is such that you physically cannot withdraw the piston from the bottom.

It's standard practice for pistons & rods to be carefully inserted down the bores from the top with the head off, using a piston ring compressor. There's no other way on virtually all engines...

 

Was the car sitting for a long time, and possibly the rings are stuck? Maybe you could try an engine flush- anything before pulling the motor because at that point you may as well buy a used motor with good compression and call it a day....

 

the engine has a bed plate wich meens that the lower portion of the block sperates to drop the crank out. It doesnt use caps liek other engines that would allow dropping the crank and pistons out the bottom. BUT you cant install them this way. out the bottom motor work is really only for installing new bearings. I would look at buying a remanned short block from Motorcars ltd and put your heads on it.

 

What's the advisable way to do a motor flush on these engines? I have done it on cars from the 40-60's - but not on one of these new-fangled jobs.