Larry was a tremendous help, he is a professional mechanic and it was a joy watch him diagnose my #6 cylinder problem. Been thinking a lot about the likelyhood that the 0 compression in #6 is because of carbon build up on its exhaust valves per the Jaguar Tech Bullletin dated 8/97 03.1-10 that Larry gave me. Per this Bulletin, it is clear that all 95-97 XJRs within VIN range 720001 - 792388 are subject to excess carbon build up, particularly from city driving. And mine was sitting for 5+ years likely adding to the tendency for its exhaust valves to stick open. I am on the 4th set of plugs due to carbon fouling in the less than 50 miles it has been driven while trying to get it repaired. I was surprised at how much carbon had built up on the present plugs with 12 miles on them?? Likely my fuel injection system is set too rich??

What other possible ways are there to remove excess carbon on these exhaust valves likely causing one or both valves to stick or be blocked open = 0 compression? Happened to find several Youtube videos on the use of SeaFoam to remove built up carbon in an engine. SeaFoam tested best of all products in doing so. Decided to give SeaFoam a try on cylinder #6's exhaust valves. 0 compression means that one or both of the exhaust valves are always open and could be reached by a directed spray. I bought a spray bottle of SeaFoam which has a very useful spray direction plastic fitting on the extra long spray tube. I cut the fairly large spray direction fitting down to fit through the spark plug hole so that it gives a 90 degree spray angle pointed at the exhaust valves. I inserted it in #6 plug hole and sprayed a small amount of SeaFoam on both exhaust valves. Letting it sit and will repeat several times over several days in hopes the SeaFoam applied directly to the valves will dissolve the blocking carbon on the valves and/or their stems? If it works and #6 starts firing, assuming there is carbon build up in all cylinders, I plan to SeaFoam the whole engine via spraying it as directed into the throttle opening. Very hopeful I will not have to pull the cylinder head to get my XJR engine healthy again!

I am also expanding my thinking about my extra ordinary oil loss/usage? Maybe it is leaking it rather than burning it as Larry could find no indication the engine was burning oil. I have had main seals leak a little and quarts of oil in classic cars due to flat spots that develop on the seal from sitting. Will investigate that possible source of my oil loss.

Thank you again Larry!!!

 

Would you happen to know the number of that TSB?

 

That would be Tech bulletin 03-1-10.

 

All the Bulletin says at the top for ID is "Sedan Range" "Date 8/97" and (Bulletin Number) "03.1-10" Hope that helps.

 

Rmbaker, good luck with your engine. I do have a used '95 XJR engine and transmission that I bought a couple of years from a friend for project that I never got around to. I bought it as a good used engine, but I personally have never heard it run. It does have compression on all cylinders and I see nothing that worries me externally on the engine. The car had hit a curb pretty hard and tore up the suspension.

I see that your in Arkansas and my shop is 30 miles east of Dallas (75189) so not too terribly far. These engines are pretty scarce and it's just sitting on a pallet in my shop collecting dust. PM me if you have any interest in it.

Thanks
Kevin

 

Kevin, thanks for letting me know you have the engine I may need. I am part way through the process of trying the SeaFoam on my 6th cylinder and should know if it works to let the exhaust valves work again by end of week. Or is an exhaust valve damaged and that is why it will not hold compression?

I have some questions about the engine you have: 1) how many miles were on the XJR when the accident occurred? 2) will you sell only the engine? 3) what are you willing to sell the complete engine for? 4) could you swap engines for me at your shop? 5) If so, what would you charge for the engine and labor?

 

Rmbaker47
(1) I'm not sure on the mileage. The instrument cluster had already been scavenged when I got the car.
(2) No, I don't want to separate the engine and transmission assembly. However, the price for both is quite reasonable in my opinion, see #3 **
(3) I'll take $500.00 for the engine and transmission.
(4) No, sorry I just don't have the time these days.
(5) N/A

 

Kevin, Thanks for the answers to my questions about the XJR engine. Your price is reasonable. I am in the middle of trying to determine exactly what is wrong with my engine. If all goes well I will know a lot more by the end of this week. We are returning to our Arkansas summer home next week towing the Jaguar. Will get back to you soon about my interest in your engine.

 

Rmbaker47,
Hopefully it's not too serious. I pulled the engine and transmission together when I did mine. It seemed to be the path of least resistance for what I was doing.

Good luck with your engine. I'd like to have British Racing Green XJR6 myself. (not that I need another )

 

Update on my SeaFoam experiment on no-compression cylinder #6. I have put a thimble full of Sea Foam in #6 2 times a day for 5 days and rotated the engine a turn or two each time to force the SeaFoam around the exhaust valves in hopes of removing any carbon build up in the valve seats or on the stem preventing these valves from closing? I started it day 5 (yesterday) to learn what effect if any the SeaFoam was having on possible exhaust valve seat/stem carbon build up. Engine started smoother and ran stronger, particularly above 2000 rpm. Still idling like one cylinder is not firing? Engine strong above 3000 rpm for first time or maybe the first time I pushed it above 2000 rpm? Cylinder 6 plug tip wet after start test indicating not firing? I decided to SeaFoam all 6 cylinders with a thimble full of remover after start test and did so twice with two engine rotations to distribute the remover in the cylinders and valves. Started the engine this morning (day 6) - started quicker and stronger I think and reved past 2000 rpm to 3500 rpm very strongly. Still idling like a cylinder was not firing?. Played with throttle in the 3000 to 35000 rpm range and it is strong with no roughness like at idle or up to 2000 rpm. Pulled all the plugs to SeaFoam again and all plug tips dry = firing except #6 cylinder - still wet with SeaFoam so not firing. Looking more and more like one or both of the exhaust valves in cylinder #6 are damaged, not just carbon blocked. Will repeat SeaFoam treatment today and tomorrow and start engine again tomorrow for final try at seating #6 cylinder exhaust valves to compress and fire? Will be trailering Jaguar up to my summer home garage Monday to pull the head and have the valves repaired it seems.

 

Easy on the revs in P or N! There's a TSB - sorry, can't remember the number, but cautions you that revs above 2000 may cause transmission damage. It may be that the TSB only applies to NA cars with the ZF and supercharged versions with the GM xmsn are exempt from that warning.

 

Thanks for the "heads up" on the TSB about engine reving. I did not rev it at 3000 rpm for more than a minute - just surprised and pleased to have it rev up and wanted to try to clear any carbon build up in cylinder #6 by reving a bit. Will be careful per your info.

 

I noticed you have an Andy Brkt on your 96 VDP. What has been your experience installing and driving with it? Would you recommend it for and XJR engine?

 

Hello RMBaker. Recommend bring #6 piston to top and filling that cylinder to the bottom of the spark plug thread. Perform this for a few times and then crank over engine with spark plug removed so as not to hydraulic. Reinstall plug and coil and attempt to fire. As to your question about the Andy Bracket your going to need that and a over drive S/C pulley then a K&N air filter. I should have brought over enough tools to drop the exhaust manifold and looked in the #6 exhaust port. Shoulda, Coulda, Woulda, Old R&B song I think.

Larry Louton

 

I've got 2 Andy brackets. Excellent piece of gear. "Sensible" throttle response (as in you can easily sense the difference it makes, not as in "well that's a sensible, reasoned, conservative amount of throttle response") Increased fuel economy as an added bonus. I believe Andy offers a re-programmed ECU for the supercharged version, incorporating the same change that the bracket effects, except you don't need the bracket. Before buying the bracket, you probably want to make sure a previous owner did not already fit ANdy's ECU, well, look at your crank position sensor bracket as well and make sure you don't already have one. I think I did a how-to on installation, which is very easy on the NA car, can't say for the supercharged, but anyway, pics in there of Andy's bracket and it is easy to spot the difference between the two.

 

A random thought, if number 6 plug was sparking, would it not be dry, even if the exhaust valves were stuck open?
‘If the plug is wet, is the simple explanation not that it isn’t sparking? Are you sure the coil is working, and that the wiring to the coil is continuous?

 

There are four strokes to a four cycle engine. Intake stroke, Compression stroke, Power stroke, Exhaust stroke. If one of the previous doesn't happen, Spark doesn't matter. Ask any Diesel.

 

Thanks for that fascinating insight Larry, I am sure it will assist others as much as it helped me.

Returning to the matter in hand, we seem to have come a long way from the initial post regarding possible engine removal to remedy a head problem, via catastrophic oil consumption through to a technical service bulletin for intermittent poor idling due to carbon build up on exhaust valves.
Clearly the latter seems like a better place than the former, although the course of remedial action might not be so different.

For my own part, I am struggling to extrapolate from the carbon build up / irregular idle point covered in the service bulletin to a complete loss of compression on a single cylinder, which is what we seem to be chasing. To clarify, what were the compression test readings? In the event that cylinder 6 had any compression, I stand by my point regarding the wet spark plug being suspicious in and of itself. If there was no compression at all, and the other cylinders were OK, I would respectfully submit that we are not in service bulletin territory.
I am also unclear where we stand regarding oil consumption at this point, but you have not said there is any evidence of lack of oil pressure. Unless it is actually pouring out the car, and provided the engine doesnt overheat, I would be sorely tempted to take it for a long drive and see how things develop. As the service bulletin implies, that helps remove any carbon build up, and generally benefits an engine which has not been used for a long time. If the oil consumption continues, again, I dont think we are in service bulletin territory

 

Hello countyjag, After the compression test notes of 160psi to 175psi of cylinders 1-5, A leak down test was performed on #6. Compressed air was introduced into the #6 cylinder and came out the tailpipe. No half moons found on piston where exhaust valve could have seized and hit piston. All other cylinders were inspected for scoring. None found. The vehicle fits the bulletin condition of carbon build up on exhaust valves, The vehicle probably was parked five years ago because this condition. Owner of vehicle is flat bedding vehicle to home town in Arkansas but is practicing better cars with chemicals theme until then. Without a compression stroke to atomize fuel, (exhaust valve leak), The fuel will just puddle. When RMBaker gets settled in Arkansas again, I might take a road trip to further investigate this matter.

Larry Louton

 

Hi Larry,
Thanks for the detail regarding the compression test results, which I would summarise as cylinders 1 to 5 in good health, cylinder 6 zero compression. The fact that the compressed air found its way out of number 6 and out of the tailpipe obviously points to exhaust valves, as you have diagnosed, but it all sounds a bit beyond the situation described in the service bulletin. Even allowing for Jaguar's customary mastery of the understatement, "intermittent poor idle" seems a long way short of total permanent loss of compression. I mention this not to have some sort of semantic debate, but because I think it might affect the potential cure.
What if the condition developed during the lay up of the vehicle, rather than being the cause of it? What if the exhaust valves ( or valve?) in number 6 are stuck in the position the engine came to rest in? Surely carbon build up from city driving described in the service bulletin would have affected all of the cylinders to some degree and we might expect weaker compression readings all round?
It is obviously good news that the piston appears not to have been in contact with the valves, and coupled with the fact that there is no compression would suggest that the valve(s) are stuck part way through their travel from closed to open. Assuming that there is no untoward noise from the valvetrain, ( is this assumption valid do you think?) I am concluding that the travel of the camshaft is not impeded by a seized valve or for that matter a seized tappet. It flows from this that as the camshaft attempts to open the valve by pressing down on the tappet, the tappet moves down, pushing down on the valve. If the tappet or the valve did not comply with the wishes of the camshaft, there would be an ugly sound of some description, and possibly some signs of damage by now. In the absence of any such noise or damage, it would suggest that the valves are still capable of some movement, including to the fully open position, and back to some point clear of the piston face at TDC. As I write this, it strikes me that I dont recollect anyone saying that the valve clearances have been checked.... what if the valves are being held open by inadequate clearance....? You never hear of that on these engines, but what if the valves are burned, or someone screwed up an attempt to reset the clearances? A broken valve spring comes to mind as a possibility too. Again, I havent heard of that on these engines, but...
I agree that the chemical theme makes sense for now, and it would be great if it worked. In parallel, the valve clearances might usefully be checked if they havent already, and the operation of the cam lobes on the tappets examined for clues as to the extent of valve travel. Logically, if the valves are being held open, the clearance should be outside of specification. Camshaft removal might be a next step too...