2014 XJR with 62K miles on it. Seemed to be idling rough for the last month or so. Driving fine and power was fine. But it kept getting worse. No stalling but the engine would hang at 1000 rpm when coming to a stop. Then if you waited a minute it would drop down to the 700-600 rpm range and start running rough. No check engine lights but it got so bad my wife mentioned that my car did not sound right.

Some searches on the forum and they all pointed to the PCV diaphragms leaking. Or at least some kind of vacuum leak. Finally I got a check engine light with the 4 codes listed in my title. I had already purchased the RKX ones that supposedly are made with "Military Grade Fluorocarbon". Now will these be better than Jaguar's? I don't know but they are only $25 for the pair.
RKX PCV Diaphragms

The factory manual has you remove the SC and that would have made it much easier but I did not want to do all that work. Several threads about replacing them with the SC on so I decided to give it a shot and if it did not work out I could always drop back and remove the SC to complete the repair.

Here's where they are on the 5.0L SC V-8.





From what I read the problem is as always a severe lack of working room to do the repair. Imagine that!





I removed the wipers and the cowling underneath. Removed the strut tower brace on the passenger side of the engine. Fought the rubber pad off the cam cover. Dis-connect the vacuum hoses in the way. Remove the large PCV hose from the back of the PCV system and on the engine. I also against my will removed the secondary bulkhead on the passenger side for more working room. Maybe you can get to the PCV stuff with it in but again just no room to work.

Now Jaguar did carve a little bit of access into the bottom of the SC lid but not much.





As posted before there is a foam pad of some kind between the SC and the engine. The edge of this protrudes and gets in the way of the PCV caps coming up and off the engine. So you will need to trim this back with a razor knife. The foam has been cut in the above picture and is no longer visible.

The only way I could remove the OEM ones was to use a 90 angle pick and break the little tabs off on the caps. I could not get to the back ones but once the cap gets loose it's spring loaded and is pushed up and off the mounting tabs. This next part is tough so I struggled for a while until I got the cap off. I used a thin SS ruler to push the spring down while I manipulated the cap until I got it off. It was a pain!

Since until this point I had not found any problems I was worried that changing these diaphragms might not fix the vacuum leak. Then I would need to start over with my troubleshooting. But it was obvious once they were out and inspected. Just as many have posted mine had a split.





But now the fun begins! Installing the caps without breaking the tabs AND getting the spring centered is a bit of a challenge. Again I used that thin SS ruler to hold the spring down while I messed around trying to get that plastic cap back in place. This was by far the hardest part of the job followed by the removal and replacement of the secondary bulkhead. One trick on the bulkhead is there are two plastic push pins used to hold the insulation onto the bulkhead. They stick out on the back of the bulkhead and get in the way when removing or installing them. Clip them off flush on the backside. Not much help but a little bit.

After installing the caps the large PCV hose did not seem to be attached very well on the end pipe.
This connection;




The hose is Jaguar AJ812235 or LR010867. As I have found before for some reason the LR part is cheaper than the Jaguar one? About $85-$110 depending on where you get it.

The end of the hose appeared to be somewhat distorted. Maybe from the heat or from me taking it off and on a couple of times.
Does not look bad in this picture but it looked to me that the plastic ring was crooked?




Here is the entire hose.





While I was in there I decided to replace that terrible heater hose setup at the rear of the engine. I removed the stock one. Again!




And replaced it with this simplified one. These are used on the later models but will back fit the earlier cars.





I did trim about 1" of hose off where the red circle is. I removed the clamp cut the hose and re-installed it. Just seemed to fit a bit better to me and it was easy to do. Not shown in the picture is the brass bleeder screw that I have had for a while. So another bit of plastic swapped for metal.

One casualty was the large plastic wire harness cover that is hinged at the back of the engine. I had damaged it when I did the rear water manifold and now I broke the hinge portion clean off. I circled where the hinge is on this cover. The engine is so close to secondary bulkhead that there is no room for the cover to swing open.
I don't know if Jaguar even sell's this separately?




I did not drain any coolant and only lost a cup or so when I removed the rear heater hose. Got it all put back together and no codes and the engine seems to idle better. I think these caps had started leaking vacuum some time ago and finally got bad enough for me to notice and then set codes.
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Ugh, I hate removing the secondary bulkhead. It puts you at risk for pinching important wires when reinstalling and fiberglass gets all over your hands. Do you think you could do the job with it remaining installed?

 

I thought long and hard on that. You mentioned what happens if you work around those bulkheads. The insulation pad is very weak and very yellow! So it comes apart at the slightest touch and looks like crap. I guess I would like to replace it with some good stick on sound pads. Those are so much tougher. I did less damage to the insulation by removing the bulkhead completely. I was hoping that since I had done it before that it would easier the 2nd time.

It did not appear to be and I struggled and cussed just the same.
Every time I get near them I end up trying to glue the black back over the bright yellow if only for cosmetics.

So for me no. Remove the secondary bulkheads for working room. Not saying it can't done with them in. I am sure others have done it that way. Heck I would bet a number of guys have just taken those damn secondary bulkheads out and left them off for good.
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Great job at identifying & fixing the problem Clubairth1, thanks for sharing the process.
I do get envious of those of you with the SC option, but I gotta say these things are so much easier with the NA engine.
Without the blower on top it's easier to get those two bulkhead panels off & access everything.
And for my wife, the NA has plenty of power as it is thankfully.
And truthfully, the NA 5.0 in my Range Rover gives enough power for me too.
Thanks for the helpful experience of what a torn PCV valve will do & how to replace them.

 

Thanks much for the compliment and I think it should help others in the future. I try to use pictures as I am completely confused by some of these posts with only a wall of text and no spaces!

I think the 5.0 NA was the sweet spot as far as engines go in the XJ. Great power and mileage plus a nice driving experience. A good compromise all the way around. Sorry to see it go but dropping that version did simplify Jaguar engine lineup so I assume there were cost savings involved.

Yea the repair was very cheap but I found it difficult because of the SC and I was too lazy to remove it. Another example of big money savings from DIY repairs. But at the cost of some blood, sweat and tears!

I wonder what that would have cost at a dealer?
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Club,

Nice write up!

Having just replaced the PCV on my wife's V6, I got to say I'm amazed you managed to get the new caps seated correctly with the blower on! I did hers with the supercharger off during the Y pipe replacement, and even then, the little tabs were a swine to get seated properly.

wombat

 

Well I knew if that failed I could remove the SC in the end. I found the installation tip in another thread about using a thin bit of metal to hold the spring down while you manipulate the plastic cap into place. This was much easier said than done but since I knew it had been done before I kept at it.
Like the great UK expression "It was a bit fiddly"!

Man what an understatement!
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