Hi all,

After fixing my fuel injector failure I was experiencing an engine vibration between about 1.5k to 1.8k RPM.

I did a smoke test to check for vacuum leaks and found none.

As I don't know when the last time the spark plugs where changed I decided to jump right in and change them. Glad I changed them as the old ones where in a real mess and were bound to be having issues. Images below show the condition of the old spark plugs.

How hard can changing spark plugs be? I've done it lots of times on other cars without any problems.

Firstly it took hours to strip down the car to get to the rear cylinders 5, 7, 6 and 8. Then getting out the coil packs was a pain on the left bank due to really tight space. I thought the other side would be easier to access. The right bank was even tighter to get the coil packs out.

I managed to get all the spark plugs changed and correctly tightened.

My car has an LPG system fitted so that made the job even harder as I had to remove the valve lubrication system as it is mounted on the plastic housing by the brake master. I also had to remove the LPG ECU and cabling as it is mounted by the air filter housing so had to be moved so that I could access cylinder 8.

I then put all the car back together, reattach the coil packs, engine covers etc.

Then went to test the car. Started the car and there was a very loud bang and the car was running really rough and very loud as though there was a hole in the exhaust. It was also making a clanging noise a the same time.

The noises where coming from the right bank either in cylinder 2 or 4.

I quickly switched off the engine.

I then had to remove the engine side cover again and I removed the coil pack from cylinder 2.

I really wasn't sure what on earth I was going to find. I was expecting to see a completely blown out spark plug as it sounded like the cylinder had no spark plug in it.

When I pulled out the coil pack it came out with the spark plug in the end of it snapped off at the base. Image to follow.

So now a routine spark plug change has turned into a task to retrieve the threaded section of the spark plug from in the spark plug hole still screwed in place !

I have no idea why this brand new genuine spark plug blew in this way. It appears to have failed as there is a clear burn mark down one site which I'm guessing then caused the plug to fail and essentially get blown apart from the force of the combustion.

So the car is currently on the driveway until I can get a few hours to extract the rest of the spark plug. I will let you all know how I get on. I just hope I don't get any issues getting the thing out. Going to try extractors first and go gentle as it shouldn't be seized in place.

Thanks,

Chris

 

This is the condition of the old spark plugs - god knows how long these have been in the car. Luckily none of them had seized in place - phew.


condition of old spark plugs

 

And this is what I found in cylinder 2 that appears to have failed on start up

Note the burn mark on one side which is also where it appears to have split from the bottom section of the plug.


Blown spark plug with burn marks

 

So what miles on the car ? I think the spark plug replacement interval is 70k miles. Bad luck with that bad one, BTW ! Hope you can extract the threaded portion OK.

 

+1 good luck. I have a feeling your going to be removing the cylinder head at a minimum and hope those spark plug remnants didnt puncture a hole in your piston or score the cylinder wall or so long engine.

 

NEVER saw such a thing on any spark plug, let alone a new one.

Good Luck to you removing the remnants of the plug, bad break to say the least.

Both my Jaguars appeared to have original plugs in them, the 04 had about 90,000, the 07 had about 98,000, miles when changed.

Both cars plugs were a bit tight on removal for a turn or so, then all was well.

The book with the car, calls for first spark plug change at 100,000, thought that was a little too long myself, but the cars both ran fine.

 

Hi guys,

Yes this has to be just bad luck with a faulty plug possibly.

I too am hoping that there is no debris got into the cylinder. I can see that the whole of the threaded section is still in place so I will try an extractor first and take it gently to try to avoid breaking it further. Then I will put a hose pipe attached to a vacuum cleaner into the hole down into the cylinder and hopefully that will remove any small debris.

The car has 142k miles on it and I can find other service information in my paperwork but not spark plugs. The LPG was fitted back in 2013 and it is clear that the spark plugs would not have been changed any time after that time as the LPG cables go through the plastic housing and I had to completely remove them to get to cylinders 7 and 8. I suspect they have just been left because I gather that the previous owners didn't seem to care too much about the car

I'll let you know how successful or not I am with getting the remnants out.

Thanks,

Chris

 

Hi all,

Finally got around to taking a look at getting the remaining thread out as I've been unwell for a while.

I'm pleased to say it came out with very little effort - thank god.

I used my number 5 screw extractor attached to an extension bar. Just placed it initially in the top of the thread and gently twisted using a little downward pressure to begin to get a grip. It then just released and I could then turn it by hand and it slowly came out on the end of the extractor.

Then placed a garden hose into the hole attached to the end of a vacuum cleaner and sealed together with electrical sealant tape. Placed that right down into the spark plug hole and vacuumed as much as I could. When I checked the remnants of the plug there didn't seem to be anything missing so I think I was lucky not to get anything in the cylinder.

Phew - glad that all worked out

Now just got to work out why cylinder 5 and 7 are reporting misfires when the car is taken over 3K rpm.

The broken plug I've just sorted was in cylinder 2 so it's not related to that plug.

My engine vibration at 1.5 to 1.8K RPM has now gone though so it was a spark plug related problem.

Thanks for all the support guys.

Cheers,

Chris

 

Glad things went well

 

Picture of the spark plug thread stuck in the hole - you can see the tip of the bottom of the spark plug in the middle of the hole right at the bottom. Luckily that did not break off when the plug failed.


Spark plug thread broken in the bottom of the spark plug hole.

 

And this is what came out in one piece - phew.

You can also see how I fashioned together the extractor and my 3/8" extension bar as the end of the screw extractor is stupidly square instead of hex.


Extracted broken spark plug thread.

 

This is also another view of the blown spark plug showing a better view of the scorch mark where the plug failed. Now going to take this up with the supplier of the plug as this should not have failed in this way.


Scorch mark on new NGK blown spark plug.

 

JX350. Others far more experienced than me can correct what I am saying, but plugs 4 and (particularly) plug 7 appear to have been immersed in oil while in the plug tube; could this be what is causing misfires? Plug Boss Seals? Cam Cover Gasket?

 

Hi EsRay,

I'm not sure at the moment what is causing the misfires. I only had a slight misfire (engine vibration at 1.5 to 1.8K RPM) before changing the spark plugs. There was no fault codes at all when this occurred. Now that I have changed the plugs I am now getting fault codes registered when I rev the car over 3K RPM and they are misfire codes on cylinder 5 and 7. I can't remember which plug came out of which cylinder so I'm just going to have to check the cylinders that are now reporting the faults. It could be the coil packs, the plugs, oil seal leak or a compression problem. It is strange that the misfires are registering on the same side of the engine though. I will get to the bottom of the problem in the end. Just haven't got the time to look into it further at the moment due to my current workload. So for now the car is on the drive again.

Thanks,

Chris

 

Chris,
I had an ongoing but intermittent misfire on my cylinder 2 for some time. New plugs. New coils. Wiring Pin Tests passed. Eventually I found out it was caused by the injector on number 2. When I had all 8 injectors professionally cleaned and tested, that injector was blocked and 'dribbling'! If you have a strong constitution, you could look right through the following link: https://www.jaguarforums.com/forum/x...-207661/page2/
If not, please just read thread 33 and bear it in mind?

 

Yes I've already replaced a failed injector on cylinder 5 before I did the spark plugs so I know how to replace the injectors. I didn't have a misfire on that cylinder until after I've changed the spark plugs so it must be plug or coil pack related. The injectors are a bit more difficult to replace on my X350 as I have an LPG system attached so I have a second set of fuel pipes and two sets of injectors to remove to get to the petrol injector fuel rail. The LPG fuel injectors sit over the top of the petrol fuel rail on each side of the engine so they are in the way and have to be moved out to get the petrol fuel rail off.