Hi
This summer I bought my beautiful 2000, 3.0 litre s-type, the first jag I have ever owned. I must say it is the nicest car I have ever possessed and I have had some nice cars over the years.
The car has 64k miles on the clock and a full service history.
It has however developed a fault.
A few weeks ago it started missing and occasionally the engine light would flash then go out. Engine temperature remains constant, even in traffic.
I took it to a local garage that I have used for years. Boss there said it was probably plugs as the car is 13 years old and plugs get changed at 70k. He noted that there was some dirty water around the back two plugs which he had to remove before replacing them. He figured the car may have been steam cleaned under the bonnet prior to sale by the dealer.
This job completed I drove it for a couple of more weeks and the fault resurfaced.
This time I have had the coil packs replaced as water around the plugs may have caused problems there. Test driving it, the fault recurred. So he has taken the car apart again and more water was apparent, again around the back two plugs.
This guy is no fool and is not someone who normally chases lost causes and has checked just about everything he can think of for a leak.
The other possibility is a head gasket failure which would probably mean scrapping my beautiful car. I have been without the car now for nearly two weeks, I have not even asked how much I have already spent.
Anyone got any ideas?

 

Maybe water getting from windshield down past the cowl. Seal could have failed. Several posts about this, with fix if you Search, but should be pbvious to a mechanic.

 

Thanks,
Yes I thought of that. My drive is steep so tried reversing on after fault recurred. Still misfiring though. Fault started during heavy rain but persists even though weather has been mostly dry lately. Very despondent now, wife has been brilliant though, bless her!
Maybe when the bill arrives things will be different?

 

+1 jagv8

I'd put money on it being water getting past the windscreen seal, it then drips directly onto the plug/Coil covers and collects there. Destroying the coils.

Very common problem with easy fix

 

Thanks for that.
Car is at garage, probably still in bits. I will speak to the boss later when I get my daily update and suggest this solution.
Like many mechanics, he sneers when you mention the internet or forums. However, it is the suggestion I originally made when he said the plugs were wet. We had some very wet weather around then, plus my car sits nose down on a pretty steep drive. Not been too wet lately though and he insists he can smell coolant.
Coolant smell isn't too surprising to me as he has been taking hoses off all over the place.
Will update when I have more news

 

Monitor coolant levels. If it's not dropping, look elsewhere.

 

Thanks Mikey,
I haven't got car back yet though it is good advice.
Peter

 

Peter - I have done a few things...

1) Search the cowl water intrusion fix thread as suggested and complete.

2) Check the gasket surface on the COP cover. Sometimes it will become brittle or compromised. You can switch COP covers to the other side or get a new COP cover gasket. That alone should protect water from getting from the cowl/engine bay into to the COP's and into the spark wells.

3) I had a slight external water intrusion problem with cyl #8 - due to both the cowl and COP cover gasket being worn - I placed a layer Hylomar on the top part and back of the COP gasket and no issues since. (I tested)

4) As suggested - make sure it's external water intrusion, opposed to a coolant intrusion issue. If it's coolant - that's a bigger problem...

Thanks

 

Well, got the car back on Friday, Have had new header tank and associated pipework replaced as well as new coil packs and the previously replaced plugs. Car starts and runs beautifully until it gets warm, then starts to miss a beat. Not as bad as before and no engine management light in evidence, but obviously still not right. Frightened to drive it too far now in case of break down, though in fairness the car has always started and got me home.
Mechanics offered to replace head gaskets for £1200. I asked if they thought it would cure the problem, they weren't confident.
I would go ahead if they were sure of a fix but they are not, so what now?
Car much too nice to scrap but not the great driving experience it once was if you are constantly waiting for it to start missing!

 

Find another mechanic

 

Did your mechanic find any evidence of oil in those spark plug wells?

If so, did they change out the cam cover gaskets and spark well O Ring gaskets? if not - you may have well fried out one or more replacement coils.

Or, you have bigger mechanical issues lurking.... since you have the 3.0 I wouldn't necessarily worry about tensioners but you may have a vacuum leak at full warm up - I would advise on not driving until you get to the root cause(s) of your driveability issue and +1 on finding a new mechanic!

 

I'd vote for water left from pressure washing under the hood. Whenever I do this, I remove the coils and blow the water out. However a little water will misfire big time.


If you have good plugs and new coils you should not have any misfire. Check the wiring harness too to make sure that the insulation is not worn off and dropping voltage.

 

Water's not meant to get in there. Worth figuring out if it is and which seal isn't working.

 

Thanks to all for your interest and replies.
No, there was no suggestion of oil being present around the spark plug wells, so that is a good thing , yes.
I found that the heater is not getting so warm as it was since the system has been flushed and new coolant installed. Probably just an airlock though.
I do think a second opinion from another garage is called for but will probably investigate possibilities after Christmas now.

 

Just bare in mind misfires will destroy the cats

 

Thank you so much for your help last year with my S type. The end result was a car too damaged to repair. Water was dripping on to the block past a faulty windscreen seal as suggested by the above contributors. During the investigation, the garage removed the inlet manifold to replace the pugs and coil packs. They failed to replace a gasket on the manifold. This meant that water from the windshield was sucked into the cylinders causing damage to the engine and catalytic converters. Sold car to a nice man (cheap) who was prepared to repair car as a project.
I now have bought an 2000, X308 4.0 Sovereign which I hope to have more luck with. I have also found a Jaguar specialist in Cornwall, G&D motors in Falmouth who I hope will enable me to care for this old girl properly.
Thanks again for all your help.
Peter.

 

Thanks for updating, Peter!


Now you must immediately go back to "Search" and read everything posted about timing chain tensioners! By my reckoning, your 2000 probably didn't leave the factory with the greatest, most reliable version and thus is at risk unless they have been changed subsequently. Also beware the thermostats on those tend to stick closed rather than open, so keep a sharp eye on coolant temp and for extra credit, search "water pump" on the x308 forum for tales of the plastic impeller and associated woes.


Not to discourage you, I think you've made a fine trade, but there are things you must know to keep it in fine nick.....

 

Hi Before buying the car I read the excellent buying guide that I found here at JEF, borrowed from Piston Heads.
My car is a late 2000 4.0 V8 Sovereign registered in September, (UK "X" reg). This should mean that while the liners are probably nikasil, it should have never been filled with high sulphur fuel. This could be an advantage as nikasil was chosen by Jaguar for its hard wearing qualities.
The timing chain tensioners were changed last year (for the second time in its life) which would have been the latest tensioners available.
The history shows that the thermostat has been changed at the same time and the water pump assembly changed over by Jaguar recall during a service.
The car has covered 64,500 miles to date with a service every year. My usage should not add more than 2-4 k miles per year as the car, whilst used frequently is not a requirement, just something I want to want to drive and enjoy.
All in all my new cat purrs beautifully and is even more smooth and powerful than the S-type it replaces, (there was a Vauxhall Omega in between which was ok but didn't feel right after my 1st Jag).
Hopefully I have covered all bases and now have a nice car to love and polish.
Peter