Brutal, thank you for posting. If you don’t mind, I had a couple questions (big surprise):

- Are you seeing clean intake valves/ports on both N/A and S/C 5.0s?

- Do you have any thoughts on why Gausten is seeing buildup on the LR 5.0s? Or are you aware of any optimization to Jaguar’s AJ133 that the LR’s lack? (It would be nice to believe so, but seems counterintuitive.)

Thanks again for the info- 40K miles with no appreciable carbon buildup is very encouraging.

 

BTW, the AJ133 also has a 2-stage switchable tappet system similar to Porsche's. This permits a minimum overlap, short duration cam grind to be used at low engine speeds minimizing the EGR effect -- assuming the valve timing is adjusted to achieve this goal. If so, like the Porsche engines there might be an inherent advantage in the carbon build up department compared to other engines without the ability to switch cam lobe profile while still desiring a good, lively, top end.

Jaguar's AJ133 switches to the high rpm lobes at 2800 rpm. This tells us two things...

Firstly, the high rpm cams are not truly high rpm optimized cams -- they are more like a "normal" camshaft a typical engine might use these days. If it were truly an aggressive grind the NA AJ133 won't be making 385 hp, it should be making closer to 450hp, and the switch over point would have been closer to ~5000 rpm (ie. like Honda's J35 SOHC i-VTEC V6).

Secondly, a cam grind that is ditched at 2800 rpm probably have very little lift and/or overlap. This is good for a nice smooth idle and promotes good cruise economy by increasing intake velocity and enhancing scavenge completeness at low engine speeds. A side effect of that the short duration, minimum overlap cam grind will also have essentially no overlap induced EGR effect -- good for minimizing carbon migration up the intake tract.

 

I hear 300Cs suffer from carbon build up. You should check yours for problems.

 

Variable valve timing with a low rpm switch over is for an engine designed to optimize torque, as Jaguar engines are. Most drivers lack interest in low torque high revving engines, they are tiring to drive and can be tiresome.

 

Whats the issue with the outlet pipe (what's the outlet pipe for?). Is this something we need to watch for?

Thanks

 

So I'm in the middle of what sounds like it might be related to this thread. I'm at about 47k miles in on a 2010 XF Premium (5.0), and what started as a handful of various coolant leak related issues/fixes, has turned into a rough idle, car stalling and the 1,3,5,7 pistons miss-firing. I get a call today from the dealership letting me know that after sending the "black box" data to Jaguar they're being told to remove the heads on the engine to see if there was damage to the engine during the whole coolant leak fiasco I've been dealing with for the past several months.

Needless to say, I'm concerned. But I don't know how concerned I should be... guess that depends on what they find. On top of that, I've only got 3k miles left on my warranty before it cuts over to the extended warranty, which probably doesn't cover most of what I've been dealing with.

It sucks, because I love this car (after 10 years of BMW's), but I'm nervous about staying with Jag after all this. What would you do if this was your car?

 

I have a partial update. The issue which they thought was being caused by carbon fouling ended up being related to a coolant leak that happened 5 months ago. When they got the heads off to look inside, half the engine was shot/damaged from overheating. Warped cylinders, warped pistons, etc.
Dealer said don't worry, not your fault, and it looks like we will be putting in a new engine.

 

Glad you caught it before it went out of warranty. There have been a lot of issues related to water pump failure and subsequent coolant leaks on the XF; primarily the '10+ 5.0L engines I believe. I don't remember having a problem with my '09 XFS (4.2L S), but I did on my '11 XFR (5.0L S). I think there are quite a few threads on here which provide some detailed information. Good luck with everything.

 

Oh, and by the way, BMW has had their fair share of engine related issues, especially with all of their vehicles using their N54 and N55 engines (3.0L twin-turbo and twin scroll turbo straight-6 engines), i.e any vehicle with the *35i designation and associated SUVs. The fuel pumps kept going bad and either putting the cars into barely-drivable "limp mode" or making them completely undrivable. It's been so bad that BMW actually extended the fuel pump warranty to 10 years or 120,000 miles on many of them. I experienced this failure personally on my previous '09 335i convertible, when it refused to start in the middle of a parking deck and had to be towed out - all due to fuel pump failure.

My intention in bringing that up certainly isn't to bash BMW (of which you said you've driven for the past 10 years), but rather to point out that plaguing engine issues aren't exclusive to Jaguar. BMW makes some of the finest automobiles around, and they still got slammed by something similar.

 

There is a certain VIN range and above in the XF 5.0L 12 MY that the new or improved water pump was being installed....I had my dealer check mine and I was safe or had the new style pump.

 

Yeah, but the difference is that BMW extended the warranty to deal with the issue. I had to pay $1200 for the water pump when it went out at 60,000 miles.

That was disappointing, and Jaguar really should've stepped up to pay for it.

 

[QUOTE=
My intention in bringing that up certainly isn't to bash BMW (of which you said you've driven for the past 10 years), but rather to point out that plaguing engine issues aren't exclusive to Jaguar. BMW makes some of the finest automobiles around, and they still got slammed by something similar.[/QUOTE]

I understand. I've done a lot of reading recently, and have been surprised to find how wide spread these issues are with BMW, Audi and others. I was nervous and questioning everything because of how often my car has been in the shop this year. I'm the butt of more than a few jones at work because of it this car. But all that said, the dealership has been awesome, and I still really, really love this car.

Before I knew what the diagnosis was, I started looking at 5 and 6 series bimmers, as well as the panamera's and Teslas, but after having this XF, I'm definitely going to have to stay with Jaguar for a while. The driving experience, the styling, and now the support, both at the dealer and online, is impressive.

So here's hoping the surgery goes well on my car.

 

Was one of these mine?

 

Can you tell us a little more about the problms with the inlet pipe. Is that something we should be keping an eye on?

Thanks

 

Other than a leaking water pump, which Madison Jaguar cheerfully covered under warranty, no issues with the engine on my car at all.

If it's that big a deal later on, I'll yank the heads and clean them up. No big deal. OTOH, I like doing stuff like that.

 

Here are pics of my 5.0l XF engine with plenty of deposits on the valves at about 50K miles. I think deposits will attract more deposits, so I am cleaning all the intake valves now so the air flows better.

https://www.jaguarforums.com/forum/x...3/#post1496747

 

There are more photos in this thread of the carbon build up on the intake valves and ports.

https://www.jaguarforums.com/forum/x...ebuild-177468/

Very well documented post. I suggest you check it out! It's awesome seeing the internals of the engine in its various states of disassembly.

 

You should use E85 or water/methanol........

 

You should research how direct injection works and why intake valves foul before making rubbish recommendations.

 

I do not post rubbish recommendations:

" The main reason is that fuel and added detergents are not hitting the back of the intake valves. By injecting the fuel directly into the cylinder instead of at the back of the valve, the gasoline and detergents can’t clean the valve and port. "

So, when you spray water/methanol near the TB or at least before the intake ports, you keep clean the backsides of the intake valves as well as ports.