Hi all - revisiting this topic. Anyone know if anymore of the 3.0 V6 S/C (AJ126) engines have experienced rattling and/or need to have tensioners and guides updated? With time and mileage increasing, I'm anxious to understand if this has subsided, or really is a thing.
I'm craving a X351 XJ with this engine, and am hopeful that this issue is less of a concern now.

 

Get the 5.0 SC. You will thank me later. Yes, they can get the same timing problems as the V8 but also have the added complexity of the balance shafts.

V8 or GTFO IMO.

 

What year car do you have? The early cars had more problems as Jaguar made running changes to improve this.
Somewhere around model year 2014 they did the latest upgrade.

Remember that the V6 and V8 share the same block so all the front end stuff is almost identical. Helped Jaguar because it kept a lot of the parts the same regardless of engine type. Also don't forget the water pump is really the failure prone item. Don't let the car overheat that will kill the engine.

Also change oil more often than the factory intervals. A lot of guys including me now do 6K-8K miles oil changes. One guy even went to 2K intervals and never had a bit of trouble and he had a 2010 5.0L SC XFR!
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Thanks Club!
I finally got back into a Jag yesterday. 2016 XJ, 3.0 s/c. Low miles @ 47k and good maintenance, which I will continue AND supplement as you've done.

 

47,000 miles on my 3.0, the only problem has been a slight smell of coolant, accompanied by a slow loss. I raised this at the last service and they changed the thermostat housing, which fixed the loss, but a slight smell remains.

I'm on the original water pump.

They also replaced the supercharger coupling under the CPO warranty, as I mentioned the classic switch off rattle. Made no difference whatsoever.

 

Hi other Mark - I am noticing the slight smell of coolant as well...will be taking it into my dealer ASAP for them to sort through.

 

Let us know what they found/fixed. I have a slight coolant smell as well. No coolant loss after thousands of miles, though. New water pump and pipes. Pressure tests OK. I heard somewhere that all these engines have this smell; something to do with venting. May be legend or wishful thinking.

 

you should be ok regarding the tensioners. I have not heard of any major cases on the 3.0

 

... Depending on the post you're talking about, I think they did (Mark SF did, anyway)!

 

The cooling system doesn't have an atmospheric catch tank, so it's probably venting some hot air sometimes from the header tank, and that will smell of coolant.

However, as well as the smell, whenever I added coolant to take the level to the full mark, that extra would disappear and the system always wanted to settle at the low mark. Now, after the fix, it has remained at the high level. It still does smell slightly of coolant.

I think it had a slight leak at high pressure.

So if your system pressure tests OK, and the coolant will stay at the high level, a slight smell is normal. On the other hand, a loss of coolant should be investigated.

 

MarkSF are you saying the coupling was changed but you still have a clunk on shut down?
Yes I swear my XJR always has a whiff of antifreeze smell and I have not lost any coolant ever. Water pump changed almost 30K miles ago.
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Great info all - I have not noticed any loss of coolant either (albeit I've only been monitoring for 7 days now, but with plenty of use), but just as described only a minor whiff after it gets hot.
Will report back any updates.