hi everyone which Jaguar ENGINE is more reliable.
AJ126 from year 2015 until today as production not sure when it was ended.V6 with supercharger around 340-380hp.
V8 petrol 5.0 L AJ Gen III V8 with or without supercharger , installed on XJ and other jaguar cars... from year 2009 untill 2020 i think. i think engine is called AJ133?

 

They are basically the same engine. With either one, you want 2014 or newer because of the upgraded timing chains.

 

Which one is the most reliable and easier to maintain, and with less issues?
i heard both engines suffer premature chain wear and some other issues...
Is the v8 engine more expensive to maintain, i am not talking about fuel, just for repair and maintenance?

 

I am not joking. It's literally the same engine. So it's about the same for cost of maintenance. The cost difference is so small, that if that little of a difference is a big deal to you, then you won't be happy with a Jag.

 

So replacing timing chain on both is the same price,are both engines with the same or simular prices in terms of parts and labour.
i guess , and both have same issues and same reliability none is far reliable than other ?
I know that v6 is created from v8 but i guess they are some difference are both engines controlled by bosch ecu?
My main concern is the reliability , also v8 is much more hard to find and see compared to v6...

 

If you want parts prices, go to the website of one of the OEM parts dealers and look up the parts you want for both versions of the engine to see how the price differs, if at all. I know a supercharger snout for a V8 is less than V6 by about $200.

 

Is the labour absolutely the same in terms of prices and hours etcs for v6 , like in v8.

 

What specific labour operation or operations are you referring to?

Here is an X351 having new timing chains, guides and tensioners installed on an AJ126:




Work on the timing chains can be done with engine in situ.

This particular vehicle also needed new head gaskets, and received an aluminium water outlet, oil cooler adapter, and other cooling system parts. It was not possible to replace the head gaskets without removing the engine and gearbox:




Replacing the head gaskets and other necessary parts is 25 hours of labour, exclusive of machine work on the heads, valves, and setting valve clearances. The amount of labour for the AJ126 and AJ133 for the same operations are equal. Machine work on the AJ133 cylinder heads is more.

 

Thanks you have answered my question with that 25hour of labour i guess most repairs are engine out job.
In that case , is this engine which is older better option in terms of reliability AJ33S and also easier to work on?

 

I have heard the 6 cylinder has less issues with timing chain....

 

Could that be because the V8 existed years before the V6 and they both had their timing chains updated around 2014?

 

Not quite.
The V6 came out in 2012 and has only ever had the updated timing chains, and it was around the same time that the V8 timing chains were updated. I don't think there were any further updates since 2012, maybe a minor tweak or two but nothing major.

 

Maybe that the timing chain drive components are the same for the 32 valve V8 and the 24 valve V6 (with 25% less load on the chain drive) could also contribute.

 

Ignoring the early TSUBAKI system, there have been 3 versions of the INA timing chain tensioner system on the JLR 5.0 V8 Supercharged and 2 versions on the V6 Supercharged engines. Most of us are aware of the original wear prone INA system and of the final updated design mentioned above but there was an intermediate modification to the hydraulic tensioner plunger that many are not aware of. This is what was fitted to the original V6 SC engines and 2012/2013 V8 SC engines.

The image below shows the original and the intermediate plunger design - the intermediate having done away with the step on the end of the plunger. This will have marginally improved the wear characteristics but it was still excessive and was followed by the significant redesign of the tensioner and the guide which solved the original wear problem. (perhaps this intermediate plunger design was an interim fix while the new system was being designed???)

This info is based on what I have actually seen while replacing worn timing chain components but I dont have exact dates or which models/VIN numbers were affected. I have not encountered the intermediate design on any Land Rover V6 or V8s simply because I have not done any tensioner work on these cars from around 2012/2013 so I do not know if they were affected but I would imagine so because the Jaguar and Land Rover variants of these engines came from the same factory.

The video linked below shows this intermediate design in a 2013 Jaguar XF 3.0 SC engine at around the 11 minute mark.

 

Thanks for that.
So other than two updates of the tensioners and one update of the guides, has anything else in the timing system been updated since the initial switch from Tsubaki to INA?
In particular the chains.
I'm trying to figure out if the timing chains in my AJ126 in my Oct 2014 built F-Type maybe need replacement and whether or not better/revised chains and/or other timing related parts (eg tensioners, guides etc) may have been fitted to the AJ126 after my car was built in Oct 2014.
The engine is very rattly especially at cold idle but it sounds to me much more like the classic worn SC coupler than timing chains.
When I first got the car in Sept 2106 with some 26,000 km on it the SC coupler rattle was obvious so I took the car to the dealership to get the coupler replaced under warranty (the whole SC snout per the official warranty fix) but I've never been convinced they actually did the work as the rattle didn't seem to change at all and lately (last two or three years) it has been getting worse. Still only some 74,6xx km so not at all "high mileage".
I had some work done by my favourite shop some three or four years ago and while I was there I described the engine rattle to the shop boss (not a mechanic himself and he never bothered to listen to the engine), and he rabbited on at length about "it's the timing chains, we have done dozens of them, yep it's the timing chains for sure", and he then quoted me $7,000+ AU for the job. Seeing as I was not at all convinced it was the timing chains I declined his generous offer!
I suspect he was talking more about the early AJ133 than the AJ126 but I didn't press the point.

 

I dont know of any chain improvement on the INA system as the chain itself was never the issue. They do stretch with mileage and obviously an engine that is used hard will put more stress on the chain but that applies to any make of car. I doubt the original chains are made from metal that stretches more which needed a change but one never knows what happens with the "men in white coats" in the design bureau.

The SC coupler noise is very distinctive and is a lower pitch than timing chain rattle. Its also very random wheres a timing chain noise would be rhythmic. I did a coupler change on a noisy supercharger going from the original type to the solid version, only to find that the noise remained which was very disappointing.

This is an excerpt from EATON's patent on the torsion damper and explains what causes the noise.

Torsion damping mechanism for a supercharger
US 8042526 B2
During non-supercharging, low engine speed or idle speed operation, the meshed teeth of the blower timing gears may be substantially unloaded and may bounce or clash back and forth against each other through the backlash therebetween. The bounce or clash may produce an objectionable noise known as gear rattle and is believed to be caused by torsionals in the supercharger drive torque provided by periodic combustion engines.

During past research on this problem faced by JLR owners, I came across a video of an Eaton SC on some Amercan V8 engine which uses the same SC unit as the JLR engines. The vehicle was nearly new and the SC noise was very pronounced. Whether or not it was rectified is unknown but it may relate to your snout being changed while the noise was actually more on the meshed teeth and not the coupler/snout.

A couple of years ago I was asked to do the tensioner/guide upgrade on a 5.0, 2014 L494 (Range Rover Sport new shape). The agent said that according to his parts manual, this 2014 model still had the old system fitted so I ordered the parts and got busy. I always remove the lower timing chain cover first so I can inspect things before going any further and found they were the latest version. This tells me that there is a grey area around the change over so your F-Type may or may not have the latest although I would imagine its has the new.

There is a JLR shortcut procedure to change the tensioners and guides only which is particularly useful on lower mileage engines. Once the chains have stretched excessively it becomes risky doing the shortcut due to the fact that even the upgraded tensioners can only accommodate a certain amount of stretch. Many garages either dont know about this procedure or dont want to take the chance that some other component may be badly worn which could mean them getting blamed for future failures but the cost saving is substantial over the full procedure which changes so much unnecessary stuff.

Sorry I cant be more specific with regard to your year/model. Perhaps your local agent can shed some more light on what you have fitted.

 

Thanks again.
Yep, I know about how the sound of a worn rattling torsion isolator is very different to the sound made by a loose timing chain, but I didn't know about the possible gear teeth rattle and maybe that is what my car has.
I know for sure my F-Type has the INA chains coz they have three links vs the Tsubaki which have nine links, very easy to check by taking the oil fill cap off and taking a peek at the top of the clearly visible chain. I am 99.9% sure the AJ126 never got the Tsubaki chains and I am 95% sure that all AJ133s from 2012 onwards also got the INA chains. Only 95% sure coz maybe some AJ133s destined for Range Rovers got the old gear so as to use up parts inventory.
No point in contacting my local agent they are clueless!

 

Absolutely. Only the very early 5.0 2009/2010 got the Tsubaku system which means anything after that is 100% definitely INA.

 

I have the rattle and my tech found a loose supercharger coupler. On another question posed, could it also be that as the 6 cylinder has less torque there is less strain placed on the chain?

Also, could it also be because (unless I am mistaken) Jaguar designed it with a single row (WHY???) chain that these chains are just very, very sensitive to the timing being absolutely accurate?

Double row timing chain, benifit vs cost [Archive] - Australian LS1 and Holden Forums.

Also: -
"When street engines were flat tappet lifters and non bearing trunion rocker arms, there was a lot of friction to the valve train and the friction would be transferred to the cam and add to the stress on the chain. Chains would stretch and sometimes break or slip a tooth on the sprocket. Double rollers allowed for better handling of the stresses and resulted in less failures or stretching.
Newer engines with roller lifters and roller rockers have less friction and a single roller is often enough. There are often tensioners on the chains to keep the stretching from becoming an issue."
Source: - https://www.ls1gto.com/threads/when-...often%20enough.

 

It's really not that hard to remove the intake parts and remove the supercharger belt so you can feel if the coupler is bad. It should not have any free play or noise when gently rocking the pulley left and right.