I posted on here a month ago about my very sad Jag (5.0L S/C 70k) - my saga has continued to worsen. Whilst driving about a month ago the engine suddenly when into limited performance mode. I pulled over it was extremely unhappy - car rocking side to side, rough idle and then cutting out.

Long story short - the first garage I took it too tried replacing all the spark plugs and coils, checked for an air leak, checked the catalytic converters, checked the fuel line... It then went to a Jaguar / Land Rover specialist who diagnosed a slipped timing chain.

I have now had the timing chain replaced with the newer tensioners but sadly the car is still unhappy, and the specialist has told me that I am sadly one of the very unlucky ones for which pistons have met valves. I am told the options are: 1) replace the engine with a refurbished or used one. 2) An attempted repair of pistons and valves (high labour time, and still risk that repair won't work), 3) possibly sell the car to the garage and be done with it.

Waiting for quotes for each. Any thoughts? Has anyone else managed to repair one of these engines after that has happened?

 

As I explained in the previous thread, the tensioner failure is such a well-documented failure point with the 5 litre V8 that I cannot believe that any self-respecting specialist would not check for valve to piston contact during the course of the work. It is a ten-minute job. The relevant cylinder head can then be removed whilst the timing chains are off and an assessment made as to whether only valves need to be replaced or whether the piston/rod damage is such that the engine is not economically repairable. If the piston damage is solely restricted to limited marking of the crown then I would live with it and simply replace the valves.

This would all have been relatively straightforward whilst the chains were off but I'm afraid your garage has made a serious oversight as pistons meeting valves is very likely in the circumstances you describe and the specialist should have known this and acted accordingly.

The best you can do is to have the pistons, bore and valves inspected by a competent specialist using a borescope/endoscope and an assessment made as to whether the damage to the pistons puts them beyond use. If the piston damage is slight then you might get away with a valve change. However, much of the previous work would have to be repeated. You could ask for the cost of the repeat portion of the work to be borne by the specialist as they really should have checked all this out the first time around and I suspect that you would have a valid legal claim here in the UK.

You were only "very unlucky" in the sense that the timing slipped at all. Once a slip is confirmed, valve to piston impact is quite likely and a competent engineer would have checked rather than making an amateurish assumption. The easiest step at this point would be a simple compression test on all 8 cylinders. This should show you which cylinders need close inspection. Any garage or DIY mechanic can do this very quickly. I'm only a DIY mechanic with my own lift but I would not have made this mistake. It's a pity that you did not show the specialist my previous post as that might have set them on the correct path but hindsight is always easy.

I'm really sorry that this all seems to be bad news, Edmund.

Richard

 

Thank you for the description @RichardS .

From an engineering standpoint, some of the other engines I have, have been designed in a way that the pistons could never touch the valves as the pistons do not travel high enough and the valves can not fall low enough; unless of course they somehow become disconnected from the rocker arms, which is nearly inconceivable.

But I mention ‘nearly’. I did have a fiat engine, many, many years ago where this did occur; the valve did become disconnected.

The description I’ve read over many years now states “timing chain slipped”. Granted there may be play with the tensioner…. but HOW does a chain skip on a sprocket unless a significant number of teeth are missing?? Almost makes me want to purchase such an engine to investigate this situation…. I said almost;-).

A forums search for “timing chain slipped” shows a number of hits. But I can’t find a thread which categorically and pictorally demonstrates the damage. If someone knows of one…

 

Haven't seen your prior posts.. This was your first symptom? Restricted performance? Usually timing chain issues begin with a startup rattle and get worse from there.

 

You are right Guy. Non-racing engines up to about 30 years ago tended to be non-interference because of the lower compression ratios and lower octane fuels. In more recent times engines have become higher compression to improve fuel economy and that requires a very small compression space so the valves inevitably come into contact with the piston crown if the valve timing relative to the piston position is not as set by the engine designer.

The slippage in the 5.0 V8 is caused by poor chain tensioner design resulting in the tensioner becoming too "loose" and allowing too much play in the chains. The chain has to work hard to push the cams around against all the valve spring tension so once it has a fraction too much play in it, it becomes easier for it to slip over the teeth on the sprocket rather than actually turn the cam. If it slips just one tooth then the damage is probably limited to the valve as it only just kisses the piston. Once it slips another tooth, and it will if the engine is not stopped immediately after the first tooth, then the damage just gets worse and worse. Of course, even that initial slippage could be more than one tooth so it's already terminal.

I've seen a couple of videos on Youtube showing the damage resulting from such a slip with the 5.0 V8. I'll try to find one and post up a link.

EDIT This video shows a chap using a cheap endoscope to show the piston damage on the same engine. It's a 10 minute job so I have no idea why Edmund's specialist did not do it:

Richard

 

@RichardS . Wow!
Thanks for that.

I too am weary of so called “specialists” who don’t follow a methodolgy of “root cause analysis” before “indescriminate part swap out”.

 

That’s a huge red flag for me. If the place that has worked on the car and failed to resolve the issue wants to buy the car, I’d say run.

 

My 2012 X Kr is currently At s Jag dealer in Michigan replacing the timing chain. In addition to that I had to have a couple of fuel injectors replaced. The amount of labor cost alone is staggering. I'm picking it up today and keeping my fingers crossed. Car has 61k on the clock

 

It should be fine provided that the chains were simply getting noisy and neither of them had actually slipped. If the dealer finds that one or both of the chains had slipped, and that should be obvious to them when they strip the front of the engine down, and all they do is re-set the timing and fit new chains, then they are failing in their duty and you will probably be left in the same situation as Edmund. I would specifically ask them if the cam timing needed resetting and take it from there.

Richard

 

My injectors (well, one injector) failed at 63k. I replaced the bank. If you get it done at a dealer, cost IIRC per injector is around $400+. The actual Bosch injector retails everywhere else for $80. So if you do all 8, that's a delta of $2600+ in just where someone orders the parts. Just FYI in case anyone else is looking at doing this.

 

Is this timing chain issue occurring with low mileage cars as well?

 

I think that the problem with the alloy stud in the 5.0 V8 tensioner can start to happen from a relatively low mileage around 50k onwards although it would be more likely around 100k and above depending upon the frequency and type of oil changes. There is usually some warning provided by the cam chains at the front of the engine becoming noisy but if this happens the tensioners must be replaced with the new steel design before any damage is done.

The unusual aspect of Edmunds failure is that, according to the dealer, an ODB scan showed misfiring on all cylinders but did not show any cam timing error codes even though the rough running does now appear to have been confirmed as having been caused by the cam chain jumping teeth. I find this lack of relevant fault codes very unlikely and I suspect that the dealer was either not using suitable ODB software or was not interpreting the results correctly.

Richard

 

What is recommended as a preventative measure for this issue with regards to oil changes? Is it frequency (once a year regardless of how few miles) and/or type of oil? Has the recommended type of oil that Jag has historically used changed? Even with low mileage cars? I currently have 14,000 miles.

 

This is a good summary of the issues with some interesting observations about oil changes: Timing Chain Problems 2010-newer Jaguar Land Rover AJ V8 Engines - JE Robison Service - Bosch Car Service Specialists ? the blog

 

If it's confirmed the damage indeed occurred I'd insist the specialist who performed the replacement provide the repeat labour at no charge inconsideration of their failure to perform a proper inspection prior to performing the repairs in the first place. As this motor was fitted to SO many Land Rovers and Jaguars since 2009, it should be common sense and standard procedure to perform these inspections.

 

Thanks for that link.
Oil change intervals on the AJ133 (and AJ126) has been a hot topic on this site and others for many years, as well as the related oil type/viscosity/brand topics.
After lots of reading and research I came to the conclusion many years ago that the JLR specified oil change interval of 15,000/16,000 miles or 12 months whichever comes first is way too long and I started changing the oil twice as often as that so every six months. These days I only do some 5,000 miles per annum so I have recently changed back to every 12 months. This extract from the linked document supports what I have been doing:

"We have photographs showing curves worn into chains and gears by 100,000 miles even in what we thought were well serviced motors. That leads us to question whether the factory spec oil is good enough, and whether what we thought was a conservative service interval is still too long.

These engines originally ran a Castrol 5-20 Jaguar/Land Rover rated synthetic oil with a high performance filter. A few other makers are now supplying JLR rated oil; all are high end synthetics. We suspect the factory service interval is too long, having watched it move from 15k to 10k. At Robison Service, we have long recommended 7,500 mile intervals out of caution, having seen these lubrication failures in engines whose insides otherwise looked clean. Some people question whether that is low enough, and whether we should recommend 5 or 6k.

If you change the oil more often than necessary, your incremental cost is small and there is no other downside. If you don’t change the oil often enough to prevent engine wear, the only 100% would be a new engine, for almost $30k. On a 90,000 mile Rover, all the repair costs are going to be on you. How would you choose to bet?"

I have also changed to ILSAC GF-6A oil as it is touted as being specifically formulated to reduce timing chain wear.

 

Hi All,

Thanks for all the input. Whilst I sweated over the cost of a whole replacement engine, the garage decided to go ahead and replace the engine heads (free of charge if it didn't work) as a last ditch attempt to rescue the engine. I had a phone call last night to say that it SEEMS to have fixed the problem and the engine is back up and running.

Nervous wait today as they are going to take it for a good test drive this evening to make sure they are 100% happy with it, but hopeful to have the car back tomorrow. Still got a significant bill coming my way for the cost of replacing the timing chains, then a refurbished set of engine heads + all the labour... BUT significantly less than a new engine.

Hopefully will find out later.

 

Thanks for the update @edmundjbradbury . I for one would be confident in rebuilt/overhauled heads.
And yes, repair bills by proper professionals can be expensive… but consider the alternative you experienced: bills by the unqualified can be expensive as well… and still not address the issue.
Best of luck. Looking forward to hearing of the success.
Cheers.

 

I wonder whether someone at the specialists has read this thread and thought "Yeah, we are on sticky ground here legally" and then decided to do what they should have done in the first place?

Richard

 

Or perhaps some just do what’s right?