AJ-V8 pdf Racing Green

[J44EAG]

The strengths and weaknesses of the AJ-V8 are discussed in this document.

http://www.racinggreencars.com/modern/J ... Engine.pdf

Mike Kennedy

[HeLLCaT]

interesting didnt know that about these motors

[mike020150]

It's a good summary but there may be a misprint where engine blowby is discussed. It's my understanding that during warranty Jaguar condemned engines exceeding 39 litres/minute, i.e. those with 40 lpm onwards, not 50 lpm as written in the article. In my experience, good engines have readings of 20 lpm or less and the symptons of impending failure increase steadily as the reading increases. Mike.

[GrandTourer]

I agree, Mike
I also wonder when that piece was actually written (I remember seeing it before somewhere), as there is this 'famous' misinformation again, stating that engines with the Nikasil coated bores ended with the introduction of the 2000MY (ie VIN nos. up to 042775).
I have spent an awfull lot of time to research this so called fact (and many others incl. Jaguar World Monthly have also) and it emerged that the first steel-linered engine left the Bridgend production line something like the 19 Aug 2000 (this is from memory, but I can look up my records for confirmation or correction if necessary). I can also state the engine serial no, but can't be bothered to do that at the moment. It has been said so many times in the past.

BTW, I was amazed that the article in the current JEC Club Magazine, June 2010 edition, entitled 'Driving the Dream' has the same mis-information in it (unfortunately the author's name has not been given in the mag, otherwise I would have contacted him/her personally).

I can also tell you that my 2000MY XK8 was assembled in the second half of April 2000 and the engine was manufactured in April of the same year and it has Nikasil coated bores. Despite the assurance in writing by the Jaguar Customer Services Dept to say otherwise, as they just read off a crib-sheet.
It all stems from the Jaguar Service Information notification that engines from MY2000 onwards are no longer at risk from the 'Nikasil problem', which most people reading that interpreted it as the time the change over to steel linered engines took place.

I bought my MY2000 car on that misinformation, expecting it to have a steel linered engine, but am, after a six-and-a-half year ownership, glad I have the Nikasil engine. I am convinced it will outlast steel linered engines.

[J44EAG]

Interesting observations from both Mike H and Karl.

I`d agree that 50litres per minute of blow-by seems excessive. The method used by maintenance shops is the same as I used to use when I was involved in the light aircraft industry. ie to pressurise a cylinder on the compression stroke, note the blow-by reading and listen for where the air came squirting out. Carb, exhaust or crankcase venting. It was easy to tell if valves or bores were worn. It is a good method of telling the general health of an engine. 20 litres per minute would seem a more acceptable figure for a good engine.

I would agree with Karls suggestion that a Nikasil bored engine could well last longer than a steel lined version. Nikasil is a wickedly tough coating and any wear found after high mileage is more likely to be found on piston rings.

Add to that the amazing lubricating properties of modern "designer" specified engine oils and wear can be reduced given regular oil changing regimes to very small levels. Exceed or ignore oil changes and that is a different story. Even modern oils have a finite life.

I ran a Nikasil 530i BMW V8 for years. I never had a moments trouble with that engine and it was still going like a rocket after 230k miles. Clearly it had never consumed high sulphur content fuel and escaped the scourge of the Nikasil engines duing that period. I see no reason why Nikasil engine Jaguar V8`s should not carry on giving trouble free motoring for many a long year yet. With the passing of high sulphur fuel, so has the cause of the problem.

Mike

[Nik]

Hi Mike ,
I agree with both you and Karl
I have the orginal Nikasil in my 98 XK8 and it had a blowby of 18Ltrs per minute three years ago and 15Ltrs per minute last year
The engine has covered just short of 127,000 miles , always starts and runs perfectly , and uses virtually no oil between oil changes which are carried out every 5,000 miles or twice a year .

In my opinion the key point is NOT high sulphur petrol in it's self BUT short journeys or not allowing the engine to achieve full operating temperature before switching off ,

All the best ,

Nik

[J44EAG]

Hello Nik.

Indeed both high suphur content and oil degradation due to lack of engine temperature achieved on short journeys is extremely destructive.

I made brief mention of the effects of short journey useage on page 40 of the March 2010 magazine. It echoes your thoughts above.

Without wishing to hyjack this thread, on a slightly different tack, I also touched the subject of oil breakdown on gearboxes on page 48 of the June 2010. Regular oil servicing is vital to the modern Jaguar for reliable and reasonable longevity. Good maintenance on the lines you suggest could make extremely high mileage possible without too many problems.

I agree totally with your view point.

A few months ago I wrote a long and detailed article about the effects of oil degradation. It went to nine drafts and 50 hours work before I was satisfied with the content and thrust of the copy. I`m indebted to Mike H for his kind perusal of the original script and for his benevolent tolerance and correction of my corrupted grammar, punctuation and numerous editorial errors. I understand that this article is likely to make an appearance in our magazine in due course and I hope members will find it a useful insight into the effects of black oil!.

As an aside, I also asked a former Civil Aviation Authority mentor of mine for his comments on the copy. Being a dour Scot he replied that
"Its ok of your interested in oil". Personally I`m a great fan of the stuff and all the why`s and wherefore`s within the subject. Hence my efforts in that vein.

To return to the thread, I think the discussion that has ensued since I posted the link on this subject has been most productive and useful to us all. I hope this can continue for a while yet as I`m sure there will be other useful information from members that can allow us to improve our knowledge even further.

What a useful tool these Forums are for us.

Kind regards.

Mike

[GrandTourer]

Well said Mike
Looking forward to the oil issues in a future magazine issue.

[J44EAG]

This link adds a bit more fuel to the fire.

Note particuarly the last part of the link which gives times and dates that the last Nikasil engines were produced.

I`m intregued about the reluctance to install LPG on Nikasil engines. Is this because LPG has less lubrication qualities than "wet" petrol?

Perhaps you know something about this Karl/Nik?

http://www.go-lpg.co.uk/Nikasil.html

Mike

[mike020150]

It just looks like a severe case of overcaution to me in case the LPG were to be blamed wrongly for pre-existing nikasil engine damage but subsequently attributed to the LPG conversion! Mike.

[Nik]

Hi Guys ,
As far as I can recall was there some problems with lack of upper cylinder lubrication with early LPG conversions
I'm talking well before the XK8/R was even conceived when I say early

If that is the case , has the problem been eradicated with new LPG systems

Looking forward to the article on lubrication , I for one will find it most interesting ,

All the best ,

Nik

[J44EAG]

I seem to recall that LPG burns hotter than petrol, is "dryer" than petrol and therefore a form of upper cylinder lubricant is required to replace the loss of petrol lube qualities.

The use of a reservoir bottle for lube oil is quite a common feature in many LPG installations, presumably for the above reasons. Several V6 Jags I`ve seen have been so fitted.

I need to delve further on this subject. Does anyone know more about this issue?

Mike

[mike020150]

I'm sure a lot of the information (misinformation?) about LPG probably dates back to the time before hardened valve seats were used for unleaded fuel. Of the many tests I ran on modern LPG equipped vehicles (not Jaguars), my fleets didn't highlight excessive valve seat wear as an issue and therefore didn't need any additional upper cylinder lubricant to counteract the higher combustion temperatures of LPG. Mike.