L322 2006 v8 LPG buying advice help

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Greg0ry66

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I would appreciate any advice on an intended purchase. 2006 HSE V8 petrol, converted to LPG in 2010, 76k miles FSH, 1 owner, jaguar engine. Purchasing from a trader so sale of goods act protection. Price is 13.5k.
I think this is a good deal, but I have some concerns over the effect of the LPG conversion on the engine. Unsure how many of its miles on LPG, but I'm guessing around 30k. Any thoughts/experience/advice would br very useful. It will be a 2nd car so I don't expect to do any more than between 6 and 7k miles per year in it. I do very few short runs, usually 25 miles plus, and would expect to keep it around 3 year. Obviously, I can use petrol to avoid damaging it (further...) but would rather use gas. If I do damage the valves/seats, how much of a pain/cost is it to whip the heads off and replace valves/seats? I would be likely to use a local LR specialist who charges 40 plus VAT per hour.
Thanks in advance
 
From my understanding the Jag 4.4 AJ V8's don't like LPG to much....not 100% sure what the issues are and it may just be doom-mongering from those who don't like LPG conversions, but I have heard these reports so many times it is well worth investigating.

The later L322's were better than the early models, but still suffer gearbox troubles.

Search the Jag forums and also try fullfatrr.com as they have a good deal of information on the later model L322's....
 
Saint.V8 said:
That's what I thought (as above) but not sure why...any clues??
Click to expand...
maybe this ant:eek:

Due to the ever increasing cost of LPG and the unsuitability of most modern petrol engines from around 2006 onwards most now suffer from severe exhaust valve and valve seat recession when converted to run on LPG. This is caused by cheap and poor quality materials being used in the manufacture of the exhaust valves and seats, and also the discontinuation of Manually Adjustable Tappets, Self Adjusting Hydraulic Tappets and engines with VVT Variable Valve Timing.
In most modern multi-valve engines in a bid to reduce prices and ease of manufacture, the makers have opted for fixed clearance or solid tappets which cannot be adjusted without extensive work and often the removal of the cylinder head. These components and materials are fine when running on petrol only, I will explain in more detail below.
This is where the problems with valve seat recession starts, LPG once vaporised is a pure vapour and has no lubricating properties at all, this then passes through the inlet valves and into the cylinder where it is ignited by the spark plugs, combustion takes place and the hot spent gasses exit through the exhaust valves.
Because these gasses are very hot and contain no lubricants or additives they very slowly start to burn the valve face and valve seat of the exhaust valve away, this process (called recession) over time eventually causes the valve to recede in to its seat eventually reducing the valve or tappet clearance to zero. Once this has happened it is only a matter of a few miles before the valve head starts to disintegrate causing loss of compression and misfire. This will also lead to catalytic converter failure if the vehicle continues to be driven with misfires by way off unburnt fuel passing through the exhaust system to the catalytic convertor.
On some cars such as:
All V6 Jaguar / Ford Engines
All Freelander 2's
All V8 Discovery 3's
All V8 Range Rover Sports with super-charged and normally aspirated engines
All V8 Range Rovers manufactured after 2006 with super-charged and normally aspirated engines All the above Land-Rovers now use Ford engines.
Also most Fords
All Vauxhalls after 2006
Subaru, Hondas, Toyotas, Lexus and Nissans can suffer in less than 10,000 miles, even with lubrication systems such as Flashlube fitted these oil injection systems help a little but will not prevent wear entirely.
Pre 2006 L322 Range Rovers with BMW engines and Older P38 4.0 and 4.6 V8 Rover engines are fine and will easily cover large mileages
 
wil2813 said:
maybe this ant:eek:

Due to the ever increasing cost of LPG and the unsuitability of most modern petrol engines from around 2006 onwards most now suffer from severe exhaust valve and valve seat recession when converted to run on LPG. This is caused by cheap and poor quality materials being used in the manufacture of the exhaust valves and seats, and also the discontinuation of Manually Adjustable Tappets, Self Adjusting Hydraulic Tappets and engines with VVT Variable Valve Timing.
In most modern multi-valve engines in a bid to reduce prices and ease of manufacture, the makers have opted for fixed clearance or solid tappets which cannot be adjusted without extensive work and often the removal of the cylinder head. These components and materials are fine when running on petrol only, I will explain in more detail below.
This is where the problems with valve seat recession starts, LPG once vaporised is a pure vapour and has no lubricating properties at all, this then passes through the inlet valves and into the cylinder where it is ignited by the spark plugs, combustion takes place and the hot spent gasses exit through the exhaust valves.
Because these gasses are very hot and contain no lubricants or additives they very slowly start to burn the valve face and valve seat of the exhaust valve away, this process (called recession) over time eventually causes the valve to recede in to its seat eventually reducing the valve or tappet clearance to zero. Once this has happened it is only a matter of a few miles before the valve head starts to disintegrate causing loss of compression and misfire. This will also lead to catalytic converter failure if the vehicle continues to be driven with misfires by way off unburnt fuel passing through the exhaust system to the catalytic convertor.
On some cars such as:
All V6 Jaguar / Ford Engines
All Freelander 2's
All V8 Discovery 3's
All V8 Range Rover Sports with super-charged and normally aspirated engines
All V8 Range Rovers manufactured after 2006 with super-charged and normally aspirated engines All the above Land-Rovers now use Ford engines.
Also most Fords
All Vauxhalls after 2006
Subaru, Hondas, Toyotas, Lexus and Nissans can suffer in less than 10,000 miles, even with lubrication systems such as Flashlube fitted these oil injection systems help a little but will not prevent wear entirely.
Pre 2006 L322 Range Rovers with BMW engines and Older P38 4.0 and 4.6 V8 Rover engines are fine and will easily cover large mileages
Click to expand...
I see, so it is to do with valve seats....great find Will, cheers.

(for what is worth, my BMW 4.4 has a Flash Lube system fitted :D)
 
The BMW engines are fine on the gas but the Jag units really need flashlube fitting. If the LPG installer was any good it will already be fitted and if it is then you have nothing to worry about - apart from the obvious Range Rover part of the equation.
 
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