henrytilly

Active Member
hi , guys thinking of buying a p38 4.6 , but i would like to know their pit falls , what are they like on fuel i know they are thirsty but will i see 20 mpg , also do they lpg well or not , thanks
 
Main problem is cylinder liners slipping. I've got one for sale with just that problem. Otherwise in brilliant nick with a long MOT, but an expensive repair for whoever buys her.
 
If you want one to run LPG, go for the 4.0 as the 4.6 prefers petrol and has a tendency to burn valves on hotter LPG than the 4.0.

LPG is bad because it offers no cooling nor lubrication to the valves. It is a gas and it burns.

Petrol is loaded with lubricants and does cool the valves when it is sprayed in on the injector...
 
You might see 20mpg being very careful on a steady run on the motorway but if you are mainly round town bet on 13mpg, general knocking about mixture of short and longer runs I get around 16mpg.

Look at a few vehicles before choosing, try and buy an MY99 car onwards with a Thor engine they are more powerful and generally more reliable. I would personally avoid anything on LPG as it can cause more problems and I dont believe its worth the effort unless you are doing massive miles and avoid anything on springs as working air suspension is the best thing about the cars.
Main issues are electrical with things ranging from radio/navigation system problems to the BECM (main car computer) to remote locking issues and door locks causing all sorts of mischief. Most of it is fairly simple to resolve and there is a wealth of information on the internet on how to fix most things.
To give you some idea, I bought a "good" late model vogue and have poured about £800 into it in servicing and repairs in the last 6 months and covered 1100 miles. I think most people would consider that fairly normal for a P38.
 
P38 doesn't rust like the classic, but any old motor has challenges. Check everything before you buy. If you can do the jobs DIY then it will be interesting but fun. If not you will need deep pockets. air suspension is easy to fix (mostly leaks), but nice when you get it working. Maintain it and you will have good motoring.

Slipping liners depends on how the block was cast, and how they were fitted. Some seem to have support at the bottom of the casting (found this on my 4.0 recently) and hence cannot slip. Others need replacing with top-hat liners, or may never give issues.

Electrics can be challenging, but most issues are corroded connections which are easy to resolve. Check signs of water leaks all over the inside.

Check drivers footwell near heater for O-ring leaks. They are difficult to change without removing the dash . . . .but it can be done at home in a day.

Plenty of buying advice on here, so use the search. Others will add more stuff to watch for.

and lastly you aint gonna get 20mpg overall, but can be done on a motorway run, depending on how heavy your shoes are.
 
never had a problem on any p38s ive owned on lpg 4.0 or 4.6

+1. No problem with LPG.

Read up on the slipped liners. As PWood says some were different and there is a way to tell from the block, I think.

Budget another £1000 for inevitable niggles. There's generally something. New airbags and compressor, probably. Maybe a new battery or RF receiver or both. Heater o-rings as above. If you're wiling to fix it yourself he parts are cheap as chips off eBay. If you're paying someone else then maybe you need to look at something without a green oval on it.
 
many thanks guys for your swift replys , the dury is still out on wether i get one or not maybe the bmw diesel engine is the way mmm , well thanks for all your advise cheers
 
I am not sure why LPG gets a kicking.....I have run LPG cars for years and as long as it is all maintained and set up correctly there are no issues.

The Rover engine converts well and had hardened valve seats so regression is of little issue. If worried about it you can fit a flash lube system which adds a fine mist of lube to the inducted air to keep the seats cooler and lubed up.
 
As already said Rover V8's are very good running LPG. No difference between 4.0 & 4.6 running LPG. The 4.6 does come with a much stronger transmission though - go for a Thor. Mine will give 20 mpg on a good run on LPG but then not quite standard as i have a very high compression - better for running LPG.
Slipped liners are a real problem. Mine's on it's 3rd engine (this one top hatted). Interestingly, my old engine had the step at the bottom of the liner but it still slipped (not pressed in fully during assembly).
 
I run a diesel. I think if I had my time again I would go 4.6 with LPG.

Diesels have their own issues: FIP tends to wear out around 120k miles and that's £700 just for a reconditioned pump.
 
I have had 6 from the first 2 door petrol though to the p38 and think they are the dogs do dahs. with a bit of attention and maintanance,they are brilliant.The thing is you may get one that hasnt been looked after,so talk to the seller and get a feel for his interest in the car. wether he did it himself or had a garage do the work . it will be his attitude will tell you loads.
 
+4 or whatever we are up to on the LPG count....

Mine came already converted, and runs happily on the stuff. It was converted about 4 years before I bought it - but have recently just serviced the whole LPG system with new filters, hosework and injectors. Like anything, if you look after it and service it then it will run for ages. The 4.0 and 4.6 engine are pretty much identical when it comes to block/heads - it's the crank that's different between 4.0/4.6 to give a longer stroke - so no issues on either size for LPG.

When I bought mine, I spent about £250 on top of the purchase price fixing the things I noticed on the test drive/looking at the RR... I then probably spent about £2K on the things I found along the way, maintenance, and preventative maintenance over the last 4 years. But then it's lovely to drive, they are a lot cheaper now than when I bought mine, and the V8's sound lovely...
 

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