LPG and Knackered Engine on Disco V8

[MrWillfin]

Hi guys!

Ive come across a Discovery 3 V8, which has a BRC LPG conversion. The car has been run on LPG for 160k miles, from 40k and now on 200k.

The car is a non runner, as there is no compression in any of the cylinders. This would seem to point to valve seat recession, which with new valve seats cut into the heads, is an easy fix.

Is there anything else on the engine, bottom end wise, that could be overly worn or near to let go because of LPG?

The Jag V8 engine in question is well known to run to over 300k miles when just run on petrol, so thinking it would be just the valve seats that need replaced.

Thanks!

[anonymous-user]

Not because of LPG, no, just the usual wear and tear of 200k miles.

[ChimpOnGas]

I'm surprised it did 160k on gas before it gave up.

Because unlike the venerable old Rover V8 fitted to earlier Range Rovers & Discoverys the Jag V8 is not really a suitable candidate for LPG due to its soft valve seats.

This however can be completely resolved with a top end rebuild, tell your engineer the car will be run on LPG and he'll fit harder valve seats when he rebuilds the heads.

The rest of the engine or the rest of any other engine for that matter will not suffer from running it on LPG, indeed once proper hardened valve seats are fitted the engine will last longer burning gas that it would burning petrol.

This is because LPG burns cleaner & it doesn't wash the oil from the bores as petrol will.

Solve the chocolate valve seat problem and the Jag V8 will do hundreds of thousands of miles on gas.

[Mr Taxpayer]

Prevent valve seat recession by fitting an electronic valve-lube system (e.g. Flashlube). Some lubs systems use the inlet manifold vacuum to draw the lube in. Electronic ones pump it in and are essential on turbo- and super-charged engines... like my WRX Impreza.

[anonymous-user]

Induction method isn't related to the need for flashlube, it's all about the valve seats which are generally very soft in scoobys.

[HustleRussell]

charltjr said:

Induction method isn't related to the need for flashlube

He didn't say it was, he said induction type influences what type of flashlube system to fit.

[Mr Taxpayer]

I'm aware of the soft valve seats (common to a lot of japanese engines) and run the Flashlube one setting higher than than nominally recommnded.

[MrWillfin]

Thanks Chimp, great explanantion.

I have been a bit unsure as to whether to have the system recommissioned once its been rebuilt, but I think I will go with the hardened valve seats and have the system checked over for reuse.

Cant wait to have it all stripped to see if the rest of the engine is ok!