M116 380 LPG (gas)

[heckflosse]

There's a 1980 380SL for sale near me which I'm thinking of looking at. Addmitedly I was looking for either a 280 or 300SL due to fuel consumpsion but this has had a profesional LPG conversion, 85000 miles, history and is advertised as mint (are'nt they all).

Apart from Insurance problems what are the pros and cons of LPG? Does it shorten the life of the engine or have any other ill effects.

 

[mikeanddot]

Hi heckflosse,
There seems to be a lot of divided opinion on LPG within the Forum - Andy Gayle has forecasts of doom ( see previous LPG threads on this forum ), based on his considerable maintenance experience. All I am qualified to say is that I have used LPG for over 2 years now in a 1989 190E, which has over 100k on the clock, with no ill effects whatsoever. Economy runs at 24 mpg, rain or shine, the oil stays very clean between changes ( every 5000 miles ) and I expect the exhaust system to live longer due to reduced acids/condensate in the system.
Find out who installed the LPG system - if it was an LP Gas Association approved installer, then there should be a certificate to cover the security of the LPG Tank for insurance purposes ( no increased premiums for LPG, by the way). This will go some way to establishing the integrity, or otherwise, of the installation - there are some bad/dangerous ones out there. If you can satisfy yourself on these points, then welcome to the world of 34 to 40 p./litre.

 

[david searle]

There is lots of anti-LPG views about, some based on very poor installations - and these should be avoided.

But if you have a reasonably good installation, then LPG problems can often stem from "backfire" problems, where the gas ignites in the inlet system, which can damage air intake boxes and other bits. These problems can be reduced by fitting a gas injected system, or by fitting anti-backfire devices, but these can mask rather than fix the problem. According to some of the good LPG fitters, LPG ignites easier than petrol. The backfire problems can stem from the breakdown of the ignition components. Arcing across leads that doesn't cause a problem when running on petrol, can start to cause problems when running on LPG, and it is this that causes the backfire problems. LPG will only work effectively on a well maintained car. The ignition system needs to be replaced more often than with petrol, and using better quality parts.

Some of Andy's views seem to be based on problems with LPG systems that have been fitted some time ago and have started to go wrong. The LPG fitter doesn't want to know, leaving Andy to help the customer fix the problems. When the problem is not fixed easily, Andy seems (unfairly) to receive the brunt of the customer's frustrations.

But a good LPG system that is well set up and well maintained can give significant cost savings - if you do enough miles and keep the car long enough. You will get a 10% reduction in mpg, a good system well fitted can cost £1500+, and you should budget for higher ignition parts cost - and you can lose space in the boot.

Having said all this, I looked into it and decided that it was cheaper and less risky to leave my 260E running on petrol.