S class (W140) and LPG

[ipsg.glf]

OK, I've been hankering after one of these for years.

So the plan would be to get one (either an S280 or S320) and LPG it. As lng sa I can see 40MPG from 70MPH I think the finances stack up.

Anyone been there, done that, with this sort of car?

Cheers

[XB70]

Why?

30mpg at 70mph is easy without LPG (though not on the S280) and the £3000 or so for a decent LPG install buys a LOT of petrol

My S600 sits at about 29mpg on the motorway since the engine is doing nothing and barely ticking over

[alsem]

Putting a S class on LPG is like feeding lettuce to a lion! It's stupid.

[OdramaSwimLaden]

Ignore the d*ck....

I had use of an 06 S500 with a 120L (I think) LPG tank in the boot for a month last summer......it makes perfect sense if you're keeping the car for a while, like a big engine and do many miles.. It did the equivilant of 50mpg!

Make sure you go to an accredited LPG company.

Edited by OdramaSwimLaden on Sunday 12th June 18:06

[jith]

OdramaSwimLaden said:

Ignore the d*ck....

I had use of an 06 S500 with a 120L (I think) LPG tank in the boot for a month last summer......it makes perfect sense if you're keeping the car for a while, like a big engine and do many miles.. It did the equivilant of 50mpg!

Make sure you go to an accredited LPG company.

Edited by OdramaSwimLaden on Sunday 12th June 18:06

I think you should ignore the crass, ignorant insults to other members on here and listen to professional advice.

I have had 3 cars in the workshop over the past 4 months with LPG conversions. All 3 owners had this done due to the misconception that their cars were heavy on fuel, and that the answer was an LPG conversion.

The first was a Range Rover 4 litre V8. It was actually running on 5 cylinders. A compression test revealed all cylinders good and within 5% of each other. It was fitted with the wrong spark plugs. 2 of the high tension leads were shorted on the exhaust manifolds. The air filter was absolutely filthy. A diagnostic revealed no less than 3 of the lambda sensors either shortened or high readings. The MAF sensor was completely shorted out. The breather filters and flame traps were completely blocked.

Now here's the thing: the company that fitted it, who were "accredited", were supposed to have diagnosed the vehicle for suitability before fitment, and actually stated they had on the invoice. Unbelievable incompetence. 3 of the LPG tubes to the injectors were loose and leaking and the ECU had been bolted to the lower inner wing so that it got soaked when going through water.

I repaired all the faults and set the engine up properly and suggested that the customer run it for a feww weeks on petrol only. He returned the following week to tell me he was getting 27 MPG on petrol and has no intention of turning the LPG back on.

Last week I had an absolutely stunning Jaguar in with only 27000 miles on the clock, despite the fact that it was a 1997 XJ6 4 litre. The owner had just purchased the car and immediately had it converted, by one of the largest specialists in this area. The car was running on 5 cylinders and, once again, had the wrong spark plugs fitted. A diagnostic revealed that No 1 (rear) coil pack was down, no spark.

Why the hell did they carry out this conversion when the vehicle had serious running problems that resulted in extremely high fuel consumption?

I fitted a new coil pack and the correct set of plugs and the Jaguar once again purred. It will be interesting to find out what kind of consumption the new owner now gets.

The whole point of this is that many vehicles are very badly tuned or set up and this is the cause of excessive fuel consumption. An LPG conversion will not improve things and in actual fact can result in damage to the engine due to pre-ignition if the system is not functioning correctly. I would also question the long term reliability issues of these LPG systems on modern, highly stressed engines that are not designed to burn this kind of fuel.

J

[BigBen]

OdramaSwimLaden said:

Ignore the d*ck....

I had use of an 06 S500 with a 120L (I think) LPG tank in the boot for a month last summer......it makes perfect sense if you're keeping the car for a while, like a big engine and do many miles.. It did the equivilant of 50mpg!

Make sure you go to an accredited LPG company.

Edited by OdramaSwimLaden on Sunday 12th June 18:06

That is quite amazing. I got 23 mpg out of my last tank of petrol on my S500 which was a result of me driving carefully to see what would happen. 50mpg on LPG suggests about 30 on petrol doesn't it ?

Ben

[alsem]

OdramaSwimLaden said:

Ignore the d*ck....

I had use of an 06 S500 with a 120L (I think) LPG tank in the boot for a month last summer......it makes perfect sense if you're keeping the car for a while, like a big engine and do many miles.. It did the equivilant of 50mpg!

Make sure you go to an accredited LPG company.

Edited by OdramaSwimLaden on Sunday 12th June 18:06

Look at this picture:

These are proper cars, they are great to own and drive, and a v8 with 300.000 miles can drive like new.

But do you know why they are all together at the same spot? they have a LPG installed, most of then suffer backfires at some point and they lose horsepower by the LPG.
Plus if you have an engine that has been run in for 30 years on petrol and you change the fuel to LPG the engine will never run as good as it used to be. some say the engine wears twice as fast on LPG compared to petrol, in my experience it wears more like 3 or 4 times as fast.

This picture is taken at a w126 garage which I regularly visit just for fun, my S (the red one) still runs on petrol, but 50% of the cars are on LPG, and 90% of the problems with these cars are in combination with LPG.
Yes I'm a dick, but at least I have a nice car

[OdramaSwimLaden]

BigBen said:

OdramaSwimLaden said:

Ignore the d*ck....

I had use of an 06 S500 with a 120L (I think) LPG tank in the boot for a month last summer......it makes perfect sense if you're keeping the car for a while, like a big engine and do many miles.. It did the equivilant of 50mpg!

Make sure you go to an accredited LPG company.

Edited by OdramaSwimLaden on Sunday 12th June 18:06

That is quite amazing. I got 23 mpg out of my last tank of petrol on my S500 which was a result of me driving carefully to see what would happen. 50mpg on LPG suggests about 30 on petrol doesn't it ?

Ben

Late 20's; yes.

It depends where and how you were driving. On the motorway it is feasable to see 30mpg on the motorway.

[albundy89]

Why does everyone slate LPG? I run 5 vehicles on it including a 4.6 range rover which according to computer averages 18.5 mpg and believe me fairly brisk driving.
I have the luxury of a 2000 litre tank to fill from and my last bill came in at 59.9p per litre plus vat of course figure the maths and cost for yourself.
Incidentally being a fairly heavy motor some nitrous is added so makes it slightly more expensive and faster to run.

[blueango]

Hi there, I've just been reading through the posts with regard to LPG conversions on Mercedes S class and I thought I would just add my experience, it might be of interest.
I found myself in a situation last year where I needed to change from a manual to an automatic gearbox. I previously had a ford galaxy 1.9 diesel which I was quite happy with and it consistently returned around 45 mpg. I live in a rural setting with mainly country lanes mixed with some expressway driving. As I said I had to change to an auto gearbox so I ended up buying a Mercedes S280 W140 which had an LPG conversion on it. I didn't know what to expect really, I just hoped it would be economical. I had a few initial problems with it as mentioned elsewhere in these posts (misfires, bad plugs, not serviced etc) Anyway I sorted these problems out and started using it on a daily basis. I have a gas tank in the spare wheel well which I think is between 70-80 litres. It normally costs me around £40 to fill from empty at 66ppl. I've been collecting my receipts for a few months now so the other night I sat down and worked out what sort of return I was getting mpg wise. Let me just say, I love the car, I don't drive particularly fast on the A roads and I stick to 70-80 on the expressway. A lot of people say there is a big power loss when using LPG, well I don't go along with that, I don't really find any difference at all but maybe that would be a problem if you drove everywhere flat out. Anyway I was quite amazed to find out that the mileage I was getting on the lpg was approaching 50 mpg! I would say combined with the petrol it uses on the initial start up included I'm safely getting as much mileage as I was out of my ford galaxy diesel, But I have to say it's certainly a much nicer car to drive and to be in!
Hope this is of interest to anyone thinking of going the LPG route I am so impressed that I'm now seriously thinking of going for a coupe with a V8 or even a V12 and getting it converted