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crofty1984

Original Poster:

10,338 posts

88 months

[news] 
Monday 14th February 2011 quote quote all
Um, that's the question.

kambites

39,700 posts

105 months

[news] 
Monday 14th February 2011 quote quote all
I know of some cars that have covered huge mileages on LPG with no obvious detriment to their reliability, so I'd say no, or at least not much.

Motorrad

4,976 posts

71 months

[news] 
Monday 14th February 2011 quote quote all
If anything as it's a cleaner fuel a properly set up system should actually cause less wear surely?

Ozzie Osmond

15,998 posts

130 months

[news] 
Monday 14th February 2011 quote quote all
There is no evidence I'm aware of that LPG causes greater wear.

crofty1984

Original Poster:

10,338 posts

88 months

[news] 
Monday 14th February 2011 quote quote all
I'm talking about a 6-cyl W124 merc with about 120k on the clock, so I guess even if it only does 200k rather than 300k before dying I've still got my money's worth.
Though the responses so far are encouraging!
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Max_Torque

7,518 posts

101 months

[news] 
Monday 14th February 2011 quote quote all
The low Lubricity of LPG (compared to gasoline) does lead to elevated wear of the valve seat and guide. However, that elevated wear compared to gasoline MAY not be the "weak link" as it were. i.e., a decent modern engine valve seats and guides can easily do >200kmiles if properly looked after, so even if LPG reduced that by 25%, it would still not likely be the first item to fail. (also, wear in this area is unlikely to be catastrophic, generally just resulting in a little more top end noise and maybe a small increase in oil consumption)

LPG conversions can also suffer from cracked exhaust manifolds as typically the EGT increases whilst running on LPG. However, most people fit LPG for economy reasons, so tend to avoid spending large periods of time at WOT! (i have seen high wear and cracking on a fleet of delivery vans fitted with lpg, as i guess they still get driven flat out everywhere ;-)

grimfandango

372 posts

69 months

[news] 
Monday 14th February 2011 quote quote all
Motorrad said:
If anything as it's a cleaner fuel a properly set up system should actually cause less wear surely?
I also thought or maybe read somewhere that it caused less wear as it was a cleaner fuel.

AndyLB

386 posts

48 months

[news] 
Monday 14th February 2011 quote quote all
Having done 40,000 on LPG I can say in terms of wear, I had the head off mine for a head skim, timing chain & HG jobby and no wear is apparent over and above what would be expected running on petrol.

Away from wear, the head was remarkably uncoked and the oil stays biscuit brown far longer than petrol cars I have had.

Of course on cars with the soft valve seats, more wear will occur on LPG if correct lube is not added.

Faust66

943 posts

49 months

[news] 
Monday 14th February 2011 quote quote all
My girlfiend's daily driver is a 2.5 V70 with approx 160k miles on it.

She had an LPG conversion done about 50k miles ago and I've got to say that I've noticed no changes in either the performance or reliability of her car. She's got a very heavy right foot (I maintain she was a white van driver in a former life!) so I'm pretty sure if LPG causes excessive engine wear I would've noticed by now - I do all the servicing on her car.

If I could justify the cost, I'd have my car converted tomorrow.

JollyGrnMonster

869 posts

81 months

[news] 
Tuesday 15th February 2011 quote quote all
Max_Torque said:
The low Lubricity of LPG (compared to gasoline) does lead to elevated wear of the valve seat and guide. However, that elevated wear compared to gasoline MAY not be the "weak link" as it were. i.e., a decent modern engine valve seats and guides can easily do >200kmiles if properly looked after, so even if LPG reduced that by 25%, it would still not likely be the first item to fail. (also, wear in this area is unlikely to be catastrophic, generally just resulting in a little more top end noise and maybe a small increase in oil consumption)
how would valve to valve seat seal or nonseal due to seat errosion cause a change in oil consumption?

It would cause loss of compression and loss of power, increased fuel consumption etc

Simon

Max_Torque

7,518 posts

101 months

[news] 
Tuesday 15th February 2011 quote quote all
JollyGrnMonster said:
how would valve to valve seat seal or nonseal due to seat errosion cause a change in oil consumption?

It would cause loss of compression and loss of power, increased fuel consumption etc

Simon
did you miss the "and guide" bit ?? ;-)

The Wookie

Attendee

9,957 posts

112 months

[news] 
Tuesday 15th February 2011 quote quote all
I was going to say valve seats, but as said they're so long lived in anything recent then it probably wont be the first thing to go wrong with the engine.

rallycross

5,684 posts

121 months

[news] 
Tuesday 15th February 2011 quote quote all
LPG is amazingly clean burn fuel, our volvo v70 LPG (bi fuel factory fit) has done 130,000 miles with regualr servicing and the engine is as good as new, never had a problem. In fact its done 25,000 miles in the last 14 months, when the plugs came out for inspection they were like nearly new. If you put your hand over the end of the exhaust its as clean as if it was new, no black ring mark from burnt fuel.

I think a good LPG system will help a car last much longer than normal petrol because the fuel burns so clean.

littleredrooster

2,501 posts

80 months

[news] 
Tuesday 15th February 2011 quote quote all
AndyLB said:
....Of course on cars with the soft valve seats, more wear will occur on LPG if correct lube is not added.
Added to what? The LPG?

bigfatnick

813 posts

86 months

[news] 
Tuesday 15th February 2011 quote quote all
with regards to the valve seat wear issue of lpg, the aussies have a kit that sprays lube into each inlet port at a carefully metered rate. I think it gets fitted to rover v8's on lpg a lot.

Life Saab Itch

37,053 posts

72 months

[news] 
Tuesday 15th February 2011 quote quote all
littleredrooster said:
Added to what? The LPG?
You can buy a kit that vacuum-mists some snake-oil directly into the inlet manifold.


entwisi

711 posts

75 months

[news] 
Tuesday 15th February 2011 quote quote all
That will be flashlube...


Personally I've covered > 250K miles on LPG over 3 cars, all weer fine and teh oil that comes out isn't much different in colour or feel than that that went in its so clean burning.

I found it smoother but it is more susceptible to poor quality spark so make sure the ignition system is in good condition.

my V70 2.5 LPT was sold at 230K and still running fine..


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