Does LPG cause early head failiure?

Hi

To all out there running P38's on LPG - does long term use of LPG cause the head to fail??

There are a couple of ads on ebay and autotrader at the minute with folk saying they have replaced heads and not ran the car on LPG since! - the reckoning been that running them on LPG runs the engine hotter than on petrol and this caused them to fail.

I'm on the look out for a converted P38 at the moment and stuff like this is really making me think twice n putting me off!

Thanks in advance.

chrish22 said:

Hi

To all out there running P38's on LPG - does long term use of LPG cause the head to fail??

There are a couple of ads on ebay and autotrader at the minute with folk saying they have replaced heads and not ran the car on LPG since! - the reckoning been that running them on LPG runs the engine hotter than on petrol and this caused them to fail.

I'm on the look out for a converted P38 at the moment and stuff like this is really making me think twice n putting me off!

Thanks in advance.

Click to expand...

i have a 96 P38 4.6 hse on lpg with engine rebuild 10k miles ago! the extra heat developed by using lpg is apparently easily dispursed by the stock cooling system, i have never seen my gauge any higher on lpg than i have on petrol! never.
i know the gauge is only an "indicator" and not to be taken seriously but it dont move!

and it dont wash the oil from the bores either!! got to be good...........

Worked for a dealership many years ago and was disturbed at the number of vehicles that came back requiring valve clearances adjusted repeatedly, and then we discovered that it was the LPG conversion that was causing the engines to run so hot that it was burning the valves and seats. "****ed the engines" The conversion fell on it's arse at that time and I would like to think that modern materials have irradicated this issue, But I would not convert.

david451 said:

Worked for a dealership many years ago and was disturbed at the number of vehicles that came back requiring valve clearances adjusted repeatedly, and then we discovered that it was the LPG conversion that was causing the engines to run so hot that it was burning the valves and seats. "****ed the engines" The conversion fell on it's arse at that time and I would like to think that modern materials have irradicated this issue, But I would not convert.

Click to expand...

Also burning petrol (LRP) causes soft fluffy sooty bits (tiny amounts) which pass over the valve seats and surfaces and slightly cushion the valves when they close, stopping them beating themselves into the seats and wearing as much.

This fluffy soot was caused by the lead in good old fashioned 4 star, when it was removed and unleaded was the flavour of the month older engines needed new special valve seats as they suffered the same fate.

Though I think that LRP (lead Replacement Petrol) has an additive that does the job that lead used to do, but without the nasty stuff that lead does, i.e. poision you!

david451 said:

Worked for a dealership many years ago and was disturbed at the number of vehicles that came back requiring valve clearances adjusted repeatedly, and then we discovered that it was the LPG conversion that was causing the engines to run so hot that it was burning the valves and seats. "****ed the engines" The conversion fell on it's arse at that time and I would like to think that modern materials have irradicated this issue, But I would not convert.

Click to expand...

how long ago was this? would it be down to the lack of lead in lpg compared to leaded petrol at the time, engines now have valve guides and seats to run on unleaded which would cure the problem, maybe??

edit, snap!!!

redrange said:

how long ago was this? would it be down to the lack of lead in lpg compared to leaded petrol at the time, engines now have valve guides and seats to run on unleaded which would cure the problem, maybe??

edit, snap!!!

Click to expand...

It was a while ago, about when the fords were having "running on problems" due to heat, and fuel shut off valves were fitted to the carbs, and then the valve to purge the engine with cold air. At that time the engines had been made to run hotter to be more efficient but the heat produced, and the lean mix produced the running on problems.

I think we were still running on lead fuel at that time.

Its a shame fuel is so expensive because the v8 is the untimate engine, but the cost of an LPG conversion is also so expensive, combined with the limited technical ability of garages to repair it, and few supply points.

I think at that time most valve seat inserts were cast and likewise for the guides. I remember changing a set of inserts for the much harder material but can't remember what it was called, I cut them and the valves with 5 angles for performance and the guides were changed for phosphor bronze but both had to be made because you could not get them off the shelf at that time.

Did you see the program on tv recently a 4x4 is born, lots of interesting information but too much focus on the suzuki and not enough on the landie, also the guy who kept the museum claimed the gaylander was very capable, but looking at the threads on this site I think he must have bumped his head.

Thanks for the info chaps. I've took the plunge anyway and bough an LPG'd 4.6 HSE - I'm sure I'll have lots more posts n questions over the coming months and if the LPG doe sseem to cause any issues I'll be sure to share them!

Thanks.

Hope to see some pics of it, Was at an outing at the weekend there in argyll forest and there was an awesome example of a P38, He is considering getting the multi point system fitted to his 4.0 HSE.