Thread: V8s on LPG - Flash Lube Required

Not taking sides but my experience,

Had a F150 302windsor on LPG, installer insisted on fitting Flash-lube vacuum fed, vehicle had a slide on fitted and towed a boat, was impossible to get the feed right, it really worked when loaded up or on a fast run Adelaide to Melbourne, if it was adjusted for town running it used no Flashlube at all on the run over which was when it needed it, if adjusted correctly for the run over when loaded and low vacuum then it would use a full bottle in a day driving around town at light loads and high vacuum. Ended up doing a valve at 180K.
Next vehicle an 80 series Cruiser 4.5 multi valve petrol auto, had LPG fitted at 1000Klms, no flash lube, most of its life had a 3tonne van on the back so was running at its GVM or over most of the time,did get the valves checked at 40K for the first 200K, last two times needed no adjustment so went back to normal intervals. Have just sold that vehicle with a tad over 300K on it no problems at all with valves, probably 280K of them on LPG, it does start on petrol then change over automatically, compressions were all fine when sold. That vehicle worked - hard !

DD

I work on and also fit LPG to industrail vehicles.
Most early industrail LPG conversions were with motors with soft valves and valve seats and it is extremely rare to get any sort of valve or seat trouble.
None of these motors get valve lube and most never run on petrol.
I have fitted LPG dual fuel systems to my own vehicles and for friends.
I have also repaired and serviced customers work vehicles etc with LPG conversions and valve saver systems fitted etc.
This is what i have learnt.
1
Any motor on LPG will burnt out valves and valve seats in short order reguard less of valve/ motor design or seat hardness in very short order and if fitted with valve saver lube systems or not.
2
Any motor on LPG can get normal valve wear reguardless if fitted with hard valves/ seats or not or valve saver systems or not.

If you think about the above statements the factor for valve wear must be useage and application.


A motor governed to 2000 rpm ....ie generator or a forklift will last forever with soft valve seats.

Any motor taken to full power and held at full power with the motor on LPG tuned to deliver that power WILL BURN VALVES in a few minutes

A good example was a old G60 patrol I had on gas with a 4 litre P40 motor with non harden valves and seats.
One run up a mountain pass with a full load and a twin axle trailer on the back which was loaded did the valves sustained power in short order.
That same vehicle after a valve job with standard seats and valves again lasted many years on doing the same sort of work.
The reason was afterwards I used petrol on the hard climbs and if I did use LPG on hard climbs I would only use 3/4 throttle and take my time a bit more.

Another example is a forklift with a 4.5 toyota multi valve motor with harden valves and seats governed to 2000 rpm burning out the valves in short order and costing about 3k to get the head sorted afterwards.
The forklift was used in a saw mill and the saw dust would block air flow though the radiator and the motor would run a little bit hot at times.
Changing the operator and getting a regular weekly radiator blow out solved the problem.

LPG is slower burning than petrol and this allows more heat soke in the valves and valve seats, which will soften metal under power or high engine temps.
Valve saver will not work very well under very high temps.

I found common sense ( which is rare these days ) good LPG systems which are designed and tuned for the application and if dual fuel try to petrol for those really hard climbs or loads.

Valve seat wear on a motor can also be greatly reduced by running a colder themostat as heat will be conducted away from the valve and seat quicker and into the head or block on LPG or motor which run at full power for long periods.

Valve saver helps, but too much can cause deposits in the motor.

It all comes back to the LPG system fitted/engine design/application and operator.

One other factor is the tune/ set up of the gas system itself and air fuel ratios under load.
Correct gas system design and LP Gas air fuel ratio for the application will keep valve temps lower and last longer.

Another point is people shop around for price on LPG conversions and in 99 % of cases the cheapest gas system is fitted and you get a system which will make the motor run on gas ............but Will Cause Problems or not get the gas running in a way which is best for the motor or long term driveablitly.

Ron

We had the misty work vans on LPG.Many did close to 300k's,never had an engine problem,this was over the last 20yrs.The early one's,i think around '93,possibly maybe until '95 did have flash lube injection kits fitted.From then onwards,none had flash lube,still no issues.

The hi aces we have now are LPG factory fitted(no flash lube),have had no engine issues so far,but only have around 120k's on them.One of them has played up a bit with faulty plugs or terminals on the injectors,this was sorted under warranty.

About '94 Mitsubishi Australia realised it needed the LPG proof engines as much of their sales volume was to fleet customers. So they generally don't have valve problems from then on, especially the engines made in Lonsdale SA. Earlier Mitsi's were a pain on gas.

Toyotas are variable in their life on gas, the early 2.7 4 cyl engines ('99 on) were a disaster on regular gas conversions. Others as I mentioned below depend on the engine supplied by the factory.

As for avoiding full load heating and valve burning, switching to petrol is a good idea. I set some LPG injection systems to automatically run a percentage of petrol under load which has a similar effect as well as some lubrication. Full automatic petrol injection under load is an option too.

Having said all that my ol' P76 V8 would tow anything up to 2 tons at any speed on straight gas, so long as the temp gauge needle hadn't wandered off into the red. Boot nailed to the carpet was the normal method of operation for towing on the local freeway hills, it's done over 250,000km since I got it, runs as sweet as the day I first converted it.

It must also be noted that some of the Mitsy vans,around '94..? were not gas compatible at all.

Our tojo vans are late model 2.7's so hopefully they are OK.I think the system is Landi Renzo,same as the taxi vans use.

Talking about Mitsubishi & Toyota's is immaterial, they have different engines. Garry's asked about the later LR V8's which are a totally different beast.

I can only speak from my experience of running mine on LPG for 50k miles. I didn't have a flashlube kit and can feel the difference in the engine now, it's certainly down on power (albeit not by enough to worry) and does have a few rattly valves, it'll need a re-shim at some point. Having said that, none of this affects the car, it's more down to me having had it for so long and intending to keep it.

I did *a lot* of research into it when I first bought the car as it came with the LPG system already fitted. The information all points to the Jag engine not being able to cope with LPG and it varies on how long it'll last for. I ran mine on petrol for probably 30% of the time and that's meant to assist in extending the life of the valve seats.

The best, most informative discussion I had was on a trip into JE Engineering in Coventry. A couple of hours with them left me with the view that at some point, I would have problems but until that point came it wasn't worth doing anything other than budgeting for the fix. According to JE, LR changed the material in the valve seats soon after full scale production started, although the exact date isn't known, it's thought to be sometime in 2006. JE investigated valve seat failure for JLR, apparently they ran a bunch of NA & S/C RRS's to failure on LPG after considering the option of offering them on LPG from the factory. They determined the failure & the cure, but JLR never took it up so they invested in the tooling themselves and began offering the conversion. The cure is a modified set of exhaust valve seats, JE sell the heads for about £1500 a pair. I budgeted for a pair and was set in my mind that at some point I'd need them. I was happy with that so didn't bother with the flashlube, to me the flashlube was never a 'cure', it was just a workaround that may or may not have extended the life of the exhaust valve seats. JE had a cure and at the same time I could have gas flowed heads with a bit more poke, so they're a winner all ways round

Anyway, information about it from JE is here

Petrol Engines | Range Rover

Jaguar/Land Rover AJV8 Engine
Normally Aspirated

JE are still devoting development resources to enhancing the normally aspirated AJ engine, even though it is coming to the end of its OE use. JE intend to continue using it in the 'Liberator' and thus have some exciting developments to offer, notably our big-valve polished and ported heads. Please enquire for full details of these components which give up to 60 more brake-horsepower than standard, with suitably re-programmed electronics. With its surfeit of power for normal use, the AJV8 is particularly suited to LPG modification which gives dramatically enhanced economy. However, the AJV8 engine has been found to be susceptible to valve recession when using LPG due to the valve-seat material used in OE manufacture, and the "dry" nature of the gas with no lubrication additives as found in petrol. JE have developed two alternative configurations to overcome this problem.

Standard valve size: JE-modified heads with 16 all new 'beryllium-free' exhaust valve seats per head. These valve seats are state-of-the-art, incorporating as they do the latest NASCAR-developed alloys of copper, nickel and unobtainium (!) These alloys were developed to replace the copper/nickel/beryllium seats previously used due to the highly toxic nature of airborne beryllium dust. JE can machine and fit these valve seats in-house, unlike the previously developed tungsten carbide seats which were, not surprisingly, as hard as our tungsten carbide cutters and thus had to be machined off-site at not inconsiderable cost.These JE valve seats are machined, cut and ground to the optimum shape for performance and long life. Valves individually hand-ground to fit individual seats, ports shaped to improve gas flow and camshafts and followers fitted to optimise minimum tolerance specifications.

Per pair (exchange) £1328.00 Fitting £1015.00.

For total peace of mind, especially when intending to cover very high mileages, it is wise not to rely entirely on 'FlashLube' with an LPG converted normally aspirated AJ engine and to fit the JE modified heads. In any event, LPG converted cars should always be run on neat petrol from time to time. With the Supercharged engine it is very strongly recommended that the JE modified heads are fitted when having an LPG conversion. In fact, JE will not carry out such a conversion without written indemnity from the customer.

I'm not trying to sell it nor do I have any affiliation with JE, I just found them to be the most 'straight' when it came to talking about LPG conversions. I found many many others offering to install the flashlube kit who left me feeling like there was no way on earth I'd trust them with my very expensive RRS, they were just spouting sales drivel and couldn't actually answer any questions about failures. For me, the JE conversion was the cure to a known problem. Flashlube for these Jag engines is just a workaround that might not actually be successful. You pays your money and makes your choice.

I can't recall ever seeing a flashlube set up in my D1 (my dad had it in his old valiant), I don't think I had one. I had the car from 113xxxkm to 238xxxkm and still going strong when I sold it (though I was convinced it HAD to kick the bucket soon and was terrified of the motor rebuild costs). Wish I'd never let it go now

Hmmm My D3 V8 has recently (in the last 12 months) been converted to Gas. They also fitted a Flashlube kit. Will have to see what happens. The tip about using diesel in good though as the flashlube oil is quite expensive (relatively).

Ivan