Diesel Gas Troubleshooting

If the exhaust fitting is damaged or blocked or burnt away it may not be delivering sufficient vacuum signal to the converter and so it will back off in it’s delivery of gas. That is presuming no other fault is present. Even a split hose to the exhaust fitting could cause the issue too. The diaphragm of the converter has to breathe and if a small hole or filling a wasp may have partially blocked the atmospheric breather intake.

unless you are a liscenced LPG repairer you
are doing illegal work ,get the proper people to fix it

mechpete

facing a similar problem in a wrangler truck which we use for towing roadside assistance nyc, consuming too much fuel, will fix that from mechanic then will share the problem here.

Sorry I can't help but wondering what sort of Lph your getting combined and do you get a noticeably power increase running gas Thanks.

Peter T37
The turbo may be working perfectly and the oil, not grease, doesn't use grease for lubrication, is a result of an oil leak. Turbo seals may be weeping after many km's but it doesn't automatically mean the turbo is on the way out. Just replacing it may not be the issue. Did the mechanic verify it IS a turbo seal oil leak or just casually glance at the area and presumed "turbo"?
You said earlier that the gas system got it's vacuum from the exhaust flow spud port, now you say it gets it's vacuum from the turbo. Unless there is a venturi unit to restrict the turbo intake in order to create a vacuum point related to intake flow, then it may not be like that.
If the vehicle runs well and has normal power as you mentioned it did, then the turbo must be operating ok. Why would you replace the turbo then fix the gas given the turbo works? Isn't it the gas which isn't working?
Do all the primary simple checks for leaks and performance first.

If the Gas ECU gets it's speed from the alternator then it probably reads the phase pulse frequency. If a diode is blown in the alternator, quite common on those Hitachi ones, my daughters did one recently. The pulses of output will therefore be reduced by 2/3 and so will amp output drop by 2/3. That may cause a gas reduction because it thinks speed has dropped 2/3. If you run the engine and turn on all electrics, what is the voltage held up by the alternator? If low and maybe dropping under load, then I would consider and alternator check. A simple test with a digital oscilloscope will show the pattern is wrong, ie, 2/3 missing. No load voltage will still be quite ok though. If your alternator growls at relatively low speeds then it is a diode.

Although not 2/3 drop in gas use it is 55% though and close to the 2/3 sensing drop of an alternator frequency loss. If the gas ECU sees it too and drops the fueling rate to approx the same that seems quite pausible .

The Lovato Diesel Gas system is obsolete and the Diesel Gas System Australia website appears to have done nothing since about 2012.
The websites "news" stops at 2012, along with the testimonials from "satisfied" customers.

This gels with the fact that the LPG installation industry has virtually collapsed in the last couple of years.
LPG installers have virtually completely disappeared here in the West, maybe there are still a few operating in the East.

The addition of LPG fuelling or conversion lost any competitiveness a couple of years ago due to cheap petrol and diesel, and increasing LPG prices.
The oil companies ensure the pricing of LPG remains at a level that makes conversions marginal.

The Lovato company is Italian and makes lots of LPG equipment and still sells it in areas of the global market where LPG conversion is still attractive.

However, the addition of LPG vapour to the intake of diesels, is, and always has been, a "dicky" arrangement that cannot guarantee a precise level of LPG for differing loads and driving conditions.

For this simple reason, the Diesel Gas systems have fallen right out of favour in recent years.

Having opined all of the above - if you wish to persevere with the installation, I would be getting the LPG vapouriser/regulator dismantled and inspected (the vapouriser/regulator is also sometimes referred to as an evaporator/reducer).

These vapourisers/regulators contain a diaphragm, numerous seals and o-rings, and some valves.
All of these components are subject to degradation of the materials of which they are constructed.
Diaphragm material degrades and splits, and valves fail to seal or actuate properly after several years of work.

In addition, the vapouriser/regulator body is made of alloy, which normally contains coolant passages, and these alloy bodies often corrode internally with cooling system degradation and corrosion.

There has also been a problem with LPG degrading the inner lining of the hose material used in earlier LPG installations.

The hose used in earlier LPG installations was unable to cope with the chemical attack of components in the LPG, and this released liquid phthalates from the hose construction - which created a brown, sticky liquid, that built up in vapourisers/regulators, which damaged the diaphragm, and which caused LPG system malfunctions.

There is also, normally, a small paper cartridge-style filter element on the LPG vapouriser/regulator, which should be replaced about every 20,000-30,000 kms.

If you do a Google search for "Lovato RGJ regulator" you will find quite a bit of information on them, including a video of a bloke assembling/repairing one.

One has to be aware that, as a previous poster pointed out, you need to be a licenced gas installation technician to start getting involved with LPG installation repairs, or you could end up in trouble - particularly if there's an accident.

As regards the turbo, you can check whether the turbo is performing satisfactorily by checking the turbocharger boost pressure (manifold pressure) under load.
The vehicle manufacturer will supply specifications for the level of boost required, and the figure for when the boost level is not satisfactory.

Turbochargers are relatively simple devices, but they run at fine tolerances. The shaft through the centre of the turbo runs on simple plain bronze bushings, lubricated by pressurised oil supplied by the engine oil pump.

The wear tolerances in these bronze bushings is very low. Wear in the bronze bushings means the shaft will displace from its central position, and thus allow the compressor wheel (intake) or turbine wheel (exhaust), to contact the intake or exhaust housings.

Once this starts to happen, the compressor or turbine wheels will become damaged, and the turbocharger is toast.

The turbocharger shaft oiling system is simply two piston-ring type seals, which wear, and which then allow oil to seep into the intake or the exhaust.

In this situation, the wear in the sealing rings means an increase in oil consumption, an oily intake manifold downstream from the turbocharger, and/or an increase in blue smoke in the exhaust.

Of all these signs, the easiest sign to find is an oily intake, which shows the turbocharger is nearing the end of its serviceable life.

Cheers, Ron.