Diesel Gas Troubleshooting

Submitted: Thursday, Apr 25, 2019 at 16:54
ThreadID: 138217 Views:4348 Replies:6 FollowUps:12
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I have a Lovato diesel gas system on my 4.2 diesel patrol. Gas consumption has dropped from 3.5L / 100km to 1.6litres / 100kms with the difference being now made up with increased diesel consumption. I have changed the gas particle filter with no change. The system does have a ECU. Engine speed information comes from the alternator.


Two hoses leave the gas filter housing. One goes via a solenoid shut off valve to a fitting on the aircleaner hose injecting the gas. There is not jet here it is simply piped into the intake. The other hose goes down to some sort of device on the exhaust which I assume provides vacuumn.I have attached some pictures.

Any suggestions as to what could be going wrong would be appreciated.
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Reply By: RMD - Thursday, Apr 25, 2019 at 17:24

Thursday, Apr 25, 2019 at 17:24
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.
AnswerID: 625150

Follow Up By: Peter T37 - Thursday, Apr 25, 2019 at 17:46

Thursday, Apr 25, 2019 at 17:46
Thanks that sounds like a logical explanation, after all it has a new filter and the ECU should not need attention. I assume the solenoid valves either shut or open, they dont become stuck half way.
Do you know the best way to test for sufficient vacuum. I am thinking I just connect up a vacuum pump to the hose leaving the gas filter and see if it holds a vacuum from the exhaust fitting The convertor has a overflow / vent hose pointing downward open to atmosphere so I will check that for blockage.
Your assistance is appreciated
FollowupID: 898786

Reply By: mechpete - Thursday, Apr 25, 2019 at 17:43

Thursday, Apr 25, 2019 at 17:43
unless you are a liscenced LPG repairer you
are doing illegal work ,get the proper people to fix it

AnswerID: 625151

Follow Up By: Peter T37 - Thursday, Apr 25, 2019 at 17:52

Thursday, Apr 25, 2019 at 17:52
Ok thanks, for your suggestion its often a good to have professional help
FollowupID: 898787

Follow Up By: Member - Keith P (NSW) - Thursday, Apr 25, 2019 at 19:49

Thursday, Apr 25, 2019 at 19:49
Another thing I noticed is the turbo looks a bit greasy too...time to fit a catch can methinks...but it could be a contributing factor nonetheless...

Cheers Keith
Nothin is ever the same once I own it ...........

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FollowupID: 898788

Follow Up By: RMD - Thursday, Apr 25, 2019 at 20:30

Thursday, Apr 25, 2019 at 20:30
What is wrong with finding a fault and rectifying the situation. It is all external to the gas delivery anyway. If it obvious then it can be done safely with no legal issues.

Keith P
Oil near a turbo doesn’t prove or dismiss oil in the blowby gas stream. If the oil is coming out then there is a leak. Oil in the blowby gas is entirely normal. Intake site of turbo is a vacuum and exit is pressuring and shouldn’t leak anything. I wouldn’t be fitting a catch can to cure another fault.
FollowupID: 898789

Follow Up By: Peter T37 - Friday, Apr 26, 2019 at 20:26

Friday, Apr 26, 2019 at 20:26
Keith a mechanic has told me the greasy turbo is a sign its on the way out. Thats a bit dissapointing at 170000kms as its has had 5K oil changes.As the gas gets vacuum from that source I think I will get the turbo replaced before it fails and then take mechepetes advice and get a gas man to look at it.

It seems that if its not a crook turbo causing a vacuum issue it may be the control valve near the gas filter that controls the flow of gas may be faulty. At least now I have some more clues than before as to what the issue may be.

The vented hose to the mixer / convertor was not blocked when inspected.
FollowupID: 898798

Reply By: Martin b9 - Thursday, Apr 25, 2019 at 20:51

Thursday, Apr 25, 2019 at 20:51
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.
AnswerID: 625152

Reply By: Batt's - Friday, Apr 26, 2019 at 21:26

Friday, Apr 26, 2019 at 21:26
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.
AnswerID: 625180

Follow Up By: Peter T37 - Saturday, Apr 27, 2019 at 23:36

Saturday, Apr 27, 2019 at 23:36
There is more power on gas but still less than petrol powered vehicle.
It uses when its working properly 3.5 litres of gas per 100kms and 12 litres of diesel around town and sitting on 100kph. Higher still in a head wind because of trade body. Its a ute with a trade body.
You wont save much money on fuel.
I would be looking at a vehicle that has power to begin with
The gas system is just another thing to go wrong that will most likely require professional help.
Diesel is more expensive than petrol.
FollowupID: 898805

Reply By: RMD - Saturday, Apr 27, 2019 at 08:59

Saturday, Apr 27, 2019 at 08:59
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 .
AnswerID: 625190

Follow Up By: Peter T37 - Sunday, Apr 28, 2019 at 13:32

Sunday, Apr 28, 2019 at 13:32

I have attached a picture of the source of the hose going to the gas filter housing. On closer inspection from underneath it appears to come from the compressor side of the turbo so I guess it may not be vacuum.
The alternator is new. The gas issue was present before the alternator was replaced and the same gas issue remained after it was replaced due to it not charging so that is probably ok. i dont know what controls the amount of gas that is allowed into the motor. I think the converter / mixer which is hot just converts liquid gas to vapour.
The mechanic presumes turbo from a glance. I will clean it and see if I can see the source. Labour and GST is around $3 a minute so just trying to work out how best to get it sorted.

FollowupID: 898810

Follow Up By: RMD - Sunday, Apr 28, 2019 at 18:12

Sunday, Apr 28, 2019 at 18:12
Maybe the new alternator isn’t working properly or the speed signal is missing from both the last one and the new one. That will reduce it. Do you know for sure the signal IS getting to the gas ECU ? Logically the gas ECU controls a flow cont roll on the evaporated/converter. Is the gas converter water heated? If it should be then perhaps the water flow is slow or missing and the converter gets frozen inside while going fast.
FollowupID: 898813

Follow Up By: Peter T37 - Sunday, Apr 28, 2019 at 19:03

Sunday, Apr 28, 2019 at 19:03
I dont know how to test whether or not its getting the speed signal. At the moment i am hoping the issue is a paper liquid filter that is inside the convertor that should have been changed with the more visible vapour filter. This could be causing a restriction I found this helpful.....
https://www.youtube.com/watch?v=KvSnkGID5Dk so at least i know what is involved for my licensed professional gas installer.

The convertor is water heated and thats very hot to touch. The liquid filter seems the next best logical step. The turbo i did clean and after a short run the compressor side was as dry to the touch so I will have to monitor it and see what is causing the greasy look.
FollowupID: 898815

Reply By: Ron N - Saturday, Apr 27, 2019 at 12:20

Saturday, Apr 27, 2019 at 12:20
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.
AnswerID: 625191

Follow Up By: Peter T37 - Sunday, Apr 28, 2019 at 15:52

Sunday, Apr 28, 2019 at 15:52
Thanks Ron for your reply. I did check the intake between the turbo and intercooler and there was no oil in the hose. I have cleaned the turbo and will try and see where the oil leak is.

Yes there is a vapour gas paper filter and this has been replaced recently.
thanks for the Lovato RGJ Regulator google suggestion. There is also a paper filter here which is before the vapour filter which could well be a source of restriction so I will have my licenced gas installation technician service / replace this item. Apart from the vapour filter and check for leaks I did wonder before what there was to service.

Do you know if the solenoid looking device pictured next to the round vapour filter housing is just a shut on off solenoid or does it control gas flow if so what is it called ?

I think the gas is worth fixing seeing it is already installed by the previous owner. The gas install business was booming when the govt was giving out 1K for gas installs as part of their drive at the time to reduce dependency on fossil fuels and deflated once the hand out was removed.

Your assistance and thoughtful reply was appreciated.
FollowupID: 898811

Follow Up By: Ron N - Sunday, Apr 28, 2019 at 20:28

Sunday, Apr 28, 2019 at 20:28
Peter, I'd suggest the oil leak may be coming from the gasket that seals the oil supply pipe flange.
You can probably make a new one fairly easily, out of some sheet gasket material - but ensure the gasket material and gasket sealant is capable of withstanding high heat levels.

The solenoid has only two positions, on or off. It is most likely actuated by a signal from the ECU when the conditions are right to inject gas.

Some solenoids, such as those on electronic fuel injectors are designed to actuate on and off very rapidly - but I would have to say the solenoid on your vapouriser/regulator is only designed to operate intermittently, as the demand for gas is sensed by the ECU.

If you can find an instruction or installation manual on your Lovato vapouriser/regulator online, you will probably be able to acquire the information on how the vapouriser/regulator valving works.

I'm having problems trying to find any information on your setup, because it appears your RGJ regulator is an "early type", and is now obsolete.

It seems that Lovato are now concentrating on producing current model vapouriser/regulators, that are set up only for fuel-injected petrol engines.

The essence of operation of the vapouriser/regulator is simply that the unit is heated by the engine coolant, which enables the vapouriser/regulator to change the LPG from a liquid to a gas.
The unit also regulates the gas flow, in both liquid form, and after it is converted to the gaseous form. There's also an overpressure valve fitted to prevent excessive pressure.

You're correct on the gas installation subsidy. In W.A., the subsidy ran up to $3000 at one stage, and it seemed there were gas installers on every corner of every street in the industrial areas.
Nowadays, you're struggling to find any gas installer that's still in business. Those that are, are merely supplying parts and doing repair work on LPG systems.

Cheers, Ron.
FollowupID: 898817

Follow Up By: Peter T37 - Monday, Apr 29, 2019 at 14:24

Monday, Apr 29, 2019 at 14:24
The Lovato RGJ class 123 is a diesel gas specific regulator / reducer. A kit is available from Lovato in Ridleyton Adelaide for fitting by my licensed gas installer technician.

I have ordered a Provent 200 catch can which I will fit and see what develops with the Turbocharger if anything. The oil feed appears to be a very small pipe running along just under the exhaust manifold. What looks like the oil supply pipe flange is the EGR pipe. I had applied degreaser when I took the pic.

Anyway thanks for the assistance given. I think at this stage the liquid gas filter thats in the regulator is probably the cause of the gas issue.
FollowupID: 898858

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