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LPG, CNG & LNG - General Info and Issues Share experiences and problems

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Does anyone have ever disassembled the LPG distributor?

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Old Aug 7th, 2016, 09:49   #51
CNGBiFuel
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I'm sure my kit came with a manual that was PDF in format. That si where that value came from. I still had it scribbled on my manometer. Not got my manual now, but pester before purchase. Why would any seller keep it a secret?

Just found my notes:

T an output of the low-pressure regulator to your gauge via a length of tubing. I think later type regulators have a tapping. There’s a tapping on the distributor.
At idle running gas you should see 0 to 0.3 bar.
Remove the hose from the pressure release at the pressure regulator See a value of 1-1.5Bar at idle.
Do this with a full or near full tank or the regulator will lie to you or you'll set it up wrong.
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Old Aug 19th, 2016, 13:10   #52
Lpgc
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Old thread I know...

All good advice above.

In case the fault isn't found to be the tank or reducer solenoid: Vauxhall and V70 LPG distributors have a built-in flow shut-off solenoid, so this would be a 3rd solenoid valve to check. The tank and reducer solenoid certainly switch at the same time (wired in parallel) and as memory serves the solenoid on the distributor is wired in parallel to those too (or if memory serves incorrectly the distributor solenoid is switched separately and petrol switched off when this solenoid opens).. This info could help with roadside diagnostics (checking solenoid clicks / gas flow while running temporary power to solenoids) during the engine none run situation.

I've had plenty LPG distributors to bits including on factory converted V70's. The distributor is of a very similar design to those fitted on the Vauxhall versions but it's stepper motor has built in stepper motor control electronics, so at least the motor is incompatible with the (more common) Vauxhall versions and is more expensive. If the electronics go faulty on the stepper, will of course mean a new stepper and they do go wrong. As is the usual arrangement for this sort of flow control distributor, the motor drives a worm gear inside a threaded sheath, the flow control plunger is on the same shaft as the sheath so as the sheath moves in and out of the motor unit the plunger moves with it... As the threaded parts age in some situations the plunger can become stuck, either because threads have completely worn out, because threads have worn in a particular section (plunger position), or because the locating slot in the sheath (prevents the sheath spinning with the worm gear) has worn/broke. In the 2 latter situations it can be possible to get them working again, if only temporarily, by taking apart and re-threading the sheath onto the worm or managing to effect a repair to the locating slot, but during over-run conditions the position of the plunger may be told to fully restrict the flow of gas and if it gets stuck in that position (due to worn gear in that position) the effect can be the same as a failing solenoid (no gas situation or not enough gas for the engine to run due to extremely weak mixture / or sometimes if it stuck in a certain position the engine might run with incorrect mixture perhaps over only a very narrow rpm/load range). I think it's surprising the stepper units last as long as they do because the gear will spend most of the time going back and fro over a very similar range of positions (wear in same place) with the stepper moving almost continuously while the engine is running on LPG, perhaps more load on the gear than might at first be considered because it is also spring loaded, the locating slot isn't very strong at all. Besides the stepper motor / plunger arrangement, save the shut-off solenoid there isn't much to go wrong inside the distributor units, the plunger simply moves up and down to expose a greater length of gas outlet slot, one slot per distributor gas outlet. Another thing that can go wrong (seemingly not in the OP's case) is the manifold mounted gas entry points which incorporate a one-way flow valve (five on a 5 cylinder engine of course), if one of those gets stuck it can restrict gas flow so lean the mixture to the effected cylinder. Should be able to blow down the feed pipes to them but not suck.

Word of warning on stepper assemblies, when removed from the distributor, if wiring is still connected and ignition switched on there is a great chance of the sheath coming right off the worm gear... and then there's the problem of re-threading it when you can't spin the sheath without breaking the locating slot/tab. If this happens you need an assistant to turn on the ignition, at which point the motor moves to pull the sheath in and out, got to have the wiring connected during the pull-in movement and disconnect it during the push-out movement. The ECU commands the stepper to do the in/out movement so it can find the full closed position / reference point (knows it's full closed when it sees no further movement of the motor when the motor is trying to push out, but for a time this will put a lot more torque/stress on the threads and is a situation when a failure is likely to occur).

Distributors on V70's not the easiest to access but by unbolting the distributor from it's mounting position and disconnecting a few of the injector pipes from distributor outlets, distributor can then be moved to a handier to access location and pipes re-attached ready for testing next time the problem occurs.

Given the age of components, likelihood of future failures of other components after replacement of some component(s), sometimes difficult to obtain components and the expense of many of those parts, some people consider it a better bet to replace failing factory fitted kit (only under bonnet components required) with aftermarket kit (will come supplied and fitted with warranty and any future diagnostics much simpler) rather than take the risk of future problems due to failing components. Both myself and Classicswede have replaced failing factory fitted systems (including on Volvos) with aftermarket systems on owner's requirements after advice and taking the above into consideration - Not a big gamble repairing/changing a low cost factory fitted component, particularly if that component has been 100% identified as the only component at fault, just that in many cases it can be difficult to be 100% confident only one component is at fault (e.g. a failing ECU or stepper motor control electronics could give very similar symptoms to a wide range of other problems). Such repairs can seem a less attractive option if component(s) come at a significant fraction of the cost of replacing the factory system with a new system, particularly if question marks remain as to condition of other factory components. I have replaced a couple of factory systems on V70's even after identifying very likely just a single component problem (e.g. failed stepper motor electronics, an obvious fault due to missing cover from stepper motor electronics and corroded electronics) even for such types as hard nosed car dealer Arthur Daley whom might usually not have worried much about a system failing a few months down the line on the car's new owner - given the gamble of the cost of the part and potential for another part to be on it's last legs or already faulty (can't test the other parts properly until that part is fitted, proof in the pudding), seems even Arthur Daley types are sometimes willing to pay a bit more for less of a gamble and the assurance of a permanent and warranted fix!

Simon

Last edited by Lpgc; Aug 19th, 2016 at 14:08.
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Old Aug 31st, 2016, 11:28   #53
volvotwofortyfive
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Quote:
Originally Posted by Lpgc View Post
Old thread I know...

All good advice above.

In case the fault isn't found to be the tank or reducer solenoid: Vauxhall and V70 LPG distributors have a built-in flow shut-off solenoid, so this would be a 3rd solenoid valve to check. The tank and reducer solenoid certainly switch at the same time (wired in parallel) and as memory serves the solenoid on the distributor is wired in parallel to those too (or if memory serves incorrectly the distributor solenoid is switched separately and petrol switched off when this solenoid opens).. This info could help with roadside diagnostics (checking solenoid clicks / gas flow while running temporary power to solenoids) during the engine none run situation.

I've had plenty LPG distributors to bits including on factory converted V70's. The distributor is of a very similar design to those fitted on the Vauxhall versions but it's stepper motor has built in stepper motor control electronics, so at least the motor is incompatible with the (more common) Vauxhall versions and is more expensive. If the electronics go faulty on the stepper, will of course mean a new stepper and they do go wrong. As is the usual arrangement for this sort of flow control distributor, the motor drives a worm gear inside a threaded sheath, the flow control plunger is on the same shaft as the sheath so as the sheath moves in and out of the motor unit the plunger moves with it... As the threaded parts age in some situations the plunger can become stuck, either because threads have completely worn out, because threads have worn in a particular section (plunger position), or because the locating slot in the sheath (prevents the sheath spinning with the worm gear) has worn/broke. In the 2 latter situations it can be possible to get them working again, if only temporarily, by taking apart and re-threading the sheath onto the worm or managing to effect a repair to the locating slot, but during over-run conditions the position of the plunger may be told to fully restrict the flow of gas and if it gets stuck in that position (due to worn gear in that position) the effect can be the same as a failing solenoid (no gas situation or not enough gas for the engine to run due to extremely weak mixture / or sometimes if it stuck in a certain position the engine might run with incorrect mixture perhaps over only a very narrow rpm/load range). I think it's surprising the stepper units last as long as they do because the gear will spend most of the time going back and fro over a very similar range of positions (wear in same place) with the stepper moving almost continuously while the engine is running on LPG, perhaps more load on the gear than might at first be considered because it is also spring loaded, the locating slot isn't very strong at all. Besides the stepper motor / plunger arrangement, save the shut-off solenoid there isn't much to go wrong inside the distributor units, the plunger simply moves up and down to expose a greater length of gas outlet slot, one slot per distributor gas outlet. Another thing that can go wrong (seemingly not in the OP's case) is the manifold mounted gas entry points which incorporate a one-way flow valve (five on a 5 cylinder engine of course), if one of those gets stuck it can restrict gas flow so lean the mixture to the effected cylinder. Should be able to blow down the feed pipes to them but not suck.

Word of warning on stepper assemblies, when removed from the distributor, if wiring is still connected and ignition switched on there is a great chance of the sheath coming right off the worm gear... and then there's the problem of re-threading it when you can't spin the sheath without breaking the locating slot/tab. If this happens you need an assistant to turn on the ignition, at which point the motor moves to pull the sheath in and out, got to have the wiring connected during the pull-in movement and disconnect it during the push-out movement. The ECU commands the stepper to do the in/out movement so it can find the full closed position / reference point (knows it's full closed when it sees no further movement of the motor when the motor is trying to push out, but for a time this will put a lot more torque/stress on the threads and is a situation when a failure is likely to occur).

Distributors on V70's not the easiest to access but by unbolting the distributor from it's mounting position and disconnecting a few of the injector pipes from distributor outlets, distributor can then be moved to a handier to access location and pipes re-attached ready for testing next time the problem occurs.

Given the age of components, likelihood of future failures of other components after replacement of some component(s), sometimes difficult to obtain components and the expense of many of those parts, some people consider it a better bet to replace failing factory fitted kit (only under bonnet components required) with aftermarket kit (will come supplied and fitted with warranty and any future diagnostics much simpler) rather than take the risk of future problems due to failing components. Both myself and Classicswede have replaced failing factory fitted systems (including on Volvos) with aftermarket systems on owner's requirements after advice and taking the above into consideration - Not a big gamble repairing/changing a low cost factory fitted component, particularly if that component has been 100% identified as the only component at fault, just that in many cases it can be difficult to be 100% confident only one component is at fault (e.g. a failing ECU or stepper motor control electronics could give very similar symptoms to a wide range of other problems). Such repairs can seem a less attractive option if component(s) come at a significant fraction of the cost of replacing the factory system with a new system, particularly if question marks remain as to condition of other factory components. I have replaced a couple of factory systems on V70's even after identifying very likely just a single component problem (e.g. failed stepper motor electronics, an obvious fault due to missing cover from stepper motor electronics and corroded electronics) even for such types as hard nosed car dealer Arthur Daley whom might usually not have worried much about a system failing a few months down the line on the car's new owner - given the gamble of the cost of the part and potential for another part to be on it's last legs or already faulty (can't test the other parts properly until that part is fitted, proof in the pudding), seems even Arthur Daley types are sometimes willing to pay a bit more for less of a gamble and the assurance of a permanent and warranted fix!

Simon
The clearest, complete and condensed analisys I ever heard/read on this LPG system, my most grateful compliments.

Regarding the bold part of the above "quote", unfortunately it's impossible to pull out the distributor due to the lack of space (more or less 1 inch and half...) between intake manifold and cooling fan (I've posted a picture before)... Anyway I've tried to remove the distributor but the results were only a small injury on a finger and a greatly wounded pride
I probably will try again but previously removing the whole intake system (petrol rail, manifolds, throttle unit). I also planning to change the position of the distributor, for an easier maintainance in the future.
Many many thanks to Lpgc for this message
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Old Aug 31st, 2016, 13:57   #54
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Quote:
Originally Posted by volvotwofortyfive View Post
The clearest, complete and condensed analisys I ever heard/read on this LPG system, my most grateful compliments.

Regarding the bold part of the above "quote", unfortunately it's impossible to pull out the distributor due to the lack of space (more or less 1 inch and half...) between intake manifold and cooling fan (I've posted a picture before)... Anyway I've tried to remove the distributor but the results were only a small injury on a finger and a greatly wounded pride
I probably will try again but previously removing the whole intake system (petrol rail, manifolds, throttle unit). I also planning to change the position of the distributor, for an easier maintainance in the future.
Many many thanks to Lpgc for this message
If you remove the cooling fan shroud you get enough room to access the dizzy, or you can go in from underneath. I done mine recently by just removing the air intake to the air box and the radiator fan pack.
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Old Aug 31st, 2016, 17:43   #55
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Originally Posted by NI_Volvo_Nut View Post
If you remove the cooling fan shroud you get enough room to access the dizzy, or you can go in from underneath. I done mine recently by just removing the air intake to the air box and the radiator fan pack.
Oh, thanks for the suggestion; initially I also thought to remove the cooling fan but in my minds I believed it was more complicated: in one of unnecessary interventions made in the workshop volvo, they changed water radiator and putted on an oversize version; its thickness is much greater than the original and therefore the space is is further reduced. Furthermore, thanks to the manifold removal, I would check the status of LPG injectors, difficult at the moment (expecially the #3). Anyway, I'll check your option, thanks!
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Old Jan 5th, 2017, 22:24   #56
LincolnImp
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Default V70 Bi Fuel Stepper

Could you advise how to make arrangements to order a stepper motor please.
Thanks in advance,
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Old Jan 5th, 2017, 22:44   #57
CNGBiFuel
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I have these however before you leap to any conclusiosn, better be sure you need one. Too pricey to be wrong.

Read this thread first:

http://www.volvoforums.org.uk/showthread.php?t=258466
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