Volvo Bifuel gas distributor cleaning
Posted: 2009-05-20, 09:54
Howdy Folks!
If you have diagnosed (see topic "En service tip för Volvo Bifuel ägare") that you have a dirty gas distributor in your gas system, it is quite easy to clean the most important area of the device, the V-shaped grooves of the sliding cylinder. Even if you are not quite sure if the distibutor is really dirty, it is not a bad idea to clean it regularly anyhow to optimize the engine performance & lifetime and to minimize the pollution.
I assume that all Volvo Bifuel models have a similar gas distributor, mine is from year 2000. Propably also many other gas systems in different gas powered cars use a similar type of gas distributor, so these instructions can be useful with many other than Volvo Bifuel cars also.
About liability: Everyone self-servicing their cars do it on their own risk. I just describe here how I have done things, I cannot quarantee that nothing could go wrong for you if you follow them. Always think about your own system, if something seems to make no sense, do it better. And please tell the better way here afterwards to others too! From my experience, who ever is usually confident enough to service his/her car, should be also able to service the gas system. However the gas system does contain flammable fuel, stored at a high pressure, so safety should always be the most important thing in mind. But when you think of the properties of methane and compare it to petrol, it is easy to be on the safe side. Pressurewise: high pressure can be released from the part of the system that is to be opened. And why not play the game extra safely: run the gas tank as empty as you can before servicing. This way there is not very much pressure anywhere in the system, even if the valves should fail. Flammabilitywise: Everytime you will be releasing any gas out of the system, be sure that you do it in a big space, which has good ventilation, e.g. garage doors wide open, or at best: outdoors. This said, you should be ok when you know your system, think smart what you do, and do it carefully. But now let's go on with the cleaning of the gas distributor:
- Before the operation, these equipment would be good to have (have atleast WD-40 or similar)
-- a 3mm hex spanner to disconnect the stepper motor
-- a 0,15 mm feeler gauge to open the V-grooves
-- a can of brake cleaner to remove sticky dirt (optional, use carefully, can harm rubber/plastic parts)
-- a can of WD-40 (or similar) to clean & lubricate the parts
-- a can of Teflon spray (PTFE) to lubricate the parts (optional)
-- a soft haired bottle brush, of about 1 cm diameter
-- a long haired (atleast 1 mm) microfiber cloth (preferably 2 pieces), make sure it's absorbant, clean and lint-free.
-- painter's masking tape
- Depressurize the gas system. There are basic instructions to do this in the topic "Volvo Bifuel gas system depressurising". Different gas system setups can have some differences, but the main idea should work in all: when you run the engine with gas and shut the valves on every gas tank, the motor consumes the rest of the gas in the pipelines and then dies.
- If you did the depressurization outdoors, and the weather is windy/dusty, it's better now to drive the car (with petrol) into garage. It's not nice when the wind blows more dirt into the system when you try to clean it.
- Switch the electrics off. Disconnect the stepper motor electrical connector.
- Screw open the two 3 mm hex bolts on the stepper motor.
-- Start with the harder one to reach, and put it (and the washer) away.
-- Then when you start to loosen the easier one, hold the stepper motor still with the other hand so it does not bounce away. It might be stuck, but there is a spring that will push it up once it loosens. Put the bolt and washer away.
- Take a grip of the stepper motor with your better hand and work it gently loose. You can feel the force of the spring now.
- Carefully let the stepper motor to raise and the spring to fully open. Take the corrugated washer under your gripping fingers, so it won't get lost when you lift the stepper motor away.
- Lift the stepper motor away and take a grip of the sliding piston with your other hand. The piston may come off from the head of the stepper motor so don't let it fall to the ground. Place the combination on a clean place.
- Take the spring from the distributor and place it to the clean place.
- Point the bottle brush to the center of the microfiber cloth and wrap the cloth around the brush hairs. Spray some brake cleaner on the cloth (so it is moist, but not dropping), about 5 cm is surely long enough to reach to the bottom of the distibutor cylinder. (If you use too much cleaner and some of it enters to the membrane in the bottom of the distributor, the membrane might be damaged. Luckily the membrane is not expensive however and it is easy to renew.)
- Push the cleaner device carefully to the distributor cylinder, all the way. If the brush and cloth combination is too thick, try to find a smaller brush
or a thinner cloth.
- Let the device stay in the cylinder for a minute to allow the cleaner to soften the dirt.
- Carefully lift the device about 1 cm and press it down again, and make this kind of cleaning moves for some time and finally lift the cleaning device out from the cylinder.
- Clean the stepper motor mating surface (above the cylinder) with the cloth. Ensure that there is a small ball in a cutting, which prevents the cylinder to rotate. If it somehow came off when you removed the stepping motor, find it and put it back.
- Take the 0,15 mm feeler gauge, wipe it clean. Carefully stick it into a V-groove, and work it's way to the bottom of the groove. Lift the feeler gauge and clean it with the same side of the cloth that was initially towards the sliding cylinder. Stick and clean the feeler gauge into the groove until no dirt seems to stick into the feeler gauge. Repeat the procedure into all six V-grooves.
- Shake the cloth to get rid of loose dirt. Wrap the cloth again around the bottle brush, clean side out. Spray some WD-40 into the cloth (5 cm's).
- Clean the sliding cylinder again with up-down moves to make sure no dirt is left in the V-grooves.
- When you take the cleaning device out of the cylinder, observe carefully that no dirt is seen on the cylinder wall. The cloth can have a little lint on it, so remove any lint or other dirt from the cylinder wall with a clean finger.
- Seal the cleaned cylinder with some masking tape.
- Wipe the stepper motor, spring and sliding piston clean with the cloth, apply more cleaner if needed. Take the stepper motor O-ring off to clean it and the area good. If the O-ring seems worn out, replace it. If you don't have one in hand and are in doubt of it's condition, check afterwards if the stepper motor leaks and replace just the O-ring if necessary. Put the O-ring back to the stepper motor and spray a little teflon on the O-ring.
- Clean your hands and place the stepper motor, the corrugated washer, the spring, the sliding piston, the stepper motor bolts and the 3 mm hex spanner to a clean place near the engine, where you can reach them all easily. Place the corrugated washer into the stepper motor and leave the motor lying sideways, so that you are able to grip the motor with one hand, keeping the corrugated washer with the motor.
- Remove the masking tape seal from the mating surface. Make sure the aligning ball stays in the cutting.
- Place the spring into the distributor.
- Take the sliding piston between your other hands two fingers and have a look on it. The end which will go towards the spring has grooves inside it.
- Clean the insides of the sliding piston with the teflon spray. Shake away excess teflon liquid from inside of the piston. Then take a grip from it's edges and clean the piston wall with teflon spray. Shake away excess teflon liquid from outside of the piston.
- Place the sliding piston on the spring with the grooved inside towards the spring.
- Carefully press the sliding piston to the cylinder and test that it will slide flawlessly all the way to the bottom.
- Hold the piston in the cylinder with your other hands first finger.
- Take the stepping motor to your better hand, holding the corrugated washer in place with fingertips. Take the grip so that the stepper motor electrical connection ends up pointing to right direction.
- Carefully connect the stepping motor to the sliding piston. Guide the cusp in the end of the stepper motor to one of the little holes inside of the
sliding piston. Take your other hand finger off from the sliding piston and let the piston find freely a good position with the stepper motor attached to it.
- Carefully push down the stepper motor. If the O-ring seems to make pushing very hard, spray a little more teflon to it.
- Screw the stepping motor bolts back and re-attach the electrical connector.
- Open the gastank valves and start the engine. It may stall first when you try to run on gas, but start it again.
- Look, smell and feel that there is no gas leak anywhere. If you did not change the O-ring and it seems to leak, it has to be renewed.
Best Regards, Hewey
edit: added a safety note about brake cleaner usage
If you have diagnosed (see topic "En service tip för Volvo Bifuel ägare") that you have a dirty gas distributor in your gas system, it is quite easy to clean the most important area of the device, the V-shaped grooves of the sliding cylinder. Even if you are not quite sure if the distibutor is really dirty, it is not a bad idea to clean it regularly anyhow to optimize the engine performance & lifetime and to minimize the pollution.
I assume that all Volvo Bifuel models have a similar gas distributor, mine is from year 2000. Propably also many other gas systems in different gas powered cars use a similar type of gas distributor, so these instructions can be useful with many other than Volvo Bifuel cars also.
About liability: Everyone self-servicing their cars do it on their own risk. I just describe here how I have done things, I cannot quarantee that nothing could go wrong for you if you follow them. Always think about your own system, if something seems to make no sense, do it better. And please tell the better way here afterwards to others too! From my experience, who ever is usually confident enough to service his/her car, should be also able to service the gas system. However the gas system does contain flammable fuel, stored at a high pressure, so safety should always be the most important thing in mind. But when you think of the properties of methane and compare it to petrol, it is easy to be on the safe side. Pressurewise: high pressure can be released from the part of the system that is to be opened. And why not play the game extra safely: run the gas tank as empty as you can before servicing. This way there is not very much pressure anywhere in the system, even if the valves should fail. Flammabilitywise: Everytime you will be releasing any gas out of the system, be sure that you do it in a big space, which has good ventilation, e.g. garage doors wide open, or at best: outdoors. This said, you should be ok when you know your system, think smart what you do, and do it carefully. But now let's go on with the cleaning of the gas distributor:
- Before the operation, these equipment would be good to have (have atleast WD-40 or similar)
-- a 3mm hex spanner to disconnect the stepper motor
-- a 0,15 mm feeler gauge to open the V-grooves
-- a can of brake cleaner to remove sticky dirt (optional, use carefully, can harm rubber/plastic parts)
-- a can of WD-40 (or similar) to clean & lubricate the parts
-- a can of Teflon spray (PTFE) to lubricate the parts (optional)
-- a soft haired bottle brush, of about 1 cm diameter
-- a long haired (atleast 1 mm) microfiber cloth (preferably 2 pieces), make sure it's absorbant, clean and lint-free.
-- painter's masking tape
- Depressurize the gas system. There are basic instructions to do this in the topic "Volvo Bifuel gas system depressurising". Different gas system setups can have some differences, but the main idea should work in all: when you run the engine with gas and shut the valves on every gas tank, the motor consumes the rest of the gas in the pipelines and then dies.
- If you did the depressurization outdoors, and the weather is windy/dusty, it's better now to drive the car (with petrol) into garage. It's not nice when the wind blows more dirt into the system when you try to clean it.
- Switch the electrics off. Disconnect the stepper motor electrical connector.
- Screw open the two 3 mm hex bolts on the stepper motor.
-- Start with the harder one to reach, and put it (and the washer) away.
-- Then when you start to loosen the easier one, hold the stepper motor still with the other hand so it does not bounce away. It might be stuck, but there is a spring that will push it up once it loosens. Put the bolt and washer away.
- Take a grip of the stepper motor with your better hand and work it gently loose. You can feel the force of the spring now.
- Carefully let the stepper motor to raise and the spring to fully open. Take the corrugated washer under your gripping fingers, so it won't get lost when you lift the stepper motor away.
- Lift the stepper motor away and take a grip of the sliding piston with your other hand. The piston may come off from the head of the stepper motor so don't let it fall to the ground. Place the combination on a clean place.
- Take the spring from the distributor and place it to the clean place.
- Point the bottle brush to the center of the microfiber cloth and wrap the cloth around the brush hairs. Spray some brake cleaner on the cloth (so it is moist, but not dropping), about 5 cm is surely long enough to reach to the bottom of the distibutor cylinder. (If you use too much cleaner and some of it enters to the membrane in the bottom of the distributor, the membrane might be damaged. Luckily the membrane is not expensive however and it is easy to renew.)
- Push the cleaner device carefully to the distributor cylinder, all the way. If the brush and cloth combination is too thick, try to find a smaller brush
or a thinner cloth.
- Let the device stay in the cylinder for a minute to allow the cleaner to soften the dirt.
- Carefully lift the device about 1 cm and press it down again, and make this kind of cleaning moves for some time and finally lift the cleaning device out from the cylinder.
- Clean the stepper motor mating surface (above the cylinder) with the cloth. Ensure that there is a small ball in a cutting, which prevents the cylinder to rotate. If it somehow came off when you removed the stepping motor, find it and put it back.
- Take the 0,15 mm feeler gauge, wipe it clean. Carefully stick it into a V-groove, and work it's way to the bottom of the groove. Lift the feeler gauge and clean it with the same side of the cloth that was initially towards the sliding cylinder. Stick and clean the feeler gauge into the groove until no dirt seems to stick into the feeler gauge. Repeat the procedure into all six V-grooves.
- Shake the cloth to get rid of loose dirt. Wrap the cloth again around the bottle brush, clean side out. Spray some WD-40 into the cloth (5 cm's).
- Clean the sliding cylinder again with up-down moves to make sure no dirt is left in the V-grooves.
- When you take the cleaning device out of the cylinder, observe carefully that no dirt is seen on the cylinder wall. The cloth can have a little lint on it, so remove any lint or other dirt from the cylinder wall with a clean finger.
- Seal the cleaned cylinder with some masking tape.
- Wipe the stepper motor, spring and sliding piston clean with the cloth, apply more cleaner if needed. Take the stepper motor O-ring off to clean it and the area good. If the O-ring seems worn out, replace it. If you don't have one in hand and are in doubt of it's condition, check afterwards if the stepper motor leaks and replace just the O-ring if necessary. Put the O-ring back to the stepper motor and spray a little teflon on the O-ring.
- Clean your hands and place the stepper motor, the corrugated washer, the spring, the sliding piston, the stepper motor bolts and the 3 mm hex spanner to a clean place near the engine, where you can reach them all easily. Place the corrugated washer into the stepper motor and leave the motor lying sideways, so that you are able to grip the motor with one hand, keeping the corrugated washer with the motor.
- Remove the masking tape seal from the mating surface. Make sure the aligning ball stays in the cutting.
- Place the spring into the distributor.
- Take the sliding piston between your other hands two fingers and have a look on it. The end which will go towards the spring has grooves inside it.
- Clean the insides of the sliding piston with the teflon spray. Shake away excess teflon liquid from inside of the piston. Then take a grip from it's edges and clean the piston wall with teflon spray. Shake away excess teflon liquid from outside of the piston.
- Place the sliding piston on the spring with the grooved inside towards the spring.
- Carefully press the sliding piston to the cylinder and test that it will slide flawlessly all the way to the bottom.
- Hold the piston in the cylinder with your other hands first finger.
- Take the stepping motor to your better hand, holding the corrugated washer in place with fingertips. Take the grip so that the stepper motor electrical connection ends up pointing to right direction.
- Carefully connect the stepping motor to the sliding piston. Guide the cusp in the end of the stepper motor to one of the little holes inside of the
sliding piston. Take your other hand finger off from the sliding piston and let the piston find freely a good position with the stepper motor attached to it.
- Carefully push down the stepper motor. If the O-ring seems to make pushing very hard, spray a little more teflon to it.
- Screw the stepping motor bolts back and re-attach the electrical connector.
- Open the gastank valves and start the engine. It may stall first when you try to run on gas, but start it again.
- Look, smell and feel that there is no gas leak anywhere. If you did not change the O-ring and it seems to leak, it has to be renewed.
Best Regards, Hewey
edit: added a safety note about brake cleaner usage
Great contribution in this section of the forum! 
Keep up the good work!