Volvo Bifuel gas system depressurising
Posted: 2009-05-07, 15:54
Hi All,
This manouver should be always done before opening any part of the gas system. Ok, there are many many valves in the system, and I would not bother to do it if I was changing just the gas injectors to the intake manifold, but unless you are 100 % sure of the safety, do it.
Next about the liability: I can only tell here how I have done the procedures to my car, because I know the system set-up pretty well. I have opened it many times and am still writing here. So if you have a similar car (different year models can have different systems), and do the same things that I did, maybe also you will not blow up your car and yourself with it. So let's tell here how have we done the things, and then everybody decides theirselves, whether they are confident enough to do self-service with their cars.
My car is a Volvo V70 Bifuel from year 2000. It has one big gas tank in behind the rear seat backrest. Basically the operation is easy: start the engine, let it run with gas for a moment, close the manual shut-off valves from the gas tank, let the motor consume the rest of gas in the system and finally die. Nothing complicated. The hard part is to be able to operate the shut-off valves. When you have completed the other things that required the gas system to be depressurized, and are sure that every part of the system is properly assembled and will not leak, DO NOT FORGET TO OPEN THE MANUAL SHUT-OFF VALVES AGAIN, if you wish to drive again with gas. I forget it every freaking time ; )
To reach to the valves, first flip down the backrests and the cover dressing. Screw off (anti-clockwise) the round plastic shield from the passenger side of the tank end. Be careful when the shield goes off from the threads, just slide it away as much the electric wires allow, to be able to reach the two closing valves. The closing valves are operated with 3/16" hex bit, these little hex socket pits are located in the centers of the two big hex bolts which sit on the exposed valve unit. So when you have tested that you can actually operate the valves, you can proceed with the above mentioned steps. Actually, I think that it would be enough to close only that valve which leads the gas to the engine, but I have always closed them both to be sure. Just make sure that the motor dies.
From what I've heard about newer Bifuel models, they have slightly more complicated systems with those 2 little extra tanks. But I think the little tanks are upstream from the big tank, so basically shutting the both valves of the big tank ought to do the job. I don't know should the little tanks be manually closed too (only one valve per tank)? Maybe it's safer to close them too when the motor has died? I've also heard that with 2002 or older models, a connector at the big gas tank strap (going to the magnet valve?), should be first disconnected to kill the motor, before closing the big tank manual valves. With the models 2003 and newer, the same thing would be done by disconnecting a relay from position RMI 17, located somewhere in the trunk. Someone else please correct me, if I have understood something wrong about these newer models.
Best Regards, Hewey
...U gotta fight, for your right, to cruise on...
This manouver should be always done before opening any part of the gas system. Ok, there are many many valves in the system, and I would not bother to do it if I was changing just the gas injectors to the intake manifold, but unless you are 100 % sure of the safety, do it.
Next about the liability: I can only tell here how I have done the procedures to my car, because I know the system set-up pretty well. I have opened it many times and am still writing here. So if you have a similar car (different year models can have different systems), and do the same things that I did, maybe also you will not blow up your car and yourself with it. So let's tell here how have we done the things, and then everybody decides theirselves, whether they are confident enough to do self-service with their cars.
My car is a Volvo V70 Bifuel from year 2000. It has one big gas tank in behind the rear seat backrest. Basically the operation is easy: start the engine, let it run with gas for a moment, close the manual shut-off valves from the gas tank, let the motor consume the rest of gas in the system and finally die. Nothing complicated. The hard part is to be able to operate the shut-off valves. When you have completed the other things that required the gas system to be depressurized, and are sure that every part of the system is properly assembled and will not leak, DO NOT FORGET TO OPEN THE MANUAL SHUT-OFF VALVES AGAIN, if you wish to drive again with gas. I forget it every freaking time ; )
To reach to the valves, first flip down the backrests and the cover dressing. Screw off (anti-clockwise) the round plastic shield from the passenger side of the tank end. Be careful when the shield goes off from the threads, just slide it away as much the electric wires allow, to be able to reach the two closing valves. The closing valves are operated with 3/16" hex bit, these little hex socket pits are located in the centers of the two big hex bolts which sit on the exposed valve unit. So when you have tested that you can actually operate the valves, you can proceed with the above mentioned steps. Actually, I think that it would be enough to close only that valve which leads the gas to the engine, but I have always closed them both to be sure. Just make sure that the motor dies.
From what I've heard about newer Bifuel models, they have slightly more complicated systems with those 2 little extra tanks. But I think the little tanks are upstream from the big tank, so basically shutting the both valves of the big tank ought to do the job. I don't know should the little tanks be manually closed too (only one valve per tank)? Maybe it's safer to close them too when the motor has died? I've also heard that with 2002 or older models, a connector at the big gas tank strap (going to the magnet valve?), should be first disconnected to kill the motor, before closing the big tank manual valves. With the models 2003 and newer, the same thing would be done by disconnecting a relay from position RMI 17, located somewhere in the trunk. Someone else please correct me, if I have understood something wrong about these newer models.
Best Regards, Hewey
...U gotta fight, for your right, to cruise on...