I have a first-generation Lego Pneumatic set (nr 8851) that I recently took out of storage. I remembered from the last time I built the set that the pneumatics weren't working and I just confirmed that this is still the case.

After some experimentation, it turns out that the pneumatic distribution block is not doing its proper job of providing pressure only on one outlet and suction only on the other outlet, so it seems to be broken internally.

My question is, given that this part is specific to the first generation pneumatics and has been out of production for over 30 years, is it worth it to look for a replacement of this part, or is it to be expected that due to the age of the parts, the internals have deteriorated to the point that I need to be very lucky to find a working one?

Another option I am willing to consider it to try to repair the piece I have, so any advice in that direction is also welcome.

  • If all else fails, you could replace its function with two non-LEGO "check valves" and a tee — the hard part would be finding valves small enough that the entire assembly (including any tubing adapters needed) takes up a reasonable amount of space.
    – Kevin Reid
    Nov 25, 2020 at 1:48

1 Answer 1


I do not own such piece, so cannot tell if they all are broken by this time. However I have a suggestion regarding acquiring a replacement.

Bricklink is a dedicated to trading just LEGO items, so I can recommend to look here for replacement. While some of the sellers do not check functionality of all the items they sell it is considered items should be in a working state unless stated otherwise. It would be best to ask a seller (that you have chosen to buy the item from if it works) to test the piece if you ask them before placing an order.

The item you should be looking for on Bricklink is called Pneumatic Distribution Block 2 x 4 with Non-return Valve.

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