How to make a watertight seal?

[LegoLord1880]

Recently I'e been doing some vacuum engine experiments. My engines always get more performance from using lubrication, but I'm wary of using olive oil, since it left a really gross residue on some of my pieces. Eventually I realized water would work just as well, but would need to be applied often because of how things it is. I came up with a splash lubrication system, which uses a sealed crankcase filled with water that is splashed up onto the cylinder walls when the piston goes down. It works great, but the water leaks out from between the bricks and constantly needs to be topped off. I've been using saran wrap between the layers of bricks, but I guess that's not enough. Does anyone have tips on how to seal the crankcase?

Also, I would appreciate it if anyone has a water pump design to use for the water cooling system I developed. It needs to be able to pump water through a pneumatic hose.

[aFrInaTi0n]

I am not sure if I am of help anyhow, but I just thought of some sprayable rubbers / there are some manufacturers offering products for cars.

Name of one product is:

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Plastidip

My idea would be, it could be applied between the bricks and any standoffs can easily trimmed away - et voila you should have the gap between both parts filled with a hardened rubber on mostlikely the whole touching surface area between the two parts.

But I never tested this for myself and it may be a stupid idea.. unfortunately wisdom for stupidity of an idea can just be found out with trying the idea.. 

[LegoLord1880]

Hmmm. Seems like it could work, but I don't want to do anything that could permanently stick the pieces together. Maybe I'll try more plastic wrap, and between each layer. Previously I had used only a double layer on the baseplate in the bottom of the oil pan.

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