Inline Twin Engine Ep. 15

To continue the work on the engine, the next series of parts are for the cooling system, staring with the pump.

The gears for the pump are made from pinion stock, parting off two blanks.

Inline Twin 215 (800x600)

To ensure both gears are exactly the same width, parallel and flat, my friend Brian helped me out with his surface grinder.

Inline Twin 216 (800x600)Inline Twin 217 (800x600)

The finished gears, with the shafts installed.

Inline Twin 218 (800x600)

The pump housing is milled from bronze.

Inline Twin 219 (800x600)Inline Twin 220 (800x600)Inline Twin 221 (800x600)

along with the rear cover.

Inline Twin 222 (800x600)Inline Twin 223 (800x600)

The finished pump housing parts:

Inline Twin 224 (800x600)

With the gears installed.

Inline Twin 225 (800x600)

And the pump installed on the engine.

Inline Twin 226 (800x600)

For the plumbing to connect the pump output to the cylinder block passage, I made a couple of fittings. First the fitting to the cylinder block:

Inline Twin 230 (800x600)Inline Twin 231 (800x600)Inline Twin 232 (800x600)

The original plan was to bend tubing from the pump to the inlet fitting, but that was an utter failure due to the small radius in my design. As solution, I made an elbow to be able to make the corner around the cylinder block.

Inline Twin 233 (800x600)Inline Twin 234 (800x600)Inline Twin 235 (800x600)Inline Twin 236 (800x600)Inline Twin 237 (800x600)Inline Twin 238 (800x600)

The plumbing installed on the engine:

Inline Twin 239 (800x600)

To make the connection from the coolant outlet passage on the cylinder head to a radiator hose, I needed to make a fitting. I took the inspiration for this fitting from a thermostat housing.

The fitting is made of two parts:

Inline Twin 240 (800x600)

To assemble the two parts, slight press fit and some JB Weld for good measure.

Inline Twin 241 (800x600)

The fitting installed on the engine:

Inline Twin 242 (800x600)

The next set of parts I made were the pulleys to drive the pump. I’ll be using two O-Rings as drive belts.

Inline Twin 243 (800x601)Inline Twin 244 (800x599)

The bearings installed in the pump pulley.

Inline Twin 245 (800x600)

The pulley installed on the pump:

Inline Twin 246 (800x600)

At this point is was time for a test run. I used a pulley I messed up earlier and had to remake, chucked up in my drill motor to drive the pump.


Thank you for visiting my shop.

If you have any questions about the engine or any of the other projects, please leave a comment below, or email at yogisworkshop(at)

For other projects from the shop, please check out the Projects Page in the top menu.


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