Friday, 26 July 2013

Crankshaft Assembly

Clean those oil ways. If you recall, we dug out the gunge during strip down. During the rebuild, we used various sizes of bottle brush to get into each oil way and scrub them clean. You will be able to see the ends of these brushes by looking into the appropriate oilway.

Before you attempt to clean the oil ways in the crankshaft, make sure you understand the lubrication system. Mr. Waller, as you would hope, has a good illustration in his book:
4G Lubrication System

The picture he shows is from the iron-engine 4G, but it is similar for the Mk1 & Mk2, with the following exceptions:
  • the Mk2 uses a gear pump, not the piston pump shown
  • the Mk1 & Mk2 take their rocker feed from near the rear crankshaft, from the pump return to the tank
  • the oil pressure relief valve in the Mk1 & Mk2 is in the end of the front crank. There is a drilling from the outboard side of the timing side bush into the crankcase, protected by a small sheet metal cover (shown here) on the inside which is riveted to the crankcase.
You can identify each of these oil ways in the crankshafts as a separate drilling, and clean them individually. Note that the long drilling between the crankpins, the one that passes through the central flywheel, is drill from both ends and is not straight in practice.

Use some new plugs for the oil galleries. Punch and Loctite them in place.

Next stop, connecting rods. As you will have recorded, when you stripped the engine, the 'O' mark on each rod faces the front. We are using new nuts, torqued to Ariel's specification and provided by AOMCC hero Brenton Roy.

Go and have a beer. When you have finished both crankshafts, you will have earned it!


  1. Discovered Doombar several months ago, what a nice beer.
    PS your gearbox article has saved me many hours and much worry.

  2. Excellent! Glad you found the blog useful.

  3. I just tore down my 1950 and found the connecting rods with the O marks towards the rear. I thought it had never been opened before but now I wonder. Are you positive the O marks face front? Thanks

  4. Mine did - I'm not sure if that's important as I believe the rods are symmetrical. It's 5 years since I have been in there though!