I replaced the front crank seal, but it turns out it wasnt really leaking that bad, the front timing cover has a crack in it. Looks like the chain has rubbed from the inside or something has been crashing around in there. It's a bit strange as there is no timing chain rattle or other strange noises, so I cleaned it up and put JB weld over the crack. Seems to have fixed the problem. I dont really want to spend to much time or money on the engine, as I would like to replace it with something a bit more modern. The head on an 18 r is truly horrable, pre crossflow, intake and exhaust bolted together, cast iron, 2 timing chains, that said it goes really well, the fuel injection has brought it to life.