Ottawa Disaster

I drilled out the retaining pin in the old conrod and pressed out the journal - actually it was very easy to get out. I then crushed the existing journal metal in the current conrod and removed it. I did this to save the pin because it is cast in place out of bronze. I filed down the pin enough to make it possible to get the new journal in. I opened up the conrod end with a small jimmy bar slightly. I located where the pin would be on the journal, and enlarged the existing hole so it would fit over the existing pin. I then pressed in the journal - right in easy, the pin and hole lined up and click it was home. So far so good. Next I drilled the oil hole (the old one was slightly offset to the hole in the conrod I'd just put it into.

I reassembled the conrod into the piston and inserted the wrist pin. I tightened up the set screw which stops the wrist pin moving (this time I put a locker nut on it to stop it backing out like it did last time - it probably should have had one anyway). I reinserted the assembly through the bore and connected it up the big end to the crankshaft and secured the back half of the journal and did up the retaining nuts. Again, so far, so good. (Note that at this point I failed to tighten the bolt which keeps the small end secured to the journal.)

I lapped the valves using my favourite lapping compound - toothpaste! Works really well and gives your engine fresh minty breath. I made a new head gasket. Because all my gasket material was in storage and I did not want to drive all the way out to the storage place (here is the root of my mistake today). I went to the local "autoparts" store and bought some gasket material from the local man with pimples. They did not have any uncut head gasket material so I settled for some cork with embedded steel. I thought to myself, it is only to get the engine running to see if the journal is good - it will not have to last long. I put this new gasket in and reassembled the head being careful to not overstress the broken rocker arm bracket (as mentioned in the last installment). Once I got it all together I adjusted the valves (new gasket was thicker than the old one) - after checking that it had compression and blew on exhaust and sucked on inlet I took her out onto the grass and tried to get her running. Of course it would not go - then I remembered that the new gasket was thicker, and adjusted the governer arm to the carb so the butterfly valve would actually open and admit a fuel charge.

The engine started first time and ran really well - so well that I grabbed my camera and started taking some video. Then I could hear that familar knocking of a loose wrist pin journal and thought, but it couldn't be... so I went all around the engine listening for the noise and decided it definately was the wrist pin. I stopped the engine and stuck my hand into the (hot!) piston to see if it was loose. It was, I checked the bolt and it was loose - then I called myself a few choice names and returned to the garage for a pipe spanner. After tightening the bolt I was just getting her running again and had just swapped the detent mechanism from start to run, and was leaning towards the head to adjust the fuel to lean her out (you have to start the Ottawa really rich or it won't start - they all seem this way) when BANG the side of the head (where the old freeze crack was) hit me smack between the eyes followed by loads of hot water. Fortunately I'm not burnt, but the engine is dead!

Basically the inferior gasket material let go even earlier than I ever thought it would allowing combustion pressure into the part of the head which should not ever receive that kind of pressure - the water jacket. The old crack let go and off it sailed right into my face. I took the engine back to the garage and took off the head for a look, well no real damage to the engine apart from the gaping hole in the side of the head. I'll have to get it stitched up by someone (anyone who lives in Melbourne good at brazing?). I've had enough for today and will put it all away. I just wanted to walk away and vent some steam before I touched it again. This is a good constructive way to do it - so maybe someone else won't make my mistakes!

I'm going to have to find someone to help with the repairs very soon to get it ready for Lake Goldsmith in November. I just KNOW something else is lurking in this engine waiting to jump out at me. At least I remembered to tighten up that bolt before the journal was wrecked - the knock was not evident before it blew up!