Retrieving the Fallen Push Rod.
Sounds like a war story, doesn't it? "We always retrieve our fallen!"
But it's not like that. It's like this:
When you look at the front of a diesel engine, all the works are in about the top half. There will almost always be at least two, and often three, pulleys there. The lowest pulley is mounted to the crank shaft, which transmits the power of the combustion from the piston out of the engine and on down the line to, in our case, the propeller.
So that lowest pulley is even with the bottom of the driving parts of the engine. There may be an oil pump or something in there below that crank pulley, but not much.
So what, you may be wondering, is all that engine stuff below the crank pulley if there aren't any moving parts in there?
It is, in essence, a tub full of oil. The working parts don't run around down in the oil, at least not in any engine built in the last forty or fifty years. That would fill the oil with bubbles, which is the last thing we want. What happens instead is that a pump, usually driven off the camshaft, delivers that oil under pressure to all the parts that require lubrication, and from there it returns through internal passageways back to the sump, also called a crankcase or oil pan. And what I had done is drop the push rod down through one of those internal passageways.
My first thought was to fish it out with a telescoping magnet. One who loses parts inside engines from time to time as I do owns such things. But the big one on the bendy shaft was too fat to fit down through the passageway. Oops, the skinny one on the stiffer shaft was too fat too. Hmmm. What is Plan B?
At times like this it is not unheard of for me to panic and jump over some obvious fix and go directly into some massive, incredibly difficult overkill mode to recover my lost part. I really wasn't in the mood to fall into that trap. As I have already made clear, this engine is darn hard to work on where it is, and looks darn hard to remove to boot.
8 bolts would drop the oil pan off the bottom, but of course the oil pan was full of oil so I would have to drain it first, which one has to do from time to time and I probably ought to do, anyway, but then again from looking at it I was unsure whether the oil pan would come out of the space it's in even if I unbolted it.
When all else fails, read the manual. One useful thing I got in this transaction was an original Yanmar engine service manual, and I had been keeping it close at hand to refer to throughout the project so far anyway. If nothing else another look would give me time to recover my composure and not jump half-cocked into some stupid scheme or other.
In there I noticed, under directions to renew the piston rings, an instruction to take off the side plate and, working through the opening, unbolt the big end of the piston rod from the crank shaft. That meant that the side plate had to open the block as near as possible to the top of the oil sump, which meant that there were not likely to be any serious obstacles between that opening and the sump proper.
Of course, removing the side plate required laying, stretched out full length on the cabin sole with my arms held "above" my head, i.e. what would be above if I were standing, reaching into the "engine room" and removing four bolts, two of which I could actually see. Until I lay down, that is. I had to give blood, but only a modest amount, and the side plate generously moved aside, leaving me access to an opening as big as both my palms together.
Back to the magnets, and starting with the big one. I poked it blindly down into the crank case and fished around, pulling it up from time to time to see if I had caught anything.
The third time was the charm. Up with the magnet came the errant push rod.
I had to give another drop or two of blood, but soon the side plate was bolted back in place. I had not broken its gasket anywhere in the process. I gave thanks.
Last modified: 20 Oct 2011 02:10 | Deleted user