Saturday, June 23, 2007

Albin engine, Part 2

The day after the boat was relaunched, I tackled the problem of the recalcitrant engine again.

This time I pulled the spark plugs and found, to my horror, water.

What did work the day before when I was cranking the engine was the water pump. It dutifully circulated water through the raw water cooling system and out through the cylinder head to the inlet on the exhaust pipe.

Boats use the engine cooling water to cool the exhaust enough so that it can flow through a flexible rubber hose instead of a metal pipe like a car exhaust.

What makes this wet exhaust system work is, well, engine exhaust. It pushes the cooling water through the exhaust hose and muffler and back out into the ocean.

If the engine doesn't run there is no exhaust. So what you end up with is a very efficient system for filling the exhaust hose up with water until it backs up into the manifold, through the valves when they are open, and then into the cylinders. If you crank on a dead engine long enough you may ruin the engine.

Thus I belatedly learned Rule No. 1 for attempting to start a balky engine when the boat is in the water. Turn off the cooling water sea cock until the engine is running.

My immediate reaction, after turning off the cooling sea cock, was to run the starter while a mix of water and air sprayed out through the spark plug holes. Then I started spraying copious amounts of WD-40 into the cylinders and kept cranking. When I wasn't seeing water anymore, I checked the oil dipstick to see how much water had ended up in the crankcase. Not much. I changed the oil, cranked some more and then changed the oil again.

I still didn't know why the engine had not started. In fact, I didn't learn that until several weeks later, when I had time again to do more diagnoses. In the meantime I bought a compression tester. When I hooked it up to a spark plug hole and ran the starter, I discovered that the engine didn't have any compression.

That's when I decided to call me friend and Ensenada Race crewman John Dickerson, who owns Automotive Restorations in Downey, CA and has decades of experience with cars and engines. He also has been a boat owner for years, currently owning a Catalina 34.

The recommendation was to pull the head off the engine and view the damage.

The good news was that the cylinders looked fine. They were not rusted, nor scored. And there was no ridge at the top. Clearly the cylinders had been honed in a recent engine overhaul, and per the receipts the seller provided, there undoubtedly were new rings on the pistons.

The Albin O-21 two-cylinder gas engine in my boat was manufactured in 1967, according to the serial number history. Serial number 1 was built in 1925, so this was an old and relatively simple design.

The valves popped up and down on the starboard side of the cylinders, seating in the engine block. The simple flat cylinder head was cast with combustion chambers that extended off to the side of the cylinders to allow the gas-air mixture to be sucked into the cylinders and the exhaust gases to flow back out. The carburetor was bolted to the bottom of the exhaust manifold and had its own passageways to feed the gas-air mixture to the two inlet valves.

It was the exhaust valves that were frozen in place. The valve for the front cylinder was recalcitrant, but it would move if tapped with a rubber mallet.

By soaking the valve stem with penetrating oil, tapping it down, cranking the engine to raise it again and repeating the process over and over, I eventually got that valve free.

The exhaust valve for the rear cylinder wouldn't budge, however.

John suggested filling the valve chamber with penetrating oil and giving it a few days to work.

After 10 days of trying that, the rear valve remained frozen in place. By now I also had removed the manifold and could see that the lifter for that valve, which bobs up and down on the camshaft low in the cylinder block, also wasn't moving.

Clearly the engine would have to be removed and John graciously volunteered work space in his shop and help getting the engine out.

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