[Marshall V. Daut]

It looks as if it's time for another one of my LONG "Why does it always happen to me?" stories that had similar symptoms. Being in this hobby since 1966 has afforded me a great number of "opportunities" for things to go wrong with my Model A's. Because of my penchant for making long, virtually non-stop cross-country trips in Model A's between Arizona and Iowa during the 1970's until just a couple years ago, you can bet if something is going to go wrong, it will happen while crossing the desert or on a lonely stretch of Kansas plains at 2:00 in the morning. Anyway, the following is what happened to me, and just might be what you're experiencing, too.
A Model "B" block I was running in a '31 Deluxe Roadster mysteriously kept losing coolant overnight once I had reached my Iowa destination, and after very long driving periods. The fact that this was a sure-to-crack-someday Model "B" block should have been my first clue. I noticed that each morning the car was somewhat hard to start, which I chalked up to the considerably colder early morning weather in Iowa than what the old girl was used to in Arizona. Once the engine did start, it misfired for a couple minutes before smoothing out. The first couple of days going through this always resulted in the engine beginning to run warmer than usual within a few miles. I often had to add 1 1/2 gallons, sometimes almost 2 gallons! Everything was fine after
that - until the next morning when this annoying song and dance started all over again = hard starting, misfiring engine for a few minutes, low coolant level (which contained anti-freeze).
Finally, one morning while the engine was warming up and misfiring, I happened to walk around the back of the car to check something unrelated to my problem. That's when I saw coolant spewing from the exhaust pipe and onto the ground into a puddle, or vaporizing. I watched this for a minute or two until the engine smoothed out. I noticed that the coolant coming out of the exhaust pipe now was only a few drops. There had to be an internal leak some place. I filled the almost empty coolant supply and enjoyed another day of vacation, mentally noting what I'd do the following morning.
When that time came, I didn't even try to start the engine. Instead, I removed all the spark plugs and cranked the engine over with the starter. WHOOSH!!! Coolant came flushing out of #3 spark plug hole. I then went through the process of removing the cylinder head right there in the motel parking lot. (The manager LOVED that!!!). You can guess what I saw when the head came off: coolant in the cylinder! Near the exhaust valve seat was a crack running to the cylinder. Coolant was draining into that cylinder overnight, hence the hard starting and misfiring scenario. You see, a Model A engine stops in one of two places about 95% of the time. Apparently, when my engine was stopped each evening, #3 piston was at the bottom of its travel in the cylinder, or at least low enough to fill with leaking coolant. When trying to start the morning each morning, the coolant was being compressed by the piston travel and forced out of the opening valves. Once enough coolant had been displaced from the cylinder so that incoming fuel could ignite, the coolant already leaked into the muffler was blasted out of the tailpipe. The crack in the block from the valve seat into the cylinder was what was causing all my problems.
I talked to a local engine machine shop, who recommended I pour Pioneer ceramic block sealer into the radiator (after flushing out as much residual anti-freeze as I could from the system). This was done and the instructions followed to the letter, i.e., allowing the sealer to harden in plain water after running the engine for a while so that the sealant could penetrate the crack. The water and sealant were then drained and all possible air passageways were opened, such as spark plug holes and the radiator cap, so that air could cure the ceramic sealer. 24 hours passed. Coolant was replaced and guess what! And it worked! I was able to drive the car all the way back to Arizona without any further coolant loss problems. That %$&*(# Model "B" block was yanked and snapped up by the next poor sucker, who believed all the hype about Model "B" engines. Baloney! CRACK CITY!!!!
So, I'd suggest you start your engine after it has sat overnight with the full complement of coolant and see if coolant comes out of the exhaust pipe. It's easy to overlook this because who stands BEHIND the car when there are problems with the engine? That's how I discovered where my anti-freeze coolant was disappearing. Maybe you have a similar situation? Your engine might not stop where the coolant
could drain into the cylinder overnight (meaning the piston stopped close to the top of the bore), but while driving, the coolant will flow from the crack into the cylinder, where it will be atomized by the explosions. It's after the car has sat with coolant draining into cylinder that the hard starting begins. If you can naturally let your engine stop on its own to its usual position, hand crank the engine a little farther so that the pistons change positions relative to their cylinders. If the engine is hard to start the next day, remove the spark plugs and see if coolant flushes out. If so, you've got a cracked block, most likely between a valve seat and the cylinder. Let's hope not...
Marshall
Fina