I haven't been sailing since the January 7 fire, but since our temporary apartment is walking distance from the slip, I can at least run the engine every week or so to keep its intestinal fluids moving. When I did, a few days ago, nothing came out of the exhaust except hot air.
Nothing. Not a drop. That's a first.
The cooling system had been boiled out only last August, using the Barnacle Buster immersion system. It has performed well since, with robust output from the water-lift muffler and an operating temperature pegged at 180F. What the devil could stop all water from circulating through the heat exchanger? I found it hard to believe.
Check One was of the raw water pump. Old impeller looked fine. Put in a new one anyway. Started engine, no exhaust water. But is the impeller actually spinning? Took off the Oberdorfer cover plate, started engine, observed spinning. Raw water pump worked.
Check Two. Groco bronze raw water filter. Clean the basket. With thruhull open, filter overflows as expected. Raw water filter worked.
Check Three. Disconnect hoses from Oberdorfer raw water pump. I have seen calcium deposits in the pump elbows before. But nope, elbows were clear.
Check Four. Detach 2' exhaust hose from water-lift muffler. Remove water-lift muffler and hose and place in cockpit to permit entry to engine bay.
Check Five. Crawl headfirst into lazarette. Detach heat exchanger salt water hose from where it enters exhaust elbow. This is a common point of blockage where salt water enters hot pipe. Hose and exhaust fitting were clear of obstruction.
Check Six. Remove all hoses from heat exchanger. When coolant hoses are detached, coolant will pour out. But it is not necessary to drain all coolant out of the engine. A bucket placed under the upper hose will catch the gallon or so that drains out of the manifold tank. Bucket placement is awkward but a beach towel spread beneath absorbs most spills. When the lower engine coolant hose is detached from the heat exchanger shell, no additional coolant runs out.
Check Seven. Detach heat exchanger from engine bracket and place in cockpit for examination.
I was expecting to find obvious blockage so as to justify all the blood and cursing and discomfort.
Here it is:
...
The point of raw water entry from the Oberdorfer to the heat exchanger was sealed entirely by mineral deposits inside and out.
There was no other clogging anywhere. The rest of the heat exchanger looked pristine and newly boiled, and I could see unimpeded through the tubes. Even the pencil zinc remained nearly intact, and had not been changed since last August. I believe the galvanic isolator I installed at that time has led to a longer lifespan.
Why would deposits create 100 percent blockage only at the point where raw water enters the heat exchanger?
Beats me. I'll boil the heat exchanger out of duty, but all it really needs is to have that single occlusion knocked away.
I've never missed the check for visible exhaust water every time I start the engine. But complacency or distraction is possible for anybody, and skipped items on a routine checklist have led to many funerals in general aviation. A dry exhaust on a marine diesel is rare enough to be unlikely, which makes it all the more easy to ignore that routine check for exhaust water.
Removing a heat exchanger is not the fun it used to be. But it is still more fun than the seizure of all four cylinders, a plume of smoke, and a tow to the nearest Betamarine dealer for a new diesel engine.
What are we paid to do this stuff ourselves? Well, a new engine is $15K. I'll write that check to myself.
(Listed as Thelonious blog entry.)
Nothing. Not a drop. That's a first.
The cooling system had been boiled out only last August, using the Barnacle Buster immersion system. It has performed well since, with robust output from the water-lift muffler and an operating temperature pegged at 180F. What the devil could stop all water from circulating through the heat exchanger? I found it hard to believe.
Check One was of the raw water pump. Old impeller looked fine. Put in a new one anyway. Started engine, no exhaust water. But is the impeller actually spinning? Took off the Oberdorfer cover plate, started engine, observed spinning. Raw water pump worked.
Check Two. Groco bronze raw water filter. Clean the basket. With thruhull open, filter overflows as expected. Raw water filter worked.
Check Three. Disconnect hoses from Oberdorfer raw water pump. I have seen calcium deposits in the pump elbows before. But nope, elbows were clear.
Check Four. Detach 2' exhaust hose from water-lift muffler. Remove water-lift muffler and hose and place in cockpit to permit entry to engine bay.
Check Five. Crawl headfirst into lazarette. Detach heat exchanger salt water hose from where it enters exhaust elbow. This is a common point of blockage where salt water enters hot pipe. Hose and exhaust fitting were clear of obstruction.
Check Six. Remove all hoses from heat exchanger. When coolant hoses are detached, coolant will pour out. But it is not necessary to drain all coolant out of the engine. A bucket placed under the upper hose will catch the gallon or so that drains out of the manifold tank. Bucket placement is awkward but a beach towel spread beneath absorbs most spills. When the lower engine coolant hose is detached from the heat exchanger shell, no additional coolant runs out.
Check Seven. Detach heat exchanger from engine bracket and place in cockpit for examination.
I was expecting to find obvious blockage so as to justify all the blood and cursing and discomfort.
Here it is:
...The point of raw water entry from the Oberdorfer to the heat exchanger was sealed entirely by mineral deposits inside and out.
There was no other clogging anywhere. The rest of the heat exchanger looked pristine and newly boiled, and I could see unimpeded through the tubes. Even the pencil zinc remained nearly intact, and had not been changed since last August. I believe the galvanic isolator I installed at that time has led to a longer lifespan.
Why would deposits create 100 percent blockage only at the point where raw water enters the heat exchanger?
Beats me. I'll boil the heat exchanger out of duty, but all it really needs is to have that single occlusion knocked away.
I've never missed the check for visible exhaust water every time I start the engine. But complacency or distraction is possible for anybody, and skipped items on a routine checklist have led to many funerals in general aviation. A dry exhaust on a marine diesel is rare enough to be unlikely, which makes it all the more easy to ignore that routine check for exhaust water.
Removing a heat exchanger is not the fun it used to be. But it is still more fun than the seizure of all four cylinders, a plume of smoke, and a tow to the nearest Betamarine dealer for a new diesel engine.
What are we paid to do this stuff ourselves? Well, a new engine is $15K. I'll write that check to myself.
(Listed as Thelonious blog entry.)
