Don, I have a 1983 Catalina 30 with Remanufactured FWC A-4.
During our annual cruise last summer, the black iron hex reducer holding the elbow on the aft end of the manifold gave out halfway between Watch hill and Block island. I spent the better part of a week replacing the manifold, and entire exhaust pipe assembly. It was like a scavenger hunt, trying to find what i needed in dusty garages and harware stores. When reinstalling the manifold, i felt the aft stud give a little, but hoped beyond hope that it was tight enough and it would work. I also replaced the elbow with a larger one that did not need a hex reducer.
The motor never quite ran well after that under load and i attributed it to a dirty carb since i let it flop around when it was disconnected from the manifold. It also seemed to run hotter than it had in the past. We limped home and made it through the season, laid it up for winter and lo and behold, winter did not heal the problems.
Well i just commissioned the boat yesterday, full dissassembled and cleaned the carb, replaced cap, rotor and plugs and she started with the first crank. There was a little more blue smoke than i liked, but thought that any sticky parts just needed to get loosened up for the season.
Under load, the same problem still happened, except now it is apparent that the stud was not tight enough and i am getting exhaust gases in the engine room, reducing the available oxygen, causing rough running. Hope fully no blow by directly from exhaust to intake. The cabin smoked up quite a bit and it ran smoother with the engine room covers open.
I accepted this and throttled back to make it to the dock. After 30 minutes, i again decided to see if the manifold had magically healed itself and went back to high throttle. It seemed better, until the engine just cut out. The temp was pegged at 240 and i assumed high temp cutoff switch was the reason for the shutdown. I waited about 30 minutes and could not restart even after the temp had fallen below 160F. I know i had fuel becuase i jumped the pump to feed the carb before cranking. I also hotwire it so i can be right at the engine when cranking.
So now for my questions:
Stud replacement: The studs are original and i chased the threads with a bottoming tap before i put them back and i installed them with neverseeze, not permatex, but i strongly suspect the threads in the block pulled out. What now? I see your replacement kit in the catalog, is that what it is for? Do you drill it larger and then tap it again?
Manifold gasket: If i just fix the stud, is it likely that the manifold gasket is good enough to simply tighten it back down?
Overheat: I have read everything available on overheat as this has been my constant bugaboo since the motor was installed. This overheat is the worst i have ever had, the first time it shut down due to high temp. It usually runs at about 200-210 if i push it under load. I have good flow from the exhaust and the fresh water flow into the heat exchanger feels vigorous (mixing valve long since removed). I check it by sticking my finger inside the HX just upon start to feel the flow. The bypass hose is plugged with a metal plug with a ~1/8" hole drilled in it. Is the manifold issue a likely contributor to the excessive overheat?
Not restarting: I assume that the ignition is cut off upon overheat by an overheat cutoff switch. I see two devices, one on the block and one on the HX. I assume that one is the temp sender and one is the cutoff switch. Shouldn't it start working again once it cools?
Thanks,
Paul
During our annual cruise last summer, the black iron hex reducer holding the elbow on the aft end of the manifold gave out halfway between Watch hill and Block island. I spent the better part of a week replacing the manifold, and entire exhaust pipe assembly. It was like a scavenger hunt, trying to find what i needed in dusty garages and harware stores. When reinstalling the manifold, i felt the aft stud give a little, but hoped beyond hope that it was tight enough and it would work. I also replaced the elbow with a larger one that did not need a hex reducer.
The motor never quite ran well after that under load and i attributed it to a dirty carb since i let it flop around when it was disconnected from the manifold. It also seemed to run hotter than it had in the past. We limped home and made it through the season, laid it up for winter and lo and behold, winter did not heal the problems.
Well i just commissioned the boat yesterday, full dissassembled and cleaned the carb, replaced cap, rotor and plugs and she started with the first crank. There was a little more blue smoke than i liked, but thought that any sticky parts just needed to get loosened up for the season.
Under load, the same problem still happened, except now it is apparent that the stud was not tight enough and i am getting exhaust gases in the engine room, reducing the available oxygen, causing rough running. Hope fully no blow by directly from exhaust to intake. The cabin smoked up quite a bit and it ran smoother with the engine room covers open.
I accepted this and throttled back to make it to the dock. After 30 minutes, i again decided to see if the manifold had magically healed itself and went back to high throttle. It seemed better, until the engine just cut out. The temp was pegged at 240 and i assumed high temp cutoff switch was the reason for the shutdown. I waited about 30 minutes and could not restart even after the temp had fallen below 160F. I know i had fuel becuase i jumped the pump to feed the carb before cranking. I also hotwire it so i can be right at the engine when cranking.
So now for my questions:
Stud replacement: The studs are original and i chased the threads with a bottoming tap before i put them back and i installed them with neverseeze, not permatex, but i strongly suspect the threads in the block pulled out. What now? I see your replacement kit in the catalog, is that what it is for? Do you drill it larger and then tap it again?
Manifold gasket: If i just fix the stud, is it likely that the manifold gasket is good enough to simply tighten it back down?
Overheat: I have read everything available on overheat as this has been my constant bugaboo since the motor was installed. This overheat is the worst i have ever had, the first time it shut down due to high temp. It usually runs at about 200-210 if i push it under load. I have good flow from the exhaust and the fresh water flow into the heat exchanger feels vigorous (mixing valve long since removed). I check it by sticking my finger inside the HX just upon start to feel the flow. The bypass hose is plugged with a metal plug with a ~1/8" hole drilled in it. Is the manifold issue a likely contributor to the excessive overheat?
Not restarting: I assume that the ignition is cut off upon overheat by an overheat cutoff switch. I see two devices, one on the block and one on the HX. I assume that one is the temp sender and one is the cutoff switch. Shouldn't it start working again once it cools?
Thanks,
Paul
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