Love the forum! Invaluable resource for those still committed to the Atomic-4.
Have a strong running late model raw water cooled A4 in my 1973 Tartan 30. Boat is on the hard, and have been performing some upgrades and maintenance to the motor (water jacked side plate stud upgrade, thermostat housing replacement, block water jacket cleanout and backflush, etc.). After buttoning up the engine and trying to start, noticed that no water was being drawn into the engine at the source (a large bucket). Traced the issue to the exhaust manifold (water flows freely and cleanly through the block to the thermostat housing), and it looks like the exhaust manifold cooling passages are totally blocked.
Have tried to backflush and forward flush with fresh water under pressure plumbed with a garden hose to the intake and outflow fittings on the manifold - no water will move through them.
Couldn't get the manifold hose elbow fittings off on first pass, and rooting around with a wire hanger through them didn't do much due to the hard angles, etc.
Engine was acid-flushed a year before being put on the hard, ran at proper temp, and saw light use during that time. Boat has been on the hard for a year in Seattle while performing some upgrades. Probably could have done more winterizing by draining all water from the block and manifold or running antifreeze through the system. Did leave hoses disconnected throughout the winter, and there are no external signs of freeze damage, cracking, etc.
Any ideas on how to proceed getting the passages unstuck if pressure water won't do it? Have never pulled the freeze plugs before, and not sure what that would buy me. Are the internal passage shapes complex enough to preclude effective 'rooting' out in place?
Of course, would prefer not having to yank the manifold off of the boat to boil it or something drastic like that...
Any help or ideas would be appreciated.
Have a strong running late model raw water cooled A4 in my 1973 Tartan 30. Boat is on the hard, and have been performing some upgrades and maintenance to the motor (water jacked side plate stud upgrade, thermostat housing replacement, block water jacket cleanout and backflush, etc.). After buttoning up the engine and trying to start, noticed that no water was being drawn into the engine at the source (a large bucket). Traced the issue to the exhaust manifold (water flows freely and cleanly through the block to the thermostat housing), and it looks like the exhaust manifold cooling passages are totally blocked.
Have tried to backflush and forward flush with fresh water under pressure plumbed with a garden hose to the intake and outflow fittings on the manifold - no water will move through them.
Couldn't get the manifold hose elbow fittings off on first pass, and rooting around with a wire hanger through them didn't do much due to the hard angles, etc.
Engine was acid-flushed a year before being put on the hard, ran at proper temp, and saw light use during that time. Boat has been on the hard for a year in Seattle while performing some upgrades. Probably could have done more winterizing by draining all water from the block and manifold or running antifreeze through the system. Did leave hoses disconnected throughout the winter, and there are no external signs of freeze damage, cracking, etc.
Any ideas on how to proceed getting the passages unstuck if pressure water won't do it? Have never pulled the freeze plugs before, and not sure what that would buy me. Are the internal passage shapes complex enough to preclude effective 'rooting' out in place?
Of course, would prefer not having to yank the manifold off of the boat to boil it or something drastic like that...
Any help or ideas would be appreciated.
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