Original copper exhaust system - any good?
Just wondering if any of you have replaced your original copper exhaust system that came with the P30? If so, what did you put in its place? and Do yo have any photos? I am doing an engine overhaul, and mine looks somewhat corroded and potentially leaky, so I am trying to figure out what path to take. Has anyone ever repaired theirs ? or had it checked for leaks? In my reading here, and other places online, I find that these are actually good systems if they are solid. Any info or feedback around this topic would be of help. Thanks!
There is a potential 'flaw' in the *steam riser pipe* exhaust systems used in the P30. Internal to the vertical pipe section is a small 'diverter cap' that prevents water injection from flowing INTO the dry exhaust vertical riser-pipe which if not there (eroded away) will lead to water backflow into the engine. On old installations especially the copper assembly should be cut apart, the 'witches hat' be visually inspected or replaced ... an easy job for a 'red-metals' shop/welder. Can easily be 'assayed' with a flexible optical 'bore-scope' ... find a shop that has one to do the assay.
If the system was adequately protected by the use of 'pencil zincs' (at the 'drain' on the bottom of the riser ... replaced yearly, etc.) the copper usually will be found to be intact.
How to check the integrity of riser-pipe system: Take the whole assembly, both the vertical section AND the radiused horizontal jacketed section that leads to the vertical riser pipe to a 'boiler shop' and have them "pressure test" (quite high pressure water) and simply check for leaks emanating into the 'dry side'. Copper is easy to 'work', the components are 'common' and a boiler or heat exchanger shop will be able to either rebuild or repair a 'faulty' heat riser system and at 'economical' prices.
Also a good time to pressure check the (A4) exhaust manifold for pin holes between the dry side and the wet side ... pin holes can be quite common with old engines ... can easily be repaired by 'brazing' or simply get a 'new' manifold from sources like Moyer Marine Atomic 4 Engine Rebuilding and Parts
Pin holes and 'slab rust' (which can intermittently BLOCK the cooling water flow in the exh. manifold and the riser system) will be quite common on engines that were 'dried-out' (no antifreeze) for long term or winter 'storage'... this is the reason that large ships NEVER shut down their engines/exhaust systems as such keeps the formation of 'protective' ferrous (black) rust intact on the cast iron.
hope this helps.
Thanks for the detailed response ! Now I truly understand exactly what I have been wondering about... Great diagram - it makes complete sense. I am currrently midstream in a rebuild, and am active in the forum @ Moyer Marine... You can read about my progress here : The adventure continues... - Moyer Marine Atomic 4 Community - Home of the Afourians
I have looked at that corroded exhaust system with a furrowed brow many a time since beginning this project, and wondered with worry about what a nightmare replacing it could be, or where to even begin ... Now, I will take your advice and get it out of the boat and try to have it evaluated, and if necessary, repaired.
Thanks again for sharing this information - it is because of knowledgeable, generous folks like yourself that we can all enjoy engaging in the process of doing our own work on our beloved vessels, and perform these tasks with confidence, vs. paying the boat yard outrageous sums of money to do it for us.
Cheers, mate ! :)
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