"I've gone ahead and bough
"I've gone ahead and bought a whole new exhaust set of parts. Bought three sets of each gasket too. On the port side, (new manifold), I pulled off the tailpipe and then pulled off the riser, cleaned & inspected both. They looked great, free of debris and only mild corrosion, gasket surfaces smooth, no cracks. Same result on the starboard side. Pulled it's manifold to replace it. Only thing I found was in the head, looks like a casting defect on the verticle web between the center two exhaust ports. Could be a crack, it has smooth edges like it's a defect. No water present, carbon, yes. Where is the coolant cavity located in the head of a 318?
I also have to ask, when I pulled out the last manifold bolt, the most aft lower bolt, water came out. This normal? Did the same on the other side when I did it. I towled out the valve seat to remove the collected water.
This is the first time I have gone down under the engine. Found my oil leak. All the bolts on the starboard side oil pan were either loose of missing, port side all tight? (too many beers my dear mechanic?). Remember I bought this fine beast in February. Also found the dipstick connection loose and leaking. Also found a brand new looking petcock at fwd starboard side just above the oil pan, in the block. Is this the coolant system drain?
Surprize! Found a freezer plug that looked suspicious, all crudded up and paint peeling. Poked at it with a screwdriver, gush, the engine emptied of water into the bilge. Now wouldn't that have been a nice surprize at an in-opportune moment, (going over the bar? or perhaps while landing a slab?).
Jeff, yes manifold gaskets, I too thought this could be the cause. Did not find anything amiss. At fwd end a Solid gasket except at top which has a hole for the freshwater entry, same gasket at the other aft end, which has hole at top for water to flow from riser to manifold, then another totaly Solid gasket on the other side of the riser, to the tailpipe, separating where the now warmed salt water enters and exits with the exhaust out the tail. Note the catalogue at my marine store shows both gaskets with possible use at all three locations? ?? Also one catalogue does not show the "freshwater distribution pipe", other one does. Still trying to figure that one out. Am taking your advice and reversing coolant flow direction, (my maniflods don't have coolant pipes. Only question I have is that the engine is tilted so much, lowering the top of the riser to about 1" higher than the "to be" freshwater entry at the fwd end of the manifold. Will this cause an air lock? Took of the thermostat and will replace. I am going to look at the sea water pump but probably not the engine f/w pump, it's not leaking anywhere and water is being pumped.
So all this does not explain the coolant system bubbling into the exhaust pipes.
What is going on?"
