This is on my Volo-Penta AQ170C/280 in a 22 ft Fibreform
OK, here is the problem as it has progressed. Originally I had a overheating problem when using the muffs on land. Through this forum, I ended up drilling some holes in the thermostat and the overheating went away. I even ran it for over 10 mins at fast idle. It was good. Then I had recurring problems with sealing rings leaking - and through the forum again, got them solved. Then I had on major water leak where the exhaust attaches to the boot prior to exiting the transom. Got that solved by resetting the bandclamp properly. Great!
Finally got it into the water on Sunday and decided to stick near shore for the first while to ensure everything was OK. After watching the water temp climb to normal and stay there as I tootled around and no leaks around the sealing rings. So I opened it up and right away I smelled rubber overheating. Put the engine in neutral and checked things. The rubber exhaust boot had some water coming out of it but not enough to cause a concern (I thought). Then I noticed that the water outlet through the transom wasn't really putting out that much water. And the rubber smell was getting worse and we were about 1/4 to 1/2 mile offshore. Turned to head back to the marina and smoke was now emminating from the boot along with an acrid smell of burning rubber. Glanced at the water temp gauge and it was pegged in the 'hot' range. I put it in neutral and the revs went crazy so I put it in gear again only slow. Not getting any oomph from the engine due to overheating. I gave it one last full throttle (for what it was worth) then shut it down and coasted towards the dock with the aid of oars. Current started taking me to the rocks but the engine would not restart. I was able to push off with the oar and another boat (Thank you!) towed us over. I was soooo pissed off at the boat. By the time I got it out of the water the engine had cooled considerably but would not restart to flush the system. I went back to the boat today and pulled the exhaust manifold off and the boot. Man, the boot seemed like it was mostly liquid rubber. I turned off the through-the-hull water pick-up and hooked a hose to the system and all ports seem to flow well. And there was no water in the oil so I assume the head gasket was OK although I didn't take a compression check of it. My impeller was replaced before I bought the boat in April and I did recheck it and greased it slightly a month ago. Anyway I took the manifold home to clean it up and check the water passages. All seems to be OK. Now I know the manifold is old and it looks it but a new one is really expensive.
So, my question to you is this:
Can a leak in the exhaust boot cause this problem? I can't see how it could. I am wondering if the head gasket or the manifold failed (manifold gasket looked good) only to allow water to flow into the exhaust therefore sending bitching hot steam into the exhaust boot and causing it to fail. Water diverted like this would also cause major overheating, I would think. How could this be tested while off the boat?
Man, this boat is starting bother me alot!
OK, here is the problem as it has progressed. Originally I had a overheating problem when using the muffs on land. Through this forum, I ended up drilling some holes in the thermostat and the overheating went away. I even ran it for over 10 mins at fast idle. It was good. Then I had recurring problems with sealing rings leaking - and through the forum again, got them solved. Then I had on major water leak where the exhaust attaches to the boot prior to exiting the transom. Got that solved by resetting the bandclamp properly. Great!
Finally got it into the water on Sunday and decided to stick near shore for the first while to ensure everything was OK. After watching the water temp climb to normal and stay there as I tootled around and no leaks around the sealing rings. So I opened it up and right away I smelled rubber overheating. Put the engine in neutral and checked things. The rubber exhaust boot had some water coming out of it but not enough to cause a concern (I thought). Then I noticed that the water outlet through the transom wasn't really putting out that much water. And the rubber smell was getting worse and we were about 1/4 to 1/2 mile offshore. Turned to head back to the marina and smoke was now emminating from the boot along with an acrid smell of burning rubber. Glanced at the water temp gauge and it was pegged in the 'hot' range. I put it in neutral and the revs went crazy so I put it in gear again only slow. Not getting any oomph from the engine due to overheating. I gave it one last full throttle (for what it was worth) then shut it down and coasted towards the dock with the aid of oars. Current started taking me to the rocks but the engine would not restart. I was able to push off with the oar and another boat (Thank you!) towed us over. I was soooo pissed off at the boat. By the time I got it out of the water the engine had cooled considerably but would not restart to flush the system. I went back to the boat today and pulled the exhaust manifold off and the boot. Man, the boot seemed like it was mostly liquid rubber. I turned off the through-the-hull water pick-up and hooked a hose to the system and all ports seem to flow well. And there was no water in the oil so I assume the head gasket was OK although I didn't take a compression check of it. My impeller was replaced before I bought the boat in April and I did recheck it and greased it slightly a month ago. Anyway I took the manifold home to clean it up and check the water passages. All seems to be OK. Now I know the manifold is old and it looks it but a new one is really expensive.
So, my question to you is this:
Can a leak in the exhaust boot cause this problem? I can't see how it could. I am wondering if the head gasket or the manifold failed (manifold gasket looked good) only to allow water to flow into the exhaust therefore sending bitching hot steam into the exhaust boot and causing it to fail. Water diverted like this would also cause major overheating, I would think. How could this be tested while off the boat?
Man, this boat is starting bother me alot!
