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Hutch58 03-11-2010 09:26 PM

OMC Saildrive cooling
 
Boat is a 1977 Islander 26 with an OMC Zephyr Saildrive. I have no cooling water ouflow at thru hull, but good circulation through power head and thru the hose to the manifold. Not sure where it is plugged and the exhaust riser bolts are seized. I will work on running down the location of the blockage, but any suggestions are welcome.


Now, a sanity check. I need to move the boat from the eastern shore of the Chesapeake to the western shore before the end of the month. If i can't locate and clear the blockage,any reason I can't simply put an extension on the outflow hose and lead it (carefully and securely) overboard? Most of the trip should be under sail, but I need to motor through a couple of areas.

timangiel 03-13-2010 08:24 PM

I'm not sure I fully understand you as to where you have good water flow and where you do not. Is there water exiting the exhaust riser at all?

You say there is no water flowing out of the thru hull, but are you still getting exhaust out?

Hutch58 03-13-2010 08:49 PM

Water flow checked as follows:

Hose from pump to riser - good flow
Hose (outlet from head) - good flow
No water from thru hull, but exhaust is exiting as normal

I suspect the outlet passage through the riser is plugged.

timangiel 03-13-2010 08:52 PM

Here is a diagram of the path of water flow thru the engine.
Sail Drive Cooling

If you are saying that you have waterflow in the hose labeled "out" up to the point where it connects to the exhaust riser, then it would seem that the blockage is in the riser and extending that hose overboard might work.

Becareful though because that might create an exhaust leak at the point where the hose is removed from the riser.

Some folks have had problems with exhaust riser blockages caused by engine coking.

Hutch58 03-13-2010 10:47 PM

That wouldn't surprise me. The PO apparently was one of those who thought a little extra 2 stroke oil was "insurance". The mixture was a bit rich when I drained the tank .... 50:1 does not mean 50-50 :-)

I can block off the out "inlet": at the riser. I think for short periods (no more than five minutes) I might be okay - I don't want to run the exhaust "dry" too long for fear of catching the exhaust hose on fire.

Appreciate the help!

timangiel 03-16-2010 11:39 AM

I had not really considered the possibility of the the rest of the exhaust path overheating. Although I don't think it would actually catch on fire (but I admit I could be wrong) I would be concerned about melting or deforming the water muffler because you may have a hard time finding a replacement if you need one. You may be able to extend the water line and attach it to the drain port of the water muffler instead of sending it overboard. That way you would have water in the water muffler and in the exhaust path from the water muffler back. That migh help reduce the risk of overheating something.

rallen1950 03-21-2010 11:22 PM

rallen1950
 
Quote:

Originally Posted by Hutch58 (Post 579604)
Boat is a 1977 Islander 26 with an OMC Zephyr Saildrive. I have no cooling water ouflow at thru hull, but good circulation through power head and thru the hose to the manifold. Not sure where it is plugged and the exhaust riser bolts are seized. I will work on running down the location of the blockage, but any suggestions are welcome.


Now, a sanity check. I need to move the boat from the eastern shore of the Chesapeake to the western shore before the end of the month. If i can't locate and clear the blockage,any reason I can't simply put an extension on the outflow hose and lead it (carefully and securely) overboard? Most of the trip should be under sail, but I need to motor through a couple of areas.

Sorry, I don't have any suggestions to offer but I wanted to post a reply since I seldom come across another 77' Islander 26 owner. I've owned my Islander for over 20 years and still believe it's a great boat. The only thing I didn't care for was the OMC Sail Drive. Even with zinks the aluminum lower unit was an issue. About 15 years ago I pulled the saildrive and glassed over the bottom. I added a 15 h.p. extra long shaft outboard. I replaced the old fuel tank with a plastic one and ran the line through stern to the outboard so wouldn't have to deal with a portable tank in the cockpit. The old tank was aluminum and was clogging my fuel filter with a powder substance even though I pulled it once and flushed it out.
Anyway that's the only complaint I have after all these years. My boat is located in a slip in Southern California. You own a very nice boat , enjoy and treat her well. If you have any other Islander 26 questions let me know and I'll try to help. The Islander 26 was one of Robert Perrys early designs, shortly after he designed the the Islander 28. Another very fine boat.


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