I am fairly new to I/O and stern drives. I have a 1992 Rinker 186 Bowrider with the 4.3L Yamaha Stern drive. I am having cooling issues. So far I have done the following after reading the posts I have found in this forum.
Replaced the Raw water impeller, it is located front right lower on engine, belt driven.
Removed risers and exhaust manifolds
Removed hoses and flushed entire system
Everything seems to flow correctly now.
Compression on all cylinders is over 125 psi and within 5% of each other.
Spark plugs look good.
Thermostat tested on the stove and seems to be working properly.
I bolted everything back up and put the outdrive on muffs and everything seemed to work and cool properly.
Didn?t even get to 140F.
I took it out today and it started to overheat again, just putting around.
I removed the main hose from the sea water pump and it is pumps water.
I removed the hose on the top right of the thermostat housing which leads to the exhaust dump and riser when the thermostat opens or if the popit valve opens.
I noticed that i have exhaust pressure from the riser, and no water from the thermostat housing.
After about 30 seconds, the thermostat opened and water came out the housing so I put the hose back on.
Immediately the temp came right down and everything seemed to work fine, like I had to PRIME the cooling system by removing this hose for 30 seconds. Worried I trailered it back home and inspected everything.
I have noticed that I am missing the left side flapper. After running water in the exhaust and looking and putting a fish tape in the exhaust, I do not think it is blocked or that the flapper fell down in it. I bought it this way so I have no idea where it went.
My question is, since the riser does have exhaust pressure and it could lead to the thermostat dump hose, how much exhaust pressure should I have if any? I am thinking that the exhaust pressure is more than the water pressure and it is preventing water from flowing through the thermostat like it should.
Any ideas or suggestions would be great.
Thanks -
Replaced the Raw water impeller, it is located front right lower on engine, belt driven.
Removed risers and exhaust manifolds
Removed hoses and flushed entire system
Everything seems to flow correctly now.
Compression on all cylinders is over 125 psi and within 5% of each other.
Spark plugs look good.
Thermostat tested on the stove and seems to be working properly.
I bolted everything back up and put the outdrive on muffs and everything seemed to work and cool properly.
Didn?t even get to 140F.
I took it out today and it started to overheat again, just putting around.
I removed the main hose from the sea water pump and it is pumps water.
I removed the hose on the top right of the thermostat housing which leads to the exhaust dump and riser when the thermostat opens or if the popit valve opens.
I noticed that i have exhaust pressure from the riser, and no water from the thermostat housing.
After about 30 seconds, the thermostat opened and water came out the housing so I put the hose back on.
Immediately the temp came right down and everything seemed to work fine, like I had to PRIME the cooling system by removing this hose for 30 seconds. Worried I trailered it back home and inspected everything.
I have noticed that I am missing the left side flapper. After running water in the exhaust and looking and putting a fish tape in the exhaust, I do not think it is blocked or that the flapper fell down in it. I bought it this way so I have no idea where it went.
My question is, since the riser does have exhaust pressure and it could lead to the thermostat dump hose, how much exhaust pressure should I have if any? I am thinking that the exhaust pressure is more than the water pressure and it is preventing water from flowing through the thermostat like it should.
Any ideas or suggestions would be great.
Thanks -