"150 Opti overheats at idle 17
"150 Opti overheats at idle 170-180F and when I throttle back from cruising speed 200+F. On plane 100F. Checked therms. they start to open at 125F. Pulled poppit out it looks good no holes in diaphram spring good. Impeller looks good some wear on plate and in housing. Screen for air comp. small amount of debris but not clogged. The lower unit was replaced two years ago because of damage. Repaired by the local dealer. I did notice when I disassembled lower unit that dealer did not put silicone on the top of divider between exhaust and water pump chambers. As called out in the repair manual. The opening between the two chambers is approx. 1/8"X 3" when not siliconed. In all the forums that I have read there has been no mention of this gap. Could this be causing the O/H problem? At idle exhaust could enter pump chamber and when I throttle back from cruise speed also. Those are times when water back pressure would be high in the hub area and exhaust would go into the pump chamber. My water pump pressures are within specs. Good tell tale. I am replacing all parts mentioned with Merc. parts. I have also read that there are two 1/8" holes under powerhead that could be plugged. I see no access without major disassembly. Also read of a recall for this problem. Have not seen any postings after 2007 for this problem. When it does O/H I bring neutral speed up to 2000 RPM and it cools off quickly, down to 140-150F and were good to go again. My warrenty just ran out in June. Cooling system wouldn't be covered anyway. But I don't want to fry the power head. Is there anything else I could be missing? I'm sorry if this seems like a post of the past but the missing silicone sealer has me wondering.
Thanks Jim"
"150 Opti overheats at idle 170-180F and when I throttle back from cruising speed 200+F. On plane 100F. Checked therms. they start to open at 125F. Pulled poppit out it looks good no holes in diaphram spring good. Impeller looks good some wear on plate and in housing. Screen for air comp. small amount of debris but not clogged. The lower unit was replaced two years ago because of damage. Repaired by the local dealer. I did notice when I disassembled lower unit that dealer did not put silicone on the top of divider between exhaust and water pump chambers. As called out in the repair manual. The opening between the two chambers is approx. 1/8"X 3" when not siliconed. In all the forums that I have read there has been no mention of this gap. Could this be causing the O/H problem? At idle exhaust could enter pump chamber and when I throttle back from cruise speed also. Those are times when water back pressure would be high in the hub area and exhaust would go into the pump chamber. My water pump pressures are within specs. Good tell tale. I am replacing all parts mentioned with Merc. parts. I have also read that there are two 1/8" holes under powerhead that could be plugged. I see no access without major disassembly. Also read of a recall for this problem. Have not seen any postings after 2007 for this problem. When it does O/H I bring neutral speed up to 2000 RPM and it cools off quickly, down to 140-150F and were good to go again. My warrenty just ran out in June. Cooling system wouldn't be covered anyway. But I don't want to fry the power head. Is there anything else I could be missing? I'm sorry if this seems like a post of the past but the missing silicone sealer has me wondering.
Thanks Jim"