Sea Strainer and Water Pressure
07-05-2012, 07:40 AM
#1
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Sea Strainer and Water Pressure
I have a factory installed fresh water flush and single sea strainer setup in my 35. The fresh water flush is plumbed into the sea strainer and has a shutoff gate valve.
I've always had low water pressure on the stbd motor but it is now becoming problematic (too low/overheating). I've rebuilt the water pumps several times and even switched pumps from port to starboard. The low water pressure always plagues the starboard motor. These are 496's.
Every once in a while the pressure on the stbd motor will come "alive" for lack of a better term. Almost like an air pocket works it way through. But it is usually short lived and only when traveling at high speed with the drives trimmed out a bit. Then without warning it will just start dropping again.
It is not sensor related as the low pressure is indicated on both the mechanical dash gauge and the Smartcraft. The engine temp also rises when the pressure drops. The port motor pressure is always rock steady. The problem motor pressure flucuates widely up on plane but usually steadily drops until I get the alarm. Off-plane at idle both motors have normal pressure.
Where do I look next since it can't be pump related? Since both motors feed off the common strainer it can't be a restriction at the drive inlet feeds. The only think I can think of is a collapsing hose from the strainer to the stbd motor pump inlet? Maybe the strainer feed is clogged to that motor? Due to space limitations I actually can't remove the strainer cover unless I pull the battery and strainer off of its mount. It is tucked under the stbd motor just enough to make access a huge pain. Looking into the strainer cover there is nothing in there. Clear of any obvious debris.
Anyone else have the factory installed single strainer setup?
I've always had low water pressure on the stbd motor but it is now becoming problematic (too low/overheating). I've rebuilt the water pumps several times and even switched pumps from port to starboard. The low water pressure always plagues the starboard motor. These are 496's.
Every once in a while the pressure on the stbd motor will come "alive" for lack of a better term. Almost like an air pocket works it way through. But it is usually short lived and only when traveling at high speed with the drives trimmed out a bit. Then without warning it will just start dropping again.
It is not sensor related as the low pressure is indicated on both the mechanical dash gauge and the Smartcraft. The engine temp also rises when the pressure drops. The port motor pressure is always rock steady. The problem motor pressure flucuates widely up on plane but usually steadily drops until I get the alarm. Off-plane at idle both motors have normal pressure.
Where do I look next since it can't be pump related? Since both motors feed off the common strainer it can't be a restriction at the drive inlet feeds. The only think I can think of is a collapsing hose from the strainer to the stbd motor pump inlet? Maybe the strainer feed is clogged to that motor? Due to space limitations I actually can't remove the strainer cover unless I pull the battery and strainer off of its mount. It is tucked under the stbd motor just enough to make access a huge pain. Looking into the strainer cover there is nothing in there. Clear of any obvious debris.
Anyone else have the factory installed single strainer setup?
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07-05-2012, 10:18 AM
#3
Charter Member
2 motors feeding from a common strainer. That seems odd! Sounds like the 1 motor is pulling more water than the the strainer can supply for 2 motors, starving the second motor. Have you tried to bypass the strainer and make each motor independent?
I'd think the best and most fool prroof would be to add a second strainer and keep them separate.
I'd think the best and most fool prroof would be to add a second strainer and keep them separate.
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07-05-2012, 10:47 AM
#4
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Thread Starter
It is a HUGE strainer, probably holds about 3 gallons and I was told it was an offshore type of unit. Meaning that is has extra capacity for when the boat is launching out of the water it will never starve the pumps. But as you guys suggest is the 496's aren't keeping it full. When the motors are running at idle the water is running into the strainer but is never "full". Even when running it on the fresh water flush, I can fill the strainer and as soon as I start one motor the strainer drains and is just being fed by the incoming flush water.
As far as extra plumbing...yeah. Hoses between the transom plate, to the gate valve, to the strainer, to the back up the pump. I would say at least 6 feet of hose/connections before the water actually gets to the pumps. (With a stop in the strainer on the way)
I guess I will try bypassing the strainer. I'm assuming that I can find a hose coupler to bridge the gap when I disconnect the strainer. What size hoses typically go to the inlet side of the water pumps?
As far as extra plumbing...yeah. Hoses between the transom plate, to the gate valve, to the strainer, to the back up the pump. I would say at least 6 feet of hose/connections before the water actually gets to the pumps. (With a stop in the strainer on the way)
I guess I will try bypassing the strainer. I'm assuming that I can find a hose coupler to bridge the gap when I disconnect the strainer. What size hoses typically go to the inlet side of the water pumps?
07-05-2012, 03:16 PM
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It is a HUGE strainer, probably holds about 3 gallons and I was told it was an offshore type of unit. Meaning that is has extra capacity for when the boat is launching out of the water it will never starve the pumps. But as you guys suggest is the 496's aren't keeping it full. When the motors are running at idle the water is running into the strainer but is never "full". Even when running it on the fresh water flush, I can fill the strainer and as soon as I start one motor the strainer drains and is just being fed by the incoming flush water.
As far as extra plumbing...yeah. Hoses between the transom plate, to the gate valve, to the strainer, to the back up the pump. I would say at least 6 feet of hose/connections before the water actually gets to the pumps. (With a stop in the strainer on the way)
I guess I will try bypassing the strainer. I'm assuming that I can find a hose coupler to bridge the gap when I disconnect the strainer. What size hoses typically go to the inlet side of the water pumps?
As far as extra plumbing...yeah. Hoses between the transom plate, to the gate valve, to the strainer, to the back up the pump. I would say at least 6 feet of hose/connections before the water actually gets to the pumps. (With a stop in the strainer on the way)
I guess I will try bypassing the strainer. I'm assuming that I can find a hose coupler to bridge the gap when I disconnect the strainer. What size hoses typically go to the inlet side of the water pumps?
