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Hi everyone. I have a problem that is making my hair fall out. My 140 df outboard will have good water out of the water the pees out till i hit 3000 to 3500 rpm. Changed the impeller, thermostat, popet valve, and both the exhaust and water temp probes. Have no idea what would cause this. Its like some mechanical gate is opening and dumping the water pressure. I have never heard of a water pump lossing presure as rpms increase. Any help would be appreciated
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Did you change the water pump housing when you put the new impeller in?
That would be my next step. A slight imperfection in the houisng shape can cause a loss of water pressure so always a good idea to replace hpusing and impeller as a set. -
Is it possible that by that RPM you're planing enough that the water inlet isn't getting clean water and is sucking air? You don't mention the boat but a pontoon for example has horrible water flow around the motor at higher speeds..Comment
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Its on a sea cat. Blew up the lower case 2 years ago. This is a older lower and has to older water pump. Going to change the compleate pump as soon as i can. Had mo trouble last year but did notice this issue. Thanks for the suggestions.
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What year and model is your Sea Cat? I have a 96 SL5C.Originally posted by Twin 140 View PostIts on a sea cat. Blew up the lower case 2 years ago. This is a older lower and has to older water pump. Going to change the compleate pump as soon as i can. Had mo trouble last year but did notice this issue. Thanks for the suggestions.Comment
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If the older lower has the "sub-water pick up" tube, that goes above the prop, to under the water pump, make sure the grommets have a good fitting, otherwise exhaust gases can blow into water pickup cavity at higher rpms, interfering with water pump intake.
They have this on my 2 strokes, gave me problems.
Exhaust can also blow into water cavity at exhaust plate, if a hole is in the separator plate.
Good luck.Comment
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