300 promax losing lots of water pressure near WOT and getting warm, poppet??

[dschifan]

My port motor has been losing water pressure when i am getting on the throttle as well as warming up as i stay into it. My other motor at wot runs around 18psi, port runs around 5 maybe. the motor has a new impeller and t-stats, anyone have any ideas what this sounds like? i was thinking the poppet maybe? the motor does not piss to well in general and even has lower water pressure at idle than the other one, only time it shows decent water pressure is around 4k and its around 10 psi. thanks!

[dschifan]

any ideas of something to look for before i go tearing into it?

[Go Time]

Definitely replace the poppet valve assembly. It's cheap and regulates the backpressure on the watersystem and will affect temperature at WOT. By the way, it sounds like you may have a motor hieght issue or something mounted on the transom in front of the gear case with pressure going to 10 @4K then coming back down @WOT. Are you using a sportmaster LU?
By the way, what are your temps? Are you sure you don't just have a gage thats off? Swap your gages and see if you still get the same readings. Our 300X motors never run much more than 8 psi and the motors run~160 degrees WOT.
Hope this helps.
Mark

[tony brimeyer]

Definitely replace the poppet valve assembly. It's cheap and regulates the backpressure on the watersystem and will affect temperature at WOT. By the way, it sounds like you may have a motor hieght issue or something mounted on the transom in front of the gear case with pressure going to 10 @4K then coming back down @WOT. Are you using a sportmaster LU?
By the way, what are your temps? Are you sure you don't just have a gage thats off? Swap your gages and see if you still get the same readings. Our 300X motors never run much more than 8 psi and the motors run~160 degrees WOT.
Hope this helps.
MarkI just went through the exact same problem with my 300x/sportmaster. After trying everything we could think of, we dropped it 1/4 inch on the jackplate-problem solved!

[dschifan]

thanks for the replies, i know its not a motor height issue its the same height as the other motor that runs fine and it does run around 160 on temp. Like i said even at idle it does not piss as good as the other motor and does not really measure on the water pressure gauge at idle but when reved up it does show decent water pressure. even at cruise speed the port motor runs a easy 10 degrees hotter than the other one, i am thinking the poppet would be the best thing to go through as well. my gauges are good and working. could it the housing on waterpump not sealing or worn out a little bit and once under high rpms does not seal ?

[NICE PAIR]

check your poppet valves. I have, after replacing both pumps, adjusted pressure to be the same, by stretching the spring/spring slightly.

[tony brimeyer]

thanks for the replies, i know its not a motor height issue its the same height as the other motor that runs fine and it does run around 160 on temp. Like i said even at idle it does not piss as good as the other motor and does not really measure on the water pressure gauge at idle but when reved up it does show decent water pressure. even at cruise speed the port motor runs a easy 10 degrees hotter than the other one, i am thinking the poppet would be the best thing to go through as well. my gauges are good and working. could it the housing on waterpump not sealing or worn out a little bit and once under high rpms does not seal ?You would get water in your case and it would be mixed in with your oil, try dropping it a bit and see what happens- easy and free.

[msg11]

I think you are going to have to tear down the motor, take the exhaust plate off the mid and check the plastic coupler that hold the copper tube from the lower unit to upper plate. If there is a clean area in side the tuner there may be a spilt in the coupler. That was my problem, cured water pressure and temp for me.