DF175 won't pee

[Marlinlane]

Need some help guys. I have twins, both with 600+ hours on and running great. We run them literally every day. The other day I noticed stbd wasn't peeing. Replaced the water pump with the whole water pump kit from Suzuki and no joy. Went back to make sure the impeller was spinning clockwise, which it was. Then, with the LU off, blew water through water intake and it pee'd great. Put the LU back on, no pee again. Pee'd for 1 minute, than stopped. Pulled all three cowlings and blew air both ways, nothing came out. Put the LU back on, put the boat in the water, pee'd for 1 minute, then no pee. Not at any RPM. I am pretty confident the water pump is good as I replace them every 100 hours and this one seems no different than any of the others. Not sure what else it could be and it definitely pee'd strongly since we bought it.

Any help or direction would be great. I live in an area where we have one mechanic and he's not the strongest with boats.

[keakar]

run an acid wash through it to clear out any corrosion then see what happens.

I would agree its got to be something other then the impeller

[jHydroman]

On my DF 140's I have found that you have to blow the pee hole with an air nozzle with a rubber tip to get a good seal to clear the obstruction.

Also my pee stream was will weak at idle, I found the thermostat stuck full open, flow OK at higher RPMs

Jim

[Solarman]

no pee stream

Have you tried running on muffs?
Any chance the exhaust seal and plate just under the water pump is damaged/burnt-out?
This would allow exhaust to block/stop water from getting to the pump. The exhaust seal is shown in gear case picture for your model.

[Marlinlane]

Update

Still need a bit of help here. All the same problems, however, we can shoot air through the peephole and it will pee for hours with no problem. We come off plane, no more peeing. Shoot air up there, peeing great.

Clearly, there is a blockage floating around in there. My assumption was that it is some biologic (i.e. sargassa ball) blocking in there. My problem with that now is that it should have broken up and passed through by now. It is definitely not from the water pump gasket or impeller as I have inspected them thoroughly (before replacing them with new ones) and they are 100%.

I am going to pull the thermostat tomorrow and see if I can see the blockage, but my hopes are very low.

Because I can get it to pee by putting water up the water tube when the lower unit is pulled, I know the blockage is above that. It also seems very unlikely that it is below or at the oil pan. My terrible fear is that it is in the engine holder, since that's where the pilot water hole is and shooting air in there fixes the problem every single time.

My questions are 1) am I thinking correctly and, 2) is there a way to get inside the engine holder without pulling the block?

[18pontoon]

The DF70 has 2 removable hoses with gaskets at the top of the engine- one with the thermostat on the block and one with the pressure valve on the exhaust manifold. The DF175 could have the similar dual water tubes or even more. I would look for all tubes to open and flush. If there is a way to run water through the passages both ways, then it could help jar whatever is in there loose.

[artdf175]

Would try flushing with the pee hose removed
Take a wire and push through pee hose connection and try reaming /twisting. Hook up your hose to flush port so you can get it to flush out anything that could cause a plug at the same time
Also have you inspected thermostat ? Get a new gasket first. You will tear up old one removing the thermostat