mercury 25hp 4 stroke water tube clogged

telfordsam

Recruit
Joined
Jan 22, 2023
Messages
2
I have a 2011 25hp mercury 4stroke that i have replaced water pump and thermostat, thoroughly checked all water lines and still cant get water up thru copper water tube to block. I can blow thru all hoses and block clearly. Any help will be greatly appreciated.
 

alldodge

Supreme Mariner
Joined
Mar 8, 2009
Messages
37,564
Remove the lower and place in bucket of water.
Can the shaft be rotated and have water come up the tube?
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,225
Unless you block off the intake under the cavation plate, it wont pick up on a hose. Will work fine in a bucket...
 

QBhoy

Admiral
Joined
Mar 10, 2016
Messages
7,176
As long as you have the intakes submerged or can verify it’s definitely getting a good supply…and you’re then not getting water up it…that assumed, one might think that it may be clogged with salt deposits further up or it’s not together right and drawing air somewhere.
If it’s salt deposits…I just recently managed to clear out an old Yamaha with the same issue. Believe it or not, I took the lower unit off and turned the thing upside down almost…then poured vinegar into it to soak…after a wee while…I then got a small plastic syringe that came with kids medicine or something…and injected some more vinegar into the tell tale outlet. Did that a few times and eventually it cleared it all out.
 
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