Water cooling problem

[g5665]

Hello people of Yamaha 25MKii and YSM8

For long time didn't had any problems with the old YSM8

Recently was working with it and suddenly the sound changed and i rapidly noticed that the cooling water had stop flowing...

Was quite easy to realize that something was wrong with the water pump... impeller was more than dead...just the central pin had survived (after 6 months working - i had it changed last time i had the engine checked).

Was quite straightforward... went to get a new impeller, removed the water pump, replace the impeller, checked the water flowing from the pipe connecting to the seacock...everything was ok...
Installed the new impeller...installed the pump...connected the belt...everything ok...

However... the water runs...and reach the engine...i removed pipe by pipe to check if any was dry but all had water...
Only the water doesn't come out to reach the elbow!
Is it possible to be something wrong with the water pump...not making enough pression to send the water up and out?
If so...what need to be done? Change to a new pump? And if so, any suggestions?

Spent the whole afternoon getting greasy... and very disappointing!!!!

 

[Yam]

hello,

Maybe a piece of the old impeller close the passage of water.
look at the mixing elbow sometimes is really durty inside and the passage of water is not clear.

 

[Boffin]

You should check follow the suggestion from Yam . And there is a drain valve underneath the cylinder head , you can open the valve ( with the lever in horizontal direction ) to see any water coming out . Last time I disassemble the cylinder head and find a lot of skeleton of sea creature and broken piece of the impeller inside the water chamber that block the water flow .
Use water to flush from the revert direction may be useful , but you have to disconnect the impeller .

 

[g5665]

Good afternoon all

Just for an update on what was done yesterday...
The pump seem to be ok and the impeller changed...
Removed pipe by pipe...checked all clean...
But still no water comes out in the back...
today will do the cleaning of the cylinder head...maybe the problem lies there...
Lets see what the day reserves today...

You should check follow the suggestion from Yam . And there is a drain valve underneath the cylinder head , you can open the valve ( with the lever in horizontal direction ) to see any water coming out . Last time I disassemble the cylinder head and find a lot of skeleton of sea creature and broken piece of the impeller inside the water chamber that block the water flow .
Use water to flush from the revert direction may be useful , but you have to disconnect the impeller .

 

[g5665]

Problem solved and water coming out...clean...
All water pumping system cleaned...
The main problem was in the valve under the cylinder exactly... completely dirty...
Let's see until when it will hold clean with the "clean" waters of Pearl River delta!!!

Thanks everyone

Good afternoon all

Just for an update on what was done yesterday...
The pump seem to be ok and the impeller changed...
Removed pipe by pipe...checked all clean...
But still no water comes out in the back...
today will do the cleaning of the cylinder head...maybe the problem lies there...
Lets see what the day reserves today...

 

[dee.yeah]

Would a intake water filter be useful? I have one installed in between the seacock and engine.

 

[Boffin]

That is a must in tropical water , it traps the small sea creatures go into the cylinder head .
I once found a small fish in the filter.