Pumps water until gears are engaged???

[displaced47]

My old (71/72) 8 hp mariner (actually a made in japan yamaha) pumps water but the water stops pumping when I put the motor into gear (either forward or reverse) any ideas?

 

[Bob_VT]

Re: Pumps water until gears are engaged???

Your impeller is probably worn....... or slipping. Time to take it apart and check it.

 

[displaced47]

Re: Pumps water until gears are engaged???

I'm waiting on one to arrive from the UK (they are very scarce) but hopefully that will solve the problem.

 

[Capt Ken]

Re: Pumps water until gears are engaged???

I believe the water pickup is under the cavitation plate just above the prop. If it is, remove the prop and try it again. That will tell you if the prop is somehow throwing exhaust gasses into the water pickup

 

[displaced47]

Re: Pumps water until gears are engaged???

I had it all apart today and it appears to have the water pump housing of the later serial number 8A... makes me worry that the impeller I ordered will be incorrect. The one in there was still complete but every fin was cracked at the hub!

 

[Don S]

Re: Pumps water until gears are engaged???

My old (71/72) 8 hp mariner (actually a made in japan yamaha)

I think you may find that only the power head is from Yamaha, the rest of the motor is Mercury.

 

[displaced47]

Re: Pumps water until gears are engaged???

I don't know mate... it has the Yamaha tuning forks stamped on every cast alloy part and on most of the component parts too... still waiting on the impeller...

 

[displaced47]

Re: Pumps water until gears are engaged???

Hey all,
I got the impellers from the UK which were the ones suggested for my serial number range and they are too big around the drive shaft. My shaft looks to be about 5 mm's narrower. I could try the one for the next range of serial numbers but this could be a very long process... DOES ANYONE KNOW SOMEWHERE YOU CAN SEARCH IMPELLERS BY SHAFT DIAMETER?

thanks all