Water Pump

[igofishn]

I have twin 1991 150 yamaha's. Today I noticed that the starboard motor has alot of airbubbles coming up from the lower unit out of the vents behind the pump and the telltale does not have as strong a stream as the port motor. Just changed Water pumps, T-stats, pressure valves. Am I somehow sucking air into the water pump? I have been changing the pumps every other year since 1997 and never had a problem. Engine runs fine at idle, cruise and wide open. Just don't want anything to happen while out on the water.<br /><br />Any suggestions.<br /><br />Thank You,<br /><br />Carlo

 

[sloopy]

Re: Water Pump

Why are you changing pumps every year? The air coming from the LU is normal, it is the exhaust (sp) from the engine.

 

[igofishn]

Re: Water Pump

Thanks Sloopy,<br /><br />I change the water pumps every other year. Why would I only see these bubbles from the starboard motor and not the port.

 

[rodbolt]

Re: Water Pump

have you been removing the rubber dam and holder and cleaning them each time? occaionally it will raise due to corrosion and water pressure at idle will suffer.

 

[igofishn]

Re: Water Pump

Thanks rodbolt,<br /><br />Not sure exactly what you are talking about so I have to say no. I can't find this in the yamaha manual either. Are you talking about the rubber piece about 2 1/2 inches long just behind the water pump? What is the purpose of this piece anyway? Do you recommend pulling the boat and fixing this or it will be ok for this season. I use the boat about 50 hours per year.<br /><br />thanks

 

[rodbolt]

Re: Water Pump

depends on if its an issue.<br /> if it idles fine and runs fine with no overheat then run it, make sure your alarm sounds at start up for the self test.<br /> yes its that small piece of rubber and no its not in the book its in 30 years of experience and watching others get bit by it.

 

[igofishn]

Re: Water Pump

What is the purpose of this rubber piece anyway?<br /><br />Is there any issue with the air bubbles that I posted on my orignal post. The Air is coming out from just above the cavitaion plate vents.<br />SLOOPY says the Exhaust is normal, but is there a reason I dont see airbubbles on the port motor. I thank you for sharing your 30 years of experience with me.