Waterflow Problems...Yamaha 150 Pro-V 1986

[Paintufast]

I have a 1986 procraft 17.5 F/S. It has a 1986 Yamaha 150 pro-v on it. I have been working on the motor to get it back in shape. I have gotten it running last fall and was having an overheating problem so I replaced my water pump. Now that I have it running again this spring it is STILL overheating after just a few minutes at idle. I have noticed that it isn't flowing water out of the small drain hole that it should be coming from (I don't know the technical name, its the drain hole on the lower back part of the main body of the motor).

Looking at the motor from the back of the back there is a large water line near the bottom of the crankcase. Where the line enters the motor at what looks like a thermostat. I opened this up and noted a spring and plug which I assume is some sort of thermostat, and quite a bit of corrosion inside here. It is also not wet at all inside there after the motor runs for 1-2 minutes at idle *no longer than that to keep from overheating*

I am trying to diagnose why the motor isn't getting water pumped up into it despite the brand new water pump, and I am at a loss of what to look into, where to go from here. Any and all suggestions would be greatly appreciated. I can post any pictures you request or videos of the motor running etc. I just need to know what would be helpful for everyone to see to diagnose this problem. Thanks in advance!

 

[99yam40]

Re: Waterflow Problems...Yamaha 150 Pro-V 1986

pic of what you call a stat would help, it may be a stat or a PRV.

Did you replace the pump housing , kit, or just impeller?

Did you make sure you hit the tube when putting back together?

 

[Paintufast]

Re: Waterflow Problems...Yamaha 150 Pro-V 1986



These are pictures of what I believe is the thermostat that goes into the bottom of the block. The black plug and spring is what came out of those connection at the block.

The smaller tube, I believe is a drain tube where I should see water coming out if I am actually getting water into the block.

When I reassembled the water pump I did a kit, I cannot recall for sure but I think I replaced housing and all. I followed a DIY video I found so everything SHOULD have been reconnected appropriately, but I wouldn't swear against anything.

I had one suggestion from a contact up here to try to pull the impeller back out and backflush to be sure there isnt a clog from the old impeller as it broke down. But I am not sure how to perform this "back flush". Any suggestions?

Thanks for the help, sorry for being so clueless on this topic.

 

[99yam40]

Re: Waterflow Problems...Yamaha 150 Pro-V 1986

that is the PRV
the stats are on the top of heads and need to be pull and tested or just replaced with new

If the impeller came apart then Yes there can be pieces in passages causing blockage and overheat. It is never a good idea to run a motor until parts fail. Yamaha has recommendations on replacing parts to keep this kind of stuff from happening.

I would pull stats, drop lower unit again and then hook up a water hose to tube into motor and flush it out the stat openings, then replace stats with new. If that does not solve your problem with over heat you may need to open up motor to clean passages of rubber pieces or other build up.

Pump housing does not come with kit, has to be ordered separately. If there is signs of melting of the plastic housing it needs to be replaced