Engine flushing issue again

[sandflyer]

Thanks for helping with my post titled "Open Engine Flushing" on the Yamaha Forum.

The engine is 1990 150 Yamaha

I inherited the engine from a fellow that started having a heating problem after the engine was serviced (spark plugs, water pump and whatever else is included in service) by a "mechanic" that was in his new town. After the service was performed the engine was not run again until the owner settled into yet another town (approx 6 months).
When he finally did get to run the engine it would buzz after running at high RPM. Ran fine at lower RPMS and starts perfect.
He would just run at RPM's low enough as to not overheat. Maybe 10 hrs.

After reading the numerous posts on the forum I began the rather simple task of checking the systems.
Servicing the PRV, thermostats, temp sending units, new water pump and housing and I installed a water pressure guage.
While I had the all the ports open and the lower unit was off I figured I'd rinse out all the areas that water would normally flow.

I noticed that there is something about an inch into the main water tube right above the water pump housing. None of the parts manuals show this tube much less anything in this tube. A check valve maybe?

When I replaced the impeller... the one I removed was in new condition. The stainless steel plate that the impleller rides on had signs of wear. All of that is now new. I also noticed the the main drive shaft does not quite ride in the exact center of the impeller housing.

I havent run the engine since I performed all these tasks but am trying to cover all bases prior to reinstalling the lower unit.

[jb123]

ensure lower unit and throttles are in neutral and use plenty od never seize on your mount bolts. dont hesitate to replace your stats and prv parts, unless you want to always question them.

[slim]

if your talking about the water tube in the midsection, there is not supposed to be anything in there. get a pair of needle nose and pull it out. it might be a piece or an old impellar. let me know what you find cause i know of something else it can be.

[Operaman]

Slim confirmed my thoughts. I would think that should be a clear shot, nothing in there.

[Ken]

sandflyer,
Anytime you do a water pump repair and pieces of the old impeller are missing, you can just about bet they have gone up the pump tube if you can't find them in the cup/housing anywhere.
The drive shaft is suppose to be off-center in the cup/housing. This is so to make the impeller paddles compress on one side and expand on the other - this brings water in on the suction side and pushes water out on the compression side up thru the tube.
Good luck [img]smile.gif[/img] ,
Ken K

[sandflyer]

Ken.
The shaft is not in the center of the exit hole in the housing. Am I to understand that it will center itself after the lower unit is installed?
thanks

[slim]

no, thats how it is supposed to be. that is what makes it pump water.

[slim]

ok i do see what you are talking about. can you move the drive shaft side to side easy? what does the gap do then. im thinking it is just the force of the impellar to one side that is doing this. i dont think it would cause a
problem. check the movement and let me know. i tried returning your email but it wouldnt go through.

[sandflyer]

Slim......
I removed the entire assembly and just bolted the housing only ...same thing. I reassembled everything and this time I tightend the aft bolts first then the forward bolts. The shaft is just barely rubbing and I can pull the shaft away from the rubbing area but the shaft is not loose. Its very secure in it's mount (bearings). I'm not concerned that the shaft will damage the housing cause it's just barely touching.....I more concened about the extra space on one side. I also reinstalled the old housing and its the same thing.
I think I've decided to just bolt it all together and run as is.....what ya think.
Thanks again.... no replacement for experience.