1989 70hp Yamaha cooling system flush

[utfyrfytr]

Recently bought this 89 70hp Yamaha motor. The previous owner said the water pump needed to be replaced. The engine started right up and sounded good. Only ran it for about 30 seconds. Prior to starting I did a compression check which was good the plugs were clean and there was no discoloration or signs of being over heated. After bringing the motor home I pulled the lower unit to do the impeller replacement and found the impeller in pieces. See photo. My question now is, is there a way to flush the cooling passages on that motor? I removed the pick-up screens and blew down from the water pump and blew out quite a few pieces of the impeller from there. I just don't know what may have gotten up into the motor. Thanks for any help or ideas.

 

[racerone]

I guess there are still folks out there running impeller dry.-----And still folks who do not install a new impeller every 5 years.

 

[airshot]

Only takes less than a minute to disintegrate an impeller like that. Lots of flushing is the best that I can recommend for your motor. Use both air and water for best results and look for any restrictions from water flow. Mabey someone with more experience on this motor will chime in...

 

[99yam40]

Pull the thermostat and leave the housing off so you can see what all come out when you (while you have the lower off ),hook a hose to the pipe heading up to the powerhead turn on the water and hope you get most of the pieces out of the cooling passages.
On a motor that old you may end up breaking off bolts removing head and other covers to clean out passages.
good luck.

I would do the simple things and then run it for awhile to see if overheat happens before taking a deep dive into all cooling passages

 

[Mc Tool]

Even put the hose in the t/stat housing and reverse flush it .....cant hurt .