1977 Mercury 500 Thunderbolt W/ Weak stream

[Mercurylips]

I have a 50 HP mercury with a very weak coolant stream from the pump. Just removed the lower and expected to find a badly worn impeller, but it looks just fine. I haven't experienced any overheating problems but thought the pump would need some help since everything else needed attention before I bought it and after. Feel free to have some fun with the stream thingy but keep in mind that none of us is getting younger by leaps and bounds. I am also going to change out the seals since the gear lube looks like a pistachio milkshake. Thanks for any help, Mike

 

[Scott Danforth]

i would replace the impeller since you have it apart

then I would check to see if there is debris in the cooling passages of the power head.

 

[Mercurylips]

Any way to flush it out with out taking the head apart? I was wondering if the stream could be effected by putting the impeller in backwards?

 

[Mercurylips]

After replacing the seals in the lower and rebuilding the water pump, I decided to pull the boat out of the garage and use a garden hose with an adjustable nozzle, before replacing the lower, and spray it up the copper coolant tube located next to the exhaust sleeve. After several healthy shots of water the tell tale was spraying a very great amount and it looks like I can finish putting the motor back together. I will update when I can. There appeared to be some sand and gunk in the pipes that needed to come loose.

 

[Mercurylips]

Put the lower together with the motor and hooked it up to the muffs. Water stream is very adequate so now I can get it out to start fishing. Nice when an idea actually works.