TOPIC: Finding a errant impellar fin clogging cooling

Ok I made the cardinal sin...trying to wake up an old Merc 500(1975) without first replacing the impeller.

I R&R'd the carbs and got her fired up and running but not pumping. Pulled the lower and the impeller was shot with only one or two fins still intact. Got a new one and replaced and fired it back up
and it was pee'ing ...albeit not as strong as a 5 year old at a church picnic. It was staying cool and figured on the muffs it was sufficient. btw I also know that water was getting into the water jacket because it was leaking out a bolt hole that holds a clamp for the plug wires that I had not tightened sufficiently.

BUT..... today I fired it back up to adjust the idle screws etc after the rebuild but it was no NOT circulating water at all.

I pulled the water line inside the cowl and it was clean. Removed the foot and ran a wire up the water tube as far as I could and ensured that the tube lined up with the water pump and put it back together.

Still no water getting into the head.

What to do now to find that piece of rubber clogging things up?
Do I pull the water jacket? Can I see the inlet and outlet into the powerhead that way or, and please I hope this is not the case, do I have to pull the powerhead off?

I am not sure of the path inside the motor. Its too bad because I have it running like a top.

Thanks for ideas.

Tim

at this point best bet is to pull the power head, pull the water jack cover at the spark plugs, pull the exhaust cover's and blow out all the cooling ports with compressed air. sounds like allot of debris has gotten through the system. why risk it?

THanks Jim.

I just had a thought....before doing all that.....I believe that the copper water tube can be pulled out of the leg right?

If so I will remove the foot...check and double check the water pump etc in there and check to see of the tube is clogged.

After that if I find nothing I will do the jacket pulls etc. and proceed to head pull.

Keep you posted.

Tim

Did you check between the water inlet and the pump this will also get filled when an impeller disintegrates. remove the grill from the inlet and blow air from the water pump out the inlet.

Awesome idea also. I will try that thanks.

Tim

Ok I pulled the lower unit again and found the brand new impellar a real mess...broken and melted in the water pump cup. I found a few pieces under the water pump in the intake. I replaced the impellar and the water pump housing and put it back together and it is pumping and running very nice now.

Just gonna have to keep a real close eye on the tell tale in case another errant piece of rubber is still in the jacket or somewhere.

Thanks for the suggestions.

Tim

make sure the impeller is loose on the drive shaft if not you can be back in there again.