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Mercury 7.5 Thunderbolt

M

mruff

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To start, I am completely green behind the ears when it comes to outboards. I do have considerable mechanical experience but this is my first outboard. First off I bought a 1973 Mercury 7.5 HP. I intend to use it on a 14ft flat bottom for duck hunting. I bought the motor about 6 months ago and when I started it for the first time I couldn't see the impeller was working at all. So I bought an impeller and didn't repair it until today. After the new impeller it still isn't getting water through the engine and out the water exit. I am only getting exhaust out where the water should be coming out. I thing I did notice though was the water is gurgling and bubbling out of the bottom. Keep in mind the prop is set in neutral when it is doing this. When I rev the engine I still am not getting any water out. Any ideas? Any help is appreciated.
 
When these motors have run very hot this is what happens.------------There is a plastic washer at the top of the copper water tube and it melts and then blocks water flow.----------It might be worthwile to remove the powerhead to inspect this.------------Sounds like a lot of work , but actually a straight forward easy job.
 
racerone said:
When these motors have run very hot this is what happens.------------There is a plastic washer at the top of the copper water tube and it melts and then blocks water flow.----------It might be worthwile to remove the powerhead to inspect this.------------Sounds like a lot of work , but actually a straight forward easy job.
Click to expand...

When I pulled the bottom end off a rubber washer came off and wasn't sure where it went back to... Is there a diagram or something to reference when working on this?
 
Ok. Just to make sure I inderstand everything. Pull the lower unit to make sure I did not turn the prop counter clockwise while installing, which I,m sure I did. By turning ccw does this flip the impeller to churn water the wrong way? If the impeller is set thr right way then pull the powerhead and check for a rubber washer at the top of the copper tube to make sure it is in place? Hopefully this fixes it. Duck season is getting close
 
There is a PLASTIC washer around the water tube at the top.------------It is inspected by removing the powerhead !------------I have seen these washers melted and blocking waterflow to the motor.------------I can not do the work for you, I can only point you in the right direction.------------At this point I nor you know if this washer is melted or if it is good.-------Replacements are a better material.
 
One more question. Assuming I need parts for this older mercury where is the best place online to buy them. I had a hard time even finding the impeller but was able to find it locally.
 
That impeller is in stock at any good Mercury dealer.----That impeller needs to be replaced on a regular basis and everybody has stock !!!
 
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