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| Author |
Message |
    
Michael Steele
Visitor
| | Posted on Thursday, May 08, 2008 - 06:19 am: | 
|
Hi guy's,Problem:15 ft.low profile runabout(G3)with a 1972 merc.50 horse s.s.It goes fine at low and med.speeds,but when you punch it she takes off like a bat out of hell for about 20 sec.then the rpm's shoot up and the power goes down.If you back off the gas she goes back to normal.(it's like shifting to "n" with the gas wide open)I do have a hydrofoil.Cavitation? Gearbox? Linkage? Any idea's....thanks Mike |
ikia
Visitor
| | Posted on Thursday, May 08, 2008 - 07:46 am: |
|
Mark the prop and hub to see if the hub is spun. And it could be cavitation as well.Lower the motor if prop hub is OK. |
JB
Advanced Member
Username: beckerjs
Post Number: 941
Registered: 11-2005
| | Posted on Thursday, May 08, 2008 - 09:25 am: |
|
Ikia is dead on, 1 question, does the lower unit of the engine hang below the bottom of the boat?
http://www.themarinedoctor.com/cgi-bin//YaBB.pl?num=1175964588 |
Michael Steele
Visitor
| | Posted on Thursday, May 08, 2008 - 12:26 pm: |
|
JB,Ikia,
I measured from the bottom of the transome to the center of the prop.7 inches.That puts the top of the prop 1.5 inches below the boat,and the hydrofoil about even with the bottom of the boat.Trouble? Could you explain marking the prop to check the hub.Also,how do I lower the motor.P.S.should I remove the hydrofoil to see if that helps. Thanks....Mike |
JB
Advanced Member
Username: beckerjs
Post Number: 943
Registered: 11-2005
| | Posted on Thursday, May 08, 2008 - 12:44 pm: |
|
draw a line on the prop from 1 blade straight down through the center and onto the inner hub , remove nut if you have to. The idea is that the center of the prop is rubber, when it gets old it allows the outer part of the prop to spin on the inner part of the prop hub, this should only happen if you hit something. Run engine at full power, check and see if lines still match. Remove foil if prop checks ok, run again. You cant lower engine. |
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