Merc 800 80hp L.U. problem.. (need advice)

[cop22]

When throttling quickly off the start engine will excelerate but the prop won't. If you back off the throttle the prop will engage and everything is fine. I noticed two small cracks in the Gear housing. Could the cracked housing be causing the exceleration problem or just the result of a gear or more expen$ive problem.

 

[Hooty]

Re: Merc 800 80hp L.U. problem.. (need advice)

I may be nothing more then a spun prop hub. Take it to your prop shop and tell them you think you may have a spun prop hub. They can tell ya if you do or not and if it is, they can fix it. Not expensive.<br /><br />c/6<br />Hooty

 

[emckelvy]

Re: Merc 800 80hp L.U. problem.. (need advice)

Sounds like exhaust gasses might be flowing out the cracks in the gearcase and ventilating the prop upon takeoff.<br /><br />If the cracks aren't affecting the structural integrity of the gearcase, you may be able to patch them up with some Marine Tex or equivalent. The repair would need to be faired in properly so as not to cause more turbulence & ventilation.<br /><br />If you know a good welder, you may be able to get the crack welded up to keep it from spreading.<br /><br />However, usually when these crack it just gets worse, and then your shafts, gears, and bearings are in jeopardy.<br /><br />If you plan on keeping this motor for a long time, it might not be a bad idea to replace the lower unit.<br /><br />Ones run in a lot of salt seem to have more of these problems than freshwater motors, due to salt deposits building up in the threads of the gearcase cover ring, causing stress on the gearcase and eventually cracking the case.<br /><br />You may be able to find a decent lower unit on eBay or from one of the good folks at this forum.<br /><br />HTH and Good Luck.........ed

 

[Hooty]

Re: Merc 800 80hp L.U. problem.. (need advice)

(How rude of me) <br /><br />Welcome to iboats Cop22. Let us know what ya find out.<br /><br />g'luck & c/6<br />Hooty

 

[cop22]

Re: Merc 800 80hp L.U. problem.. (need advice)

Ed & Hooty, I really appreciate the prompt response. I will definitely check for a spun prop hub and keep my eye out for an inexpensive L.U. BTW.. what would a fair price be on a Lower Unit for this 1971 80horse Merc?