mercury 1981 inline six power loss

simn20 · #1 August 27th, 2006, 05:50 PM

hi all,

last week i was using my boat with a 1981 mercury outboard in line 6 115hp and the engine does weird thing he was running week at 4600 rpm and after a while he a sudden loss of rpm. then going back to 4600 rpm etc... the engine was habitually go to 5000 rpm. the mechanics near, say the engine as start to grip on cylinder 1 and 2. i don't know what cause it overheat or a weak carb. the engine still run smooth at idle, and start like a charm

now i wonder if it worth the rebuilding. im probably gonna have to oversize the engine and change the piston. its a 900$ for the rebuilding kit including wiseco piston + 250$ for the oversize + time to rebuild ( i dont do it myself, anyone know how long i can think of, for removing the power head from the outboard unit to complete rebuild including carb and fuel pump?).

i found already rebuild power head for 1500$ + 300$ shipping at southwest marine in Fort Myers, FL. anyone know these one? i also see that this site (iboat) have a supplier for around the same price

what you think does it even worth to spend time and money to this unit?

your comments are welcome

denny4 · #2 August 27th, 2006, 10:57 PM

Weeellll, i see i'm not alone. We have the same problem,.. sort of . I sent mine in to get the timing &carbs done,... they couldn't do it,....my # 4 had no compression hence the power loss . so i too are looking at a rebuild ( winter project ). Getting the powerhead off is the easy part and the rest well , i'll let my mechanic buddy do,providing there isn't much damage and if so you'll snag your fishing lures on it CAUSE IT'LL BE ON THE BOTTOM OF THE RIVER!!!

studlymandingo · #3 August 28th, 2006, 09:16 AM

What do you mean by start to grip? I would do a compression check myself. Post the results and you will get some better ideas how to proceed.

Chris1956 · #4 August 28th, 2006, 09:55 AM

Simm, I bought a rebuilt powerhead from Southwest. They did a reasonable job rebuilding it. You need to be aware that they provide just the block, covers, crank and pistons etc. You will need to reuse everything else from your core, all the brass and stainless fittings, including the balance hose fittings, carb studs, mounting studs, rubber mounts, ign system, carbs, flywheel... It will take quite a bit of time to make the switch. It is not difficult, and you will "know" your motor inside and out, when you are done.d