'05 Merc 60 HP Bigfoot 3 CYL. TWO stroke- KNOCKING

[SunTrackerPB21]

I am the second owner..its probably got less than 200 hours on it .
Last year I thought I detected a small knocking at idle (1000 RPM). I spoke to a tech I met at a gas station (boat not there) and he said that the sound was normal. Its HARD to hear what the motor is doing at speed as its on a pontoon and is 5 ft down/under there at the rear when running fast.
I supppose we can assume the knock is still there drowned out by the roar of the motor. Anyway, the boat was put away for winter and this season, I've had it out 6 times and the sound is getting louder. Last time out, running at WOT (5000 rpm) the boat began to slow on its own to 4600 RPM @ WOT. We put it in the water yesterday and when I started it up (electric choke) it gave out a large cloud of blue smoke but then stopped smoking right away. The knock was still there..its not loud, sounds like tapping a screwdriver handle on an aluminum railing ( at Idle). I had the same TECH guy over today and we ran it up in the driveway on 'muffs' but its hard to hear the knock with the exhaust racket. He checked the compression: Cyl 1 (top) 105, Cyl 2 (mid) 110, Cyl 3 (Bottom) 125.
He pulled the plug leads 1 by 1 while running and the # 3 Cyl (best compression) didnt seem to make any difference to the running (a little rough) when he pulled the plug lead. We put new plugs in and he suggested I take it over to the lake and run it up and se how it sounded. Did that, it ran fine, right up to 5000 RPM WOT, but the knock was still there. It doesn't seem to be hurting anytning but its un-nerving..("its hard to PUSH the boat back from 5 miles down the lake" keeps coming to mind.)

The TECH says he will come back and check to see if a piece of one of the "REEDS" has broken off and may be inside the engine somewhere..beyond that, he says the engine/powerhead may have to be broken down..cound be a piston, bolt, rod or such.. He advised the motor may have to be sent to an Overhaul shop if thats the case...OUCH

Any Ideas or suggestions

 

[Faztbullet]

Re: '05 Merc 60 HP Bigfoot 3 CYL. TWO stroke- KNOCKING

Common problem with these engines(40/50/60) is if they are overheated or overpropped(lugged) the cylinder sleeves will slip up towards crank. What you may be hearing is the connecting rod hitting side of sleeve. It really gets nasty when sleeve slide up enough and rings fall behind it ,it rips the top land of piston I repair about 4 of these a year and I pin the sleeves in place..

 

[SunTrackerPB21]

Re: '05 Merc 60 HP Bigfoot 3 CYL. TWO stroke- KNOCKING

Common problem with these engines(40/50/60) is if they are overheated or overpropped(lugged) the cylinder sleeves will slip up towards crank. What you may be hearing is the connecting rod hitting side of sleeve. It really gets nasty when sleeve slide up enough and rings fall behind it ,it rips the top land of piston I repair about 4 of these a year and I pin the sleeves in place..

So what would you suggest FAZT ? The TECH that came here doesnt have his own shop/bench to tear down the motor. He's figuring the powerhead needs to be sent away..(Now says its NOT REEDS since it will go 5000 RPM @ WOT)he said something about 'breaking it in half'.. (they dont do that rebuild work here in my town) resulting in a Bill of about 2 grand for a rebuilt PH from various rebuilders I've found on the internet..there are two Authorized MERC dealers here in town ( @ $ 125 HR !!) but if they're just going to charge me (more)for a rebuilt PH by MERCURY..well I might as well send it away..or NOT ? Suggestions ?

 

[Faztbullet]

Re: '05 Merc 60 HP Bigfoot 3 CYL. TWO stroke- KNOCKING

If it was in my shop these are first things I would inspect :
1) Check flywheel to see if loose as it will knock at idle if so
2) Pull carrier in lower unit and inspect gears as a broke/chipped pinion gear will transfer noise up driveshaft and sound like lower bearing is knocking/bad

If everything was ok then pull and split motor for inspection. If the exhaust and transfer cover wasnt molding on block you could look in and see if sleeve had slipped. If your only turning 5000 rpm you need to drop 1 size on prop as motor needs to turn in the 5500 range.. Do you have faith this mech to take apart and reassemble if sleeves are the problem and you supply a work area? If so let him tear down and you can send block to a MARINE machine shop or myself for repair. If you need to send complete head out for repair pm me...

 

[SunTrackerPB21]

Re: '05 Merc 60 HP Bigfoot 3 CYL. TWO stroke- KNOCKING

If it was in my shop these are first things I would inspect :
1) Check flywheel to see if loose as it will knock at idle if so
2) Pull carrier in lower unit and inspect gears as a broke/chipped pinion gear will transfer noise up driveshaft and sound like lower bearing is knocking/bad

Checked the flywheel..its TIGHT.

"Carrier in lower unit". I'm not sure of what you mean..is that down in the bottom of the leg..toward the prop ? Ifso, that would only make noise if the motor was IN GEAR, right ?

My tap tap tap happens in neutral w/o prop turning and while in gear.

 

[SunTrackerPB21]

Re: '05 Merc 60 HP Bigfoot 3 CYL. TWO stroke- KNOCKING

UPDATE: I took the OB onto the local MERC shop who checked it out and reports the following:

Turning flywheel, it turns 22 degrees before piston #1 moves
..Turns 11 degrees before # 2 moves (this is OK they say?) and turns 22 degrees before # 3 piston moves. They recommend a rebuild/rebuilt PowerHead.

MERC wants nearly $ 5000 with labor for a rebuilt unit !! Yikes !

I checked online and found several rebuilders..some don't actually do the WORK, they send them out to jobbers on an EXCHANGE basis (core charge etc)

The Prices run from $ 1500 to $ 2500 with warranties varying from 90 day to LIFETIME. Some shipping is paid one way.

Oddly, the lowest price (1500) with best Warranty (lifetime) and FREE shipping both ways come from the same place:

http://www.boatpartstore.com/powerhead.asp who also do business as:

http://www.tenkillermarine.com/ quoting the same exact data on rebuilds.

I can only find one review on them (its on the BBB website) giving them a D- for ONE complaint..unresolved

Given that they're the CHEAPEST, with BEST WARRANTY an FREE shipping BOTH ways..well you know the one about: 'Sounds too good to be true, it probably is'

Has anyone heard of these guys or done any business with them ?

The $ 2000 /1 year warranty guys sound good too and the $ 2500 guys want me to send the Powerhead AND CARBS (only one that does this), nearly everything and the will check out/service the carbs 'in place' on the motor to make sure they're set right. That sounds good too but than again they have the poorest warranty..Only 90 days.

What do y'all think. The boat is now down for the season so there is no rush to get the job done.

 

[Faztbullet]

Re: '05 Merc 60 HP Bigfoot 3 CYL. TWO stroke- KNOCKING

It going to be hard for them to reman your engine if crank is damaged as they aint a lot of BF cranks out there. I would have to call and see if my supplier has a powerhead for that model before I would quote anybody a price.

 

[Dave1027]

Re: '05 Merc 60 HP Bigfoot 3 CYL. TWO stroke- KNOCKING

UPDATE: I took the OB onto the local MERC shop who checked it out and reports the following:

Turning flywheel, it turns 22 degrees before piston #1 moves
..Turns 11 degrees before # 2 moves (this is OK they say?) and turns 22 degrees before # 3 piston moves. They recommend a rebuild/rebuilt PowerHead.

MERC wants nearly $ 5000 with labor for a rebuilt unit !! Yikes !

I'd take a pencil and double check that diagnosis. Stick the pencil in the spark plugs holes and turn the flywheel. Don't just take their word for it. Way too many crooks out there working on these things.

 

[Chamelion]

Re: '05 Merc 60 HP Bigfoot 3 CYL. TWO stroke- KNOCKING

Hey,

What was the end result?