Need Mariner help

[hydroman6]

Brother-in-laws 1990 Mariner 60HP 3 cyl.

Abreviated history:

Oil mix system was disconnected after earlier failure (not by me), and he is running as an oil mixed 2 cycle. The engine developed a "knock" while we were fishing. When we got it on the trailer and pulled the plugs, the #1 spark plug hole was completely blocked by a piece of aluminum from the piston. I replaced #1 piston. My brother-in-law called after about 2 hours of running a break-in w/ a 24:1 mix (fast idle, slow idle ect. never constant for long periods and not above 1/2 throttle) to say that as he reached about 3/4 throttle, the knock came back. He immediately shut it down, and when he pulled the #1 plug, he found aluminum again.

Other notes: he is running the spark plug specified for this motor, without the electrode, the fuel pump in new, and all the electronics are new rapair replacements before the first melt down. I checked, blew out and put kits the carbs when I replaced the piston and they appeared fine. #2 & 3 pistons also looked good at rebuild.

I'm lost.
Thanks in advance.

[crankbearing]

Twisted Sleeve

Is this a big bore 60 Merc/Mariner. Check to see if the sleeve is twisted in the bore it was common on the 70-80-90HP models. if your lucky it slid down just enough to catch the top ring and broke of the top of the piston edge. if it slid and twisted then you are not getting all the exhaust out and the port timing is way off. Once you get the sleeve fixed, you must pin them in place. I drill three holes (one in each sleeve) near BDC and tap (thread) a 1/4 20 allen head cap screw in then grind off the threads inside and jb weld the head on the outside of the block.

If this is the small bore common three cylinder, check for carbon build up on the exhaust side and then bore all three holes and install low dome wiseco pistons at .008 skirt clearance and run 25:1 mix with Mercury Oil. This is the only way to fix these motors right and that they will stay together. This is what I do to all the in-lines with the direct charge loop scavenged piston.

Low dome pistons have .050 removed from the deflector for this pre-igntion burn off problem.

[Blackhawkguy]

Check water pump also

If the motor has the small diameter water pump, (really short viens) make sure it is pumping a stream at an idle, these motors wil burn the top piston on a weak water pump, the water does not get to the top of the block, burn the piston enough and it could hook a ring. The above mentioned problem also could be the issue, I guess the question is why did he run it again after finding pieces of meteal in the hole in the first place?

Kerry

[crankbearing]

Good point Kerry

If the motor has the small diameter water pump, (really short viens) make sure it is pumping a stream at an idle, these motors wil burn the top piston on a weak water pump, the water does not get to the top of the block, burn the piston enough and it could hook a ring. The above mentioned problem also could be the issue, I guess the question is why did he run it again after finding pieces of meteal in the hole in the first place?

Kerry

Yes your right I forgot that. DOH!!! I would have changed that auto with the rebuild and I am not sure if this is first or second gen poppet valve and T-stat you should also change both of those if you have them in your motor.

Regards,

[ricochet112]

Hi Steve,

Was the cylinder honed or resized? (excessive clearance)
Did you go through the carbs? (lean)

Does it have a tach?

I had one customer that literally burned up his 50hp Merc from over-loading it, he never got over 4K RPM's with a full load, but it did fine on light load. Max load was 900lbs, he had over 1400lbs in it.

ADD; does Jon have a new address?

[boatracer69r]

Mike-

Yeah I still have the same address. I dont know what it is, but I know my dad still has it. I will be home in the late spring and will be coming up to Washington for the Eatonville race. I hope to see you there. Everything over here is going good. It even snowed a few days ago, I think the first time in like 50 years or something, or at least that is what they are trelling us. I will talk to you later and hopegully see you at Eatonville

-JP

[ricochet112]

Mike-

Yeah I still have the same address. I dont know what it is, but I know my dad still has it. I will be home in the late spring and will be coming up to Washington for the Eatonville race. I hope to see you there. Everything over here is going good. It even snowed a few days ago, I think the first time in like 50 years or something, or at least that is what they are trelling us. I will talk to you later and hopegully see you at Eatonville

-JP

Hi Jon,

Glad to hear you're ok. I burned a few more CD's for you, do you ever get a chance to listen to them? I'll send another batch if you do. Do you need batteries?

Snow in Iraq! Pretty crazy, it made the front page of the Oregonian. I'll try to send some more your way, we ALMOST have too much. In one month on Mt Hood, from 12-16 to 1-18, the snow pack went from 38" to 140", over 225" fell in that 32 day period.

See ya soon. Mike