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60 merc problem

P

Popa Ray

Member
Hi all
I have a 60hp 2 stroke 3cyl 2 carb clamshell merc. Serial number 09602824
For the last couple of years I have an intermittent problem. Often it starts and runs fine then it drops power, sometimes when putting power on and sometimes when its been running fine at speed for for more than half an hour. Sometimes not at all.
On inspection the top cylinder is not working.
I checked for spark and it's there, changed coil thinking weak spark and no change. Stripped carb and cleaned although it was spotless with no blockages. All this work was done this week with compression checked after last outing.
I am now thinking reeds but have no knowledge or experience of them.
I was told by a merc dealer that reeds are nor not available here in UK but after a Google search I have found various types.
Does anyone know which reeds I need and have any input as to changing them, also any other causes for the problem.
I know this is an old motor but even with the current problem it starts great runs great but unfortunately only on two cylinders

Any help would be much appreciated
Ray
 
Have you run a compression test on tat top cylinder? Recommend you do that before proceeding further.

Hate to say it, but you probably have a cooked piston. Those motors are famous for frying the top pistons. Of the 15 or so to come through my shop, only 2 or 3 were okay.

Jeff

PS: I'll send you a few for postage if you need them, but reeds on those almost never fail.
 
Does spark on #1 jump a gap of 7/16" on a testing device , yes or no ?----It is a lot of work to change reed valves on that motor !-----Reed valves would not be intermittent !-----Cooling system maintained on this motor ?------Test run with a timing light on #1 cylinder and observe behavior of the light when motor falters.
 
Thanks for the quick reply much appreciated.
I forgot to mention that with the motor running with top plug out I was getting water vapour from top cylinder.
I changed both gaskets on the side jacket and the one at front that plugs go through, it has solved that.
I don't have a compression tester, I borrowed one before.
If they have a habit of frying top piston then another comp test is a must.
Please keep replies coming, and thanks again
Ray
 
I'm sure my friend did this test,,,last year with a section of ht lead with a clear plastic section to view the spark bridging the gap.
Ray
 
Apologies for the delay, I've been waiting for a compression test which was done today. Results were 160psi on bottom and middle cylinders and 153psi on top cylinder.
I left the plugs out then turned it over with a lot of throttle, there was a plume from bottom cyl little or none from middle and none from top.
I'm not sure how two carbs feed 3 cylinders but would that indicate a fuel problem, if so might it also be the fuel pump.
I know it's a lot of questions to ask but you guys seem to have all the answers and the don't mind sharing your knowledge.
Thanks
Ray
 
Top carburetor feeds #1 cylinder and 1/2 air / fuel to #2 cylinder.-----Bottom carburetor feeds other half of air / fuel to #2 and feeds the #3 cylinder.---All done through the reed valves.----Fairly simple if you have had one of these motors apart.
 
Thanks for explaining that racerone, can you shed any more light on the problem I'm having.
I'll check fuel lines tomorrow then pump. Then back to carburetor. Is it possible a weak pump could not supply enough fuel for top carb.

Ray
 
You might consider replacing the top crankcase seal (since the compression on # 1 is very good). This can be done fairly easily by running sheet metal screws into the seal and prying it out. The flywheel, stator and trigger coil has to come out, but that's not too difficult--I changed one at the boat ramp!

Jeff

PS: I doubt it's carb related since the center cylinder would mess up as well.
 
Thanks for your reply Fastjeff.
I've yet to remove flywheel or stator on this motor but if you think that could be the problem then I'm willing to give it a go.
I first have to locate a seal.
Ray
 
I thought I'd make a start today, didn't go well as I couldn't free the bolts on top of the flywheel. I found trying to jam the flywheel and undo bolts hard work on my own. My mate can't come and help as we are on lockdown here.
A friend has a impact wrench he can drop of tomorrow so hopefully it'll help. Ha ha problems before i get to the hard part of removing the flywheel ..

Ray
 
I'll bet you can't get the seal out because the flywheel hub has to be removed too, the flywheel is a complete unit that is meant to be pulled off by the proper puller.
 
Doesn't sound like the easiest of jobs without special tools but I'll give it a go, on lockdown at moment so not going anywhere anytime soon

Ray
 
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Thanks for being patient. I have just managed to remove flywheel. The top seal is accessible now, do I need to remove stator to remove the seal and is there anything under the seal that I could damage if the screws go right through.
I'm not sure if its relevant but this engine has never charged the battery and after changing the rectifier no change. Should I be looking at the stator, can it be tested and would this have anything to do with the top pot not firing.
As usual your help is much appreciated.
Ray
 
Popa Ray said:
Thanks for being patient. I have just managed to remove flywheel. The top seal is accessible now, do I need to remove stator to remove the seal and is there anything under the seal that I could damage if the screws go right through.
I'm not sure if its relevant but this engine has never charged the battery and after changing the rectifier no change. Should I be looking at the stator, can it be tested and would this have anything to do with the top pot not firing.
As usual your help is much appreciated.
Ray
Click to expand...
I looked at the diagrams but still not sure if the screws I need to use to remove the seal would damage anything if they go through.
If someone could clarify this it would be much appreciated andI can carry on with the seal removal .

Ray
 
Is there a puddle of oil around this seal , yes or no ?--------Remove sparkplugs.-------Put a few drop of oil around the area where seal contacts the crankshaft.-----Turn the crankshaft.-----Do you see any bubbles to indicate a leak ?????
 
racerone said:
Is there a puddle of oil around this seal , yes or no ?--------Remove sparkplugs.-------Put a few drop of oil around the area where seal contacts the crankshaft.-----Turn the crankshaft.-----Do you see any bubbles to indicate a leak ?????
Click to expand...
Just tried that test ,all very clean . As I have a new seal I thought I may as well change it, but concerned about possible damage with screws going through the seal.
Ray
 
So it appears that there is no leak , but you still want to " fix it " for some reason ?----Maybe I missed it but I do not yet see an answer to the spark question.-----Does spark jump a gap of 7/16" ( 11 mm ) on all leads , yes or no ?
 
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racerone said:
So it appears that there is no leak , but you still want to " fix it " for some reason ?----Maybe I missed it but I do not yet see an answer to the spark question.-----Does spark jump a gap of 7/16" ( 11 mm ) on all leads , yes or no ?
Click to expand...
Ha ha, you are right if it ain't broke don't fix it. Regarding the spark test it was done last season and while pulling the cap with engine running last week it was jumping about 1/2 inch.
Thanks for the reply
Ray
 
Have you looked at the fuel pump diaphragm ?-----Might test run the motor on a borrowed tank and hose.-----Perhaps test run with a timing light to observe spark behavior on the 3 leads.
 
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