1985 Merc 50 hp 4cyl 2stroke exhaust Clogged

[Michael F D]

The engine had been loosing top end for some time. Started by rebuilding carbs which did need it ,, but no change, then all the electric tests with meter, and compression test etc.,,,
changed the stator, nothing, switchbox , nothing. Then water starts leaking from plug#1. So I Fixed the water jacket gasket,(2 broken bolts) no improvement. Give up! Took it to the shop,, bad news ,, main crank case cover gasket leak. I am giving this repair a try as I have nothing to loose as I cannot afford shop to rebuild 80's motor. I am now waiting for the over priced flywheel puller to arrive in mail. ANyway, when I removed the power head the exhaust port that goes down into the lower unit was 80% clogged with built up carbon and a lot of it fell down the lower unit when I removed the power head. I was planning on removing the exhaust cover to replace the gasket , but now Im am wondering what I will find,,, Will it be all clogged up? How do I get the huge amount of carbon out of the lower unit in the easiest way? The manuals or the forums have nothing on the subject of "Exhaust". Did all this clogging cause back pressure that caused gasket failure? Is ethanol partly responsible for all these gaskets failing?
PS####Save yourself over a hundred dollars ,dont buy mercs overpriced flywheel holder, I took a fellow iboats members advice and got one for cars at JEGS for $15 ,Use with impact wrench to remove main flywheel nut,, it took 2 seconds. But I could not find the specified center type Flywheel Puller for less than $90. Thanks for any help, Michael

 

[latin monkey]

Re: 1985 Merc 50 hp 4cyl 2stroke exhaust Clogged

you can find them on ebay. that water leak could be coming from a bad lower crankshaft seal. since you have the powerhead off anyway, remove lower endcap and replace the seals and o-rings, might as well replace the top endcap seal while you're at it. check the crankshaft bearings for damage and/or rust

 

[latin monkey]

Re: 1985 Merc 50 hp 4cyl 2stroke exhaust Clogged

take off the lower unit and pull out the exhaust tube and clean it. when you take off your exhaust cover and baffle check them for cracks or holes and check the thermostat to make sure its working properly. be careful with those exhaust cover bolts though because they have a tendency to break especially if your motor has seen alot of salt water

 

[Michael F D]

Re: 1985 Merc 50 hp 4cyl 2stroke exhaust Clogged

Thank you very much for your input.
this weekend...........
Well I already removed crankcase bolts and end cap bolts with my
Millwalkee electric 1/2" impact wrench and I wish I had tried it on the water gasket cover ,,it might have saved me 2 broken bolts, I hope it works as well on the exhaust cover.
Anyway, the gasket between the block and the lower unit always looked suspect to me Im sure it was leaking also.It looks like all the main gaskets are failing. And then I remove the crankcase cover and TADA! the bottom o-ring was shot, even I could tell instantly, there was a dry spot right on top and there was crud all around it. I removed the bottom end cap and o-ring and cleaned the end cap carefully. There was a good amount of fairly hard crust most of the way around and then was some sort of oily loose crud in about 1/3 of the ring. The rubber ring is pitted. I have the whole gasket kit. I will do the top ring also. even though it looks perfect,,, day and night.
In the crankcase and cover itself it looks as if the crust has damaged the area at the oring. I cleaned very carefully and then finished/polished with 1000 grit .
I guess i will have to online order Loctite #514 , Merc spec, Everyone around here carries permatex brand and all the high heat tubes say NOT to use in situation with gasoline. Any way,,, I am turning the corner even though there is more to do,, learning a lot. If I can put the linkages back together correctly I think i will have a very nice motor

 

[Michael F D]

Re: 1985 Merc 50 hp 4cyl 2stroke exhaust Clogged

Merc 2 stroke Crank case sealer . Why is the correct special gasket sealer, Loctite #514 , so hard to find on the street? or a reasonable replacement.
And why doesnt the manual or the stores that sell these Gaskets seal products know anything? Everyone has a different story,, "this is the same as that,,or,, that works as well as ....etc". And then i read on the back of package"they dont work with gasoline applications",, well cross 2 strokes of the list
A marine shop told me I could get it at NAPA which closed at 5:00,,,,,, 2 minutes too late . try again tomorrow