1970 merc 115 hp water in 3rd cylinder

[astra]

Just bought a boat with this engine on it, owner had problems with the starter, took it home opened up the starter and water poured out of it. Ran well with the muffs on it. Took it out on the water yesterday idled rough, and when I gave it throttle it would stall out. ran for a bit with the fast idle engaged, finally got power and put the fast idle bar down, wot only gave me 4000 rpm. boated around for a few hours like this. then on the way back engine wouldn't go past 2000 rpm at wot. as we were coming back to dock the engine would increase power in 2 shots, one to 2500 rpm then to 3500 rpm. got near the dock shut off the engine, and wasn't able to start it for 30 min, finally got it started playing with the choke and fast idle bar. Took it home and opened the sparks, number 3 is spraying out a big mist of water, take off the muffs and the water stops spraying. What should I check for first?
ps sorry for the long post

 

[Chris1956]

Re: 1970 merc 115 hp water in 3rd cylinder

First spray some oil into #3 to cut th corrosion. Now pull teh Lowerunit, and remove the powerrhead. You need to remove the exhaust cover, baffle and perhaps the inner exhaust cover and replace any parts with rust thrus. If no holes, the gaskets may be leaking. Be careful not to break the bolts....

 

[astra]

Re: 1970 merc 115 hp water in 3rd cylinder

is there a way of checking for cracks without having to pull the powerhead? or even removing the exaust cover

 

[Chris1956]

Re: 1970 merc 115 hp water in 3rd cylinder

There is likely some way to pressure test the block to check for leaks. However, you know you have a water leak. Those motors generally only leak from the exhaust covers or baffle, unless the block is cracked. They can also leak from the lower crank seal, but this shows as water in the #6 cylinder.

 

[astra]

Re: 1970 merc 115 hp water in 3rd cylinder

I'm going to run a compression test when I get home, I was wondering if there is a way to remove the bottom cowl without removing the engine, just to get better acces to the number 6 plug,

 

[Chris1956]

Re: 1970 merc 115 hp water in 3rd cylinder

Remove the cowling support and the lower cowl will drop down some inches.

 

[astra]

Re: 1970 merc 115 hp water in 3rd cylinder

so I removed the exaust baffle and cover...cracked block how good is jb weld marine?

 

[emckelvy]

Re: 1970 merc 115 hp water in 3rd cylinder

Not so good. Unless you can have a welder weld it up and re-machine (if it's a gasket sealing surface), it's probalby a goner. Might be cheaper to locate a good used block.

Maybe some Belzona would fix it up (the Navy uses it to rebuild pump casings, it's hard and machinable), but that stuff is extremely expensive.

http://www.belzona.com/engines_casings.aspx

http://www.auto-ware.com/autoware-bin/techarchive.pl?noframes;read=11595

G'luck........ed............ed

 

[astra]

Re: 1970 merc 115 hp water in 3rd cylinder

can't seem to find anyone who sells belzona, if anyone knows of a good used block for sale please let me know