TOPIC: water is the cylinders

I got the 74 1500 I bought on my 73 mfg gypsy and it does preform any better than my 74 1150. I started double checking things and pulled a plug to see a saw it was clean. I mean it looked brand new like out of the box new with a bit of water on it. I thought bad gas so I switched tanks ran a bit and checked still clean. I then removed more plugs 3 clean 3 look normal. I am kinda stumped It runs well, but I feel it's lacking power. I the compression comes back 135 to 130 all and timing looks good. So what you think exhaust port cover leaking? Just looking for feed back

Yes you have the water jacket leak, fix it and you will feel the pwr...

Ahh HA!

I knew something sounded a little out of whack when you said it didnt perform any better than your 1150!

I am almost happy to find it cause i was so disappointed how it ran funny thing is I would have never guessed because it idles and and starts great, even runs ok

Two strokes in general aren't known for their super smooth idle, even with the big inline mercs being some of the smoother running ones out there...their inherent slightly rough idle can mask an out of whack cylinder only to rear it's ugly head when you put a load on it and try to go fast. I can't tell you how many times I've had an outboard run flawless on muffs or in the water at slow speeds only to find it flat on it's face when you give her the go... Glad you found the probable cause of your troubles.

Here's hoping it's a simple and cheap fix!!

What 3 look normal???? What 3 look wet?? I guess it must be the water jacket if 3 of em are wet. If it were just the bottom plug Id suspect lower crank seals.

Good luck, I hydro'ed a 1250 and blew the block this year so take care of it before it blows.

So at this point does the 1500 run as fast as the 1150 even with water issues?

Conrad

Whatever you do, do NOT run it any more until you get the water issue taken care of. More than likely it s a blown out gasket on the exhaust cover. Worst case scenario might be a corroded exhaust cover allowing water through.

My merc 500 had an issue similar ....replaced exhaust port gaskets and inspected exhaust baffle plate; nothing.
had the base gasket replaced....heck was thinking the block was cracked.

I ran it on ears at home still showed moisture on bottom 2 cycl.

Spoke to a local mechanic about replacing the seals...this is what we came up with....

I drained tank (internal alum.one)...refilled with 12 gallons of fresh fuel & oil and a can of Sea Foam.

Took it out on the river and ran it for 5-6 hours. no issues starting or stopping. When i got home I checked the plugs no signs of moisture.....Sea Foam will help keep those seals soft...this was 2008...this year I ran it no issues..I check plugs almost everytime out.....

I have since installed an Moeller moisture seperator to help with future issues.....i use SeaFoam with every fill up....


food for thought!
Mercury designed their motors so water flows downward.

ya Conrad they ran the same. By the way how fast is that Contender running? I need some more video. I can't wait to finish mt Sears an play with surface props

Hi,
First comment is I'm not surprised that the 1500 and 1150 ran pretty much the same on the hull you have. As I reported in the earlier post I saw 4 mph difference on a high performance hull, you will see less. There is a point where hp has to go way up to make a difference, there is a "terminal velocity" on most hulls where it takes a large change in hp to make even a small difference in speed, and 35 hp difference may not be enough to push much more speed from your rig.
As far as water goes It's hard to understand if you saw water droplets or foamy oil droplets on the plug. When I have seen water from a blown inner water jacket cover seal you get a creamy foam in the cylinder, where the water is now mixed with the gas oil mixture. You will get water in the crankcase side as well as the water will squirt in the closed ports when the piston is near TDC but leak past the piston skirt as the rings are now above the ports.
It is also typical that the piston gets scuffed on the exhaust side as the water gets hot and steams off lubricant from the piston so it scuffs. Depends on how hard you where running the motor when leaking, where it's leaking and how bad. If the piston scuffed you would have most likely locked a ring in the groove and would get a corresponding drop in compression. You did not mention which cylinders you where talking about.
Given that your compression is good across the board, the plugs look clean and the motor runs smooth, I'm gussing it's not an inner jacket but, hey I don't know everything. I run a few 1500's hard ( 74 Hydrostream Vector and 69 Switzercraft Shooting Star) and have blown up my share of them due to various reasons. I don't see how it would be possible to have clear water at the plug with out at least some signs of this foamy mix of oil/water/gas there too. When I have had leaky inner exhaust covers the motors have run awful.
Are you sure all cylinders are firing OK? Could the plug be clean and wet due to no spark at that cylinder? Possible wire or connection issues at the boots, Some people don't realize the wires screw into the cap and damage this end yanking on it. The little spring thingy on the plug end in the boot can get damaged or pulled out too. You can arc to ground in the cap with carbon tracking, I have even had defective plugs with internal problems in the conductor.
My two cents,
Randy