1995 Mariner 75HP done for?

Hey guys, i recently (very recently) picked up a 16.5 campion king fisher powered by a 95 mariner 75hp (2 stroke) and newer merc 9.9. When i purchased it i had the motor checked out, compression was good across the board the sea trial went perfect etc etc. Now on my 6th run i got the following symptoms. Just to mention, before all of this the prop got wrapped up in fishing line and we beached it to unravel it. Not sure if that could have caused any of these issues or if it's just a coincidence. The motor is oil injected.

-Smoking (white) heavily when trolling (fishing speed) and then at time not smoking at all
-it began to stall intermittently when trolling - maybe only twice over a few hours
-whenever it stalled it wouldn't start up afterwards (seemed like there was no spark, it would just keep trying to turn over) however it would always eventually start up, and it was definitely getting gas
-at one point after a stall i trimmed it all the way up and there was some dirty oil in the water around the motor
-it doesn't seem to be peeing water as well as other outboards ive had. Instead of shooting a nice solid line it kind of sprayed water out (this happened more recently) but it does seem to getting lots of water nonetheless
-before retiring for the day we tried opening it up (giving throttle) as we were just trolling all day (and all of this had happened while never going over a few MPH). It started out nice then ran rough and banged and had a slight loss of power, then all of a sudden was perfect
-the oil levels never got below 1/3 and i filled it up to half way after some of these issues prevailed

Thanks guys!

Re: 1995 Mariner 75HP done for?

Any ideas ? Thanks

Re: 1995 Mariner 75HP done for?

Fishing line and prop shaft seals seldom mix well. The oil in the water could very well be from the prop shaft seal damaged when you wrapped the line. Pull the bottom plug out and see if the oil that dribbles out is milky or not. (you might need to loosen the top fill bolt a little to break the vacuum but if the seal is chaffed and leaking that might not be necessary). Milky means water intrusion and needs to be fix pronto.
Some of the Mercs have a sputter type pee-hole at lower speeds, not sure on your model. Do you have a water pressure gauge? Did you change the impeller as soon as you bought the motor?
Have you checked the plugs? Are they oil coated or burning clean. Hours of trolling just might have partially fouled a plug or two. That could have been the cause of the backfire you heard as the fouled plug cleaned off enough to burn the accumulated gas in its cylinder. When you are trying to restart it when it stalls, you are NOT using the choke are you? Using the choke can cause it to flood and not want to start....and help to foul the plugs. Just from own experiences since 1960. Good luck and safe boating.
Greg

Re: 1995 Mariner 75HP done for?

Oily sludge in the water, poor pee, hard to re-start sometimes; all of these symptoms sounds like there may be water (perhaps intermittently) getting into one or more of the cylinders.

Do any of your plugs show any sign of being either moisture-fouled (wet, frothy emulsified oil) or "steam cleaned" compared with the others?

If this is the case and you catch it early enough, you may be able to save it.

Re: 1995 Mariner 75HP done for?

Another comment would first of all be about the pee stream. I have basically the same engine design and at idle it shoots a strong pee stream into the water at least 1" deep. The pee comes off the exhaust manifold cover. If you are getting a poor stream you have one of 3 potential problems: Clogged pee hose including elbow connector, worn out water pump/impeller or build up of corrosion inside the engine.

Checking the pee hose is a no brainer. With the engine off, and out of the water, pull the hose end from the right side of the cowling and blow in it. You should be able to move a reasonable amount of air.

Remove the stat/pop off valve cover and check the stat and valve. Cover is on the rear of the block, top left...vertical cover with two bulges in it, one larter than the other. Be sure and pay attention to how it comes apart for reinstallation correctness. The stat has a 143F opening temp but that is not the point. I want you to pull it and/or the pop off and look into the engine water jacket. It should be clean, not crudded up. You can reinstall the cover with a new gasket or take blue RTV and glue everything back in place with the gasket/what's left of it still part of the seal.....I am currently running like that and have been for several years. While you have your thermostat out you might as well put it in a pan of water on the stove and check it's operation.

Last dismantle your water pump and check for pump housing wear and condition of your impeller. While you have the impeller out you might as well replace it even if the water pump shows little sign of wear.

The hard starting could be due to overheating. While you are at it, there is a tan wire imbedded in the rear of the block water jacket cover....below the cover for the stat/popoff. Follow the wire to a connector and disconnect the wire. With the ignition switch on, take a spare piece of wire and connect it to the wiring harness tan wire (where you just made the disconnect) and short to ground on the block. The warning horn should sound. If not it affirms that you very could have had an OT condition and didn't know it.

Come back with answers.
Mark