1993 Mercury 135 Black Max 2-stroke

[gibbywmu2000]

Hello,

My outboard seems to be leaking gas, or oil, I'm not sure which. I noticed a month ago or so there is oil/gas all over the water surface near my pontoon. At first I thought it was just exhaust bubbles bursting at the surface, but now I know for sure it has to be gas/oil. Any idea where I should start checking, or what it could be? A tune up was done last year, new fuel filter, plugs, etc. I have no experience on trying to find a gas or oil leak.

Thanks!

 

[sam am I]

Could be the crappy clear factory poly hose(item "a") that is used to site the oil in between the output of the oil pump and the check valve fitting. Mine split, never knew my oil mix went to crap till noticed the rainbow in the water behind the boat one day, not good on a motor eh? No sensor for that!!.........Till now!!! Hehehe, never again.....

Other than that, ya just gotta start hunting around. Pump up the primer bulb and have a look see. BTW, if the poly is still okay, replace it ASAP, its just a matter of time. I used tygon FWIW.

 

[Chris1956]

Fuel pump diaghrams can leak raw fuel into the crankcase, and then into the water.

 

[gibbywmu2000]

Ok I will check the hoses ASAP, and the fuel pump to see if there is any leaking fuel from the fuel diaphram. I know the carbs have never been rebuilt, I'm sure they probably need to right? Probably clean all the jets out and replace the gaskets? It runs fine, but considering the motor is over 20 years old and I'm seeing rainbows of gas/oil all over the lake I didn't think that was normal..........

Should I replace that primer hose and bulb? To be honest, I'm not sure how often I'm supposed to use that..........after a week of not driving the boat? 2 weeks? I mean how long does that put fuel in the carbs if you pump it? If someone can explain the function that would be great!

 

[Chris1956]

The primer bulb is to fill the carbs with fuel, before every cold start. So prime them before the initial start of the day, and you should be good. After tilting the motor up, it may need priming as well.

 

[gibbywmu2000]

Ok replaced the primer bulb and fuel line to the motor. It was pretty old and the rubber was starting to deteriorate. So, after further inspection, I found out where this is coming from. It appears its an excess of oil that's coming out of the small ports at the bottom of the drive (thought this was where the pump pulls water in at?). Not sure why there is an excess of unburned oil coming from this.

Any suggestions now? See pic.

 

[Chris1956]

Smell that oil dripping out of the water intake ports. If it stinks, it is gear oil and you need a new driveshaft seal, gasket and Oring. If it smells like gas or oil, it is unburnt fuel. Normally unburnt fuel does not exit there.

 

[gibbywmu2000]

Chris, I'll go ahead and smell it. The thing is, this doesn't come out unless the boat is on, even when the boat is in neutral...........so I'm thinking it's definitely exhaust. If it was gear oil, it would be leaking out constantly, whether the motor is on or off right?

 

[Chris1956]

Gear oil may not leak if the motor is not running. It kinda of depends on why it is leaking. It would normally be hard for gas and oil to leak out the water intakes. That fuel would need to find a way into the upstream part of the cooling system, or leak past the waterpump base gasket.

 

[gibbywmu2000]

That makes sense, I was wondering the same thing. How could the fuel/oil get into the cooling system and leak out of the ports? Kind of strange. I just changed the waterpump (waterpump kit w/ gasket, seals,etc) so that should still be ok. Would you have any other suggestions of places to check or things that might be going on?

 

[sam am I]

Check for water in gear oil to eliminate that ^^^^..........Hmmm, its a reach, but perhaps then lower crank/adapter plate and seals if it's not the other issues of external cowl drippings and/or just normal or extra rich un-burnt oils/fuel in exhaust .

 

[gibbywmu2000]

It's definitely not coming from the cowling area........I verified and raised the trim up after I shut the motor off, and the residual water that normal keeps coming out of the ports contained the oil/gas residue............I've never seen this before, sure is strange. More of an environmental issue, I'd hate for these poor fish to keep cycling this through their gills, especially when people eat them!

 

[Dukedog]

That makes sense, I was wondering the same thing. How could the fuel/oil get into the cooling system and leak out of the ports? Kind of strange. I just changed the waterpump (waterpump kit w/ gasket, seals,etc) so that should still be ok. Would you have any other suggestions of places to check or things that might be going on?

Any unburnt fuel/oil mixture will exit thru tha prop/exhaust relief ports only as long as tha "can" is still in it. Tha only thing exitin' tha motor in tha driveshaft/water pump side of down housing is very small water discharge from tha block thru tha adapter plates.......A lot more water on tha exhaust side.
Tha "only way" for tha gear oil ta get out anywhere is bad seal, o-ring (prop and drive shaft).but usually shows up with water "IN" tha gear case. For gear oil (or anything else) ta exit those holes it has to come thru tha pump/pump base (plastic, pressed in piece that has tha big o-ring, driveshaft seal). I've never seen what your sayin' but kinda stands ta reason tha o-ring and/or base plate would be suspect......Would also "think" with leak there it would also be able ta get inta tha coolin' system since thats tha only intake ports? That's justa guess on my part....