Black ooze

[CaptainPuget]

I have a recurring problem with a 1991 Mariner 8hp 2 cycle motor. There are two holes on the back of the mid section under the power head. The hole on the starboard side is about ¼ to 3/8 in diameter, the hole on the port side is smaller, maybe 1/16 in. A nasty secretion of black ooze runs out of the small hole that appears to be a mixture of oil, water and carbon. The little hole is usually plugged with this mixture. I've tried cleaning the hole, blowing it out with air, vacuuming it out, soap water, solvents, etc. but there seems to be no end to the ooze. I believe the larger hole is an exhaust vent for pressure equalization but I have no idea what the small hole is for and the manual makes no reference to it. I'd like to find the source of the ooze and put a stop to it but I don't know where to start.<br /><br />I also own a 1993 Merc 8hp that has the same the two holes but it doesn't have the ooze problem. I treat them identically, same gas, same oil, similar usage. <br />

 

[Wellcraft 89]

Re: Black ooze

It sounds like you have water in the gear case fluid <br />and it is forcing the lube up into the lower unit cavity.Have you chk the water pump and gear fluid <br />Rich

 

[CaptainPuget]

Re: Black ooze

The gear oil is fine, no water getting in there. Here’s a picture of the stuff. Has anyone seen this before? What is the purpose of that hole and what does it connect to?<br /><br />

 

[Mercury140-I6]

Re: Black ooze

I believe that those are exhausat ports. Although I have no idea why only the one side would be oozing that stuff and not the other side.<br /><br />Craig

 

[outboardguy]

Re: Black ooze

You see that bottle of two stroke oil in the backround of your picture,there is your problem.Mercury designed their engines to run with their oil and not other manufacturers. You might try decarboning the motor with Quicksilver Power Tune and see if the carbon river eases up a bit.

 

[Merc805]

Re: Black ooze

I run my 50HP 1979 Mercury Thunderbolt on Castrol Super Outboard 2T.So did the previous owner<br />It runs beautifully in the old girl and even smells nice.<br />Mmmmmm Mmmmmm nice 2 stroke smell <br /> http://www.proformanceusa.com/castrol/castrol_outboard.htm <br />What brand is that one on the shelf ?

 

[CaptainPuget]

Re: Black ooze

Mercury engines can’t handle Super Tech, only Quicksilver? Do others here agree with that assessment? If that’s the case I’ll convert this engine to an anchor and never go near another Merc product again. I will not pay $18 a gallon for oil.

 

[Paul Moir]

Re: Black ooze

<br /><br />Is your thermostat working? Do you troll a lot with that engine? <br />If the engine is running cold for some reason, there'll be a lot more of the black goo. Your mixing the correct ratio right?

 

[Merc805]

Re: Black ooze

"Mercury engines can’t handle Super Tech"<br /><br />They can handle anything you throw at them.<br /><br />Check the VAST discussions on here...<br />As long as it's TC-W3 No probs...<br />If you do a lot of trolling ? Sometimes that will create a lot of unburnt 2 stroke..<br />Have you tried giving it a lot hard run at High revs.. Cleaned out my 6hp Auxiliary...<br />BTW All Mercs are 50:1. as you most likely know.

 

[andrewkafp]

Re: Black ooze

As quoted by one J B Cornwell.<br />""Howdy, BMurray.<br /><br />I have used Wal-Mart's SuperTech brand TC-W3 oil in my 2 strokes for several years and had excellent results. I have been told by a reliable source that SuperTech is Pennzoil. 2002-06-01<br />www.outboardrepairs.com<br /> <br />Good luck. "<br /><br />I reckon if it's good enough for J B...

 

[CaptainPuget]

Re: Black ooze

It’s a kicker, trolling is its life. I’ve propped it down to a 7” pitch to bring the revs up but it rarely sees more than ¼ throttle. Mixture is 50 to 1, I decarb often with sea foam & deep crank. I’ve considered trying a 75 to 1 mixture but haven’t tried that yet.<br /><br />Thermostat is good suggestion. I don’t know if it has one but I’ll check into that.

 

[outboardguy]

Re: Black ooze

I wasn't saying that merc engines can't run on Super Tech.All I'm saying is that the Super Tech will most likely leave more carbon deposits.As the old saying goes "You get what you pay for".

 

[Drowned Rat]

Re: Black ooze

Suggest running Amsoil Saber 2 stroke oil at 100:1. Very clean burning oil. It will eliminate your carbon problem. Do a good de-carb prior to the switch, and you won't have to worry about it any more.

 

[andrewkafp]

Re: Black ooze

Merc805's Suggestion to blow the cobwebs out works quite well. The extra heat burns up the deposits.

 

[roscoe]

Re: Black ooze

The holes are drain holes for black ooze. <br /><br />Do you decarb by adding to the fuel?<br />Or by spraying into plugholes and carb throat?<br /><br />Do a decarb with a whole spray can of SeaFoam DeepCreep. Then run it hard for 15 minutes. Get the crud out, then look for the source.

 

[rodbolt]

Re: Black ooze

hello<br /> dude your oil is fine. you have a poor running engine.<br /> what you see is unburned fuel/oil mixed with carbon from the exhaust tube. the holes are for idle relief. your engine is an air pump. remeber the suck,squeeze,bang and blow steps?? well with the exhaust 2 ft under water if the reliefs are plugged or not there the motor cannot push the waste gasses down the leg at low speeds so your idle time would be very limited in the water. but you have a carb thats begs attention or an ign coil that has failed. the blue coils were almost as bad as the yellow ones for failing.check the motor out carefully and correct the cyl that is running rich.some where your engine is not burning the fuel you give it. the oil is fine and will run for many many seasons. somne people decarb I just run mine in its operating range and let the self cleaning nature of a correct running engine do its thing.<br /> good luck and keep posting<br /> PS nice picture. I have seen that many many times

 

[CaptainPuget]

Re: Black ooze

Thanks all, I have some ideas to work on now.<br /><br /> Rodbolt your explanation helped a lot. With your explanation and a little service manual reading I think that have a better understanding.<br /><br />The 8 hp does not have an exhaust tube. The exhaust exits the power head directly into the midsection cavity. At idle, low pressure exhaust can't exit the midsection through the submerged exhaust port because it's blocked with water so the exhaust exits through these two holes above the waterline. As the engine speed increases the exhaust pressure increases above the pressure of the water and the exhaust, or at least most of the exhaust, exits via the submerged port. That makes sense, but why two holes of different sizes? I must be missing something. <br /><br />If my exhaust is this dirty then the inside of the midsection must be pretty gooey with this stuff. <br /><br />PS No thermostat on the 6,8 & work 10hp models, only on the 9.9, 10 and 15hp.

 

[ryanc]

Re: Black ooze

Hello, I use Pennzoil synithic blend on my outboard, and every thing else i run with oil. This way if my waterpump quits on me, my pistons won't freeze up. <br /><br /> rc good luck!!

 

[BillP]

Re: Black ooze

rodbolt...<br />

some people decarb I just run mine in its operating range and let the self cleaning nature of a correct running engine do its thing.<br />

Thanks for posting that. There's rampant paranoria about decarbing by folks who don't take motors apart to see what is real. The makers of SeaFoam love it.

 

[roscoe]

Re: Black ooze

Like rodbolt says, there is a problem causing the excess of unburned fuel/oil.<br /><br />The decarb should flush most of the crud from the exhaust leg also. But the reason only one of your motors is doing this, is that something is wrong with it.