Lower unit question

[RiL]

I have a 1975, 70hsp Johnson motor that has had the lower unit replaced. It was replaced just 3 months ago by a repair service here. Reason the owner had welded the prop retaining nut on for what ever reason and it had to be cut off. I bought the motor after the repairs. <br />I took the boat out and ran it about 5 times and it ran fine.<br />This past Sat. I was getting it ready for winter and hooked up the water and started the motor. After running just a short time I find a dark sludge like oil coming out from around the prop. <br />I called the shop owner and told him what it was doing and he said this was just oil that was not being burned off with the fuel and that it drained off this way. <br />This has been bothering me and I thought I would see what your thought were.<br />Thanks,<br />Rick<br />Hope this was enough info.

 

[Mumblerone]

Re: Lower unit question

You probably got the correct answer... Don't worry. Make sure the water is flowing from the pisser. I assume the motor runs OK.

 

[RiL]

Re: Lower unit question

But if oil can get out this way whats to keep water from getting in this way????<br />Rick

 

[jee70611]

Re: Lower unit question

The oil you see is probrably the unburned oil from the fuel mix coming out of the exhaust, as the mechanic said. There are seals in the lowerunit that keep the gearcase sealed. The exhaust doesn't pass through the gearcase, but rather around it in an open cavity from the powerhead to the prop. Just check for milky looking oil in the gearcase. If it is ok then more than likely you will be ok. <br /><br />James

 

[RiL]

Re: Lower unit question

Thanks,<br />So do all outboard engines do this? A couple of guys here told me that theirs did not. Got me to start woundering.<br />Rick

 

[DJ]

Re: Lower unit question

RiL,<br /><br />Yes, to a certain extent all outboards (that have flow through prop. hubs) do this.<br /><br />I can't see how much sludge is coming out. If it's really excessive, the engine possibly could use a decaronization. The dealer may have decarbed it, thus the remaining sludge. You may want to ask them.<br /><br />The only way to tell if the lower unit has water in it is to crack open the bottom drain plug and see what comes out. If it's milky, there is water. If just water comes out, still bad. If just pure oil come out, you're OK.<br /><br />Remember, whenever you loosen these screws, it's advisable to replace the seals behind them.<br /><br />If you are putting the boat up for extended storage, you should service the lower unit anyway.

 

[RiL]

Re: Lower unit question

Djohns,<br />Like I said I hav only had it in the water 5 times since I had it installed. The shop owner told me that I did not need to service it for the winter just to do my gas and the carbs. then let it run out of fuel in the line.<br />I am a new old boat owner, I did not know it had seals behind the plugs.<br />Rick

 

[RiL]

Re: Lower unit question

Guys just a little more info please.<br />1. The gas to oil mix is 50:1 but getting this unburned oil with the exhaust. Should I adjust the oil down just a little?<br />2. Your saying that the exhaust comes down through a cavity from the power head to the prop. <br />Ok, then again what keeps the water from coming up through that cavity and causing problems with the power head? In a car, if it dies in water and the exhaust is under water, it can suck water up in the tail pipe and keep it from starting. I guess I am asking cant the same thing happen with this?<br />Thanks, <br />Rick

 

[dkondelik]

Re: Lower unit question

Hi Rick,<br /><br />Per #1, Nope probably not. if you are too concerned you might want to have the oil metering checked/verified , but IF IT IS OK and you cut back the oil mix,.... well then your asking for a problem.<br /><br />as per #2, Yup, if the motor is on the boat and the boat is in the water, there will be water in the exhaust ports BUT, Power head is WAY UP HERE. Exhaust exits way down there. 2-Stroke motor. no exhaust valves. It would take some Jupitor like barametric pressure to drive water up the leg into the power head. If you drop the motor into the H20,.... well,,... that's another story.<br /><br />Good Luck.<br />Have Beer while waiting for spring.<br />Relax and Enjow your boat.

 

[alcan]

Re: Lower unit question

Ril<br /> Here's a tip, don't back your boat up to the garage and run the motor on the hose, with the door down. You'll have to repaint the door. Oil comming out exhaust is good as long as it's black and nasty. Dripping clean looking oil is bad.

 

[RiL]

Re: Lower unit question

alcan,<br /> now you tell me! Not the garage door but the side of the house. It is brick and simple green did a great job. Thank goodness.<br />Thanks,<br />Rick

 

[Chinewalker]

Re: Lower unit question

Hi Rick,<br /> Regarding your other question, don't lean out the oil mix - keep it at 50:1...<br />- Scott