TOPIC: Rookie Mistake #2 Overfill Lower Lots of Smoke?

Here's my new self-created drama (Rookie mistake 2?). I changed the lower oil and I over-filled it. After the oil change When I fired the motor I had quite a bit of exhaust smoke coming out of the top of the leg. (Just below where the powerhead bolts on.) I redrained the lower unit and refilled to make sure I had the proper amount of oil, I guessing I had 4-6 oz more than spec.

So I'm wondering. Do you think the smoke is from blow by oil from the lower? I recently replaced the lower powerhead seal. But I wasn't getting smoke until I did the lower oil change.

If it is from the lower, do you think the smoke will burn off and what seals should I check to see if I blew them out?

What kind of motor are you working on? It isn't possible to overfill the lower unit on most of them so more info will help point us in the right direction to help.
AL

Its a 1960 McCulloch Flying Scott 60. I pumped about 24 oz in. The book said capacity was 16oz. I thought I couldn't overfill it too, but even with spillage there was a lot more oil in the lower.

Last weekend I put the powerhead back on the the motor after replacing the exaust gasket, powerhead gasket and the lower main seal on the crank. I ran the motor after that last weekend and had no excess smoke.

I did the lower oil change last night and fired it up and immediately had smoke. Then... I checked the manual for the fill level, took a look at the side of the oil bottle and realized there was way more oil in the lower than needed. I drained and re-filled with the proper amount, but I still have smoke. I'll likely drop the lower tonight to take a look and clean any excess oil.

Are you talking about the lower unit gear oil ??

Dumb question I know,but this is a 2 stroke isn't it? If so, sounds like you have too much oil in your gas.

Yes lower unit gear oil and two-stroke fuel. I've been using the same tank/mix. But I do store the fuel tank on end and then lay it down on its side in the boat. I usually swirl it around before putting it back in the boat.

I would assume if I was running too much oil in the fuel mix I'd have extra smoke coming out of the exhaust port, but this smoke is coming out from below the motor towards the front of the powerhead.

I'm not familiar with the Scotts, but based on where you are indicating the smoke is coming from I suspect it is typical 2 stroke exhaust smoke that is unable to go out the underwater exhaust port due to back pressure created by the barrel of water - and the exhaust smoke is sneaking out around the top front mounts' seals that connect the driveshaft housing to the transom mount.
This is a common thing to experience on older Mercs that develop gaps between these mount points and the related seals that dry out.
I'll bet that if you are able to run the beast on a set of muffs and a garden hose the below water exhaust port would have the same smoke.

However,...I suppose it is might be possible for the excess gear lube to have been pushed past the water pump seals and a puddle of it is laying on top of the gear case somehow and being burned and smoking by the warm exhaust??? If this is the case though, I would think that before long your gear oil level would be lower than desired due to older seals??

I am just speculating though, so if a Scott guy chimes in,...Pay more attention to his insight.


If you can get 'Ponyboy' to post - he can probably give you a qualified opinion. He is the fellow that posted several videos in the Main Forum highlighted 'Favorite Glassic Videos' threads. He drives a red G3 'Reggie' among other boats. His 'Ugly Peg' has a Flying Scott motor.

Thom

Could it be leaking around your lower crankshaft seal?

Shacomm,

It's hard to believe that you have overfilled the lower unit to the point the gear lube would get into the exhaust chamber, and if it did, and it got hot enough, it should smoke out of the auxiliary exhaust tube below the power head.
As the good doctor stated, running in a barrel could push water up high enough to cause enough back pressure to seal off the bottom exhaust, and force it out somewhere else, but in the case of a Scott, is has a special idle system chamber in the leg that allows exhaust and water to be expelled from the auxiliary exhaust when the water level gets too high in the leg. This usually happens at the dock when the boat is heavily loaded.
There are only two ways gear lube could get into the exhaust chamber that I am aware of. One is up through the driveshaft cavity and that is blocked by a lip seal number 32 in the parts diagram. Number 28 is the lower water pump seal and 33 is a bearing.
The second way is up through the shift rod. but there are O rings to prevent that from happening. It's possible that the lip seal is in upside down.
Still,to get the gear lube to go through the seal you would have to have a lot of gear lube in the lower unit to get it to go that high.
Is there exhaust and water coming out of the auxiliary exhaust? It sounds more like the auxiliary is plugged.
If, and it's a big if, if you were to have gotten gear lube in the auxiliary idle chamber itself the viscosity of the gear lube might be causing too much back pressure and the exhaust is finding another way out.
Check the auxiliary and if it's OK try running with less water in the barrel, but be careful to keep the pick-up covered. Running a Scott with muffs isn't easy. The pick-up is a rectangular screen facing down and it takes a some work to come up with a way of forcing water into the pick-up.

Don

If it is in fact pushing out through a top seal then it needs replaced. I'm thinking it was winterized with lots of oil last time. I shot a few squirts of atf in my Evenrude and it smoked a long time and lots of smoke.

I'm thinking bad gas. Most of the smoking stopped when I replaced the fuel with a fresh tank. I'm wondering if my gas/oil mix had separated and the gas was evaporating faster than the oil?