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Prospect wrote: ↑Fri Jul 18, 2025 11:21 am Did you ever figure out what it was?

Haven't been back to her yet.

Still no clues.

I took it out again on the weekend. Still makes the noise. I ran it up to full power for a nautical mile or so. Hit 10knots with two of us. (Maybe time to clean the hull)

When I was putting her to bed, I saw oil/fuel slick around the stern and an inspection revealed oil smeared underneath this port:



I do not know if this is related to my noise problem, but I assume nonetheless that leaking oil is bad.

The part you have marked is an exhaust port. You should not have oil in the exhaust at all so something is wrong.

Most of the exhaust comes out through the center of the hub so anything you see on the upper port should also be happening under water. Can you see or feel any oil inside the hub? Do you see blue smoke coming out of that port when the engine is running?

Be Free wrote: ↑Thu Aug 21, 2025 9:49 am The part you have marked is an exhaust port. You should not have oil in the exhaust at all so something is wrong.

Good to know.

Be Free wrote: ↑Thu Aug 21, 2025 9:49 am Most of the exhaust comes out through the center of the hub so anything you see on the upper port should also be happening under water. Can you see or feel any oil inside the hub?

What's a hub?

I have not noticed any oil coming out underwater. I assume I should have seen a very obvious slick if it were just exiting into the water. What I saw when coming into my slip was what I'd expect from just a drip or two. And it certainly was coming from the smear at the upper port.

Be Free wrote: ↑Thu Aug 21, 2025 9:49 am Do you see blue smoke coming out of that port when the engine is running?

No. I did not look specifically, but I suspect I would notice if there were any amount of smoke coming off the back.

Hi DaveC426913!

As your engine is a bit older (if I recall correctly) some drips are bound to occur but should generally be fixable.
No your engine shouldn’t leak oil.
It’s probably something gradually working it’s way loose or a seal that has aged out and is leaking.
Or just as likely you may have spilled oil at some point along the way, it’s pooled somewhere and it’s seeping out.

If the engine exterior is entirely oil leak free but your still getting oil drips from the port you may have an internal to the engine issue such as worn bushings, seals or guides that is allowing oil to get into the crankcase vent and blown out the port. That’s a potentially bigger issue and it may be worth talking to an actual experienced certified Honda Outboard mechanic.

Just a suggestion…

Best Regards,
Over Easy

DaveC426913 wrote: ↑Thu Aug 21, 2025 5:25 pm

Be Free wrote: ↑Thu Aug 21, 2025 9:49 am Most of the exhaust comes out through the center of the hub so anything you see on the upper port should also be happening under water. Can you see or feel any oil inside the hub?

What's a hub?

The hub is the center of your propeller. Most of the exhaust comes out of there.

DaveC426913 wrote: ↑Thu Aug 21, 2025 5:25 pm I have not noticed any oil coming out underwater. I assume I should have seen a very obvious slick if it were just exiting into the water. What I saw when coming into my slip was what I'd expect from just a drip or two. And it certainly was coming from the smear at the upper port.

I'm out of town for the next day or so and I'll check my Honda when I'm back but my recollection is that any oil coming from the exhaust port will be coming from the combustion chamber. Oil that leaks anywhere else (like blowing up through the filler tube) will collect in the bottom of the upper unit and drip out of a weep hole. It's possible that there is a way for oil that has leaked into the cover may have a path through the cover and down to the exhaust port.

All of the oil you are seeing now may be from the time you reported that the oil "gushed" out when you removed the dip stick.

I went out today. Kept it under 5 knots.

Zero sign of oil leak, zero sign of oil smudge under exhaust.


(Did collect about 600 pounds of seaweed on my blades in the lagoon. Boat ground to a complete halt a dozen feet from dock. Zero steerage, zero motion. In fact, I started drifting sideways, pulled by the weed in the current. The pitfalls of boating in late August after a super hot July.)

DaveC426913 wrote: ↑Sun Aug 24, 2025 6:47 pm (Did collect about 600 pounds of seaweed on my blades in the lagoon. Boat ground to a complete halt a dozen feet from dock. Zero steerage, zero motion. In fact, I started drifting sideways, pulled by the weed in the current. The pitfalls of boating in late August after a super hot July.)

Wow!

At least you have a boat that you can lift the blades up.

Good news!

I just finished testing. There are passages that allow water in the top of the engine to drain into the collar where the exhaust port exits. The water drained exactly under the exhaust port.

What you saw was likely residual oil dripping down from your original "gush".

Thanks! That's a relief!