It could be the drain plug. Maby not the plug but the fitting screwed into the transom for the plug. Dry the transom and see if the water leaks out around the plug...

I have a 24' outlaw it had a leak , turned out to be the seal around the steering pin, I replaced the steering pin with a stainless pin , it came with a much better steal .

I'll throw in my .02 as I pulled my motor last winter due to a mysterious leak that I found with a endoscope camera and it turned out to be the y pipe o ring where it mounts to the inner transom assembly (not sure if you have silent choice or not). I would suggest buying one of these endo scope cameras and use your phone or a tablet. I backed it in the water and used the camera to find it, and I would run the motor too if you cant find it at first. As mine was significantly worse while it ran. They are worth the money especially after multiple seasons of changing things that did not fix it.

Guys thank you for all your input on the subject matter. I hope I can solve the mystery come this spring. Thank you again.

From my diary of knowledge from previous posts: Gimble Area Leak Points- Trim hose manifold, water outlet, cooling hose
connection on housing, steering pin.

I found a leak where the Captains Choice pipe connects to the exhaust wye pipe. The typical cheap hose clamps couldn't provide enough torque to make a seal so I upgraded to Awab style.

Keith

I’m also dealing with a similar problem...

I have a 1990 Mercruiser Bravo 1 stern drive on my 1990 boat. I have a water leak I have so far not been able to trace, but I can tell you what I’ve done so far, and what I can see.

All of the rubber engine hoses are brand new, with brand new high-end stainless clamps so no leaks where the raw water comes through the stern making its way to the raw water pump or anywhere on the engine.

The water pump has been removed, inspected and cleaned. The oil cooler has been removed and inspected with no problems identified.

The engine cooling system does not have a heat exchanger, water from the source, lake or ocean passes from the outdrive to the raw water pump, through the engine and back out the normal course through exhaust risers, connected to a “Y-pipe and to the outdrive through the prop. The system does not have Silent Choice, all exhaust is through the “Y-Pipe” and out the prop.

I can see water running into the boat on the bottom side of the cutout for the drive under a couple of circumstances. If the boat is in the water, I can see water coming into the boat at a rate I am estimating ½ gal/min. The water leaks in at the same rate whether or not the engine is running when the boat is in the water.

When the boat is out of the water, I hook up “cuffs” to flush the engine if I have been in salt water. If I turn on the hose leaving the engine off, no water leaks into the boat. However, if I start the engine with the cuffs on and water supplied to the cuffs, I see about the same ½ gal/min leaking across the bottom side of the outdrive cutout in the stern.

Two years ago, I had the “bellows” for both the drive shaft and exhaust replaced. Also, at that time the external rubber hose between the outdrive and stern for the raw water intake was replaced. I’ve dropped the outdrive and inspected the bellows looking for any tears or leaks that might allow water to enter that area and into the stern cutout. The repair was done in a reputable shop. Inspecting this area from inside and out, I cannot see any obvious problems. Since the bellows replacement, I have put about 15 hours on the boat/engine. The boat/engine only has 610 total hours on it since 1990.

The Bravo 1 outdrive does not have a gasket, however, there are three O-rings. One is for the shifter, one for the outdrive lubrication and one for the raw water. The gaskets were old, so I ordered out new Mercruiser gaskets and replaced them. The mating surface for the outdrive was clean and shows no evidence of any corrosion or weak spots, so I am confident there are no leaks between the raw water intake and chamber with the driveshaft. The boat has a lot of years on it, however, 95% of the time it has been in fresh water.

Ok, so where is the leak, or better yet where should I be looking? Does this sound like possibly the Y-pipe O-ring? I see suggestions to use a borescope type camera which sounds like a good idea before I go about pulling the engine. Any suggestions are welcome.

IMO this is the most revealing info concerning your problem . I would have maybe suggested examining the water transfer grommet in the transom plate that is prone to crushing and creating overheating problems with the Bravo setups but if it was that it ought to leak as soon as you turn the water pressure on . I'm sure that someone will come up with a suggestion or two.
And I presume that you really mean 'muffs' not cuffs .. as in flushing (ear) muffs ..