40hp bigtwin gearcase questions and observations

[fleetwin]

Well, this thing seems to be my career project for sure. I have always hated resealing these darn clam shell gearcases, and this one is no exception. Oh well, let’s hope three times a charm.
In any event, I am wondering about water drainage, and what appears to be a drain hole just above the gearcase bullet…

That deep pocket down in the gearcase just traps water and gunk. I guess I am wondering if that pocket is connected to the hole above the gearcase bullet for drainage? I have poked down in the pocket, and looked in the hole above the bullet, these two areas do not appear to be connected.
I would think these areas should be connected so water trapped in that pocket will drain. There is no way water will drain from this area unless the engine was removed and set down with prop shaft facing down. I don’t dare try to run a little drill down there to clear it out, with my luck I will drill right into an oil galley. I would just drill through the pocket floor, but that might introduce too much exhaust right into the prop area….
Help me understand what I’m missing here….D

[dan-in-tn]

Just went outside to look at a brand new old stock housing I have. It is the double water tube style, but the drain hole is in the same place. If you take a piece of shift cable, etc. & put it in the hole (I paint the end of mine orange) then you can see that the hole does intersect with the cavity. Hope that helps!

Dan in TN

[fleetwin]

OK, I guess I will have to find some stiff wire like that and keep probing….

[vintin]

When I got my 57 35hp Johnson that drain hole was plugged solid. I used a straight piece of 1/32 inch diameter galvanized steel wire in a drill to open it up from the top. When it is open properly after use an oily residue will drain from this hole. Some mistake this drainage for foot leakage but it isn’t. Every now and then I run a piece of thick weed eater string up this hole from the bottom to keep it open. I believe it plugs with silt from the water after a time. Now that I’m running a crankcase drain recovery system on this motor I don’t get an oily drainage but I do get water. If water sitting in this area freezes I’ve heard it can cause real problems. This may be a much overlooked maintenance item on these motors.

[chris-p]

As stated, definitely the drain. I find almost every single one I service plugged with mud dauber nests. They build it like damn concrete. I have an extra long drill bit I use to bore them out.

[adam1961]

I had encountered some that the carbon residue in there is so solid that I could not feel what was going on and drilled right into the gear housing. Then out comes the JB weld to plug the extra hole and back to work it goes.

[fleetwin]

Yeah, this is a poor design, that pocket just collects crud and plugs easily I guess. I was just so afraid of probing too much or trying a thin long drill in fear of poking into an oil galley. Like I said, this charity job has been a total pain in the butt, second attempt at sealing it properly. My other observation/question is why the heck doesn’t the spaghetti seal butt up against the oring on the prop shaft seal cap? Doesn’t line up on the small engines either? There is about a 3/16" gap between the spaghetti seal and oring, seems like this would be an automatic leakage area. I just run a little bead of 847 in this gap in an effort to ensure good sealing….
I know, pictures would be helpful, but gearcase is already back together….
Maybe I am just "overthinking" this stuff, which is one of my "special abilities"…

[dan-in-tn]

I keep a dedicated long bit with the tip ground off of it. That way it doesn’t drill a hole, but still augers out the dirt. I even run it in the hole in the side. I only blow air from the side to blow all the crap out the top. Use a bit the size of the side hole so its not so small as to break easily

On the sealing of the two piece gearcases a couple things I notice. I have quit using 847 adhesive. Started using 3M applique cement instead. More aggressive & dries quicker. Somebody posted that bulletin about sealing tips and they only put adhesive in a few {4} I believe places. I only put enough to hold the spaghetti seal in place. You do need the sealer at the rear for the junction with the bearing hub!

The other thing I think makes a difference is the orange spaghetti seal vs black. The black seems to be smaller in diameter or has a softer durometer?
Since the compression of this seal is really all that does the sealing (not gluing it) I want the best seal. Just a few of my ideas.

Dan in TN

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