15hp exhaust & water leak…why?

[johnyrude200]

I replaced the exhaust housing gasket, and I’m a little stumped why exhaust and water is coming out of this area of the motor.

[johnyrude200]

The first time I tore this down, I didn’t even think twice of these two holes. But looking at some parts motors, this is the reason why there is exhaust and water escaping. Not sure how this could happen in the first place, or why someone would intentionally do this, but this particular motor had about (not kidding) 15 ‘hack’ job repairs on it. Add 1 more to that list to make it 16 hack jobs (potentially).

Thanks for tuning in!

[Mumbles]

Your grommet is leaking.

When replacing it, it’s also a good time to check the condition of those upper mounts. As they disintegrate, the leaking exhaust will discolor the paint around them.

On the old blue boards, I showed a way how to rebuild the $100 mounts at home.

[johnyrude200]

Hey Mumbles, the exhaust was coming out of those two holes I put in my 2nd pic; the holes looked man made; like someone went to the upper exhaust housing (above the grommets) and chiseled out two holes. I further confirmed this in observation because the P/N stamping was missing the last 2 numbers, along with comparison to some parts motors good exhaust housings.

Weird one. After two powerhead removals and a transplant of everything off this motor to another housing and stern bracket, I am calling it a night. The motor runs fine (blubbers at mid range until it clears out, but it I am guessing it’s a ’75 or ’76), but having exhaust sprayed directly in my face was a clear indicator that something was off.

Will report back tomorrow once I give it another run in the new suit.

[Mumbles]

OK, I see what you mean now.

Someone take a hammer to it thinking they could loosen up those upper mount bolts?

That area is supposed to look more like this:

[johnyrude200]

I do vaguely recall that post for rebuilding, is it possible to have you re-post that info? It was quite valuable!

Thanks so much.

[johnyrude200]

well the exhaust leak is fixed, but I’m having an issue where the motor seems to be running lean; I have the slow speed set WAY out at 2.5 turns (should be around 1 turn for this model) and when I go WOT and back off, it dies off. Looks like I’ll be double checking that float setting again….

[fleetwin]

OK, can’t quite make sense of the exhaust housing picture your posted, how did you repair that hole in the exhaust housing near the mounts? In any event, I have several exhaust housings from skeletons if you need one.
Again, the symptom you describe is not uncommon for some of these engines. Bringing the RPM down slowly and holding it at the one flat spot will often cause the engine to bog and just stall out. Usually leaving the mixture a tad rich solves the problem, but you claim the needle is out 2.5 turns. Are you sure the throttle plate is closing fully, just cuz the cam isn’t touching the roller doesn’t mean the butterfly is closing fully. The linkage could be jammed/rusted, butterfly and shaft might be binding also. The only way to tell is to remove the carb and watch the butterfly from the back of the carb. I usually have to leave the cam pick up a bit retarded on some of these engines as well to avoid the symptom you describe.

[fleetwin]

PS: You mention that exhaust leaks out through that spot as well. What type of exhaust tube does this engine have? Does it have the full tube that seals to the bottom of the exhaust housing with a rubber seal ring? Or, does is have the open megaphone? Unfortunately, exhaust leaking from the upper mount area through that rubber boots on the open megaphone engines is not uncommon. Most of the exhaust is directed away from the upper mounts and down through the thru prop exhaust when the "sealed exhaust tube" is used.
But, again, I am confused by what I was seeing in your picture, looked like the exhaust housing was actually broken/open where the rubber boot/seal rides on the upper mounts. Is this what I was actually seeing?

[johnyrude200]

There were two holes by the upper rubber boot/seals connect. They looked man made, but who knows. The solution was I transplanted the powerhead to another exhaust leg/transom bracket. Issue solved. This is a ’75 motor and has the square exhaust with the rubber seal at the bottom.

I’ve fixed the fuel system; the low speed needle was missing the bearing so the carb was sucking air in causing bad operation. It still has the needle out a turn and a half or two; but the motor is running fine at all ranges other than your typical blubbering until it clears out.

New issue though is it is overheating. I have replaced the impeller, run with and without a thermostat, and torn the motor down completely for a 4th time and have yet to discover and clogs. I pulled the cylinder head and thermostat cover, and also pulled apart the exhaust cover and there were no clogs. I gave everything a once over to clear out any buildup of sediment.

I ran the gearcase separately with a screw gun and it’s pumping plenty of water, and I hooked up a hose to the water intake of the powerhead and water is passing through the powerhead freely. I’m a little stumped on this one…again. The motor doesn’t overheat rapidly, it seems to pump little water (as indicated by the water/exhaust blubber hole), then pumps a good amount when I throttle up, then as it’s starting to run hot the water supply drops off to basically nothing.

I would say perhaps I am creating an air pocket in the test tank, but no other motor has been doing this recently, and I have been working on a lot of these 9.9/15’s in the last few weeks. So I don’t think it’s an air pocket issue. The water level in the tank is well above the impeller housing.

It’s not the water intakes on the gearcase (learned my lesson last week), those are clear. What has me scratching my head is I just worked on one of these last week and that motor was pumping a TON of water, and was a ’75 model as well.

I’m putting this motor back together in the next few minutes and will double-check to make sure I didn’t accidentally put the water tube into the impeller housing outlet and fold over that grommet, but I doubt that is the problem.

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