3.3 Mariner Outboard - 1997 Change of impeller - misplaced the grommet

[Topsy]

I have just changed the impeller in my 1997 3.3 Mariner 2 stroke outboard. Unfortunately, I have misplaced the grommet (Drive shift cover) and am uncertain as to whether to purchase a replacement or not. The question is, is it only an access grommet or does it stop water from accessing the drive shaft housing? I have noticed that water enters through the square-shaped vent on the plate where you remove two bolts to separate the gear house from driveshaft housing. Further to that I have noticed water coming out of the Exhaust Relief Outlet (2 x small outlets). I, therefore, believe water enters the front of the driveshaft House and is discharged higher up the driveshaft. I Housing. Great if this is correct as it will save me more work.

 

[madabouttheboat]

I think it might allow exhaust gases to escape from the hole. Don't know if this is actually a problem, but when mine blew out (from exhaust pressure) it was definitely louder and bubbling from the hole. I don't think its critical, but I sourced one and replaced it. Think I may even have a spare somewhere, as with postage it was more cost effective to buy two and I haven't lost it since.

 

[madabouttheboat]

I have just changed the impeller in my 1997 3.3 Mariner 2 stroke outboard. Unfortunately, I have misplaced the grommet (Drive shift cover) and am uncertain as to whether to purchase a replacement or not. The question is, is it only an access grommet or does it stop water from accessing the drive shaft housing? I have noticed that water enters through the square-shaped vent on the plate where you remove two bolts to separate the gear house from driveshaft housing. Further to that I have noticed water coming out of the Exhaust Relief Outlet (2 x small outlets). I, therefore, believe water enters the front of the driveshaft House and is discharged higher up the driveshaft. I Housing. Great if this is correct as it will save me more work.

if you go on ebay and put 25-16117 into the search there are a number for sale.

 

[VicS]

I have just changed the impeller in my 1997 3.3 Mariner 2 stroke outboard. Unfortunately, I have misplaced the grommet (Drive shift cover) and am uncertain as to whether to purchase a replacement or not. The question is, is it only an access grommet or does it stop water from accessing the drive shaft housing? I have noticed that water enters through the square-shaped vent on the plate where you remove two bolts to separate the gear house from driveshaft housing. Further to that I have noticed water coming out of the Exhaust Relief Outlet (2 x small outlets). I, therefore, believe water enters the front of the driveshaft House and is discharged higher up the driveshaft. I Housing. Great if this is correct as it will save me more work.

AS said above the exhaust gases will escape though that hole. The result will be exhaust noise.
It wont affect the water flow to or through the engine.

The water flow is in through the slots in the gear case below the AV plate then pumped up to the power head via the watertube . A small proportion is bled off from the engine providing a tell-tale to show that the pump is pumping water up to the powerhead.
The remainder of the cooling water and the exhaust gases are discharged into the driveshaft housing. A small amount of exhaust gas together with a mist or a few droplets of water are discharged through the back pressure relief ports.
Most of the gases and the water normally leave via the outlet in the AV plate above the prop, near to the two bolts you mention ( there is also an anode bolted nearby).

 

[Topsy]

I think it might allow exhaust gases to escape from the hole. Don't know if this is actually a problem, but when mine blew out (from exhaust pressure) it was definitely louder and bubbling from the hole. I don't think its critical, but I sourced one and replaced it. Think I may even have a spare somewhere, as with postage it was more cost effective to buy two and I haven't lost

 

[Topsy]

Thanks for your response. It confirms my thoughts. As I am in NZ I will see if I can purchase one out here.