Thru hull exhaust conversion

[69GTOby]

We converted our boat to thru hull, but left the y pipe in place so we can convert it back when we want it quiet. I got some rubber caps to block off either the y pipe or the tips, whichever is not in use. Anyway, I have a few questions. Should the tips be tight in their holes, or should we ream out the holes so that the pipes do not contact the fiberglass (except for the flanges of course)? What is a good sealer to use for the flanges, and for the bare fiberglass on the insides of the new holes? I made some cork gaskets for the flanges as well, by the way. Thanks in advance!

 

[Bondo]

Re: Thru hull exhaust conversion

Ayuh,.... The tips need to be Water Tight to the outside,....

'n,... There's a distint possibility that you'll sink the boat, if ya uncap the y-pipe, in the water....

 

[greg82255]

Re: Thru hull exhaust conversion

Ayuh,.... The tips need to be Water Tight to the outside,....

'n,... There's a distint possibility that you'll sink the boat, if ya uncap the y-pipe, in the water....

I used 3M 4200 sealant on my exhaust tips. Haven't had any problems. If you drilled through any wood in the transom make sure to paint some resin around the exposed wood.

 

[Scott Danforth]

Re: Thru hull exhaust conversion

^+1. you need to resin the holes, then seal the tips to the transom. if you ever need to remove them, 4200 works well. if you use 5200 its permenant

 

[NSBCraig]

Re: Thru hull exhaust conversion

epoxy resin is the way to go

 

[69GTOby]

Re: Thru hull exhaust conversion

Okay, so I am now down at the lake. We finished the thru hull conversion, capped off the y pipe tops with 3" rubber caps, it's got the new carb on it, all the outdrive work is done, new fluid etc... We backed it down the ramp, and noticed water gushing in around the driveshaft area. We pulled it back out and I found a big hole in the bottom of the main bellows. I just put a new one on last year!?

Also, I just threw those 3" rubber quick caps on the y pipe tops thinking it was just for reassurance. I didn't think any water would come in since the tops are above the water line. Well, water was coming past it. I guess the clamps were not tight enough. I don't get it though... That means that before we did the thru hull conversion water would still be coming up the y pipes and... into the engine potentially? Just the extreme angle of the boat since it was still on the trailer on the loading ramp??

To end on a positive note, it ran great with the new carb, and sounded excellent! Not even too loud IMO.

 

[Bondo]

Re: Thru hull exhaust conversion

Just the extreme angle of the boat since it was still on the trailer on the loading ramp??

Ayuh,... Correct...

 

[69GTOby]

Re: Thru hull exhaust conversion

Hmm that's interesting. So, I suppose under normal conditions, once the boat is loaded in the water, it will not have water coming up the y pipe like that? That's weird. I guess I will construct some better caps just in case. And I will put in an automatic bilge pump in addition to our switched one.

I can't believe that dang main bellows is ripped again! It just doesn't make any sense... It's a year old. Oh well...

Thanks