86 Sunsport - Supertrap exhaust seal leaks

[Jetlink]

Gotcha, thanks man, I think I might take a look at that this week as I think my right trapp has developed a small leak. Looks like our season here is coming to a close so, perhaps one more trip out and then it is time to close up shop so I don't get caught when the temps really drop.

[rludtke]

Ditto what Woton said. The Supertrapps are likely the reason why so many Supras have rotten stringers. I don't think anyone really knew to re-seal the connections where the 3" exhaust tubing meets the mounting flange of the Supertrapp. I like how the Supertrapps sound, but would personally never re-install them after having gone through the expense of a stringer and floor job.

When you get them apart, and remove the mounting flange, you will see where it needs to be sealed. Use 3M 4200 or 5200.

I agree with Csuggs. I just re-sealed mine for the second time since I've owned the boat. When my floor suddenly went underwater, I knew I had a problem. But with no obvious leaks, I took a look at the pipes. Most of the sealant came right off with the supertrapp flanges. I doubt it was very water tight.

Supra simply poked the exhaust pipes through the transom, and rely entirely on the sealant goop to keep water out of the boat. And in my hull, there appears to be no drainage from the outboard sides of the boat to the center. I don't know how much water I might have in there. I drilled one of the lower supertrapp flange screw holes up in size to facilitate draining the water out of the boat in order to fix my leak.

I think the exhaust pipes should have had a welded flange on the inside that would press up against the transom, and clamp on using sealed through bolts or something better than just a pipe through the hole.

[Jetlink]

Rick, you got any pics of what yours looked like when you had the trapp off?

[tomelenbaas]

For the benefit of those of us who aren't familiar with supertrapps, it would be very helpful if some of you would post pictures. I have rubber flappers were my exhaust vents through the transom and I'm not sure if that's what you're all talking about. Thanks.

[Salty87]

For the benefit of those of us who aren't familiar with supertrapps, it would be very helpful if some of you would post pictures. I have rubber flappers were my exhaust vents through the transom and I'm not sure if that's what you're all talking about. Thanks.

it's hard to get a pic, dark exhaust tube and i've never seen after-market supratrapps.. the problem is fairly straightforward. imagine this is part of the supratrapp. the top slides into and rests against the exhaust pipe. the seam is 2-3" up the pipe so if you only worry about the transom seal, it will leak for sure. and, the sealant wears out over time so even if you never take the pieces apart...it is still a maintenance item. any 80's boats that have never re-sealed are tempting fate.

[wotan2525]

There are some photos and more info in this thread:

https://forum.supraboats.com/showthr...r-left-exhaust

[tomelenbaas]

Thanks for the photos and link. My '89 Mariah does not have supertrapps – just the traditional rubber flappers. Are they prone to the same type of leaks people are experiencing with the supertrapps?

[rludtke]

Supertrapp is the manufacturer of high performance exhaust muffler systems http://supertrapp.com/. Supertrapps are a tunable exhaust muffler and spark arrestor systems for motorcycles, cars, and Supra utilized the tuneable plates and end cap on their boats. The supertrapp products have changed in appearance over the years, but the concept remains the same. The Supertrapp muffler is a stack of disks locatred at the end of the pipe that the exhaust exits through. The disks feature a crimp to allow them to nest together when stacked, but also leave gaps between the plates for the exhaust to exit. Back in the 80's (when I was in high school) I had a supertrappp on my modified four-stroke motocross race bike. I could adjust the engine rpm acceleration rate, and move the peak power in the rpm range by adding or subtracting plates. This was helpful for tuning the bike for different race tracks.

Supertrapps were super cool in the 1980's, but I actually do not like them so much on my Supra today. Because the exhaust exits annually and not out the end of the pipe, the exhaust sprays water up on the swim step (and exhaust fumes) at idle, which is a little annoying when you are swimming up to and boarding the boat from the water with the engine running. Plus, the traps have a flange that attaches to the fiberglass with wood screws into the very thin transom (the transom is not reinforced with any wood at that location, and is only about 3/16" thick. This flange is apparently meant to hold ookum-pukky in and around the exhaust pipe, which just sticks through the transom hole. This concept relies to heavily on the ookum-pukky to seal in my opinion. If I ever tear up the floors, I am going to make improvements to the exhaust pipe to transom interface, and probably do away with the trapps. This was the source for a recent leak in my boat, that filled the right side of the boat outboard of the right main stringer, and guess what, my boat has no means of draining any water from that compartment into the bilge (totally bogus design practice). I had to drill a drain hole through the hull to get the water out so that I could do a fiberglass repair in the exhaust area. I can't help but wonder how much water may be sitting in the left side of the boat. I am very tempted to drill drain holes through the main stringers to at least get the water into the bilge area. If I redo my stringers, the boat will not go back together like this.

[Salty87]

....Plus, the traps have a flange that attaches to the fiberglass with wood screws into the very thin transom (the transom is not reinforced with any wood at that location, and is only about 3/16" thick. This flange is apparently meant to hold ookum-putty in and around the exhaust pipe, which just sticks through the transom hole. This concept relies to heavily on the ookum-putty to seal in my opinion. If I ever tear up the floors, I am going to make improvements to the exhaust pipe to transom interface, and probably do away with the trapps....

very true. you can see light shine through the transom in spots once the floors are out. i added some backing plates for the trapps to have something to grab on to. i used starboard rings with longer screws.

[rludtke]

That is a good improvement Salty. I was actually thinking of welding a flange to the exhaust pipes that would contact the inner surface of the transom, and would feature nut plates. It would be installed with sealant between the transom and the exhaust flange, and bolted to the transom with sealed bolts run through the transom from the back. I also think I would not cover this section with floors so that it could be accessed again for maintenance. I would also add, as you did, drainage limbers through the stringers.