Wet exhaust fittings sealant or not

[Sax]

I am replacing the complete wet exhaust system on my 1995 GB42 Classic with 375 HP Cat 3208TAs. The replacement hose is 8 inch Trident 252 corrugated EPDM 2 ply with helix wire. It will connect to a Centek fiberglass elbow with stainless crush rings, a Centek muffler and a fiberglass stern tube.

My question is what, if any, sealant should be used on the connections between the hose and fiberglass fittings? I want to smooth and fill the surface irregularities in the fiberglass fittings, but not make the hose impossible to remove.

It looks like Grand Banks used some sort of white sealant on the original build.

Pics of the problem, process, and replacement parts.

 

[O C Diver]

I am replacing the complete wet exhaust system on my 1995 GB42 Classic with 375 HP Cat 3208TAs. The replacement hose is 8 inch Trident 252 corrugated EPDM 2 ply with helix wire. It will connect to a Centek fiberglass elbow with stainless crush rings, a Centek muffler and a fiberglass stern tube.

What are stainless steel crush rings?

I've never used a sealant on exhaust hose. In the old days we used heavy duty worm gear hose clamps doubled on each connection. Now I use 2 T bolt clamps on each correction. The T bolt clamps will seal the hose. Offset the T bolts 180 degrees.

Ted

 

[rslifkin]

I'll second the wide, good quality t-bolt clamps. Unless the fitting has a seriously damaged surface, a pair of those should have no problem getting the hose to seal.

The crush rings mentioned are inserts for the fiberglass tubing and muffler connections intended to prevent crushing and cracking the fiberglass if you tighten the clamps too much.

 

[Sax]

I should have mentioned that I did purchase new, wide, T-bolt clamps for the install.

Concerning crush rings…on disassembly, I found that one of the previous owners of my boat did manage to crush the fiberglass elbow attempting to stop a leak. I don’t want to repeat the mistake. See pics.

The sealant is mainly to deal with the irregular surface on the fiberglass exhaust elbows and stern tube. They are of a wound fiberglass construction and have a lot of ridges. The muffler mating surface is pretty smooth.

 

[Sax]

Forgot the pics of crushed elbow.

 

[Pete Meisinger]

Hit the rubber with a heat gun before you clamp it.

pete

 

[lwarden]

Crush rings are a must on FG tubes located close to the exhaust riser where the gasses are still hot. Down the line they aren't needed IMO unless you are overzealous on clamping force. No on sealant. I have resurfaced rough FG tubes before attaching the hose to get a better seal by coating with epoxy and cabosil, mostly on elbows and other non filament wound tubes where the external surface is rough,

 

[Greg QS]

crush rings a must at the fg connections ,double clamp t bolt clamps each connection dry.

Much easier to work with is the silicon hose. You use fiberglass tube and just use the silicon as a coupling between tubes, elbows , etc. Crush rings all. Double clamp all.

 

[Comodave]

I like the AWAB T bolt clamps. No welds to promote rust and all 316 S/S. Very heavy duty.