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I have a crack in the fiberglass exhaust pipe close to where it meets the elbow. Shouldn't be a big dea was just wondering if poly or epoxy resin will handle the heat the best. Any sugestions?
Thanks, Mac

Mac,

Sand the area well with 80 grit, allowing at least a three inch perimeter around the crack. Make sure that no old surface remains, all good clean fiberglass exposed. The strongest repair will by wrapping the full circumference if the pipe.

Catalyze a small amount of polyester resin and prime the sanded area. Wipe off any excess resin and allow the prime to tack up. 1 1/2 oz chopped strand mat will be OK or use 6 oz 0/90 cloth. Either way use at least 3 layers.

Make sure that the fiberglass is fully wet out and no bubbles, but at the same time try to keep the resin content to a minimum. Said a different way, you want the glass content to be as high as possible without allowing bubbles to form in the layup.

Polyester or vinylester will withstand the heat better than epoxy. Epoxy will fail at around 250 degrees F.

Thanks Patrick, Will do tomorrow.
Mac

Captain Patrick...

Can you tell us the max temp limits for vinylester in this application?

Btw.. It was a pleasure meeting you and Bruce last Saturday! Thanks for your comments on my air box concept.

Poly/vinyl-esters won't soften and fail as will epoxy. Failure point of Poly/vinyl-esters will be in the 500 - 600 degree F range which would be the ignition point...

Pleasure was mine!

Failure point of Poly/vinyl-esters will be in the 500 - 600 degree F range which would be the ignition point...

Try telling that to a stubborn Aussie engineer on a 175' sailboat.

I got called to Rybovitch to do an exhaust repair on said boat.

Because of original design problems the fiberglass exhaust catchment(best way to describe it) system above the engine had burned up multiple times due to the water injection in the wrong place. The engineer who designed it said there was nothing wrong with the design. Also made some snid comments about us Yanks.

I asked him then why does it continue to burn up. Let me make it out of stainless and wrap it and told him rather than run it out the back on a yacht this size it should go out the side to which he said no.

What everyone was looking for including Rybovitch was a patsy to take the fall for the next failure.
After making the repair I had the engineer sign off on my work order to which he didn't read the fine print to which said basically they understood
I was making a repair to a faulty designed exhaust system and released me from all liability to future failures.

A few weeks after I got my check from Rybovitch I had a woman calling me all frantic wanting me to send them a new invoice without the disclaimer.
Sorry no and hung up.

The system was seeing on that turbocharged engine probably 800 to 1000 degrees and not being cooled by water was a no no.

Bruce wrote: Try telling that to a stubborn Aussie engineer on a 175' sailboat.

I got called to Rybovitch to do an exhaust repair on said boat.

Because of original design problems the fiberglass exhaust catchment(best way to describe it) system above the engine had burned up multiple times due to the water injection in the wrong place. The engineer who designed it said there was nothing wrong with the design. Also made some snid comments about us Yanks.

I asked him then why does it continue to burn up. Let me make it out of stainless and wrap it and told him rather than run it out the back on a yacht this size it should go out the side to which he said no.

What everyone was looking for including Rybovitch was a patsy to take the fall for the next failure.
After making the repair I had the engineer sign off on my work order to which he didn't read the fine print to which said basically they understood
I was making a repair to a faulty designed exhaust system and released me from all liability to future failures.

A few weeks after I got my check from Rybovitch I had a woman calling me all frantic wanting me to send them a new invoice without the disclaimer.
Sorry no and hung up.

The system was seeing on that turbocharged engine probably 800 to 1000 degrees and not being cooled by water was a no no.

Bruce, your a smart man, getting out of the business just proves the point even further.