Exhaust Riser rusted through

[Randy Rutledge]

My exhaust riser has a rust through in the exhaust tubing before it enters the water jacket, looks like the unit was made with 1 1/4" thin wall tubing, when the tubing was threaded the threads almost cut through the tubing.

I plan to cut out the exhaust and reuse the water jacket that appears to be sound schedule 40 tubing. Should I use galvanized or black pipe this, my guess is galvanized will last longer.

 

[toddster]

There are long, involved threads on this over at Moyer Marine. The upshot is that AYBC does not allow galvanized because exhaust can get hot enough to vaporize some of the zinc and emit very toxic fumes. No matter what you use, some fumes will be emitted until it "burns in."

I would say that if you're going to take the thing apart, replace it all. It could be all corroded inside. I tried to "fix" mine and every time I handled it, it deteriorated a little more. I think that acid-flushing the block was the final straw.

 

[Bill Sanborn]

IMHO you should definitely replace the whole thing. I tried to reuse the upper section once and ended up redoing the whole thing 2 years later. It could have been worse because the inner tube on the strand pipe had corroded which could have allowed salt water to flow back into the exhaust.

Use black iron pipe. Consider sched 80 pipe vs sched 40. You can use standard length pre-threaded pipe from any plumbing supply place. Find the big place where all of the small contractors go.

I haven't tried it but have always thought that installing a petcock in the salt water line into the stand pipe would let you drain the salt water and increase life span.

 

[Glyn Judson]

Exhaust riser rusted.

Fellas, I also was concerned about salt water sitting in my engine system and what damage it could do over time so when I built a fresh water management system for the entire boat, I included in that a means of flushing the engine with fresh water regardless of where we were. So, regardless of being in our slip, on a mooring at Catalina Island or even at anchor somewhere, I can with the flick of a handle on my 3-way Apollo ball valve I can shut off salt water intake and instead, divert fresh water from onboard tankage through the engine and exhaust. In only 30 seconds, actually 20 but 30 seems better) the water emerging from the exhaust flange changes from salt to brackish to pure fresh, my assurance that all engine related salt water has been flushed overboard. I might add that in that 30 seconds, approximately three gallons or less of fresh water is used. After killing the engine, I manifold back and the engine is ready for salt water cooling of the heat exchanger, etc the next time we start up. I think I can still dig up a schematic I made of my fresh water management system for anyone interested. If so, just contact me back channel at glynjudson@roadrunnre.com for a copy. Cheers, Glyn Judson, E31 hull #55, Marina del Rey CA

 

[Macgyro]

Great Idea

I was thinking of doing a similar thing with a hose inlet in the cockpit of my E32. I've winterized my engine with a simple 'T' connection between the pump and the seacock. The second hose off the 'T' has a shutoff valve and is normally capped off, but I've been thinking of connecting it to one of those recessed water inlets that you can hook a hose up to. I have a 5 gallon bucket that I installed a hose bib into for winterizing the powerboat, and I was thinking of running a short hose between it and the inlet. I could either fill up the bucket from gallon jugs or the tap, or the marina.

The direct connection to the water supply sounds like a more elegant solution, and for us northeasters, we have to run glycol through the freshwater system anyway, so winterizing could be simplified into one step.

I think I'll go check my exhaust pipes for corrosion first. Seems more important.

-Dean

 

[Randy Rutledge]

I cut the exhaust pipe where it enters the water jacket and then ground the weld that held the upper part to the water jacket, removed the upper part of the exhaust which was rusted off at about the level of the exit from the water jacket. another 1/2" lower and I would have had water flowing back into the engine. The outside tube and exit tube as well as the water inlet tube are all made of a thicker metal and in good shape, I plan to replace the center (exhaust) tube in the riser and the rest of the system.
I have attached pictures of the rusted mess. My one hour expected to rewrap the exhaust turned into one day.

This all started with a smell like electrical components burning when the engine was run for a while. I unwrapped the exhaust to see if there was something in the wrap causing the problem and found two holed in the pipe, a black tape and putty of some kind (looks like black duct tape) on the elbow at the bottom of the riser.

 

[toddster]

Oh yeah, "muffler repair tape." I went a few rounds with that. The only good thing about that episode was that it was during the winter. Steam leaking out of the exhaust riser kept the helmsman's seat toasty warm on the way back up the channel. Too bad it toxed-out the cabin and made the CO alarm melt down though.