Exhaust leaking and rotted through

[mary]

Hello Afourians,

when I started my engine yesterday, I noticed exhaust down below. Upon further inspection I found salt water escaping through a hole in the exhaust right above the water injection. The pipe easily split in half when I started working on removing the hoses.

Any tips as far as what to replace it with? Stainless steel or bronze? I'm looking for the least expensive, yet sufficiently good quality solution.

Should this section be wrapped with high heat tape?

Thank you!

[JOHN COOKSON]

Use black iron pipe to rebuild the hot section. If the exhaust has been working in a satisfactory manner just replace what you have. If not this is the time to modify it. I was able to remove the flange and the injection part and take them to a machine shop, get them cleaned up and reuse them. The charge was only $30.00 for the work.
The hot section should be wrapped with two or three layers of fiberglass exhaust wrap to keep the heat in the exhaust. As I recall MMI sells the wrap. Also available online or through West Marine.

TRUE GRIT

Edit: Forgot to mention the hot section is 1 1/4" standard plumbing nipples and angle pieces. Available at a hardware store or plumbing supply store. I took what was left of the old hot section to the store and matched up the various pieces.

[roadnsky]

Another good reason to wrap the hot section (pipe) is to help ward off corrosion which is obviously what killed that section.
It also appears that some water has been leaking on it.
Do you know the source?

[mary]

Thank you. You answered all my questions.

Use black iron pipe to rebuild the hot section. If the exhaust has been working in a satisfactory manner just replace what you have. If not this is the time to modify it. I was able to remove the flange and the injection part and take them to a machine shop, get them cleaned up and reuse them. The charge was only $30.00 for the work.
The hot section should be wrapped with two or three layers of fiberglass exhaust wrap to keep the heat in the exhaust. As I recall MMI sells the wrap. Also available online or through West Marine.

TRUE GRIT

Edit: Forgot to mention the hot section is 1 1/4" standard plumbing nipples and angle pieces. Available at a hardware store or plumbing supply store. I took what was left of the old hot section to theca store and matched up the various pieces.

[mary]

Thank you.

Salt water was squirting out the holes when I moved from one slip to another the other day, hence the water marks.

Another good reason to wrap the hot section (pipe) is to help ward off corrosion which is obviously what killed that section.
It also appears that some water has been leaking on it.
Do you know the source?

[Ken Rockwell]

I don't like the idea of water sitting in that pipe. I would try to reroute it so water drains out. Of course, sometimes there's no way around it

[edwardc]

I don't like the idea of water sitting in that pipe. I would try to reroute it so water drains out. Of course, sometimes there's no way around it

I think that photo is rotated sideways (look at the bit of the head & block that is visible). Looks like the pipe actually heads downwards at about a 45 degree angle, so no standing water or backflow.

[mary]

Yes, the photo rotated when I uploaded it. Not sure why.

[HOTFLASH]

Another alternative for exhaust piping

You might consider "Schedule 80" SS pipes--a bit thicker and pricier but are sturdier and last longer for the short run of a dry section. Can be found at McMaster-Carr.

Mary
HotFlash
T27 Yawl

[mary]

After getting the right socket, the flange came off easily.

Next two questions:

Should coolant leak out of the hole where the flange bolt was? Some dribbled out of the top hole. I replaced the bolt to stop it.

If I cut the exhaust hose shorter to remove it from the barb end of the injection portion, is it acceptable to splice a new piece in to cover the length that was cut? It would be simpler than adding length to the hot section or replacing the entire hose and possibly easier to remove and replace next time.

Waiting patiently for your replies, hacksaw in hand.

Thank you! Mary

[mary]

The rest of it.

[mary]

Ok, never mind. I hacked it out and I'll just remove it from the muffler and replace it.

What's up with all this pvc? Is that legit?

[mary]

Photos rotated again.. not sure to fix that

[ndutton]

Mary, please go to the forum's ABYC Standards category, open the ABYC exhaust standards and at the top of the sixth page of the pdf attachment is a table that lists the approved materials for gasoline engine exhaust systems. Dry exhaust refers to our hot sections (before the water injection fitting) and Wet exhaust refers to everything down stream of the water injection.

You won't find PVC anywhere on the table.

[mary]

Thank you, Neil. I'll be replacing that also.

There's also a pvc shut off valve that is installed in place of a seacock. What a dangerous thing to have on a boat. I understand that I am in a live and learn situation, but it would have been nice if my surveyor had brought some of these things to my attention.

busy day tomorrow.