Exhaust

[drh1965]

Has anyone had to replace the cast iron parts of a wet exhaust? I've got a Universal M18 where the cast iron elbows and riser coming out of the expansion tank are horribly rusted and leaking. The stuff was wrapped in what looks like fiberglass insulation which must have trapped a ton of moisture.

I'd like to replace the stuff but can't find a parts listing anywhere. Can anyone lead me to a source? Also, is the fiberglass insulation wrap necessary?

Thanks.

[Sandero]

I've replaced mine on a Volvo MD17. I think a clean, ie non corroded exhaust elbo is essential for proper cooling of the engine. Look up the part number and replace it!

jef
sv shiva

[GordMay]

From the online parts catalog for the Universal M18: Good Old Boat: The sailing magazine for the rest of us
(12) Heat Exchanger 2" X 12", Universal Part # 298633, Torresen Marine price $326.34
Goto: Marine Diesel Direct - Heat Exchanger Group

[drh1965]

Originally Posted by GordMay

From the online parts catalog for the Universal M18:
(12) Heat Exchanger 2" X 12", Universal Part # 298633, Torresen Marine price $326.34
Goto: Marine Diesel Direct - Heat Exchanger Group

Those are all the parts that are fine... its the parts that attach to the exhaust flagne that need replacing.

[drh1965]

Originally Posted by defjef

I've replaced mine on a Volvo MD17. I think a clean, ie non corroded exhaust elbo is essential for proper cooling of the engine. Look up the part number and replace it!

jef
sv shiva

No one sells a replacement that I can find.

I attached a drawing with the U-shaped part that I need to replace...

[Chief Engineer]

Are you referring the point at which water is injected into the exhaust?

There are several types out there...you probably need one that is 1.5" i.d. NPT

If you are just looking for a "U" bend, you can make one up from steel pipe.

In the Universal atomic-4 Installation manual, they reccomend black iron pipe.

It is cheap, it works and is not prohibitively expensive to replace.

[drh1965]

Originally Posted by Chief Engineer

Are you referring the point at which water is injected into the exhaust?

There are several types out there...you probably need one that is 1.5" i.d. NPT

If you are just looking for a "U" bend, you can make one up from steel pipe.

In the Universal atomic-4 Installation manual, they reccomend black iron pipe.

It is cheap, it works and is not prohibitively expensive to replace.

The M18 doesn't use a mixing elbow (the raw water is injected in to the manifold). So, yeah, I'm looking for the 1.25" pipe fittings and pipe needed to replace the solid "U" portion of the exhaust. Black iron should work well with cast iron (its the same metal so no galvanic cell maybe???). Have you seen a place to buy that stuff? Is your exhaust wrapped with insulation?

[never monday]

Originally Posted by drh1965

Have you seen a place to buy that stuff? Is your exhaust wrapped with insulation?

Ace Hardware
If you value the skin attached to you arms I'd recommend wrapping the dry section of the exhaust. You can use header wrap available at any hotrod shop or mail order from Summit or Jegs.

[cal40john]

Originally Posted by drh1965

The M18 doesn't use a mixing elbow (the raw water is injected in to the manifold). So, yeah, I'm looking for the 1.25" pipe fittings and pipe needed to replace the solid "U" portion of the exhaust. Black iron should work well with cast iron (its the same metal so no galvanic cell maybe???). Have you seen a place to buy that stuff? Is your exhaust wrapped with insulation?

I'm confused, you say the water is injected at the manifold, then you have a big loop. If the expansion tank in your drawing is actually a waterlift muffler I'd be less confused.

Anyway, my take based on installs I've seen, exhaust systems come separately from the engine, so there wouldn't be an engine part number.

John

[Chief Engineer]

1.25 pipe (black iron)

materials
2 elbows
1 close nipple
2 3-4" nipples (cut threaded end off or get an 8" nipple and cut in half

the exhaust wrap is specially designed for the purpose...do not use fibreglass tape

After wrapping, tie it up with stainless wire. About every 2 inches. Cut lengths to go around. Use a small pair of vise grips to twist it snug. Cut off excess with about 1/2" to spare. Twist the remaining part down into the material with a pair of needle-nose pliers to avoid snaggin stuff on it...like the back of your hand

[GordMay]

Cast Iron (Black Iron) pipe is commonly utilized for Natural Gas supply lines, and should be available at any Plumbing Supply house. Use Pipe Dope (thread sealant), not Teflon Tape.

[drh1965]

Originally Posted by never monday

Ace Hardware
If you value the skin attached to you arms I'd recommend wrapping the dry section of the exhaust. You can use header wrap available at any hotrod shop or mail order from Summit or Jegs.

Thanks for the help. I've seen exhaust wraps at Auto Performance shops for years and they are designed to be removed at will. That is a really good idea!

[drh1965]

Originally Posted by cal40john

I'm confused, you say the water is injected at the manifold, then you have a big loop. If the expansion tank in your drawing is actually a waterlift muffler I'd be less confused.

Anyway, my take based on installs I've seen, exhaust systems come separately from the engine, so there wouldn't be an engine part number.

John

If you look at Gord's picture above, part number 5 is the nipple where the raw water is injected back in to the exhaust at the expansion tank/exhaust manifold. The large loop is an attempt to keep water from backing up in to the engine if wave action is pounding the transom. The second box is the muffler.

[drh1965]

Originally Posted by GordMay

Cast Iron (Black Iron) pipe is commonly utilized for Natural Gas supply lines, and should be available at any Plumbing Supply house. Use Pipe Dope (thread sealant), not Teflon Tape.

Thanks Gord.

[drh1965]

Originally Posted by Chief Engineer

1.25 pipe (black iron)

materials
2 elbows
1 close nipple
2 3-4" nipples (cut threaded end off or get an 8" nipple and cut in half

the exhaust wrap is specially designed for the purpose...do not use fibreglass tape

After wrapping, tie it up with stainless wire. About every 2 inches. Cut lengths to go around. Use a small pair of vise grips to twist it snug. Cut off excess with about 1/2" to spare. Twist the remaining part down into the material with a pair of needle-nose pliers to avoid snaggin stuff on it...like the back of your hand

The insulation that is on there is falling apart and won't be reusable. I'll need to do something different. Perhaps the auto wraps will work.