30 O'Day exhaust

Richard19068 · Mar 20, 2015

colinhulse said:
Anyone know what the original exhaust looked like on a 30 O'Day? What I found must of been made in a weld shop. Specifically the mixing tube, where water is added. It is just black pipe with a smaller pipe welded on a 45 degree angle. I made a new one from a solid block of SS and TIG welded in the water tube from the top.View attachment 86156 View attachment 86157

Looks like you did a good job. What Engine? If it's a Universal (Westerbeke)The "original" is probably cast iron pipe from a hardware store.

Capt jgw · Mar 21, 2015

There are no factory exhaust fittings on a Universal. They were all plumbed with build in place hardware store pipe fittings, and the systems work just as well as any other. Cheap and easy to build, easy to clean out. What you have there looks like it should work fine.

sailorhokie · Mar 21, 2015

Rebuilt the exhaust riser on our M-18 out of 1 1/4" black nipple pipe. Had a similar part with welded 45 degree nipple for injected raw water. Used a Y fitting (T would work as well) with a brass reducer with nipple end. Ordered it all from McMaster. Used Permatex #3 (I think) on all threads and on exhaust flange gasket.

Josh

jibes138 · Mar 21, 2015

O'Day either made their own or bought to their specs from a third party. The exhaust is not supplied by the engine guy as it has to fit the specific boat installation. I found this article on rebuilding an exhaust and also a link to the pipe with water tube welded in . What the original poster made looks like it will work fine, wish I had a machine shop and welding equipment :>) The article is excellent.
http://www.westerbeke.com/SinglePart/NIPPLE/54202a2fdaf73b1ca82d9219

http://www.realitycheck.me/building-a-new-exhaust-riser.htm

Sefuller · Mar 21, 2015

I just rebuilt my exhaust system - sealant question

The injection pipe on my Oday 34 rusted through on my way to haul out last fall. I rebuilt the exhaust using the article Jibes linked to as a guide. I initially used Permatex, but then (as noted in the article) the pipe nipple coming out of the manifold moved and I was nervous about the thread seal being compromised. When I looked closer at the Permatex, it is only rated to 400 degrees, and I wonder if anti-sieze compound (while not a sealant) would work in this application? It has a much higher temp rating, but not sure if it will seal the threads completely over the long haul? They are all pipe threads, so fit pretty tight to start with.

DannyS · Mar 21, 2015

Your original looks exactly like mine did prior to rusting out last year. I was able to make a new one from black hardware store pipe as previous folks have mentioned. My original lasted almost 30 years, I expect the new one to go about as long.

Tom Potter · Mar 23, 2015

While removing my fuel tank a couple years ago I noticed my exhaust was shot. I pulled it off, carried it to a weld shop and they built me this custom
"Universal Diesel Header". Guaranteed to increase HP by 15%. :Liar:
I recall it not costing much, less than 40 bucks.

jibes138 · Mar 23, 2015

That's really nice Tom. Where did you get it made? In Little Washington? I just got that Westerbeke injection pipe today in the mail. It looks good but I still need to buy the rest of the pipes and elbow joints. The injection pipe is a little over 60 bucks so you got a really good deal on that header.

DannyS · Mar 23, 2015

Oooh Tom, that's a thing of beauty! Interesting that this conversation has come up since we all seem to have our issues about the same time. I'm guessing all of our boats are about the same vintage (mines an '85). So like I said before, we should
all be good for another 30 years or so.

jibes138 · Mar 24, 2015

Danny, I replaced my exhaust 9 years ago, so the original lasted 19 years. Probably the difference between fresh water and salt water that you got much longer. I'm currently using one of those cast yanmar injection elbows but it clogs up all the time and the hose barb gets solidified with salt and I have to keep screwing around with it. When it was just a straight pipe injecting water into the larger pipe I never had any of these issues, so I am going back to the original design. I'm also finally switching out the heat exchanger to the 3 inch model. I just got the new one from Seakamp and it looks great.

DannyS · Mar 24, 2015

Dave, you're probably right about salt vs. fresh. What the reason for switching to the 3 inch heat exchanger? Larger? Keep the engine running cooler?

Tom Potter · Mar 24, 2015

Hello Jibes,
Yes, the weld shop is in Little Washington. I can email the name and number if your interested. He specializes in marine aluminum and stainless welding, there was a CG boat in his shop when I was there. He also cut 3 inches off the bottom of my fuel tank and put a new bottom on to take care of a leak.

Sefuller · Mar 24, 2015

What thread sealant are you using?

As posted earlier, I was concerned about the Permatex being rated to only 400 degrees, so I re-assembled mine with anti seize compound on the pipe threads, which is rated to 1800 degrees - just not sure how it will act as a sealant? Being pipe threads they are pretty tight on their own, however.

Scott

jibes138 · Mar 24, 2015

What kind of anti seize compound? What is it made from. Hard to answer your question without knowing more about it.

njlarry · Mar 24, 2015

Tom Potter said:
Hello Jibes,
Yes, the weld shop is in Little Washington. I can email the name and number if your interested. He specializes in marine aluminum and stainless welding, there was a CG boat in his shop when I was there. He also cut 3 inches off the bottom of my fuel tank and put a new bottom on to take care of a leak.

Tom, what are the specs of the elbow. Would like to have one made.
Thanks.

Stu Jackson · Mar 24, 2015

Sefuller said:
As posted earlier, I was concerned about the Permatex being rated to only 400 degrees, so I re-assembled mine with anti seize compound on the pipe threads, which is rated to 1800 degrees - just not sure how it will act as a sealant? Being pipe threads they are pretty tight on their own, however.

Scott,

Did you use it on the threads into the flange, too?

Sefuller · Mar 25, 2015

I used Permatex 80078

"A highly refined blend of aluminum, copper and graphite lubricants. Use during assembly to prevent galling, corrosion and seizing due to weathering or chemicals. Anti-Seize assures easier disassembly. Temperature range: -60°F to 1600°F (-51°C to 871°C). Salt, corrosion and moisture resistant – ideal for marine use. Non-aerosol version meets Mil Spec #907E. Aerosol - Level 3"

Says it's suited for spark plugs, cylinder heads ...

Stu, I did use it on the threads into the flange as well.

--
Scott

jibes138 · Mar 25, 2015

Sefuller,
A pipe thread taper causes the mating thread forms to fully contact at the tip and the root of the mating pieces. Since the root of the thread form has a small radius the parts tighten up until the sharp point of the male thread digs into the root radius of the female. The amount of space between the mating threads will be extremely small and will relate to the tolerances on the angles of the thread form. Pipe threads are intended to be self sealing but sealants and anti seize compounds are added insurance and to ease disassembly. Given the high amount of metallic solids in the compound you applied, the only way it can leak is if the relatively low pressure of the exhaust gas extruded all that material around several diameters of thread through an extremely small gap. I can only speculate but I think you'll be fine and if you are still concerned, when you run the engine spray a little soapy water on the joint to check for leaks. Thanks for the info on the material, most pipe sealants I searched on maxed out around 550-600 degrees and used PTFE.