Exhaust elbow

cliff said:
As for your perception of thin wall material being no problem forget it - even 22g sheet can suffer from CP Ref: urinals fitted to one of HM Subs - corroded to hell round the welds - wrong material - 316 NOT 316L.
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Not my perception - your source. Since there are many other reasons why the welds in her majesty's pisspot could have failed, I'd be interested to know how you knew it was carbide precipitation. I hope they are not around any more, but at one time there was a big company making stainless steel exhausts for classic cars who used mild steel weld material. Not terribly clever.
 
nigelmercier said:
The PBO article it was just after I had bought a new elbow, having read it I decided that the DIY version was such a kludge that I wouldn't even consider it.
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It was I that did it, cost me 200 notes instead of 500, kludge it wasnt and i expect it to last far longer than the cast iron one. All the bits were 316, I did all the hard work in sourcing the bits and workshops, doing it again, wouldnt take as long.
ASAP is your friend. If someone wanted to really do it cheaply they could use schedule 80 carbon steel bits.
Stu
 
skipper_stu said:
It was I that did it, cost me 200 notes instead of 500, kludge it wasnt and i expect it to last far longer than the cast iron one. All the bits were 316, I did all the hard work in sourcing the bits and workshops, doing it again, wouldnt take as long.
ASAP is your friend. If someone wanted to really do it cheaply they could use schedule 80 carbon steel bits.
Stu
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Thanks to all for your contributions. There's a lot of knowledge and experience out there.

Stu, Thanks for coming on here. I'm swithering about going down your method. After all the water cooled section as supplied by ASAP is designed for the purpose, and any bend and flange that I weld on upstream, is not going to be in contact with hot salt water, just heat.
How hot does the elbow get? And is wrapping it in insulation tape sufficient to stop it radiating excessive heat around?

At present, I think the actual elbow is alright, but the water connection is destroyed, so I have to do something. The water connection is priced at something over £70, but I reckon I could make up something for nothing. It's only an elbow with a flange and a hosetail. Mind you the 2" length of rubber hose is priced at >£14. Where do they get their prices from? I can buy a metre of that for less than half the price of 2":confused:

I really got quite a fright when the water connector fell apart. It's not something which would be easy to jury-rig.

So I may make up a stainless one, using the water-jacketed tube from ASAP, but I may also make up a mild steel one, to lie in the bottom of the locker, just in case. The MS one would just be a simple flange / elbow / pipe, with a water connection welded in, so wouldn't be water cooled. It would probably need to be made longer, so that the water had time to cool the exhaust before it came in contct with the exhaust hose. I'm just thinking aloud here:D
 
This is the manifold/elbow on my marinised BMC engine. I doubt very much that it has an internal bend and tube in it, just a branch welded onto the main pipe. It is stainless, may be professionally done, and has been perfectly satisfactory for quite a long time. It is quite some distance from the engine, so not much risk of seawater getting in, at the cost of perhaps somewhat higher temperature in the engine room, which does not seem to be a problem.
7465e387b49ef439384e67e386a8a059.jpg
 
NormanS said:
Thanks to all for your contributions. There's a lot of knowledge and experience out there.

Stu, Thanks for coming on here. I'm swithering about going down your method. After all the water cooled section as supplied by ASAP is designed for the purpose, and any bend and flange that I weld on upstream, is not going to be in contact with hot salt water, just heat.
How hot does the elbow get? And is wrapping it in insulation tape sufficient to stop it radiating excessive heat around?

At present, I think the actual elbow is alright, but the water connection is destroyed, so I have to do something. The water connection is priced at something over £70, but I reckon I could make up something for nothing. It's only an elbow with a flange and a hosetail. Mind you the 2" length of rubber hose is priced at >£14. Where do they get their prices from? I can buy a metre of that for less than half the price of 2":confused:

I really got quite a fright when the water connector fell apart. It's not something which would be easy to jury-rig.

So I may make up a stainless one, using the water-jacketed tube from ASAP, but I may also make up a mild steel one, to lie in the bottom of the locker, just in case. The MS one would just be a simple flange / elbow / pipe, with a water connection welded in, so wouldn't be water cooled. It would probably need to be made longer, so that the water had time to cool the exhaust before it came in contct with the exhaust hose. I'm just thinking aloud here:D
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The heat off the uncooled bit is not a prob, the figlass (west tape) handles it great, I did a 900 mile cruise this summer with it on, I checked it a couple of times after a long engine run, no probs. As I said in the article, I stapled rad insulation plastic foil type stuff on the wood panel, it never even got warm! If you just want to do a repair to the little flange then file/drill a piece of flat mild steel to suit, then weld a mild steel 3/4" internal thread elbow on. It is just the right size that the original rubber pipe will slip on to with the hose clip to clamp it on. If the pipe is sha gged then use ordinary clear wire reinforced hose from ASAP and loop it around. This will get you away for the time being. Don't forget, the mild steel wont last long! But a lot cheaper than the VP part!
You are quite right that the bit off ASAP is DESIGNED for the job and that the bit I welded does not have corrosive sea water going thru and past the weld. I am more than confident in the design and execution. Interestingly PBO like to know what the past life/job experience of contributors is, mine was serious maintenance and repairs in the oil field and heavy industry in the UK. Things like this were my forte, in Africa and the middle east we were 3 months away from spare parts!
Stu
 
I have a 1GM10 with a high level exhaust. The Yanmar 90 degree elbow mated to the 28mm bsp adaptor failed after 10 years, the bronze u-bend with the SW inlet is still AOK. I'm not sure what's the best way of putting some kind of electrical insulation between the cast iron elbow and the pipe fitting, but it's something I"ll keep my eye on in future. It lasted 10 years so I'm not too upset.
 
JumbleDuck said:
That's the one I have. It's very nicely made and I haven't spotted any rust on it after two seasons, though I am planning to have it off for a good hard stare (and to decarb the exhaust port, if necessary) this winter. Perhaps Clyde seawater is less corrosive than Royal Navy urine?
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No "perhaps" to it - have you seen what these matlots drink? FFS it would take the chrome plating off your bumber or use it for descaling your engine.
 
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