Stainless Exhaust Elbow: 304 vs 316

[Username25]

Time to replace corroded original exhaust elbow on D1-30F.

Price for 316 (with shipping and taxes) from hdimarine, or parts4engines or ... is approx. 4 times higher vs 304 from Aliexpress.

Even if 304 is less corrosive resistant, price difference vs 316 from my perspective can't be justified.

Any experience with 304?

[GordMay]

Originally Posted by Username25

...
Price for 316 (with shipping and taxes) from hdimarine, or parts4engines or ... is approx. 4 times higher vs 304 from Aliexpress ...

409 Stainless Steel has about 0.5% nickel, 304 has 8% nickel, and 316 has 10%. This makes 316 more expensive, but, more corrosion resistant [improves the functional lifespan of the steel products by years], than 303.
This can lead to significant long-term savings, despite the initial increase in investment.
What is the dollar value difference [$ investment in upgrade], of the total needed?

[Johan Leopard51]

Originally Posted by Username25

Time to replace corroded original exhaust elbow on D1-30F.

Price for 316 (with shipping and taxes) from hdimarine, or parts4engines or ... is approx. 4 times higher vs 304 from Aliexpress.

Even if 304 is less corrosive resistant, price difference vs 316 from my perspective can't be justified.

Any experience with 304?

I can vouch for HDI, they make proper (316) kit, even ignoring that the OEM Yanmar for our boat was cast iron with a lifespan measured in months not thousands of hours.


Please note that HDI entire exhaust in 316 is about a ⅓ of the Yanmar cast iron entire exhaust for 8LV370.

A mate has been through (though not with exhausts) the Ali Express route. Frankly you cannot believe a word about what those vendors say. He got oil separators that look exactly like the German MANN version. They were thin enough that if you sucked or coughed on the pipe you could deform the separator. They had no pressure relief. They had a ¼ cup of residue form mold or drilling inside. He tossed them in a skip as getting money back would just aggravate him.

Buyer beware.

Another note on exhausts : we had Yanmar factory bellows on one motor corrode through underneath those heat shields that hide the true state of affairs. Tripped temperature, set off engine compartment fire extinguishers, shut motor down and obv caused some ‘concern’ onboard. Get some stainless cable ties (cheap), and every year strip off the heat shields and inspect the entire exhaust to avoid that little problem. Ours went south at under 3000h (on a powercat). The rest of exhaust (risers and cooling elbow were close to crumbling, the bellows just went first). I have absolutely no idea why Yanmar would ex-factory ship that motor with cast iron exhaust…

[Username25]

Originally Posted by GordMay

What is the dollar value difference [$ investment in upgrade], of the total needed?

Huge. 304 I can get delivered for around 100 euro, 316 -more than 400 euro.

[Username25]

Originally Posted by Johan Leopard51

I can vouch for HDI, they make proper (316) kit, even ignoring that the OEM Yanmar for our boat was cast iron with a lifespan measured in months not thousands of hours.

Please note that HDI entire exhaust in 316 is about a ⅓ of the Yanmar cast iron entire exhaust for 8LV370.

A mate has been through (though not with exhausts) the Ali Express route. Frankly you cannot believe a word about what those vendors say.

I have no doubt HDI kit is a top class, but could it still be justifiable the price? 304 would be still more corrosive resistant than original cast iron. So the dilemma is x4 304 from Ali vs x1 316 from HDI.

[Cheechako]

Originally Posted by Username25

Huge. 304 I can get delivered for around 100 euro, 316 -more than 400 euro.

Yeah, that's pretty big. I doubt it lasts 4 x as long, but labor is a consideration. The other thought is: how long will YOU really have it?
Actually, good cast iron can be very durable surprisingly. Not too sure about Yanmar's though, "it depends". Cast steel... not so much.
Hot exhaust gases, salt and acids are a terrible environment for SS really.

[Username25]

Originally Posted by Cheechako

Yeah, that's pretty big. I doubt it lasts 4 x as long, but labor is a consideration. The other thought is: how long will YOU really have it?
Actually, good cast iron can be very durable surprisingly. Not too sure about Yanmar's though, "it depends". Cast steel... not so much.
Hot exhaust gases, salt and acids are a terrible environment for SS really.

It is not for Yanmar, it is for Volvo Penta. Not sure about cast iron, considering how it looks now... I mean it could ended in a disaster at anytime and just by pure luck I have spotted the crack.

304 and 316 both are stainless steels and if 304 holds 5 years, then it is no-brainer for 100 vs 400 euro. My labor for myself is free.

[Username25]

[stormalong]

My stainless exhaust elbow was factory supplied in 2003. It is still in perfect condition. This was from Betamarine, I don't know what the alloy is.

I would be very skeptical about any stainless fabrications from China. Their stainless has a poor reputation and you don't know how good the welding is done. For my money I would go with a reputable supplier, even at four times the cost.

[JPA Cate]

OKay, the s/s would be better, might actually last in the 25-30 yr. range, based on the lifetime of the one Jim welded up out of 316 he scrounged, for our last boat.

You could make the experiment and go with the Chinese, questionable 304, knowing it may fail soon. You may kick yourself all 'round the barn, for being gullible, or feel it is a legitimate EXPERIMENT, and phooey on the warnings. These sorts of decisions are on spots on a gray continuum. You do what you want, and then report back after 5,000 or so engine hours, or whenever it fails.

The remarks above about Chinese s/s used to be true, and I wouldn't want to put the good money after bad, myself, but some of their products are okay. My own forays into China for *stuff* were sort of, well, the product would do, but was not of the quality level I'd hoped for, and had a shorter service life than I had hoped for. My error, the stuff was not suitable for intended service life.

Ann

[NorthCoastJoe]

My cast iron elbow on a Yanmar 3gm30f is holding up fine after 7 years the only thing I had to do was clean the water injection port. But it is still a low hours engine. My beta 50 is stainless of unknown alloy from the factory.

[barnakiel]

Originally Posted by Username25

It is not for Yanmar, it is for Volvo Penta. Not sure about cast iron, considering how it looks now... I mean it could ended in a disaster at anytime and just by pure luck I have spotted the crack.

304 and 316 both are stainless steels and if 304 holds 5 years, then it is no-brainer for 100 vs 400 euro. My labor for myself is free.

VP were cast iron ones. They used to last at least year.


A cast iron elbow may corrode fast if you never remove and clean it, or perhaps when it is not mounted so that it is dry when not working.


A SS elbow is nice, may outlive a cast iron one, but not by a huge amount. Give it extra 30% life.



Cast iron VP elbows are $$$ - more expensive than the most expensive Italian dried ham - pound for pound.



b.

[Jim Cate]

A SS elbow is nice, may outlive a cast iron one, but not by a huge amount. Give it extra 30% life.

No doubt you have extensive data to support this statement.... don't you?

Jim

[Bowdrie]

Originally Posted by Johan Leopard51

Another note on exhausts : we had Yanmar factory bellows on one motor corrode through underneath those heat shields that hide the true state of affairs.

Just taking a guess, was the bellows in a horizontal or near horizontal position?
A fellow I knew ran a custom marine welding/fabricating business.
One day when I was there, he was welding-up a custom bellows arrangement out of Titanium.
It was going to replace the two previous bellows that were of stainless and had both failed.
Bellows have a pretty good lifespan when they're in a vertical position so that any moisture/condensation can drain or otherwise dry out.
But in a horizontal position any residual moisture lays in the corrugations and can react with any sulfur from the exhaust, it forms sulfuric acid and eats away at the stainless.
In todays' world of ultra-low sulfur, the reaction is lessened but not entirely eliminated.
Bellows also suffer from impingement attack.

[Johan Leopard51]

Originally Posted by Username25

I have no doubt HDI kit is a top class, but could it still be justifiable the price? 304 would be still more corrosive resistant than original cast iron. So the dilemma is x4 304 from Ali vs x1 316 from HDI.

Imho you could go 304 but don’t go Ali Express unless you can check with somebody that was happy with exactly your product from same supplier.