Stainless steel exhaust elbow

[marioxp]

My old exhaust elbow is quite clogged, I can clean it because the metal is not significantly damaged, but as I am doing a major service on the engine (VP MD2030), and I am thinking of changing the exhaust elbow as well. As I see that many of you are recommending the stainless steel version, I am thinking about it as well.

I find a lot of Chinese ones on eBay and AliExpress, which are said to be stainless steel, but from the looks of the picture, they don't look like stainless steel to me, it's a bit too matte for stainless steel, or I'm wrong.

What do you think, are these products truly stainless steel or are they some kind of lie?

As you can see they are much cheaper.

eBay stainless steel exhaust elbow https://www.ebay.com/itm/394206712911?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20200818143230%26meid%3Dce97b45d3ef049f6acc572af869a7fc4%26pid%3D101224%26rk%3D3%26rkt%3D5%26sd%3D275394304272%26itm%3D394206712911%26pmt%3D0%26noa%3D1%26pg%3D4429486%26algv%3DDefaultOrganicWebV9BertRefreshRanker&_trksid=p4429486.c101224.m-1

AliExpress stainless steel exhaust elbow https://www.aliexpress.com/item/1005004346077012.html?spm=a2g0o.productlist.main.7.6a24KuN8KuN8St&algo_pvid=cc50757d-082c-4e75-b5f6-430a55eeeab1&algo_exp_id=cc50757d-082c-4e75-b5f6-430a55eeeab1-3&pdp_npi=4%40dis%21EUR%21125.71%21125.71%21%21%21134.52%21134.52%21%402103209b17053113276481466e87e8%2112000028843828833%21sea%21HR%212739996760%21&curPageLogUid=PJFuHIvEGzcm&utparam-url=scene%3Asearch%7Cquery_from%3A

[symphony2]

Yes, they are stainless - that is what it looks like when it is cast. Only becomes shiny when it is machined, or as with tubes, polished.
They all seem to come from the same foundry in China. They are available in the UK at much the same price as bought direct from China if you include shipping, duty and VAT. But probably not in Croatia, although you may find a supplier in other states in the EU.

[Impavidus]

We got ours from Keypart in Watford. You can also get them from ASAP supplies. Ours and David on Éternité were both changed at the same time. in 2018. Both are still going strong with no issues or internal build up. We have several video on this the most recent one is here: https://youtu.be/cNV_-Vj8IeI?si=E5nRyyZqTKqsGPH9 Hope this helps. Ant.

[marioxp]

Thank you for your answers!

We come to the illogical point that stainless steel exhaust elbow from China is cheaper than cast iron from Europe.

Can I somehow clean the preheater from soot deposits?

[symphony2]

On price that is correct. If you buy a Volvo cast iron one the price you pay has to support a world wide distribution network and the costly lifestyle of the Swedish employees. When you buy from China you are paying a source very close to the foundry that cast it and which operates from a small office with a laptop. So you get a better product at a lower price.

Not sure what you mean by the preheater. To extend the life of the elbow you need to run your engine at a good load (2400rpm) for longer periods and periodically run it at near maximum revs for a short period so that you burn off the deposits before they solidify. Then you might get life like my 2030 which when I sold it had well over 3000 hours and the original elbow.

Unfortunately that type of running does not fit easily with the typical leisure use so best to remove and clean the elbow every 3 or 400 hours.

[marioxp]

symphony2 thank you for advice, in future I will it run on higher RPMs.

When I said heat exchanger I mean on part to which elbow is connected. I saw soot deposits at the outlet towards the elbow joint.

Is there a way to clean those soot deposits? It is probably a deposit of soot and scale. I'm thinking of using a milder acid (acetic or citric).

[A & A]

I also have the problem with a soot on the exhaust elbow... OK, might sound stupid but could it by any chance work to clean the part by putting it in the oven and run a pyrolysis program? And yes, this is a serious question! :-)

FW&FS
A'n A

[JEN-et-ROSS]

Yes, I guess it would/could work but you would require a furnace rather than an oven to achieve the temperature necessary to burn off the carbon...
But it might not do the elbow much good to be red hot...
I'd just apply good old fashioned 'elbow' grease...!!

[David Gray]

Hi All, I ha e just  bought a stainless steel  exhaust  elbow and gasket from Ebay for £130 including P& P with the intention of fitting when next at the boat on B36 with a MD2030 so my question is do I need to coat the steel threaded studs with some barrier coat for the dissimilar metals ? , thanks David

[J.B.]

Hello MarioXP,

I have replaced our elbow (Volvo Penta D1) with a stainless steel one about 8 months ago, it still was the original cast elbow, our engine had more or less 850h. The original elbow was severely clogged and I would say that there where almost holes in the underside due to corrosion.

We decided to replace the cast iron one with a stainless steel version, but we coated the inside and the outside with a heat resistant coating. I have added some pictures for illustration.

J.B.

[marioxp]

I was also thinking about corrosion and galvanization, but since it was always the cast iron parts that corroded and not the heat exchanger, I conclude that galvanization is not the problem, but ordinary corrosion.  After all, galvanization occurs if two different metals are immersed in an electrolyte solution (seawater), and this is not the case here, because seawater only passes through the exhaust elbow.