What’s better Inox or aluminum exhaust elbow Volvo D2-50

[Cheechako]

Originally Posted by s/v Jedi

Well it also needs to bake in an oven… that may not be suited for baking food afterwards…



I understand that the HDI marine elbows are one piece investment cast stainless steel. Mine seems to gonna last forever…

Sounds like pretty good stuff.
In the end, all these options are just difficult to say what's best.

[Compass790]

Originally Posted by CaptainRivet

Problem on the d2-50 is
A) the cast iron elbow rusts inside and cloggs up the inlet which causes different flow pattern that creats cavital corrosion around the flange to the alu cast heat exchanger
B) this then causes that the seal partly breaks and the iron and alu cast gets in contact so you get contact corrosion and the flange of the alu cast heat exchanger corrodes away. This then causes a leak where salt water drips on starter causing to rust quickly and break down.
C) additionally then heat exchanger starts to corrode and salt water gets into the sweet water cooling cycle. Game over....

Parts4engine sells the HDI stainless cast elbow with different seals then HDI delivers as their customers experienced the same contact corrosion (see B) as with the original part.
Got told that fixes this issue but they don't have long term experience with it as they sell this different seal since 2 years.

Too me it looks like that the alu cast really solves the problem as there are no contact corrosion and much cheaper then SS version .
Just wondering why not more D2 owners choose the alu cast part...
My experience tells me if a solution sounds that good but nobody in the marine world done it that there is a major flaw that I didn't discover till now..
And I agree then I want the elbow to break before the heat exchanger.

Well at a guess the alicast will resist the salt water quite well as aluminium boats do quite well at least in not hot salt water. Think polishing is a good idea but doubt it would last long on ali, but good on ss.
At the price i would have thought the ali is worth a try if you do the install yourself. I tried to look at the ali elbows but link didn't work BTW but I looked at them googling. They look like a reasonable wall thickness which is what you want in a wet exhaust.
The only other option is to make sure an ss elbow is electrically isolated from the ali but you already know that
Maybe you should start another thread asking the life of Perkins Prima 50 aluminium elbows?
Following with interest

[Martkimwat]

Regardless of whether you use, Alloy or stainless steel, you will still potentially have an issue as the bolts are still made of steel. That being said, the stainless steel will stand up to bi metallic corrosion much better than alloy and since the issue appears to be problems with corrosion caused by the exhaust water mixing elbow, that is what I believe you need to be addressing. As long as yo have a proper gasket between the stainless exhaust elbow and the alloy heat exchanger, you should not have issues as the stainless steel mixing elbow will resist corrosion which is what causes the problem in the first place. I fitted a stainless steel elbow to my Yanmar 2GM20 six years ago and apart from light coking and sooting, (easily cleaned out) is still in good condition.The old steel elbow was notorious for burning through and allowing saltwater into the exhaust manifold which then corroded the exhaust ports and often corroded right through the galleries into the oil ways.

[kalusta]

Hi all,
I have just take out the heat exchanger on my Volvo Penta D2-55B (2004) to look at some corrosion on the flange situated at the sea-water cooling part. I have also opened the elbow which is partly corroded as well. I was going for an SS elbow as replacement when i read your messages.

I just discovered that the flange at the heat exchanger and the exhaust bow has only a thread of 3mm on one side due to corrosion while it is 7mm on the other side. Can this part be "repaired" eg with a metal paste to enlarge the thread. I am not sure if a new seal and SS exhaust bow will work otherwise, the risk is to need a new heat exchanger as well then. Any suggestions? Thanks.

[johnn33]

I am not a materials specialist but would Monel bolts together with

an isolation inert piece or two gaskets between heat exchanger and elbow be of use?
John

[CaptainRivet]

Originally Posted by kalusta

Hi all,
I have just take out the heat exchanger on my Volvo Penta D2-55B (2004) to look at some corrosion on the flange situated at the sea-water cooling part. I have also opened the elbow which is partly corroded as well. I was going for an SS elbow as replacement when i read your messages.

I just discovered that the flange at the heat exchanger and the exhaust bow has only a thread of 3mm on one side due to corrosion while it is 7mm on the other side. Can this part be "repaired" eg with a metal paste to enlarge the thread. I am not sure if a new seal and SS exhaust bow will work otherwise, the risk is to need a new heat exchanger as well then. Any suggestions? Thanks.

Is the corrosion around the SS bolt or did the wider flange corroded away around it
Or other question do you assume the root cause is the SS bolt (which will be new) or its caused by the iron exhaust elbow?

Your best chance is welding, machine surface even and bore and tab a new thread.

[CaptainRivet]

Originally Posted by johnn33

I am not a materials specialist but would Monel bolts together with

an isolation inert piece or two gaskets between heat exchanger and elbow be of use?
John

John till today the problem is the iron cast elbow that causes the corrosion.
I would mount with Duralac on the SS screws.
Maybe its better to use A2 304 SS steal screws then A4 316 SS?
Which is also the indication an SS elbow is fine.
Critical is the material of the gasket not the thickness of it. It needs to be a composite one not containing any metal as parts 4engine supplies additionally.

Maybe the corroded iron particals get into flange through the gasket when engine cools down after use as the extension off material is much bigger on alu cast via iron cast??? How can the flange completely corrode away on the whole surface otherwise?
2nd it looks like its the combo of the seal and the iron cast material that may cause the corrosion on the flange.
You really need to figure out the root cause first and only then you can figure out a solution.

Again if then the 200-400Euro exhaust elbow should be the sacrificial part, not the 3500Euro heat exchanger as it is now. And with SS exhaust elbow thats not the case.

Looking at all the pics and now kalusta ones its always the lower part of the heat exchanger corrodes away and on the whole surface not just on the inner "corner" where you would expect it.

[Jetx]

Originally Posted by kalusta

Hi all,
I have just take out the heat exchanger on my Volvo Penta D2-55B (2004) to look at some corrosion on the flange situated at the sea-water cooling part. I have also opened the elbow which is partly corroded as well. I was going for an SS elbow as replacement when i read your messages.

I just discovered that the flange at the heat exchanger and the exhaust bow has only a thread of 3mm on one side due to corrosion while it is 7mm on the other side. Can this part be "repaired" eg with a metal paste to enlarge the thread. I am not sure if a new seal and SS exhaust bow will work otherwise, the risk is to need a new heat exchanger as well then. Any suggestions? Thanks.

Earlier this year, the heat exchanger outlet flange on my D2-55A failed… corroded completely through and perforated along the bottom edge… allowing a jet of exhaust gas to escape between the flange and the elbow. In my case, the corroded area did not encroach on the threads, and I was able to repair with epoxy (JB Weld High Heat) well enough to get through the rest of the season.

I re-attached the existing SS flange gasket and used it as a “form” to press the epoxy into (bolted on the gasket only, without the elbow, with some clear packaging tape on the gasket to facilitate release). Then hand sanded the cured epoxy to give a good flat sealing face. This has held up fine for a hundred hours or so, and I know others who’ve done essentially the same repair, intending it to be temporary, and then left the epoxy in place for years.

I say give it a try. I don’t think you’re going to screw up the heat exchanger, but if it fails, you should still be able to grind it out and get the exchanger weld-repaired as has already been suggested.

BTW, the elbow on my engine had been replaced by a previous owner with a cast SS one. There was no corrosion or buildup/blockage inside the SS elbow, and yet the exhaust flange corrosion obviously continued with the SS elbow in place. I have no idea if this is because the aluminum manifold flange became sacrificial to the SS elbow, or if it’s simply salt and moisture from the exhaust stream (perhaps condensation after shutdown) setting up a corrosion cell on the surface of the heated aluminum. I suspect the latter, but who knows.

[CaptainRivet]

Originally Posted by Jetx

Earlier this year, the heat exchanger outlet flange on my D2-55A failed… corroded completely through and perforated along the bottom edge… allowing a jet of exhaust gas to escape between the flange and the elbow. In my case, the corroded area did not encroach on the threads, and I was able to repair with epoxy (JB Weld High Heat) well enough to get through the rest of the season.

I re-attached the existing SS flange gasket and used it as a “form” to press the epoxy into (bolted on the gasket only, without the elbow, with some clear packaging tape on the gasket to facilitate release). Then hand sanded the cured epoxy to give a good flat sealing face. This has held up fine for a hundred hours or so, and I know others who’ve done essentially the same repair, intending it to be temporary, and then left the epoxy in place for years.

I say give it a try. I don’t think you’re going to screw up the heat exchanger, but if it fails, you should still be able to grind it out and get the exchanger weld-repaired as has already been suggested.

BTW, the elbow on my engine had been replaced by a previous owner with a cast SS one. There was no corrosion or buildup/blockage inside the SS elbow, and yet the exhaust flange corrosion obviously continued with the SS elbow in place. I have no idea if this is because the aluminum manifold flange became sacrificial to the SS elbow, or if it’s simply salt and moisture from the exhaust stream (perhaps condensation after shutdown) setting up a corrosion cell on the surface of the heated aluminum. I suspect the latter, but who knows.

I think the key word here is SS gasket
Thats what HDI supplied and parts4engine replace with a composite gasket as several customers had the same continued corrossion then you. Alu to SS contact corrosion, the heat and salt speeds up the process...

But that again is a vote for the alu cast prima 50 exhaust elbow.

[CaptainRivet]

The Perkins Prima M50 exhaust elbow only fits old the Volvo D2-50A or B and D2-55 A or B version. The original is cast iron, the aftermarket from parts4engine is cast aluminium.
Look at the flange, if its opening is square it fits, if triangular NOT.

I have a D2-50F with triangular opening means the M50 doesn't fit
Wanted to order them...well I have garuntee till 02/2024 on both engines, so i wait till that ends and how the experience with the composite gasket on SS ones.

[CaptainRivet]

Maybe a thin layer of JB high temp weld on the whole flange would protect it from contact corrosion
Could apply that to the gasket but I think thats exactly what the composite gasket from parts4engine is doing...islolating the elbow.
If it holds for more then 100h it will hold as long as the alu...
Used it in car racing to fix alu headers, if it stands the temps more then 20h it holds up like a weld.

[kalusta]

Originally Posted by CaptainRivet

Maybe a thin layer of JB high temp weld on the whole flange would protect it from contact corrosion
Could apply that to the gasket but I think thats exactly what the composite gasket from parts4engine is doing...islolating the elbow.
If it holds for more then 100h it will hold as long as the alu...
Used it in car racing to fix alu headers, if it stands the temps more then 20h it holds up like a weld.

Has anyone experience with a type of cold welding material paste such as Quicksteel xtreme for repair? It says it can be used with Aluminium as well?

[CaptainRivet]

Originally Posted by kalusta

Has anyone experience with a type of cold welding material paste such as Quicksteel xtreme for repair? It says it can be used with Aluminium as well?

I only used jb weld high temp.

[Compass790]

Originally Posted by CaptainRivet

Maybe a thin layer of JB high temp weld on the whole flange would protect it from contact corrosion
Could apply that to the gasket but I think thats exactly what the composite gasket from parts4engine is doing...islolating the elbow.
If it holds for more then 100h it will hold as long as the alu...
Used it in car racing to fix alu headers, if it stands the temps more then 20h it holds up like a weld.

Sounds like a plan to me. You blokes might be interested in this vid, can skim thru a bit till he gets to the repair. I'd certainly give it a go with the price of the HX. I didnt check the metal type so you need to watch that in acid bath, just thought the epoxy part would be of interest

https://www.youtube.com/watch?v=aKMnLa2_RtU

[kalusta]

Originally Posted by CaptainRivet

The Perkins Prima M50 exhaust elbow only fits old the Volvo D2-50A or B and D2-55 A or B version. The original is cast iron, the aftermarket from parts4engine is cast aluminium.
Look at the flange, if its opening is square it fits, if triangular NOT.

I have a D2-50F with triangular opening means the M50 doesn't fit
Wanted to order them...well I have garuntee till 02/2024 on both engines, so i wait till that ends and how the experience with the composite gasket on SS ones.

I have asked Parts4Engines about the différent types of exhaust elbow: here is their answer:

M50 exhaust elbow is very similar to the Volvo Penta D2-55B however there is difference so it wouldn’t fit the Volvo engine correctly. Unfortunately we don’t have the D2-55 elbow connector in Aluminium therefor I could only recommend the outlet kit link below which includes the elbow and the connector
- https://www.parts4engines.com/volvo-penta-d2-55a-and-d2-55b-stainless-steel-exhaust-outlet-and-connector/