Mixing Elbow: OEM or Stainless?

[rognvald]

There are now aftermarket mixing elbows in stainless steel available for Yanmar "U" type elbows. It was mentioned in a previous post that they might be susceptible to cracking due to vibration in a corrosive marine environment. Any first hand experience on what would be the best to buy?

[Dockhead]

My boat was made with a custom stainless elbow, to suit the Halyard exhaust system.

It lasted 2000 hours and I just repaired, by having a new inner tube welded into it. The inner tube was perforated and pinhole leaks were developing.

Very satisfied with that performance. One data point.

[transmitterdan]

I have a Yanmar 4JH3E with stainless U shaped mixing elbow. Has worked for many years.

[SailRedemption]

Originally Posted by Dockhead

My boat was made with a custom stainless elbow, to suit the Halyard exhaust system.

It lasted 2000 hours and I just repaired, by having a new inner tube welded into it. The inner tube was perforated and pinhole leaks were developing.

Very satisfied with that performance. One data point.

Do you have pictures of your custom piece? What is a Halyard exhaust system?

Originally Posted by transmitterdan

I have a Yanmar 4JH3E with stainless U shaped mixing elbow. Has worked for many years.

Was this purchased or custom built? Pictures?

- Ronnie...on the geaux

[transmitterdan]

Originally Posted by SailRedemption

Do you have pictures of your custom piece? What is a Halyard exhaust system?

Was this purchased or custom built? Pictures?

- Ronnie...on the geaux

I don't know who built it. The boat had it when we bought 6 years ago. I took it off and looked inside last year but it was clean as a whistle so I put it back on. The heat resistant wrapping is just to protect things from touching the hot tubing prior to water injection. Sorry I don't have a better picture than this one.

[lifeofreilly57]

My only concern would be the order of sacrificial metals. Is the elbow isolated from the block by a lesser (cast iron) metal?
If anything is going to let go I'd want it to be he cheaper part to go.
On my last Yanmar the original cast iron exhaust elbow lasted over ten years.

[darylat8750]

I saw an injection elbow custom made out of a Nickel / Copper alloy. (Nibral maybe?) It was a beautiful thing.

[Wrong]

I researched this issue pretty extensively online before deciding to stick with the Yanmar O.E.M. cast iron U elbow.

My take is it depends on whether the riser is installed in a turbo-charged setup where salt water and heat are not a major concerns, or in a setup where the stainless elbow is exposed constantly to salt water and heat. These cause pitting in stainless that can lead to leaks.

I considered the cost of the stainless aftermarket U elbow you've seen on eBay, and by buying two of the older elbows with the straight inlet nipple, nearly got two for the price of one with the "L" inlet nipple. Same steel, same mold only different nipples. Swapped nipple from my 'spent' U elbow to the 'new' elbow and have a spare U elbow to boot.

Part numbers are 104214-13521 vs. 124070-13521.

[rognvald]

"My take is it depends on whether the riser is installed in a turbo-charged setup where salt water and heat are not a major concerns, or in a setup where the stainless elbow is exposed constantly to salt water and heat. These cause pitting in stainless that can lead to leaks." Wrong

Wrong,
A couple of questions based upon your research:

1.) Was the stainless elbow thin-walled or did it approximate the
dimensions of the original?
2.) The prices seem to be consistent for the OEM give or take a few
dollars. Did you ultimately buy the OEM or an aftermarket
duplicate?
There is also the question of dissimilar metals in the exhaust system that could lead to corrosion using the stainless elbow. This could be a concern. R

[Wrong]

Originally Posted by rognvald

"My take is it depends on whether the riser is installed in a turbo-charged setup where salt water and heat are not a major concerns, or in a setup where the stainless elbow is exposed constantly to salt water and heat. These cause pitting in stainless that can lead to leaks." Wrong

Wrong,
A couple of questions based upon your research:

1.) Was the stainless elbow thin-walled or did it approximate the
dimensions of the original?
2.) The prices seem to be consistent for the OEM give or take a few
dollars. Did you ultimately buy the OEM or an aftermarket
duplicate?
There is also the question of dissimilar metals in the exhaust system that could lead to corrosion using the stainless elbow. This could be a concern. R

The eBay ad I've seen claims the stainless elbow is equal in thickness to the OEM elbow, and comes with reverse threaded coupler. Price is approximately the same as for a recent version 124070-13521 from Yanmar. I know of one boater who got around 1,500 hrs. out of an O.E.M. U elbow. I exercised abundant caution and replaced mine at 1,080 hrs. One thing worth noting. These things are nearly impossible to clean out. But, having used a hammer to unscrew the old one from the coupler I can report the hammer method is pretty effective. With enough hammering on both sides maybe enough material can be dislodged to extend usability.

I purchased two of the older O.E.M. models @$112.00 each, no state tax from Bayshore Marine 104214-13521 Yanmar U-Type Exhaust Elbow .

The attached photo shows the difference between 104214-13521 and 124070-13521.

[Dockhead]

Originally Posted by rognvald

"My take is it depends on whether the riser is installed in a turbo-charged setup where salt water and heat are not a major concerns, or in a setup where the stainless elbow is exposed constantly to salt water and heat. These cause pitting in stainless that can lead to leaks." Wrong

Wrong,
A couple of questions based upon your research:

1.) Was the stainless elbow thin-walled or did it approximate the
dimensions of the original?
2.) The prices seem to be consistent for the OEM give or take a few
dollars. Did you ultimately buy the OEM or an aftermarket
duplicate?
There is also the question of dissimilar metals in the exhaust system that could lead to corrosion using the stainless elbow. This could be a concern. R

I'm confused. All elbows are "constantly exposed to salt water" -- that's what they do.

A turbo engine (like mine) will give somewhat cooler gasses to the elbow, since heat and kinetic energy is given up to the turbine to drive the compressor. But you still have salt water spraying into them all the time -- that's how they work.

[Dod42]

these are guys in Australia that seem to make a good product for different models. I have a friend who uses one on their Volvo seems happy. When mine needs replacing I will go here.

Hi-Tek Products Of Australia - Hi-Tek Marine

[verkerkbr]

Originally Posted by SailRedemption

Do you have pictures of your custom piece? What is a Halyard exhaust system?

Was this purchased or custom built? Pictures?

- Ronnie...on the geaux

On my Volvo MD7A I also made a riser of A4 stainless steel. I'am now using the third "edition" of it. The hot seawater and sulphur in the diesel fumes attacks the stainless steel.

The material seems OK, but small pinholes appear in the single walled stainless tubing.

This exhaust bend has to be replaced about every 6-7 Years. It is isolated with woven glassfiber tape.

Regards,


Bram

[SVJennie]

With a Yanmar 3HM35F, I had severe carbon buildup in the 90 degree nipple PN 124070-13300 (blew out seal in raw water pump). Accordingly, I replaced it with the straight nipple. All has been fine since. After 4000+ hours am still using original OEM Mixing elbow PN 124070-13520. However, I have a spare but am not looking forward to the day that I have to replace the original. And while Archimedes is said to have remarked "Give me a place to stand and with a lever I will move the whole world,” there was nothing mentioned about adjoining items getting broken.

However, I believe somewhere in this forum there is advice on how this task might be accomplished. If anyone knows where, please advise.

Incidentally, if you knew the alloy of the stainless mixing elbow on eBay, you could look up results from salt water spray testing.

Thanks!

[Wrong]

4000 hours!! How is your engine generally used? Have you checked the accuracy of your hour meter? I am skeptical of this total.

On another note, I read an engineering report on line indicating the internal design of exhaust elbows is critical to longevity. It seems to me the internal design of the Yanmar U elbow is probably the result of considerable experience and engineering expertise. So, home-made and or after market exhaust risers that do not incorporate the Yanmar internal design may be problematic.

Safest approach to dissassembling the exhaust assy. is to remove the whole thing from the engine block. Take to a muffler shop where they are experienced using brute force and heat to take things apart. A vise and big pipe wrench may fill the bill. Or, use my hammer approach remembering you are dealing with a reverse thread coupler. Can't guarantee something isn't going to break, but will venture a guess nothing will. Half the fun is in taking the risk!