Exhaust Elbow Cleaning

[belizesailor]

Doing some engine PM and pulled the exhaust elbow to clean and inspect. The visible areas looked better than I expected, given the, I hate to admit how many, years since I last pulled it. But of course the inaccesible cooling water channels...who knows. Water output volume at exhaust is fine, but I would like to try and clean internals of elbow as much as realistic.

Given that these areas are mostly inaccessible, what have others had success in using? Vinegar? Muratic Acid? ...?

[a64pilot]

When these things fail, often they cause real serious damage to the motor? Wouldn't it be prudent since it has been years to replace it?
What is a recommended replacement interval for these things anyway, assuming a stock Yanmar part.

[Vasco]

soak it in a bucket of muriatic acid.

[colemj]

I'm assuming Volvo - do you have the older tall riser elbow or the newer shorter elbows?

The shorter elbows are pretty much what you see is what you get - there is the main exhaust passage and the outer water jacket. Both are accessible with a screwdriver or like to chip out hard carbon deposits and rust.

The tall version may be much more difficult.

Our short ones would coke up 50% every 5 years, with the water jacket internally rusting badly, and I found it wasn't worth keeping up with them or buying new expensive ones. I had an open elbow design (no water jacket) made out of stainless instead. I got two of them made out of schedule 80 SS pipe with highly polished welds in Cartagena Colombia by a German machinists who lives there. The cost was $150 for both.

Mark

[belizesailor]

Originally Posted by a64pilot

When these things fail, often they cause real serious damage to the motor? Wouldn't it be prudent since it has been years to replace it?
What is a recommended replacement interval for these things anyway, assuming a stock Yanmar part.

Yes, trying to avoid that with a little PM. Physically it looks pretty good...I've certainly seen much worse.

I replaced it in 2006-7? and have inspected/cleaned once since then. Not sure of Volvo's recommended replacement interval but will check.

[bstreep]

Try EZ Off oven cleaner. NOT the "green" kind, the real stuff. Works wonders on baked on exhaust soot - much better than acid. BTW, do NOT mix it with acid!

[belizesailor]

Originally Posted by colemj

I'm assuming Volvo - do you have the older tall riser elbow or the newer shorter elbows?

The shorter elbows are pretty much what you see is what you get - there is the main exhaust passage and the outer water jacket. Both are accessible with a screwdriver or like to chip out hard carbon deposits and rust.

The tall version may be much more difficult.

Our short ones would coke up 50% every 5 years, with the water jacket internally rusting badly, and I found it wasn't worth keeping up with them or buying new expensive ones. I had an open elbow design (no water jacket) made out of stainless instead. I got two of them made out of schedule 80 SS pipe with highly polished welds in Cartagena Colombia by a German machinists who lives there. The cost was $150 for both.

Mark

Yes, Volvo, short version.

This one was not badly clogged and a bit of good old manual cleaning got rid of most of the carbon....but....it also revealed a suspicious corroded spot on the bottom of the elbow. A few good whacks with hammer and it opened right up...new elbow time.

[belizesailor]

A new Vovlo elbow is of course around $350...anyone have a recommendation for fabrication of a SS one in Panama?

[belizesailor]

Turns out the outrageously expensive new ones are back ordered until at least June 30 (same for 3 distributors). So, I'm the guinea pig for non-jacketed SS ones fabbed by Kiwi Dave in Bocas. He and Jeff The Mechanic were already working on making these and had two already made.

Installed the first one yesterday. Fit was good and test ran good with no leaks.

The raw water nipple is in the same position as original, which is handy because it fits those stupid cuffs. The tube which makes up the nipple takes a turn inside the elbow and extends an inch or two downstream. Interestingly, by the time the tail piece enters the exhaust hose it is cool, I mean water temp cool not even warm. And the exhaust gases/water exiting the exhaust overboard are cool as well. With the original elbows all the above were warm.

Unfotunately, these first two were made from 304, which I expect will last at least as long as the cast ferrous originals, but would much prefer 316. Any other opinions on longevity of 304 in this application?

[colemj]

The 304 itself will be fine - it is the quality and finish of the welds that will determine the lifespan. The biggest corrosion potential is seawater hitting a hot weld, and it sounds like your design minimizes that.

I know it is too late, but the Perkins elbows are the same as the Volvo ones (only a different color). Did you also try Perkins for stock?

Mark

[djmarchand]

One other check to make. If the holes are too big then at idle (low r/w flow) the water will not get up to the top holes and the upper section of the hose could overheat. Put your hand on the top and bottom of the hose just aft of the elbow and see if they are nearly the same.

David

[colemj]

Originally Posted by djmarchand

One other check to make. If the holes are too big then at idle (low r/w flow) the water will not get up to the top holes and the upper section of the hose could overheat. Put your hand on the top and bottom of the hose just aft of the elbow and see if they are nearly the same.

David

I don't understand what you are referring to as "holes"?

Mark

[belizesailor]

Originally Posted by colemj

The 304 itself will be fine - it is the quality and finish of the welds that will determine the lifespan. The biggest corrosion potential is seawater hitting a hot weld, and it sounds like your design minimizes that.

I know it is too late, but the Perkins elbows are the same as the Volvo ones (only a different color). Did you also try Perkins for stock?

Mark

Did not check Perkins, but will just for future reference. Given that Volvo does not actually build anything, I think it reasonably likely I will find the same stocking issue.

[Cotemar]

Here are a few pictures of some 316 Stainless Steel Exhaust Elbows for Volvo Penta.

[belizesailor]

Yes, there are some nice 316 products out there, but not convenient to here (Panama). Oddly, most of the products (as opposed to custom fab) I've found are made by British companies. The last 3 pics you posted are identical to a jacketed 316 product made by one. Looks like very nice work.

The first pic shows a Volvo parts diagram, but a picture of a stock elbow on a Beta Marine engine (sure do like the way Beta does things).