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Old 06-05-2013, 06:38   #46
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Re: Yanmar Maintenance issue: Mixing Elbow

Quote:
Originally Posted by Liam Wald View Post
This makes me wonder if there is a way to indicate the condition of the mixing elbow based upon its temperature???
When clogged, do they start to get hotter?
Compass Marine to the rescue again: the solution is to monitor your system with an infrared thermometer. (Hilarious aside, the unit can also be aimed at the ocean or lake before jumping in to prevent shrinkage)

View the excellent explanation of how to prevent engine overheating below:

Engine Temp Monitoring & Over Heating Baseline Assessment Photo Gallery by Compass Marine at pbase.com
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Old 06-05-2013, 07:54   #47
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Re: Yanmar Maintenance issue: Mixing Elbow

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Originally Posted by ironhors42 View Post
If anyone interested in stainless steel exhaust elbow, there is web site were a gentlemen make them in u.k. Prices are not that bad. He make elbow for yannar 1gm, 2gm, and 3gm motor. Here is site below for anyone who interested.

www.exhaustelbow.com
I decided to buy a new one to have as a back-up. When I went to this site I read that these are designed for "raw water cooled" engines.
Does that mean that it is NOT an issue with fresh water cooled engines?
I have a 3GM30F.
I am confused... me thinks!
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Old 06-05-2013, 08:19   #48
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Re: Yanmar Maintenance issue: Mixing Elbow

Quote:
Originally Posted by Azul View Post
Compass Marine to the rescue again: the solution is to monitor your system with an infrared thermometer. (Hilarious aside, the unit can also be aimed at the ocean or lake before jumping in to prevent shrinkage)

View the excellent explanation of how to prevent engine overheating below:

Engine Temp Monitoring & Over Heating Baseline Assessment Photo Gallery by Compass Marine at pbase.com
Wow. I have an infrared thermometer because I had lots of overheat issues with my old engine, but it never occurred to me to do a baseline on the new one. Thanks so much for sharing that.
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Old 06-05-2013, 18:26   #49
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Quote:
Originally Posted by Cheechako View Post
I repaired a heat exchanger fitting (Brazed fitting on the copper alloy) using an epoxy type stuff once. It lasted half an hour.... be careful what you try to use!

This makes me wonder if there is a way to indicate the condition of the mixing elbow based upon its temperature???
When clogged, do they start to get hotter?
It's pretty common on commercial diesels to monitor exhaust temperature. I would think it would show it well... when restricted , by water flow or exhaust restriction the temp would rise.
Even though it wasn't his primary point, Cheechako's example alludes to another thing to avoid, dissimilar metals in an exhaust elbow is no bueno. Brazing is a bad idea. Calder strongly advises against it because the combination of heat and dissimilar metal (brazing rods vs steel) can lead to VERY premature pin holing due to corrosion. Weld, don't braze and choose welding rods carefully.
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Old 06-05-2013, 18:43   #50
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Re: Yanmar Maintenance issue: Mixing Elbow

Liam -

Seawater cools in either case.

If the motor is raw water cooled the seawater passes through the motor, cools the motor, and discharges overboard via the mixing elbow.

If the motor is fresh water cooled the seawater passes through the heat exchanger, cools the "fresh" water (the coolant) , and discharges overboard.

Regard lake water, ocean water, and river water as "sea water or raw water ."

So - either way - the mixing elbow has to handle seawater discharge. And - the mixing elbow shape is generally dictated by how high the elbow is relative to the boat water line. Obviously, the elbow (45 or arch type) needs to fit the motor without colliding with the heat exchanger.

Charles

By the way - you can consider all the items at Maine Sail's site to be very reliable.
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Old 06-05-2013, 19:25   #51
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Re: Yanmar Maintenance issue: Mixing Elbow

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Originally Posted by CaptainDana View Post
Even though it wasn't his primary point, Cheechako's example alludes to another thing to avoid, dissimilar metals in an exhaust elbow is no bueno. Brazing is a bad idea. Calder strongly advises against it because the combination of heat and dissimilar metal (brazing rods vs steel) can lead to VERY premature pin holing due to corrosion. Weld, don't braze and choose welding rods carefully.
...Stock old Yanmar Heat exchanger housing... NOT an Exhaust elbow. Just mentioned it because the low temp (200F max?) didnt work. Copper doesnt weld....
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Old 06-05-2013, 19:53   #52
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Re: Yanmar Maintenance issue: Mixing Elbow

Its not going to work cut in half like that!

Seriously though I have a gen that I cant find exhaust elbows for.

I have made one (in service) and a second spare part out of easily available galvanized steel plumbing fittings.

Main part is an unequal Tee. Its 2" x 2" x 1/2"
I screwed a male male nipple into the manifold side, a male male tube nipple for the rubber exhaust hose to clamp on to, and then threaded a 1/2" pipe into the small end for the inlet water hose, and threaded a long section of 1/2" pipe into the INside of the tee so that the water will not spray back into the MFD. It ends about where the rubber starts. So fa So Good.

There are a lot of ways to cobble together an injection elbow for less than $20.00
Use exhaust repair sealant on the threads. (Holts GunGum)

The lower the material is on the galvanic scale the longer it will last.
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Old 06-05-2013, 21:12   #53
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Re: Yanmar Maintenance issue: Mixing Elbow



OEM elbow 45deg stainless at 550hrs.
Internal (exhaust pipe) was rattling around inside.
Note bird poop tig weld on water inlet & elsewhere.
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Old 09-05-2013, 11:38   #54
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Re: Yanmar Maintenance issue: Mixing Elbow

I too had a problem with a cast iron Yanmar elbow on my 3JH2TE.
As well as being blocked with scale, the water pipe inside had cracked and was spraying water back up the exhaust into the turbocharger. Needless to say the turbo did not like this and siezed - no wonder the boat felt underpowered!
My solution was to have the turbo refurbished by Turbo Dynamics in Christchurch UK. Once they realised that it was a boat engine and not a turbo racing car they were very helpful and machined out the rust, supplying a new turbine wheel to fit the slightly different shaped cavity.
The elbow was available from yanmar but at approx 500 for the cast iron version I decided to have a stainless steel one fabricated. a local welding company, Athena Welding, Poole were very helpful and made the new part for less than 300. I now have about 60hours running with the new parts and all seems well and we certainly have more power. You can find a picture of the elbow on the Athena Welding website. Athena.uk.com.

I have also had to repair the silencer(a Volvo type silencer called a Waterbreak - it is a 6" diameter rubber pipe with stainless ends.)
The ends had corroded to resemble a colander and water was leaking into the bilge. Again Derek at Athena Welding came to my rescue and made new ends which are much thicker than the originals for about half the cost of a new silencer.
Find a welder who knows his trade and work with him to save money and get a better solution.
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Old 09-05-2013, 11:44   #55
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Re: Yanmar Maintenance issue: Mixing Elbow

Oops I have just noticed my profile needs updating - no longer in Lancaster England,
Now in Poole England which is why the fabricators i used were on the south coast.
Andy N
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Old 09-05-2013, 13:36   #56
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Re: Yanmar Maintenance issue: Mixing Elbow

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Originally Posted by Liam Wald View Post
I decided to buy a new one to have as a back-up. When I went to this site I read that these are designed for "raw water cooled" engines.
Does that mean that it is NOT an issue with fresh water cooled engines?
I have a 3GM30F.
I am confused... me thinks!
I think this means he simply hasn't got round to making the trickier high-rise (gooseneck) 90 degree items.

The 45 degree thin stainless welded elbows are (generally - there are exceptions) fitted as OEM to the salt water cooled Yanmars, while the high-rise cast 90 degree elbows are (AFAIK, always) fitted as OEM to the fresh water (suffix F) engines.

I had assumed the latter is due to the location of the heat exchanger on the F engines: it makes the plumbing work better.

But the water jacket temperature of F engines is higher (better for longevity) than for salt water cooled engines, so this may have some impact on material choice, too...

My sense is that the cast-iron 90 deg risers last longer in the same service than the stainless OEM 45 deg items, but once again this is surmise.

If anyone has authoritative knowledge on these two points it would be great to hear explanations or data.
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Old 08-01-2015, 19:14   #57
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Re: Yanmar Maintenance issue: Mixing Elbow

I'll bring this thread back from the dead a little.

I have decided to take a "Proactive" approach to this problem on the MD2030s in the boat I purchased. I've purchased some beautiful Sched 40, 304 stainless elbows from
Ben at ExhaustElbow.com - Better Than Factory New.

My plan is remove the elbows yearly (or a number of hours still to be determined) and soak them in a solution of Phosphoric acid or Acetic Acid (triple strength vinegar) combined with a manual scrub where I can reach. I will inspect them closely for cracks and pinholes before putting them back in service.

I just can't deal with the fact that there is a part in the exhaust path that is slowely choking the engine. The gasket is $12, pretty cheap to know the engine will work when I throttle up.

NOTE - DO NOT USE MURIATIC ACID WITH STAINLESS STEEL.. BAD BAD, MKAY..
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Old 10-01-2015, 23:21   #58
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Re: Yanmar Maintenance issue: Mixing Elbow

Here there's a Yanmar 3GM30F-YEU with the 180 degree cast iron exhaust mixer. I think it was one of the first marine engines out of Yanmar's new European plant, in the late 80's.

A couple of years after I got the boat in 2002, the engine wouldn't start. The problem was found to be the exhaust elbow, its main chamber clogged with the diamond-hard black deposit. Replaced the elbow and the engine ran like a top. Two years later the elbow was clogged again.

Yanmar said that when the exhaust elbow clogged like that, to check that the boat was overpropped. Well, it was. Rated top for the engine is 3500 rpm, which it should reach in still water with the prop in forward. It would only reach 2600 rpm, with some black smoke, and I'd been running it like that, not knowing any better. I installed a new prop sized for the engine/gearbox and boat, same 17" with a lower pitch, and the engine gets up to 3450 rpm at the dock, running sweet flat out.

Yanmar said running overpropped was like a tractor-trailer going up a long hill in too high a gear, lugging the engine. They said with the new correct prop the exhaust elbow should routinely run clean for many years, and I expect it to be so.

I tried to chip the hard black deposit out with a hammer and screwdriver. Worthless effort, it was hard as diamonds. Maybe a grinder...?

When the second elbow was found to be plugged with the black deposit I soaked it overnight in a bucket of dilute muriatic acid solution, with a couple of tablespoons of laundry detergent added. I think that's what power plant engineers add to prevent corrosion when they clean scale from boiler tubes with acid. It removed about 80% of the deposit and the acid did not bother the bare metal, except for one tiny bright spot the size of a match head in the deposit.
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Old 10-01-2015, 23:47   #59
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Re: Yanmar Maintenance issue: Mixing Elbow

The OP says his 3GM30 is hard to start, and asks after starting techniques.

The 3GM30 here starts almost on the first cylinder every time, but there's technique involved getting it to do that.

In summer it is started normally. Turn the key and push the starter button, and it's running. This works when the temperature is above about 50 degrees F.

When the temperature is lower than 50 degrees, put the throttle down out of gear, halfway or if it's below freezing all the way, then, keeping your hand on the throttle, turn the key and push the starter button. KEEP YOUR HAND ON THE THROTTLE and TURN IT DOWN IMMEDIATELY THE ENGINE STARTS, it'll RACE. Immediately the engine starts, put the throttle down to idle and warm up the engine normally.

A couple of nights ago I started my 3GM30 at 22 degrees F like this. It didn't quite start on the first hit, it started on the, um, 9th hit, but it started. And ran beautifully.
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Old 09-02-2015, 11:11   #60
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Re: Yanmar Maintenance issue: Mixing Elbow

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My exhaust elbow of Yanmar 4JH4-TE cracked after 300 hours, I had it welded but it was not clogged. This seems to be a different design.

My welder suggested to get a stainless version. Does anybody know where from?

Note: I had used the 2 1/2 " exhaust pipe of my old 60 HP Perkins, which was too small and had caused clogging of the turbo charger. After I installed a 4" exhaust pipe it worked, but then this crack happened. I heard from a charter fleet that they had a dozen cracked Yanmar exhaust elbows.
Thank you
Wolfgang
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