Silly question about Yanmar 315 mixing elbow

[Sunshine]

The mixing elbow on my 28TE failed but I was able to limp home at idle. My question is, why didn't the bilge fill up from the seawater being pumped in to the heat exchanger?
Thanks,
Chuck

[Beta Don]

Welcome to the Albin forum!

Did the failure involve just exhaust gasses or exhaust plus seawater escaping?

If it was leaking water, hopefully your bilge pump was sending it overboard as fast as it was leaking

I had a similar failure on a Yanmar mixing elbow years ago and I plugged the hole with a ball of Marine-Tex epoxy and it held for about 50 engine hours until I got a new elbow installed. It stunk to high heaven while the epoxy cured on the hot manifold, but it held up. To this day my boat never leaves the dock without a Marine-Tex kit aboard. It has come in very handy in all sorts of emergencies

Thankfully my current Yanmar has a bronze mixing elbow. Expensive, but no more rotted out elbows

Don

[Sunshine]

Thanks for the comeback. Only exhaust was coming out, but why wasn't water coming as well, that is the mystery. I plan to get a bronze one one now.

[Tree]

Thanks for the comeback. Only exhaust was coming out, but why wasn't water coming as well, that is the mystery. I plan to get a bronze one one now.

If you can find one - let us all know as its not the best of designs.

I suspect your elbow cracked on the turbo flange? This will be why you didn't have water coming into the boat - the water mixes further down the elbow.

[catalina_mike]

Take a look at this old thread. viewtopic.php?f=5&t=5271 The elbow basicaly injects water around the outside wall of the elbow. The water injected around the outside jacket cools the elbow and cools the exhaust to help get things moving. You can see the water jacket passages in one of the photos.

[Carl]

I purchased and installed one of these, and it is the exact replacement. Far cheaper than Yanmars. have had no issues. Mine is the 6LPSTP.



http://www.ebay.com/itm/Stainless-Steel ... 1505013988

[Pitou]

I plan to get a bronze one now.

Stainless is the only way to go on your replacement.

[Tree]

Cheers for that link Carl. I've messaged the seller to see if he will ship to the UK as Both the other 2 28's here have had failed mixing elbows. Mine should be good for a while as it was replaced just over three years ago but I'd prefer a stainless one.

[Carl]

For another $25 you can get the polished version. On my flush deck you can't even see it unless you stick your head down in the hatch, so no need for that!

[Sunshine]

Thanks all, this helped a lot. I'll try to report back when work is done. Thanks especially for the suggestion on avoiding the bronze part. My manual (2002) suggests replacing elbow every 500 hours, and I'm at 1400.

[kerrye]

I don't see an answer to the original question. The OP said there was no water coming out of the exhaust. Was it going into the bilge? If so, wouldn't the bilge pump have been running and the discharge from the bilge hose would have been visible? If there wasn't water with the exhaust and no bilge discharge, isn't the implication that something else was also wrong like a failed impeller?

[Tree]

I don't see an answer to the original question. The OP said there was no water coming out of the exhaust. Was it going into the bilge? If so, wouldn't the bilge pump have been running and the discharge from the bilge hose would have been visible? If there wasn't water with the exhaust and no bilge discharge, isn't the implication that something else was also wrong like a failed impeller?

Mike gave the answer. Third post down, water still goes through the mixing elbow but not in the bilge. These elbows always break off at the flange where it's connected to the turbo, in most cases you'll get a sooty bilge.

[kerrye]

Where does the water go? He said there was no water coming out with the exhaust.

[catalina_mike]

Really without seeing it my assuming it's like all the other failures that are common. That being said the hottest most susceptible place is before the water injection. Again everyone's abilities differ but if the motor wasn't hot it has flow more than likely.

[Pitou]

The way that this particular mixer elbow is set-up, it is essentially dry. Carrying exhaust gases from the turbo flange through the mixing elbow. The heat exchanger discharges seawater into the elbow which has a secondary inner diameter to the casting that holds the seawater discharge and only mixing with the exhaust gas on the opposite end of the elbow through a "Shower Head" discharging the seawater into the exhaust hose where it then mixes with the exhaust gas. If the flange end failed at the turbo there is no seawater in this location (or at least there shouldn't be) and only exhaust gas and that is where the exhaust gas was escaping. Without photos and the limited description from the OP this is what we all surmise. I hope that helps for an understanding of how the the mixer works.

Here is a picture of the "Shower Head end of the mixing elbow. This is from my Cummins which comes standard in stainless.

20160308_081810.jpg

Here is a link to Tony Athens Sea Board Marine website for a full understanding of marine exhausts. Absolutely worth a thorough read to gain a degree in marine exhaust knowledge. Lots of good general knowledge info on this site even if you don't own a Cummins engine.

http://www.sbmar.com/tonys-tips/