Re: Yanmar Exhaust Mixing Elbows

Not sure if I missed it but how do you tell if your mixing elbow is going bad? Have a IP 485 2009 w/Yanmar 4JH4-HTE. Started to head north from Vero Beach Fl when I brought engine up to cruise rpm, 2300 noticed a rise in temp from normal. When lowered rpm to 1800 the temp came back to normal. Back at the dock checked the bottom for growth, impeller was new, strainer was clean with lots of intake water, and normal amount of water coming from exhaust. Suspect either heat exchanger or exhaust mixing elbow. Pulled the intake hose to mixing elbow and found no obstruction and looked as far into the mixing elbow as I could. Also checked the vent loop/anti syphon and was all clean. Should I think about replacing the elbow? My next step will be the heat exchanger. Does anyone know if you can remove the tube pack by only removing one end cap of the exchanger?

Richard

I have the square one on my 485 and have been trying to find out some information about it.

I havent checked it internally, but this topic suggests there is no need?

I seem to feel I read somewhere it is cast in bronze - I wonder?

however, Hayden from your posts it appears you feel this version is bullet proof?

Hi all,

I replaced the 2gm20f engine in my IP29-10 with the 3gm30f engine in 2008. I purchased the remanufactured 3gm engine from Schooner Marine.
In 2009 the engine refused to start prior to the summer commissioning due to the elbow clogging..........because I transferred the 2gm engine elbow to the 3gm engine because the remanufactured engine came with the 120 degree elbow. Since the first replaced elbow, I replaced the replacement elbow once, cleaned it once (I sandblasted the inside) and will pull and check the elbow again prior to the 2016 summer commissioning. BUT, I also recently purchased on ebay a stainless steel elbow that I plan on using when I have to replace the current elbow.
Does anyone have any experience with the stainless steel elbow. It was about the same price as the carbon steel one from Yanmar!!!!

Hayden, 2" is really too small for 35+ HP, but Yanmar has been doing it for years. Your engine really needs 3" all of the way back and some of your back pressure issues are related to the fact that IP choose to offer an engine choice, but not put the proper exhaust for the larger engine. The 3HM is marginal with the 2", but close. 38 HP just can't vent well enough with 2" when running full out.

This is a long debate, but I trust the rebuilders as they see the damage done.

As far as mixing elbows. It is amazing that they are often the most over-looked maintenance issue on a boat regardless of engine, but one that can do the most damage when they fail. The old style Yanmar elbows are so inexpensive that it is really easy enough to add it to the maintenance schedule every couple of years and keep a spare on board. They can be found for right at $100 from some places and if you do it once a year like I do, it does not add much more to the yearly changing all the fuel filters, gearbox oil and Impeller.

When we change out this engine, even if I go with rebuilding or a new 3HM, I will most likely go 3" all of the way back at that time. If we choose to go against the grain with a Beta (I am a bigger fan of Beta than Yanmar, sorry) then we will have to go 3".

Sailup
The Beta technical Drawing for the 35 and 38 hp engines show the factory exhaust elbow with a 50 milimeter (2 inch ) OD exhaust
Drawing Beta 100-10725

Conversely the sales brochure for the 39 hp Yanmar 3JH5E shows a 3" exhaust elbow
Ed

Hayden - do you know any more about the square elbow on the 485. I have found it very difficult to track down the part, let alone what it is made from etc. - not that mine as you suggests appears to be causing any issues.

OK. I apologize. I was replacing the holding tank when I replied to this and probably breathed in too many fumes... 3GM- uses 1 1/2 and a number of boat manufactures used the same with the larger engines including the 3HM and I had a lot of discussions with Beta on how that has destroyed many of the larger engines. I am not sure why I had that on the brain when replying. 3" is overkill for the engine. This while we just changed the mixing elbow last month, so I am beside myself on my reply.

OK, let me back up a moment, please.

Referring to Thor's photos in post #3341, on page 1 of this thread - it is obvious that Both ends of the mixing elbow are threaded. I haven't yet disassembled my elbow assembly, but it appears that there is some kind of nipple that screws into the long arm of the mixing elbow (the outflow arm). This is Exactly what would happen in Thor's picture. The exhaust hose would fit over this nipple (or whatever you want to call it.) (Note, I am NOT talking about the "joint" (male x male threaded joint) that goes between the elbow and the exhaust elbow, which screws into the short arm of the mixing elbow.) None of the Yanmar parts lists, or other info seems to reference the nipple that the exhaust hose slips onto, and a fellow from Certified Diesel in the Englewood, Florida area, told me today that absolutely there is not a nipple that screws into the mixing elbow, that it is Not threaded, and the exhaust hose simply slips up over the outflow of the elbow. I already have my mixing elbow, and both ends are threaded - just like Thor's picture. The Certified guy is obviously wrong.

Does anyone have a part number for the nipple that the exhaust hose mates to on the outflow side of the mixing elbow - for a 3GM30F? Please, pretty please, sugar on top, chocolate sauce, whipped cream, and a cherry. I would like to replace this nipple at the same time.

Thanks in advance.

PlumBob / Sam

Yes the mixing elbow for the 3gm30f on my IP31 is threaded on both ends. It never had a barbed fitting in the exhaust out side.
The 2 inch exaust hose fits over the outside of the mixing elbow with two clamps.. I was told that the threaded end was used for the smaller 1-2 gm. The larger 3gm30f used a larger exhaust hose and over the out side is propper. If you change the exhaust hose you will need a lift muffler to match the diffrent hose.

OK.... I'll let you know when I get in there, but it sure looks like it has a nipple in between the elbow and the hose. Hayden, thanks for the link.
THX

S

Could be. But the hose should be 2 inches.

I am not sure which elbow I have. My elbow is wrapped with a heat shield and it would be difficult to find out without taking off the wrap. The engine is a 2002 model

I recently watched a yanmar mechanic replace the core on my diesel. It should be similar to yours. He took a couple of hoses off, then removed both end caps. He next gently removed the core. It looked easy to do and I would this the next time myself. He replaced the gaskets and using a small amount of Indian head sellac to help hold the gaskets while reattaching the end plates. Her hen replaced the coolant with the yanmar brand. It him less than 2 hours. I hope this helps.
Captdds

Hayden,
Hoping to avoid your problems I am planning on replacing the 5 year old mixing elbow on my Yanmar 3jh2e engine in my IP-37 with the new version. Does Yanmar make a part for reducing the three inch outlet down to the two inch exhaust and if so do you know the part number. If not what did you use.
Thanks,
Bob

My wife and I recently purchased an IP 440. During the survey we were warned that the exhaust mixing elbow on our Yanmar 4jh3te would probably need replacing soon. Looking at the elbow it appears to be custom made and longer then the stock elbow from Yanmar. Does anyone know whether the stock elbow will work?