T-fitting in Raw Water Circuit

[Kenneth K]

Is there anything critical about the riser length (flange to elbow)?

Everything is a trade-off.

- If the riser is high enough that the water-injection point is above the water-line, an anti-siphon loop isn't really required. (except that under heeling, this height-above-waterline is reduced).

- The distance between injection point and the entry to the water-lift muffler should be at least 12 inches or so, to allow enough length to cool the exhaust gasses before they enter the (usually) plastic or fiberglass muffler. A taller riser might help with this.

- The taller the riser, the more stress it places on the exhaust flange. Engine vibrations will make the riser vibrate too, and all these forces pass through the exhaust flange.

When I rebuilt my riser (link posted in post #19) I made it about an inch taller that the Universal riser it replaced. I think it's still 4-5 inches below the bottom of the cockpit floor.

 

[Christian Williams]

Here's an E381 elbow for one visual of a riser length:

 

[bigd14]

And a 30+ for another visual.

 

[Pete the Cat]

Thanks for the responses. Yes, I think I am headed towards boiling out the exchanger, regardless. That makes sense following the effort to take it apart. The flange appears to be newer than the rest of the elbow and can be re-used. The rest of the elbow and gasket I plan to replace. Good advice on avoiding galvanized pipe. Is there anything critical about the riser length (flange to elbow)? Currently, the 90 deg brass fitting juts up right against the top of the engine box. I am considering making that a half inch or inch shorter so it fits better and easier to work on.

Yes, there is a general safety issue that that elbow should be higher than the outside water line if that is possible--an added safety measure, but it is not actually required. You want the exhaust loop to be as high as possible immediately after the waterlift muffler ( and the muffler as low as possible) to ensure you do not get sea water slopped back into the engine when it is shut down. I think the Yanmar website has a diagram of optional installation recommendations that give your their ideal measurements which are not always possible.

 

[Felicity]

Been there, done that with the identical engine and exhaust installation. My advice, replace the flange, riser pipes and mixing elbow with new ones… It’s time with a system this old, and you won’t regret it. More than half the battle is the removal that you have already done.
Mike Jacker

HI Joliba, I have to change the exhaust elbow, also, can you indicate if you know where to find part no for this?

 

[Joliba]

Felicity,
I do not recognize the exhaust elbow in your photos. There are many threads in this forum discussing options for exhaust elbows. The two I have most commonly seen are the Yanmar exhaust mixing elbow (pictured in bigd14’s post above) and the Onan 155-1058 part, which Ericson originally used for my Universal 5432 engine. I replaced mine with the same Onan part. It can be found by Google search at several dealers selling truck engine parts and generator parts. Though availability is rare, a thorough Internet search will lead to a viable source at a reasonable price.
Good luck!
Mike Jacker

 

[Felicity]

HI Joliba, I have to change the exhaust elbow, also, can you indicate if you know where to find part no for this?

Here are a couple better angles

 

[Joliba]

Is it this?:
Westerbeke exhaust elbow

 

[AlanO]

I just got back my heat exchanger after an acid flush. The outfit that did the work said the freshwater side was almost totally clogged. The parts guy said new exchangers run around $1500, so I am happy they were able to refurbish the old one. They are also putting together a replacement exhaust elbow and it took them a while to find a replacement Onan elbow. I'm not sure of the part number they ordered. I found an Onan exhaust elbow online that looked the same but the specs seemed smaller than the existing one I had.

 

[Felicity]

Is it this?:
Westerbeke exhaust elbow

Looks awefully close, I will share with my installer thanks

 

[Kenneth K]

Looks awefully close, I will share with my installer thanks

Since you had a pipe fitting break off, I would strongly suggest replacing all the pipes and fittings aft of your exhaust flange. Likely, other parts are near failure too. I like the Yanmar type elbow for several reasons, but one is this: The Yanmar elbow uses a two-sided coupler below it to attach it to the exhaust piping. One side of the coupler is reverse-threaded, so you can remove the coupler in place without having to move (or remove) any of the piping below the coupler.

Almost no other type of elbow allow this because there is just too little room in the engine compartment of most sailboats to allow large plumbing parts to be rotated around a full 360 degrees.

 

[Christian Williams]

299835 Universal Heat Exchanger

299835 and 299835CN are the same part for us, both with a Copper Nickel Bundle 299835 Universal Heat Exchanger with a copper nickel bundle. Bundle size is 3 X 13.5" It is used on Universal M-40: M-25 / M-25XP : M-30 / 5424 : M-40 : M-50 Replaces 299049 which has a 2 inch bundle as...

www.mrcool.us

 

[Felicity]

Since you had a pipe fitting break off, I would strongly suggest replacing all the pipes and fittings aft of your exhaust flange. Likely, other parts are near failure too. I like the Yanmar type elbow for several reasons, but one is this: The Yanmar elbow uses a two-sided coupler below it to attach it to the exhaust piping. One side of the coupler is reverse-threaded, so you can remove the coupler in place without having to move (or remove) any of the piping below the coupler.

Almost no other type of elbow allow this because there is just too little room in the engine compartment of most sailboats to allow large plumbing parts to be rotated around a full 360 degrees.

Thanks for your insight…like an extra xmas gift under the tree as I prep the boat for a couple months in Bahamas…

 

[Kenneth K]

Here is the Yanmar coupler fitting I was referring to--it comes with the elbow. Turn it one way and it unscrews itself from both the elbow above and the pipe below. You can't do that with any other kind of standard pipe fitting. It makes removing the elbow for cleanout/replacement much much simpler.


Better yet, buy the stainless steel elbow from HDI Marine (ebay), and you'll never have to replace it.

 

[Felicity]

It does look like a good unit

 

[Pete the Cat]

I just got back my heat exchanger after an acid flush. The outfit that did the work said the freshwater side was almost totally clogged. The parts guy said new exchangers run around $1500, so I am happy they were able to refurbish the old one. They are also putting together a replacement exhaust elbow and it took them a while to find a replacement Onan elbow. I'm not sure of the part number they ordered. I found an Onan exhaust elbow online that looked the same but the specs seemed smaller than the existing one I had.

I think you might want to look into your cooling system a bit further before you reinstall that heat exchanger. It is a different thing to have the freshwater side of it clogged--I think the shop might have been telling you something. Generally, the salt collects around the internal structures on the raw water side of the tubes in the heat exchanger. I am thinking you might need a flushing of the freshwater side of your engine and, especially, the expansion tank over the exhaust manifold--this part of the engine has a lot of mild steel parts that can corrode and clog your system. You will have to add a lot of coolant when you put it together anyway, so this might be a really good time to flush the freshwater side and tank. All these marinized tractor engines have this potential problem. Yanmar generally uses different alloys that resist rust in the system in their marine engines.

 

[AlanO]

We finally got Gravlax out for a longer cruise that required more than an hour of motoring and happy to say that the refurbished heat exchanger and new exhaust elbow have resolved our overheating issues from last summer. During up to 5 hour runs the engine temperature was a steady 170 F while cruising at 5.5 knots and 2200 RPM. There was a noticeable increase in water emitted from the exhaust. We still get some steam at the higher RPMs.

Bottom line is that Christian's initial comment early in the thread was right on the money!