Exhaust Elbow Needed!

[lindaloo]

That Onan elbow doesn't look that bad from the photos, externally anyway. The water inlets are notorious for plugging up. Take it to the same shop that will clean out the HE. Take the whole assembly to 'em, iron elbows, nipples and all. They can clean, reassemble and pressure test it. With the inlet opened up you may not need a new piece. Let the shop pass judgement.
The muffler is probably a fibreglass canister, black, with a drain screw in the side. In an E34 it's damn near impossible to remove, let alone get access to the drain screw. Hence get antifreeze in it insitu ! Might be much easier on a 32-200.

Rob L.

 

[Loren Beach]

Syphon Hose take off point

So Loren, are you saying that the siphon break hose runs from the muffler? As I said, I have not followed that hose back to the source. I also have yet to find the muffler. I think it's under the starboard lazarette flooring. Next time up to the boat I'll focus on finding that for a couple of reasons: 1) to check the condition of the muffler and connnections there, 2) to see if the sipon break originates at that point.

One of my original problems with this system this year was the decreased flow of water through the system. I limped along through the 2nd half of the season by not pushing the engine much. The water flow was not nearly as much as I thought it should be.

I also need to follow the hose from the water pump to the heat exchanger. It seems to me that it goes into a "T' fitting if I remember correctly. If that is the case, maybe somehow fresh water can bypass the heat exchanger route to the elbow.

WOW, it would be so much easier to understand all this if we had a schematic of the complete exhaust system as installed by Ericson.

Sorry it took me an additional day or two. My camera is failing and doesn't always hold a charge...
On my '88 M25XP the raw water comes from the h.e. outlet and goes up and over to port to a metal T fitting and also has a downward pointing elbow on the other end of the T. The water flow goes immediately into the exhaust elbow, and some of it goes into the end-n-downward hose that goes all the way back to the transom. This syphon break hose has a constant gentle down slope all the way to the transom.
The photos show, in a mediocre way, the hoses at the rear of our engine compartment. If any of it is unclear, just ask.
Best,
Loren

 

[lindaloo]

Right on. The h.e. outlet must decide at the tee whether to go to the transom or the elbow. 95% of it takes the path of least resistance and goes to the elbow. In Brian's case, the elbow inlet was blocked so that small syphon break hose was doing all the heavy lifting. Mine's 1/8" ID if memory serves. Not very big compared to the 1" raw water intake.
I've read of owners using a screw driver to clean out the elbow inlet, then doing a proper job back at home port.
On my E34, the path of the syphon break hose is anything but a gradual downslope. Now you've got me thinking.
I like the bus bars.

Rob L.

 

[Loren Beach]

Rob,
Better view of the wiring upgrade with the added terminal strip in reply #2 in this thread:
http://www.ericsonyachts.org/infoexchange/showthread.php?t=3404&referrerid=28

 

[Brian K]

Rob, yes the Onan elbow does look good in the picture, and it looks good in person. The real problem is there is a crack or pinhole not readily visible to the eye and water is leaking, ever so slightly, from this point. It's not at any joint or anything, it's right in the middle. Just cleaning it out will not cure the leak, unfortunately.

Loren, nice pic's. You have confirmed what I vaguely remembered, that there is a "T" in the raw water line someplace. If the elbow is clogged where the raw H2O enters the exhaust system, this woudl allow the syphon break hose to effectively bypass the HE. That explains how I could have antifreeze coming out the exhaust yet the HE is not winterized. With that said I'll have to work on introducing antifreeze into the muffler,,,, and rather quickly,,,, like Friday! The cold weather is setting in tonight it appears.

 

[mherrcat]

If the elbow is clogged where the raw H2O enters the exhaust system, this woudl allow the syphon break hose to effectively bypass the HE. That explains how I could have antifreeze coming out the exhaust yet the HE is not winterized.

Not quite following this. The siphon break should be installed after the heat exchanger, between the H/E and the exhaust elbow. If it were installed before the H/E and the inlet to the exhaust elbow was clogged, that could cause water to not flow through the H/E but still flow through the small vent line to the transom or exhaust through hull. If coolant were introduced at the raw water intake, that coolant might not make it into the H/E, but be expelled through the vent line. If your siphon break is after the H/E and the exhaust elbow inlet is clogged you would still get coolant through the vent line but you should also have coolant in the H/E. If you are not getting coolant into the raw water side of the H/E and your siphon break is between the H/E and exhaust elbow it seems like something else is going on...

I would be disassembling the heat exchanger to see if it may be clogged up as well. Seems like you would see some overheating if that were the case.

 

[lindaloo]

No phantoms

Excuse my amateurish diagram with Paint.

The raw water path is simple.

The tee simply must be AFTER the h.e.

There must be no tee between the pump and h.e. No phantom bypasses are allowed.

The syphon break hose must be much smaller ID than the hose going to the elbow.

You must be in no doubt where that tee is. Position it ABOVE the elbow, given limitations of engine compartments, covers and bulkheads, etc.

The syphon break hose main function is not as a backup cooling loop but to let air back in when the engine is shut off, to prevent syphoning of raw water into the elbow and potentially the exhaust manifold.

(Hard to believe there is a tee between the pump and h.e. on your engine. A syphon break hose from there won't work right.)

If plumbed properly, and h.e. cleaned, and new elbow, all the antifreeze from the inlet bucket will flush the h.e. and the muffler. It must.

There was an excellent recent thread on winterising, with many replies on how much antifreeze is enough, etc.

For the problem of getting antifreeze in the muffler now though, you could pour some back through the exhaust hose, but don't overdo it. A couple of cups should suffice.

Well, I'll post this and hopefully the regulars who REALLY know what they're talking about don't shoot me down too harshly.

Rob L.

 

[mherrcat]

Came across another source for that Onan exhaust elbow:

http://marineengineparts.com/shopsite_sc/store/html/page555.html

This one lists the dimensions, which might be helpful.

 

[newpbs]

If I Can Help

Brian,

Let me know if I can help. We've exchanged information in the past as I also have a 32-200. I'm all covered up for the winter now, but if you need to see how my boat is plumbed, I'm not that far away. Keep me in mind and contact me in the spring if you want to visit.

Paul

 

[Stu Jackson]

Excuse my amateurish diagram with Paint.

The raw water path is simple.

The tee simply must be AFTER the h.e.

There must be no tee between the pump and h.e. No phantom bypasses are allowed.

The syphon break hose must be much smaller ID than the hose going to the elbow.

Well, I'll post this and hopefully the regulars who REALLY know what they're talking about don't shoot me down too harshly.

Rob is right.

I've been thinking about this issue since the topic started. And it had me very concerned, 'cuz the pictures and the descriptions and the understanding of its purpose and sequence of operations sounded, well, just plain wrong.

Rob's description is spot on, and you might consider reviewing your installations.

Venting of the anti-siphon break is "optional" --- ours is under the head sink and doesn't leak anything -- if it did, I'd know it wasn't working.

I believe the flow diagrams are also in the Universal Engine manuals.

 

[Loren Beach]

You guys are probably right....

Intuitively I believe that Rob and Stu have to be correct.
OTOH, my factory setup has been working since 1988.

Wandering off-path into the Swamps of Surmise, I would guess that natural inclination to "flow" down the T fitting into the larger hose into the H.E. is secondary to the fact that the water is under pressure from the R.W. Pump and the small hose path to the syphon break hose is always going to carry a much small proportion of the water.
You have a short section of larger ID hose path vs a very long 1/4" hose path with a lot more internal flow resistance.

One other consideration (for those of us with a visible separate syphon hose exit on the ouiside of the boat) is that I can tell when the flow has slowed due to lower pumping efficiency by the lessening of the flow from the small fitting.
I recall that it was not putting out much (ie "peeing") in the last season before the whole R.W. pump was replaced.

So, just to satisfy intuition, I might re-plumb the order of those fittings when we replace those little hoses someday. (They are the last original hoses on our boat.)

Thanks everyone!

Loren

 

[mherrcat]

OTOH, my factory setup has been working since 1988.

I don't see anything wrong with your setup. Raw water into H/E, raw water out to siphon break, raw water into exhaust. The siphon break looks to be above the engine which assumably would put it above the water line. I don't think it really matters whether the vent line slopes down or up because, as you pointed out, the system is under pressure when the engine is running.

I think I read somewhere (might have been Calder) about having the vent exit even higher to prevent that constant flow of water, but it didn't work for me. I disconnected the vent line from the transom and held it outside the lazarette and above the level of the cockpit coaming and water still came out.

 

[lindaloo]

Thanks everyone!

Loren


That looks like the final word from the senior moderator !
I'm glad Mark replied first ........ but he's right. Don't be changing things now.

Stu, I'm honoured and humbled.

Maybe this is for a new thread, but .....
Last summer I visited another E34 at a BC anchorage. The previous owner had modified his syphon break. He cut two 1" holes in the back edge of his engine cover and ran a loop, fully visible now, up under the companionway stairs. Since the top of the loop was now well above the waterline he had one of those plastic pieces, with the "bicycle" valve at the top. No more small hose to the transom.
A couple of points.
-it's worked for 22 years, why change it
-you have to cut holes in the cabinetry
-those bicycle valves have been known to clog/calcify
Question: Should those valves be cleaned/tested annually, biannually? Would you use CLR, dilute muriatic?
A related question: interesting a great lakes boat (Brian's) has clogging in the elbow and probably h.e. as well. And pin hole corrosion in the elbow. Unusual? Prior salt water history? Do pencil zincs last longer in fresh water?
Brains trust, Loren, Glyn et al, ideas welcomed.
Rob L.

 

[Stu Jackson]

Here's a vented loop (anti-siphon) valve.

http://www.defender.com/product.jsp?path=-1|51|106370|316448|316445&id=102587

It does NOT have a bicycle filler inlet, it has a small duckbilled opening that allows air to pass through, thus breaking the siphon. It belongs between the raw water hose from the HX to the nipple on the exhaust riser.

But, shoot, don't just take my word for it: read Calder's Boatowner's Manual for Mechanical and Electrical Systems, Chapter 8, Diesel Engines, pages 258 & 259, 2nd Edition.

 

[Brian K]

I made it up to work on the boat today and took some pictures. Rob, your diagram is exactly the set up I have (same as Loren's). The attached picture is of the same "T" as Loren pictured, but I have the camera below the fitting looking up.

Your comments " ,,interesting a great lakes boat (Brian's) has clogging in the elbow and probably h.e. as well. And pin hole corrosion in the elbow. Unusual? Prior salt water history? Do pencil zincs last longer in fresh water?"

Yes, this was a salt water boat until the summer of 2007.
Yes, zincs do last longer in fresh water; magnesium anodes are appropriate for fresh water, I use them on the shaft but have never been able to find one for the pencil anode in the HE.
​

I had removed the end of the HE and drained the H2O that way but could not get a real good look at the HE condition. Today I took it off and it has a little bit of deposits on 1/2 of it so I'll have it cleaned. Overall it wasn't bad at all.

Paul, yes I remember corresponding with you and I thank you for your offer. With your input to the location of the muffler I was able to finally locate mine - it's below the level of the lazarette locker floor in probably the most inaccessable area on the boat!! But after removing the hot water heater and the shelf it sits on, I moved some hoses and wires and was able to get a fair view of the muffler. It looks to be in good shape and no signs of any leaking.

Since the exhaust system is disconnected right now and I can't simply start the engine to re-winterize the muffler, I had to do something different. Using my shop vac I first blew out any water in the system. Then I poured a gallon - about a quart at a time - into the open end of the exhaust hose (where the riser elbow connects to the hose) and blew that through. I am confident the muffler is now fully winterized. The second picture attached shows the open end of the HE and the exhaust hose into which I poured antifreeze. This picture needs to be rotated 90 degrees clockwise for proper viewing.

Wow, so who would have know that you could "winterize" the raw water system, see antifreeze come out the end of the exhaust, but still not have antifreeze in the HE or muffler. You all have been a tremendous help sorting this out. Thanks.

Now I just need to find a radiator shop that can give my HE a good cleaning and I need to locate the Onan style H20 injection elbow with 1 1/2" pipe thread input, 5/8" raw water input, and output to fit inside my 1 5/8" ID exhaust hose,,,, no easy task!

 

[Stu Jackson]

Now I just need to find a radiator shop that can give my HE a good cleaning

Brian,

You really need not spend any $$ on this. Get some LymeAway or Rydlyme and just soak it, if it's in as good a condition of you say it is. I've never had to do this to ours. A friend of mine runs LymeAway via a bucket through his raw water system every year or so and sometimes he's claimed to never have removed his HX!

 

[Stu Jackson]

I think I read somewhere (might have been Calder) about having the vent exit even higher to prevent that constant flow of water, but it didn't work for me. I disconnected the vent line from the transom and held it outside the lazarette and above the level of the cockpit coaming and water still came out.

Mark,

If water still came out, maybe the duckbill on the anti-siphon loop has failed. When under pressure the duckbill should close from the pressure inside the pipe,and then open when the engine shuts down to allow air in and avoid the siphon.

 

[mherrcat]

I don't have any type of valve in the loop; hence the constant stream of water out the transom. I always read about the valves clogging and needing to be cleaned so I really don't want one.

I looked up that reference from Calder; it was in his diesel engine book. He says he prefers to remove the valve and attach a hose. He goes on to say the vent hose should discharge above the highest point in the exhaust hose to prevent water "weeping" from the hose when the engine is running. He also says that if an installation like this continues to "weep" it is a "sure sign" of excessive back pressure probably due to carbon buildup. I have checked my exhaust at the elbow outlet and at the water lift muffler and there is no buildup; the size of the hose does reduce from 2" out of the elbow to 1 1/2" into the muffler.

 

[Stu Jackson]

Gotcha. Yes, there is that, too, as he wrote.

 

[Brian K]

Thanks for the tip Stu. I'll try the Lime Away since I think I have some at home.