Temp of the exhaust hose just after the mixing elbow

[rick_bradshaw]

Right now we're doing a lot to get things done that absolutely need to be done. In the process we have found that the mixing elbow seems to be quite hot; probably in excess of 140 degrees. Too hot to hold on to after the engine has been running a while. The hose after the mixing elbow is hot too although not as hot; maybe 120 degrees.

There seems to be a lot of water going into the bypass to the muffler; a small sauce pan full in a couple seconds.

At the injection point in the mixing elbow we have the normal hose for water injection. In addition we have the water from the drippless system going into the exhaust sytem at this same point.

We've taken off the muffler bypass hose and plugged and then have monitored the water to the exhaust. Not much if any change. The same places continue to get hot as before.

Question 1: how hot is too hot? We've had a prblem here once before in that a mixing elbow was improperly cast and didn't allow the water to pass through in sufficient quantity to cool. So, how hot is too hot? Is this in the "ballpark" or is it too hot?

Question 2: With all our stuff aboard, the mixing elbow/injection point is right at the water line. I'm concerned that the drippless system hose will siphon the ocean into the boat. It is here because we were told to and Tides Marine (drippless mfg) said that was the place. I'm not sure that this is high enough with our water line up a few inches. What is your feeling about the placement and what needs to be done to correct a potential problem?

TIA.

[rick_bradshaw]

I'm trying to attach a pic of a manifold that is in the exhaust cooling water system. Note that there is a 1/2" line that is to the lower muffler and, presumably, is the "anti-siphon" in the system. The largest hose is the hose to the upper muffler.

Although I haven't as yet opened that large hose uo to see how much water is going through, I think it is allowing too much water to bypass the mixing elbow.

I think this because there is carbon in the fitting where the water is injected into the exhaust, inside the mixing elbow, and the generally thought hot temperature of the exhaust hose exiting the mixing elbow. The elbow is is about 1 year old and was a replacement unit for a fitting that was mal-cast and blocked in 1 year from being installed new.

There is lots of water coming out of the exhaust at the hull. there would be since there are 2 hoses that bypass the mixing elbow. There is a bit less water coming through the injection point hose than there is through the 1/2" hose or so it seems.

My question: Does this look like the system in [/b]your[b] boat? Are the hose this large and the are they run in the same way?

I think there is too little water going into the mixing elbow and perhaps capping the hose to the upper muffler would be an improvement. Comments?

TIA.

[rick_bradshaw]

Possible clarification as to what I'm trying to find out:
1. Is there any known reason why there is a 2nd apparent anti-siphon?
2. Is there any known reason why this hose is the size it is (approx 1")?
3. Is there any known negative consequences of capping the apparent 2nd anti-siphon hose and forcing more cooling water into the exhaust mixing elbow?
4. Is there any known reason why the first anti-siphon (1/2") hose is carrying so much water and would this increase if the 2nd were capped off?

[mitchk]

I am not ableto see your picture, however mine only has 1 anti-siphon and it apears to be 1/2" or 5/8"

[rick_bradshaw]

Mitch,

Thanks for the info. I wonder why you can't see the pic? I see it when I go to the BB. I'll see if Lynn can see it on her PC.

I'm not too surprised to hear that yours is different. I was able to contact Craig Beckwith this morning. He tells me that this 1" hose is a "bypass" for "exrtra" water to go to the 2nd muffler. Today, we plugged the "bypass" temporarily and routed all that water into the mixing elbow. We got the same amount (approximately) of water out the exhaust and the exhaust hose was about 20 degrees cooler. I'm going to restrict the 1/2" real anti-siphon to a little smaller and going to reduce the "bypass" fitting to accomodate the drippless packing gland and route that there. I will then plug the hole in the 2nd muffler. That should do everything I need to do without additional heat.

A bye product is the unused hose. It is still in good shape after all these years and it is, I think, the same size as the bilge pump hose. So, I have extra hose now for that if I need it. Got to find a pony in there someplace.

Does your anti-siphon go to the first muffler or elsewhere?

Thanks again.

[mitchk]

Mine goes to the top of the built in muffler just under the helm seat. I have never really figured out the exaust sytem on the HC33? I wish there was some sort of drawing so I could see how those built in mufflers are constructed and routed?

[rick_bradshaw]

Hmmm. Mine goes to the lower muffler. That "bypass" went/goes to the upper muffler. The placement to the lower, first muffler is something I've been thinking a lot about.

AS I understand it, the upper muffler is a sort of water lock to keep water from coming back into the boat when in high seas from astern. There is some "muffling" with it but I don't think that is the real reason it is there. The lower, forward muffler is the water lift muffler that you "normally" find aboard boats.

Can anyone else out there chime in and tell us where your anti-siphon goes and maybe why it is going there? So far we have 2 places and I'm seeing more and more where these boats are not "cookie cutter" boats but very custom "under the skin"; and maybe not for good reasons.

Thanks.

[warmrain]

AFAIK the lower muffler is the traditional aqualift type muffler that is filled and emptied by water in the exhaust flow.

AFAIK the upper muffler is mostly an anti-syphon break. It is feed by a supplimental water source because it is too high to rely on exhaust water for cooling.

It is very effective... we have sailed downwind in near 20' seas without water in the exhaust.

Recognize that hulls after #131 may be plumbed differently than original boats.

~Cars

[rick_bradshaw]

Steve,

They certainly are different. I've managed to keep in my mind that basically these boats are the same but with minor changes. Mostly, I think they are the same skin deep with some exceptions.

We have disconnected and temporarily plugged the forward end of that "bypass" hose to the aft muffler and forced that water to go to the mixing elbow. When things get down to a "dull roar" we want to change the actual anti-siphon from the lower muffler to the upper and permanently close off the connection to the lower muffler that will then be vacant. It'll make me feel better if nothing else.

Thanks.

[warmrain]

The Aft (high) muffler MUST have supplimental water AFAIK, not doing so probably means weakened hull from heat or worse a fire.

The aqua lift muffler is safe and efficient... well understood...

I don't understand your issues, or why you would change what has worked for nearly 30 years...

~Cars

[chuck]

Hello,
Having grown up living and breathing boats from an early age I have seen the somewhat strange features of our exhaust systems on many different boats but never all at the same time. It has however allowed me to piece together in my mind what HC has done here with these systems which have many of the things I have seen rolled into one.

I have many times over the past years posted on this site long detailed explanations of these HC exhaust systems but unfortunately cannot remember where. However recently in "HC 43 / Isuzu C240 Issues" I have posted (briefly by comparison) what I am pretty confident is factual information about it again. I do not have time at this moment to go through all of it again in detail but I think some of these question will be answered by reading that thread.

Basically what these exhaust systems are about is:
1) The water lock muffler/ riser in the stern is to keep following seas out of the engine as mentioned.
2) The bypass line to that riser or muffler in the stern is there only so that all the water is not pushed up through the exhaust system thus decreasing back pressure. (the engines in the 43s are very low in the boat -lots of rise and back pressure). I have seen this discharged through a separate through hull rather than mixed with the exhaust discharge right at the stern. It is my opinion that HC did it that way for convrenience. When I rebuilt my system I went through a separate fitting so that I could monitor it separately which was how one of my dads boats was set up 45 years ago. (I might have done that out of nostalgia)
3) The other odd thing about these systems is that small line running from the tee to the water lift muffler behind the engine. That is put there in leau of an antisiphon valve. It is a good place for the tee to get air from (and break the siphon) when the engine is shut down and not a bad place for the water to go that will come out of it when the engine is running.

If after reading this and the other thread you have other questions let me know and I will try to help.

[Scout]

[warmrain]

[Scout]

[warmrain]

OK, so simply stated:

You replaced your exhause riser/elbow with a new custom made stainless one and now the hose that is touching the riser, under the clamps, is getting hot enough to melt.

It this is correct then I have to start to consider causes... and the cause would be something that changed.

Things I know that changed: The exhause riser. The exhaust riser is now wrapped.

Things I don't know changed: Is it the same hose? If not is it the same type of hose? (Details if it changed please e.g. was the old hose wire-cored?)

It sounds like the water volume is excellent, it is curious that your engine is running cooler (actually too cool is not good for a diesel). This may or may not be related, but it is something to keep in mind.

Now I am suspecting the design or installation of the exhaust elbow. On the originals the water is injected into a hollow cavity on the engineside of the elbow. It seems from looking at it, that the water would run back into the exhaust manifold, but it doesn't because there is a chamber inside that carries the water over the top of the elbow to be released on the downstream side. This keeps the elbow cooler. I suspect this design isn't implemented in your custom elbow.

If nothing changed except the elbow... same hose, same water flow, same hose clamps... only the elbow changed... then the elbow is the problem, and if it is custom designed then the design (or the installation) are at fault.

~Cars