Engine Exhaust Venting

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Steve Cunning

Hi There, Hunter owners.. Getting ready I hope... I have two questions maybe somebody knows. I was wondering if someone could explain how the exhaust from my Yanmar engine was to run, I believe there has to be a high point so that no water can enter the engine? and where or does it matter where the fiberglas muffler should be installed, it is right in the way under the cockpit. Also, does any body have a drawing for the hot water loop from the engine to the hot water tank, as I am not getting very much hot water when I am motoring, I've changed thermostat, but maybe I have the piping hooked wrong, it seems to me that the hottest water comes off the exhaust manifold but that is the return line the way it is installed now. I have a Yanmar 20 hp. BTW... I found out this winter that if you hook up a 3000 watt 240 volt hot water tank element to 120 volts then you draw 6.5 amps@120 volts and can run a water heater on a 1000 watt genset! Anyway, I hope everyone is getting geared up... Any responce would be appreciated Steve Cunning
 
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Brian

in general.......

I just replaced the exhaust system on my H30. I have a 15hp Yanmar, but I don't think there is much difference between the two as far as exhaust is concerned. The research I did, with the help of a local yard, gave me the following general principles- muffler manufacturers usually have info on where the muffler has to be located in relation to the exhaust mixing elbow, and depending on your set-up, will tell you wether or not you need a vented loop running from the elbow. My boat already had one so it wasn't as issue for me. I mounted my muffler right behind the engine, the exhaust hose was only about 18" long from the elbow to the muffler. This was the lowest point I could install it. Low is good as far as preventing water from re-entering the engine. From there, I ran exhuast hose back towards the hull fitting. I made the hose bend up above the waterline and then down to the hull fitting. (my engine exhaust shoots out down low on the hull, not out the transom. This made the loop easy.) It wouldn't have been as easy if my hull fitting shot straight out on the the transom. Some companies, like vetus, sell a pre-made riser that connects to the hull fitting (good for the straight out on the transom type) so you can connect the exhaust hose to it, instead of having crazy bends in your exhaust hose. I got the most usful info out of the vetus catalog, even though I ended up having to use a Centek fiberglass muffler. I just couldn't get the vetus mounted proberly in the space I had to work with. I hope this helps.
 
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chet p

pictures

if you send me your email address i will try and take some digital pictures and send them directly to you i haven't yet figured out how to post them here. i replaced my engine and everything else in the engine compartment and it was much easier when the engine was out. i don't know how i would do it now that everything is in place. my waterlift is port side just below the exhaust then it goes straight up and enters a 90 and is strapped to the cockpit sole. from there it gently slopes down to the new 2" bronze thru hull in a spot just aft of the cockpit drains. i do have a vented loop in the coolant water injection line...my engine is a 3 cyl westerbeke chet p 1keladi@msn.com
 
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Steve Cunning

Re: Exhaust Venting

Hi Brian, that you for responding, I just wanted to relocate my muffler and did not want to do any harm as far as location is concerned. I guess I should check out maybe the manufacture of the muffler.. Cheers
 
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Steve Cunning

Re: Exhaust

Hi Chet... Thanks for responding... BTW This boat is from St. Augustine brought it up last spring to Canada. I would much appreciate a picture of your exhaust, as I don't want to do any harm relocating the muffler so that I can gain some valuable space in that area. My email address is steve@proventmechanical.com. Cheers Steve S/V Southern Comfort
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Closed loop or raw water cooling?

Steve: Which engine do you have? My understanding is that if you have a raw water cooled engine (VS a closed loop system)you are not going to get that much heat from the engine. What type of water muffler did you originally have on the boat? Obviously it is best to follow the mfg. recommendation when installing one of these.
 
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