Exhaust and Cooling Systems
This page was last updated on 10 November 2001

Engine Cooling System

The Yanmar is raw water-cooled, so the cooling system is quite straightforward.  As an upgrade to the standard system, I installed a Perko bronze sea strainer in the engine room, mounted in a convenient location on the inside of the starboard engine mount for easy inspection and servicing.  I used 90 bronze hose nipples to rawwaterintake.jpg (38264 bytes) make hose connection a little easier.  The inlet is aft, towards the engine, and points straight down, which makes for an easy connection with the 3/4" hose that runs from the seacock aft of the engine room.  From the strainer output, a short length of 3/4" hose runs into a reducing nipple (plastic--I can't find a bronze one), where it changes to 1/2" hose--the size required for the connections on the engine.  Then, it's on to the raw water pump front and center on the engine.  From there, another length of hose runs aft to the internal engine chambers for eventual discharge and injection into the exhaust mixer.  I have replaced all original cooling system hoses with new 1/2" hardwall wire-reinforced wet exhaust hose.  

UPDATE!!  I really didn't have to make any significant changes to the raw water intake system when I installed the new Yanmar 2GM20F.  The only thing I changed was the hose leading from the sea strainer to the raw water pump--the new fitting on the engine is a larger size, so I was able to eliminate the reducing nipple that I had in place before.  All the better!




Exhaust System

Before lifting the engine into the boat, I had removed the exhaust mixer and thermostat housing.  For some reason, I never reinstalled it, so the first step to complete the exhaust system was to reinstall this part with new gaskets.  Next, I ran a length of 2" ID hardwall wire-reinforced exhaust hose (2" is the size of the outlet on the exhaust mixer) from inside the cabin through the port side of the engine room and up to the mixer, where I installed it with two hose clamps.  I did it this way so that I could attach the bitter end, but still have the full length of hose beneath the engine for proper fitting to the new Vetus Waterlock muffler.  The hose is expensive, and I didn't want to make a mistake cutting it.  The hose runs between the fore and aft engine mounts and then downwards towards the bilge.

With the full length of hose in place, I determined the proper length for the first section (exhaust mixer to Waterlock) and cut it to length with a serrated knife and wire cutters to nip the helical wire inside the hose.  The Waterlock fits very nicely in the bilge beneath the engine--it's almost like it's tailor made for the space.  I decided on the Waterlock for this very reason, having heard of other Triton owners who have had success with the same equipment.  The input fitting on the Waterlock is removable, and I found it easier to remove the swivel fitting and clamp the hose to it first, then to reinsert the swivel fitting into the chamber.  For now, though, I left it off.

Next, I took the remaining length of hose and, from the cabin, ran it beneath the engine and up the port side forward of the cockpit scupper seacock.  This took a lot of huffing and puffing, as the hose is quite stiff and tough to bend.  The idea is to keep the hose out of the way of the propeller shaft and couplings, and running it in this manner will do just that.  Later, I'll install some sort of clamps to keep things in place.  When I had most of the hose pushed through, I connected the bitter end to the output of the Waterlock with two clamps (AWAB) and placed the muffler in the proper position beneath the engine.  With this done, I was able to remove the slack from the output hose and reinsert the input fitting and clamp it down.  The muffler is quite rigidly held in place with the hoses and waterlock.jpg (37480 bytes)the narrow confines of the bilge, but I will probably find some more permanent means of securing it.  The thumbnail (right) shows how the Waterlock looks from the front, inside the cabin.

exhaustth.jpg (23132 bytes)The next issue deals with reducing the size of the exhaust hose from 2" to 1-1/2".  This is necessary because the new through hull fitting I installed in the counter is for 1-1/2" hose, and I didn't want to change it.  Reducing the hose size is a exhaustshutoff.jpg (30484 bytes)seemingly simple matter--except that no one makes the proper reducers.  I first looked for a fitting to work with my bronze exhaust shutoff valve (photo top left), which is for 2" hose.  I hoped to find a 2" pipe thread fitting with a 1-1/2" hose nipple on it--but none exists.  Next, I looked for a hose-to-hose reducer, from 2" to 1-1/2"; they make similar fittings out of plastic that you can find in hardware stores everywhere.  Of course, I didn't want plastic, and I couldn't find a bronze fitting like this for the exhaustreducer.jpg (28448 bytes)life of me.  The strange thing is, they make these fittings that go up in size, but not down--or at least not with the sizes I needed.  I finally stumbled upon a double female union fitting that reduced from 2" to 1-1/2"; then, it was just a matter of inserting the proper hose nipples in each side. (photo bottom left)  Phew--I thought I'd have to replace the through hull.  

The next thing to do was to cut the 2" hose to the proper length.  I decided to install the shutoff adjacent to one of the wooden fuel tank supports, which is easily accessible through the port cockpit locker and also provides a convenient place to secure the heavy bronze fitting.  After cutting the hose, I installed it on the shutoff valve, and secured the valve to the block with a couple nylon cable ties.  To cushion the valve where it rests on the hull, I cut a piece of rubber hose and slit it down the middle, and secured this beneath the valve with more cable ties.  Then, on the discharge side, I exhausthose1-40601.jpg (38368 bytes)added a short length of 2" hose, then installed the made-up reducing fitting, also cushioned with some slit rubber hose.  All hose connections are secured with double AWAB clamps.   Then, I installed a final length of 1-1/2" exhaust hose that runs into the lazarette, into a loop beneath the deck, and down to the through hull fitting in the counter.  The loop is designed to help prevent backflow if the outlet becomes submerged; the shutoff valve is a little added insurance against the same, for use especially if running before a heavy sea.

The exhaust system is complete!eath the engine, so the hose could take a more direct route without needing to twist between the engine mounts.  I was able to cut off nearly two feet of hose as a result.

Glissando, Pearson  Triton #381

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