Muffler Drains

Hi Guys

Trying to find thoughts on muffler drains - I have twin Cummins 330 6bta's and i'm trying to reduce the amount of moisture the turbos would potentially see as I do not have the headroom (or funds currently) to have a fancy exhaust with a rise out of the turbo - i'm just on stock elbows but as far as I am aware - they drain ok and water is below turbo level.

Anyhow.. i'm pondering adding a drain to each muffler (water lift, aqualift etc) so that when I shut the engines down I can empty the mufflers almost completely and therefore minimize any moisture in the exhaust - As I am Perth Australia based it generally doesnt freeze so drains are not common on lift mufflers.

What are your thoughts?

Steve

 

I don't think it will make much difference on the moisture content of the air. The hot air mixed with water is what contains the vapor. Unless you manage to flush the moisture out and replace with dry air, it won't be a significant improvement.

 

Well by removing the water I am thinking that for extended layover, the exhaust will be able to breath the warm dry air we have here, whereas if the muffler is half full then the output pipe from the muffler is blocked to the outside world. I'm really not sure in reality if this is the case?

Having the drain also has the advantage of being able to drain mufflers if I have starting issues - which may be justification in itself!

Steve

 

What material are the mufflers? You may be able to simply tap a threaded hole and put a screw with a rubber washer. That is the standard factory drain on most muflers.

 

They are fibreglass so I would be looking at using a tank connector / Bulkhead connector to get the valve onto. I can get access to the inside via the inlet tubes (I think)

Steve

 

You can simply epoxy a valve to it. They come with a self-tapping screw as a drain from the factory.

 

Hi Gonzo

There are no drains at all in the Mufflers. They are locally made and therefore don't have drains (stupidly) i'm thinking a stainless bulkhead fitting and tap may work best.. like a tank fitting.

steve

 

OK further to this (its been a while) I have now managed to strip my exhaust system and am thoroughly baffled about what I have found! - The one waterlift muffler I have had access to appears to be very badly designed in that the resting water level is the same as the inlet level - somebody has cut the side out of the outlet pipe so that it doesnt push the majority of water out, - So I either need to repair or replace - but neither is going to get done soon (limited time and funds) so I am going to persue the drain option but have been doing some research and have some questions..

Close to the mufflers I have an unused through hull and strainer (was used for deck wash which may be reinstated at some point) It seems if I was to put a drain on each muffler - tee the drain into the through hull - it could act as a simple 'automatic' drain and the mufflers would drain down to waterline level - if the pipe was maybe 3/4inch there would be minimal risk of water flowing back up into the muffler in washy seas - with the engine running it may even act as an additional outlet although i'm not sure the exhaust pressure would overcome the water pressure. I'm also unsure how much 'flow' forward motion of the boat would add if the seacock was left open (its not a scoop underneath just a dome strainer)

My other thought is after reading a little about equalisation pipes in mufflers (they are mentioned but very little detail is given) - which again acts as the above but the are fed through to just above the waterline through hull and drains the mufflers as much as they will drain at the given outlet level.

Has anyone got any real examples or details of auto draining mufflers or any further ideas?

This is just a bandaid fix until I can get some new risers (with actual rise) made and also get some new mufflers made (or these one corrected) with the main result to minimise the chances of the turbo's being washed while stationary!

Steve

 

A check valve in the drain line could prevent water entry at high speeds.
Adding a reversed scoop over the thru hull might help, though experimenting would be prudent, as you don’t want the lift muffler to run dry.
The real solution is to fix the mufflers and install proper dry risers at the turbo exit.

 

Hi KapnD

Agreed mufflers need fixing / replacing but this is a short term fix to stop the turbo's getting 'wet' when stationary and engines off (budget and wife dictates I do things a bit at a time) I think with a small pipe there is no way that the mufflers could run dry, and also the bottom of the muffler is below the water line, so will only drain so far, small pipe (3/4" or so) would also minimize any venturi effect or pressurized water exit, worst case scenario I can always shut the seacock while running and open to drain on shutdown.

Steve