Muffler drains

[5teve]

Hi Guys

Been researching and asking this issue to death with no real good or bad response. Firstly some background

I have been chasing a port engine power issue - seemed intermittent. As part of some routing maintenance I started replacing the Port engine Wet elbow with a standard cummins unit (bought cheaper than custom risers but custom are on the list) On removal of the old elbow a load of exhaust cement fell out of the joint and it appears that the turbo has been bogged up cause it was so rotted. There is not even enough of a sealing face to use a gasket! Turbo is non recondition-able so have a used unit on the way.

So onto the muffler - it looks lke it was done by someone with no clue how they work, however it does work the issue is that the outlet pipe sits too high so when engine is off the water level is at around the same level as the inlet - so in the instance of the boat pitching or rolling there is a slight chance that the turbo gets wet when the engine of off which is what has happened over the 20 years.

The end solution will be new mufflers and risers but thats a longer term view (based on free time, free funds and also we use the boat year round) so I'm looking at options to reduce this happening.

My initial solution is to add muffler drains (they have none currently) I am planning on linking the mufflers into a thru hull fitting and strainer that is not used. this will in theory allow the mufflers to drain down to water level when stationary, the muffler base is below water level so they should never be empty, but it may give me 6-8 inches more play on the muffler waterline. I was also thinking that having a one way valve (something like a bilge pump valve) before the strainer would stop any pressure running back into the mufflers underway, although the pressure in the mufflers should be greater than the water pressure. The through hull fitting has a dome strainer not a scoop fortunately (was a deck was fitting and probably will be again at some point!

I have added a crappy quick diagram below. Any thoughts or ideas?



Thanks

Steve

 

[jfm]

Your drains seem a good idea in the circs. I would use backward facing scooped skin fittings. I'd also fit a dedicated drain each side in case you have to run on one engine. Stops the "dead" engine muffler being filled by pressurised water in the "live" engine drain pipe. Your non return valve should save the day of course, if trustworthy.

 

[Latestarter1]

Some pic's of your installation would be good, also interested in your comment re turbo availability NLA is very odd for Holset..

Paul

 

[5teve]

Your drains seem a good idea in the circs. I would use backward facing scooped skin fittings. I'd also fit a dedicated drain each side in case you have to run on one engine. Stops the "dead" engine muffler being filled by pressurised water in the "live" engine drain pipe. Your non return valve should save the day of course, if trustworthy.

Yeah I have considered this especially after coming back from the local island on one engine - I was actually thinking of ball valves on each - pvc type would probably work in this instance as they should never get hot beyond operational limits - or use marelon ones.. at least this way I can then shut mufflers off - the alternate is just a one way valve on each one running to the thru hull. then they cannot feed each other.

This is just a short term fix - so for the cost of a lift out - fitting another thru hull, etc etc, I may as well just get new and correct mufflers made. Hence me trying to utilise whats there until time allows a proper fix - hard to do anything with all season boating!

Some pic's of your installation would be good, also interested in your comment re turbo availability NLA is very odd for Holset..

Paul

Hi Paul - I wish I had some pictures but looking through my gallery I have none of that section. Its basically a poor design that brings the salt water a little too close to the turbos, they have lasted a good while considering, but it could be greatly improved. It could also have been the case that the elbows were leaking internally and flushing the turbo also.. either way new system in the future will be made and be as inherently safe as it can be. New risers with wet section on the downward slope and as much height as I can get - new mufflers with the output as close to the bottom as possible without generating crazy back pressure (there is a tall loop on the output side of the muffler) any pictures i have are here https://goo.gl/photos/LGM2qVMFf3U6McTw9

The turbo is available here - sorry if I gave the impression it wasnt.. I can get a brand new one locally for a mere $3500+ aud - a recon one for $2100aud or if the old one was repairable it would have been just $1200aud with new compressor / turbine and bearings etc and a sleeved compressor housing, unfortunately it was that far gone there was not enough metal to machine out and sleeve! I have bought the used one for $300aud which was in a boat for 7 years before being removed and replaced by a 'keen' mechanic and owner that was enjoying boom times here.. no expenses spared! worst case scenario it will need a full overhaul and sleeve but even then it will be cheaper than a recon cummins part.

Cummins pricing here is crazy now. The standard wet elbows are $6500aud each list - the guy that owned the turbo said he paid $1800 total for 2x elbows and one turbo - although it was 10 years ago.. over here they are opening themselves up to the chinese making close copies and charging good money but still a 1/3 of the cummins price! I'm seriously considering a chinese aftercooler - $500us for core and housing - there are a few US companies starting to sell the copied stuff too..

Steve

 

[5teve]

OK I now have some pictures of the exhausts etc..

I'm resigned to getting some new mufflers made that actually work and reduce the volume of the pipework above waterline (2-3 feet above is a bit much for a planing boat)

Having determined the waterline I will only gain maybe an inch drain in the muffler - if done via the seacock - so I think I am going to have to run a shower sump type system for now - engines stop - valve opens - drains into sump - pumps overboard - just trying to find a solenoid valve for doing this that can deal with saltwater! a manual valve may be the go to start with.

Anyway pictures.. on the disconnected muffler the boat waterline is around the bottom of the input pipe, the high rise bend out of the top of muffler is about 2-3feet above waterline and 6inch diameter. With new mufflers I would plan more fall on the turbo outlet, less rise on the outlet of the muffler and try to decrease the volume of the output piping so that the waterlevel can stay as low as possible in the muffler.

Oh also excuse the wiring - its a work in progress of stripping unused wiring out and putting new wiring in...