Waterlift Mufflers and Flooding Dangers?

[SvenG]

If a diesel with a waterlift muffler won't start, how does one know if it is safe to keep trying or if the waterlift might be getting too full ? Is there usually a drain somewhere on the waterlift so one can go down and drain the water before trying to start again ?

Is there a danger of water filling the waterlift from the exhaust end if the stern is continually pounded by waves which more than cover the exhaust exit ? Over the holidays we ended up caught on a lee shore overnight with some pretty terrific reflected swells and waves slamming up under the stern and I could imagine every wave pushing water backwards through the exhaust.

Thanks,


-Sven

[Chief Engineer]

Most waterlift mufflers I have seen have a small plug/screw on the bottom.

Vetus mufflers have a little cap.

If the exhaust lines were installed properly, you should not get any backflow....but having been in a similar situation in St George, Bermuda years ago...I wouldn't rule it out.

[cal40john]

My Centek has a drain. Impossible to tell you how long until you flood your engine because it doesn't start, too many variables. Don't take chances.

Currently best practice is a gooseneck in your exhaust line to prevent backflooding from waves. You can also put a thruhull with a rubber flopper than slams shut when a wave hits it. What folks used to do and what is on my boat still is a seacock.

[delmarrey]

Just check to see if you have an exhaust loop well above the waterline. If so, no worries.

[Jerry Cox]

I cant see clearly the origin of the diagram that Delmarrey posted. If you look up the Centec website..(it looks a bit like their page).. it will clearly demonstrate the right way. I have fitted exhausts in a variety of boats with the engines way below the waterline. If in doubt I have fitted a goose neck after the manifold and at the transom...or wherever the exhaust exits. So far no problems. I have also fitted a sea cock on occasion where there is reasonable doubt. Just make sure it is easily accesable and serviced on a regular basis...exhaust is corrosive!. Its important to fit an anti-syphon loop/valve on the cooling water feed well above the waterline at maximum heel. Also if you have a water fed cutlass...the same applies.
Do not ever crank the motor for long without draining the system. In the past I have just disconnected the system at the goose neck till I have identified the starting. problem

[Badsanta]

I turn off the raw water intake till it starts then turn it on. I just met two guys talking about having to rebuild there low hour engines because of water in the engines. I mentioned that you have to be careful about how long you crank it as the water lift will fill with water and back up into the engine. They were both surprised, said its not in the starting directions and why didn't some one tell him. I thought it was common knowledge but as evident it happans alot.

[SvenG]

Originally Posted by Badsanta

I turn off the raw water intake till it starts then turn it on.

I'd considered that but worried that it might tear the hose at either the intake or the pump fitting due to the vacuum ?

BTW, thanks for all the informative answers from everyone.



-Sven

[James S]

If you do find you have a plug on the water-lift chamber...consider replacing it with a valve...I use a pvc hot water valve.

[witzgall]

Hi all;

We have no muffler or vented loop on our boat, just an exaust hose that leads down from the manifold and then back up a bit to the thru-hull fitting. For ocean sailing, how much of a chance am I taking from water entering from rear-breaking waves, etc?

Chris

[James S]

Its not all down hill from the engine?
Is it a wet exhaust?

[Blue Stocking]

Recently there was a thread discussing intake filters above and below the waterline.
It can vaguely tie in here in reference to shutting the intake thru-hull while you start the engine.
If your filter cap is above the water line, as my Vetus is, I usually squirt in a good amount of dish-washing detergent. This will lubricate the impeller, and flush out the exhaust hose.

[Tom.B]

Originally Posted by witzgall

Hi all;

We have no muffler or vented loop on our boat, just an exaust hose that leads down from the manifold and then back up a bit to the thru-hull fitting. For ocean sailing, how much of a chance am I taking from water entering from rear-breaking waves, etc?

Chris

Can it be fitted with a flapper valve?

[witzgall]

It is mostly, but not all downhill. I will have to measure the fall and rise.

Chris

Originally Posted by James S

Its not all down hill from the engine?
Is it a wet exhaust?

[Jerry Cox]

If you have no waterlift muffler you are in imminent danger of flooding all the time. In my opinion...after many installs..it is absolutely vital.
I also am not happy with shutting the inlet seacock off...If you do not have wire wound hose...also vital...you may well collapse the intake hose or the inner wall of the hose vausing an unseen blockage. I have seen this destroy a perfectly good Yanmar before. Raw water pumps are very powerfull even the small ones
All you have to do is run a hose from the sea water outlet over the side whilst working on the motor. Ok it can be a bit smokey if you have disconected the exhaust but only for a short while is OK.