Sudden end of Water Lift Muffler

[Bill Vanguard 281]

Hello all
I was working on my A4 today - getting her started
to test some new modifications (both piping and wiring)

After cranking many times -
I discovered a fuel pump and
oil pressure safety switch that no longer wanted to cooperate.
Replaced the fuel pump and determined oil pressure switch wasn't
operating either (tested with air and multimeter)
After leaving the engine for a 1/2 hour or so on another mission -
I went to crank engine again my newly installed and empty Vetus
Water lift exploded - luckily deck plates were on so flying shrapnel stayed in
bilge
---close call---
I don't believe carberutor had any fuel in it as fuel pump had not kicked in at
any point
in time - due to faulty oil pressure safety switch

I think cause of explosion was build up of oil vapors in water lift as explosion
was inside
of waterlift. There was no water in the water lift

Any hints from those more experienced than I? For some reason I don't care to
repeat this
experience again.

Bill

[Hulukupu]

I've never heard of one exploding. It sounds like a blockage of some kind.
Delanoy in this thread (http://www.moyermarine.com/forums/showthread.php?t=2317) cautions
against over-cranking an engine with a vetus attached for this reason.
Dave in another thread talks about two vetus units melting (http://www.moyermarine.com/forums/showthread.php?t=1430).
David

[Quetzalsailor]

Can't imagine an ignition of gasses occuring. The A4 was not running or even willing to start. No spark; no heat.

Also hard to imagine that the raw water pump, and the cranking engine, has enough oompf to blow the Vetus apart. But that's my guess.

I'd always heard that you should turn the raw water supply off if an engine refuses to start after a few cranks. If it eventually starts, you have plenty of time to open the seacock. It takes several minutes of running to heat all that iron to point of damage. The raw water is dumped into the exhaust system but needs exhaust to be blown out the tailpipe. Without exhaust, the water simply fills the exhaust system and then drains back into the engine. The next cranking is tough on the engine, and the water is not good for it, either. (Friend of mine found this out the hard way this past summer, but several oil changes and a tuneup later, the A4 is back in service.)

[bcooke]

Engine oil 'vapors' don't ignite except under extreme pressures. You said the muffler was dry and I find it extremely hard to believe water pressure could blow a muffler when water can exit through the exhaust or backflow into the cylinders. That would be one heck of a blockage and even then I think the rubber impellor in the pump would go before the Vetus.

Mufflers commonly blow up when fuel vapors get through due to cranking with a delayed ignition. I know you said there wasn't any fuel but there really isn't many other possibilities.

[Bill Vanguard 281]

All thanks for the reply's
I did leave out one small detail - I had been cranking
with the coil wire off and the last time I cranked the engine
I had the coil wire on. Must have been some Gas in
there???

Bill

[bcooke]

Classic example.

The good news is that it probably won't happen again ;-)

[Triton 336]

I did the same thing, split the vetus on center line seam when my a4 backfired.

[sscoll]

This is certainly a cautionary tale. I've zero experience with marine mufflers. The large copper ring bologna thing in the port cockpit locker seems intact. Having read this thread I'm given to doubt its longevity and will be prompted to screw around with it. No doubt I'll ruin it in short order.

Is the Vetus the only option for A4 muffling once the original starts to leak, or are there alternatives?

Steve

[Quetzalsailor]

The various 'water lift' mufflers are, I think, relatively recent (25+ years?). The older style muffler systems can be fabricated. Dad made one of 316 stainless in about 1980 after the original galvanized one that came with the 1972 boat corroded and fell apart (he drove the boat home spewing exhaust and water everywhere). Anybody with access to stainless pipe, a welder, and the design can make one. Basically, these things are hard plumbed from the engine to a place above the waterline before the water is introduced. Since the engine is bolted down, the exhaust pipe and muffler system can be rigid metal and affixed to the boat. An important detail is that the whole thing is hot, and can be quite long before a high enough place in the boat is reached, until the last bit when the water is introduced. While one positive is that the raw water injection is free of the need for vacuum breaking since it's injected high and the muffler acts as the breaker, everything else is negative. An important advantage to the rubber and plastic parts of a water lift muffler and hoses is corrosion resistance. I Googled to check my guess of the age of the idea and found references to stainless steel water lift mufflers which had corroded.

When I remade the engine beds in the 72 Morgan, I added soft engine mounts and a Vetus. The boat was much quieter, cooler, and had less vibration.

[Tim]

There are other options for waterlift mufflers, including fiberglass versions in a variety of shapes and custom SS ones. The fiberglass ones are excellent, but relatively expensive and they tend to be rather large. This can preclude them in certain installations.

The Vetus Waterlok discussed in this thread is popular because it is readily available, inexpensive, and small in size, which makes it a good fit in the tight, tight, tight, tight, tight confines of a boat like a Triton. They work well as long as one understands and accepts their limitations.

Waterlift exhaust is quiet. All you hear is the water splashing out--none of that annoying sputter/thbbbt of the jacketed exhaust system that carries for miles on calm water.

[Hulukupu]

One backfire and you loose your Vetus (and hopefully not more). Is it practical and advisable to disconnect it if you are having starting problems?

[Triton 336]

I had been cranking for some time .Clearly had the proper gas to air mixture in the vetus. I had hooked up the plug wires wrong, Fired w/ exhaust valve open and just went down the line. May be a SS unit would have made it. I think even a fiberglass unit would have been damaged. I have many hours on the vetus and other than my operator error it works well. Any water flow problem and you can melt the inlet fitting. I installed the unit under the engine so I would not have to install riser pipe far above cockpit sole level and take up locker space. Seems to work fine.

I see Briton installed in locker,may be less back pressure w/his run. Should I relocate? I can't think of a better place for the water lift muffler than under the motor,perfect fit. Lots more hose and lift ,but less stand pipe off the manifold. Briton I see you have no vented loop,does this work ok? Thanks John

[bcooke]

My exhaust was installed by the PO. It works fine and I have had more pressing issues to contend with. A vented loop on my installation would be nice but there isn't room (I tried) because the riser comes up too close to the cockpit seats on the inside. Someday, I will have a custom stainless steel exhaust riser fabricated and I will lower it half an inch for a vented loop. The water outflow leaves a 3/4" hose and enters a 1.5" empty / gas filled pipe about 18" above the waterline. Not impossible to siphon but unlikely. I keep the raw water seacock closed when the engine is not running just in case.

Given a choice, I might have gone with a waterlift under the engine. I just didn't see the need to change what was already there. Of course I lose some storage space in the locker so maybe someday I will change things around.

I do like the idea of a metal muffler because, as mentioned, if the water flow stops a plastic Vetus might melt. Metal car mufflers blow open with a good backfire so I don't see much improvement over a plastic muffler in regards to backfire survival. In theory, you should have a better chance of survival but not enough for me to lose any sleep over.

[megalops]

Hey Guys, two words of caution on running an engine with the raw water seacock turned off.

One, it will very quickly fry the impeller on the raw water pump.

Two, though the engine would take a while to be damaged the soft exhaust hoses in a wet exhaust break down pretty darn quick if they don't have water running through them. I know this from experince, Believe me, you don't want an exhaust leak, aside from the 02 risk they make a heck of a mess. There is still some grime in my engine room after four years of cleanings.