Using a Drained Vetus Waterlock Muffler

[Madryn]

Hello. This is my first post on the forum so greetings to everyone

I have looked all over before posting but haven't found anything that would answer my question.

I'm quite new to boat owning so I'm hoping those with more experience here can help me out.

I recently needed to drain my vetus waterlock (LP40R I think, or similar) using the little drain plug at the base. Now I want to run the engine again for the first time since draining the Vetus and I'm worried about whether or not I need to get water back into the Vetus somehow before I fire up the engine (Yanmar 1GM10).

I'm worried that because the Vetus will take a time to fill back up with water (especially as the engine's thermostat will be closed until the engine warms up) I will be pumping very hot exhaust gases back into a dry waterlock and may damage it, or even start a fire or something!.
I know eventually it will fill back up to its correct level once the engine warms up and the thermostat opens properly, but until it it does that will it overheat, and should I be "priming" the vetus waterlock somehow with water before starting the engine to avoid it overheating?

I could disconnect the inlet hose to the vetus and pour water in before starting, or take the thermostat out of the engine to increase cold-engine water flow but if I don't need to do that I'd prefer not to because that means unecessarily disturbing seals.

I'd really appreciate advice from anyone who has drained their waterlock in the past and knows from experience what worked best when restarting the engine.

Thanks very much for any help.

 

[prv]

You don’t need to refill it. The cooling of the exhaust happens right from the start where the water’s injected, at the elbow.

Pete

 

[dankilb]

Welcome to the forum!

Presumably the thermostat only controls the (closed) freshwater/coolant circuit? The raw cooling water should still flow into the exhaust mixer/muffler the minute the engine fires up. Indeed, just cranking the engine should start to fill the water lock.

Unless I’m missing something?! For instance, you’re not hoping to run the engine without the raw water connected (or without a hosepipe to substitute if on the hard)? If so, don’t! Neither your impeller nor the exhaust system will thank you!

 

[neilf39]

Engine temperature makes no difference to flow of raw water through to the exhaust. Exhaust will have full water flow from the start. I don't think having an empty water lock will be a problem , the gases will have cooling water and the water lock will be filled in 30 secs to a minute.

 

[Spirit (of Glenans)]

As stated above, your exhaust pipe and waterlock will contain water within seconds of starting. The cooling(raw) water is pumped through the heat exchanger where it extracts the heat from coolant that circulates around the engine, in the same way as a car radiator works. The sea water will then be pushed out in distinct pulses by the build up of exhaust gas pressure. The main purpose of the water trap is to collect the water that drains back from the swan-neck when you switch off.
I should tell you, because I suspect that you don't know, that in the event that your engine does not start, you should not continue to operate the starter more than three or four times, because water will accumulate in the exhaust hose to the point where it can overflow through an exhaust valve into a cylinder, causing expensive damage. Ideally, in your case, you have a drain valve on your water trap to remove it.

 

[vyv_cox]

In the opposite scenario I melted a plastic trap when my raw water flow failed and I had no option but to carry on motoring. As said, water flows as soon as the engine turns over and the trap will fill before the gases are hot enough to do damage.

 

[dankilb]

As stated above, your exhaust pipe and waterlock will contain water within seconds of starting. The cooling(raw) water is pumped through the heat exchanger where it extracts the heat from coolant that circulates around the engine, in the same way as a car radiator works. The sea water will then be pushed out in distinct pulses by the build up of exhaust gas pressure. The main purpose of the water trap is to collect the water that drains back from the swan-neck when you switch off.
I should tell you, because I suspect that you don't know, that in the event that your engine does not start, you should not continue to operate the starter more than three or four times, because water will accumulate in the exhaust hose to the point where it can overflow through an exhaust valve into a cylinder, causing expensive damage. Ideally, in your case, you have a drain valve on your water trap to remove it.

Yes, with this in mind I would also very much advise against pre-filling the waterlock (say, with a view to aiding cooling). You could inadvertently cause water to siphon or flood back into the cylinders via the exhaust manifold.

I don’t know if this is strictly correct, but I only allow a little water through when cranking for the very first time upon re-commissioning (either by closing the sea cock once a little water has entered the strainer or - if using a hose on the hard - opening the seacock to allow most of the water to drain down through that). I figure this still lubricates the impeller enough to crank the engine. Once it fires up, I quickly restore the full flow of water from whichever source. That may be over complicating things, mind!

 

[Madryn]

Many thanks to everyone for replying and explaining to me that the thermostat doesn't stop water flow altogether when cold (as I thought) but only stops flow through the block (still allowing water to the exhaust mixer).
I hadn't realised that (lots to learn!).

My engine (Yanmar 1GM10) is direct cooled so there is only a raw water supply and no freshwater system in it.

So, if I've understood correctly.... from the moment the engine is turned over water is being mixed with the exhaust gases regardless of what the thermostat is doing (i.e. even when cold). All the thermostat does later is divert that same water flow via the engine block when it gets hot enough.
So either way, the muffler will receive water from the get go.

Thanks as well for the warning about not turning a non-starting engine over for too long because if I do I will risk flooding the engine as the muffler fills and then runs back to the engine.

Just to explain...

I've only had the boat (a Norfolk Gypsy) about 3 weeks and have only had the opportunity to run the engine twice since I've had it. It appears to run well, having been serviced by the yard where I bought it from as part of the purchase deal.
Then we had a cold snap forecast and because I'm trying to leave the boat in the water for as long as I can (to get at least one sail before taking it straight back out again!!) I was advised to drain the engine block and drain the vetus muffler, just in case, until the cold snap was over.
Now the weather is getting more mild again so I'd like to get the engine ready for use for that "one sail", if I get a chance.

It sounds as though all I should need to do is simply start the engine again, and just check in the raw water strainer (Norfolk type) to make sure water is being sucked up? If it is then everything else should take care of itself as it was before.

On the previous occasions before I drained it it has always started within a few seconds.

Fingers crossed and thanks again everyone for your advice. I appreciate it.

Neal

 

[DownWest]

Since you are dealing with sea water, a cold snap is less important as it freezes at a lower temp. Still, caution a good thing.

 

[peteK]

No need to drain waterlock,first time I have heard anyone do it.

 

[vyv_cox]

No need to drain waterlock,first time I have heard anyone do it.

Depends entirely where you are. In my first winter in the Netherlands the temperature in January never rose above -10 C. 1997.

 

[dankilb]

No need to drain waterlock,first time I have heard anyone do it.

Mine is stainless but I still wish it had a drain plug, just for removing sources of corrosion for longevity (for both trap and engine).

It’s survived 30 years, though, and no rust in the exhaust manifold, so guess it’s fine in reality!

 

[Gixer]

Funnily enough I did the exact same thing last month, same engine and same water lock. I didn't even think about refilling the water lock... LOL.

I'm out the water at the moment and was checking the exhaust manifold (one of the 1GM10's things to check) and thought while I was at it i'll see what gunk is in the water lock by emptying it, I upended rather than undoing the drain screw though.

I just refitted it, connected the raw water hose my 'modified' plastic Jerry can and barked the engine up. Everything was fine, within a few moments water was coming out of the stern. Once up to temp I added antifreeze to the Jerry can, watched it go down and turned the engine off. All ready for winter.