Restarting under sail vs motoring

[toddster]

I'm pretty new to the A4 and my new/old boat, but I've noticed something a bit odd when restarting the engine.

When we're on flat water, the engine starts or re-starts instantly. After we've been sailing, and the boat has been bouncing around, it has to crank for 15 - 20 seconds, needs a fair amount of throttle, and starts weakly.

Seems like it might be a fuel issue - something getting stirred up? I did drain out the old gas and change the oil/water separator filter before I started the engine for the first time. Fuel pump loosing prime?

Just wondering if these symptoms seem familiar. Obviously, it would be nice to have instant engine access while sailing, for those sphincter-tightening moments. (I've been sailing small boats with no engine at all up to this point, but now there's bigger more expensive things to break!)

[edwardc]

20 seconds is too long to crank with the raw water intake open! You may be flooding your muffler and backing water up into the exhaust manifold. Any time you have to crank more than 5-10 sec, you should close the water intake until the engine starts.

In fact, this may also be the cause of your hard starting. A properly designed exhaust system should have a raw-water feed loop that goes up above the waterline for all angles of heel, and should have an anti-siphon valve at the top of the loop.

Boats without an adequate amount of loop height or an anti-siphon valve may allow water to siphon into the manifold while under sail.

In addition, if your hot-section's riser is inadequate, it can allow water from the water-lift muffler to feed back into the manifold under certain angles of heel or pitch, depending on your muffler's location.

It's a real eye-opener how many production boats did/do not meet these requirements.

Send us some pictures of your cooling plumbing and muffler, and we'll see what you've got.

[toddster]

Will do next time - sailing somebody else's boat this weekend. It's hard to see the muffler - it's in its own plywood box between the lazarette and the engine compartment. One has to crawl into the lazarette and peek over the top of the box. It does rise well above the level of the engine, but it's wrapped in a lot of insulation, so I don't know about an anti-siphon.

[sastanley]

toddster...we'll need several pictures...start from the back end of the engine all the way to the transom if you can.. the anti-siphon should be installed between the manifold and the water injection point..mine is hiding next to the sink since my engine is in the middle of the galley.

[edwardc]

I found this image of toddster's engine from an earlier post on a different thread:



It appears that there is no riser at all on the hot section! (an all too common occurrence)

If the muffler is really mounted "...well above the level of the engine" with no riser in-between, then it seems highly likely that water can back-flood into the manifold. We really need to see what's behind that bulkhead that the hot section disappears through.

[toddster]

At this point, all I can say is that behind that panel is a vertical object shrouded in insulation, within a plywood box. The pipe leading from it to the stern through-hull appears to be an ordinary piece of schedule 40 PVC pipe.

[jpian0923]

It looks like it's FWC. Can water still back up into the cylinders in this situation? I have RWC so I'm ignorant in this case.

[edwardc]

That "vertical object" sounds like it might be a standpipe. A standpipe is used instead of a waterlift muffler. If so, its a "good news / bad news" situation.

The good news is that a standpipe uses a different principle than a waterlift, and it cannot back flood into the manifold.

The bad news is that we still wouldn't know the cause of your hard starting after sailing.

It looks like it's FWC. Can water still back up into the cylinders in this situation? I have RWC so I'm ignorant in this case.

Yes, with FWC there is still a raw water path that goes thru a pump, through the heat-exchanger, and into the exhaust to cool it.

[joe_db]

My boat did exactly that. It was caused by the engine slowly filling up with water.
I redesigned the exhaust system to prevent it.
Hints included:
EDIT - Stick an anti=siphon valve at the top of the blue part

I'm pretty new to the A4 and my new/old boat, but I've noticed something a bit odd when restarting the engine.

When we're on flat water, the engine starts or re-starts instantly. After we've been sailing, and the boat has been bouncing around, it has to crank for 15 - 20 seconds, needs a fair amount of throttle, and starts weakly.

Seems like it might be a fuel issue - something getting stirred up? I did drain out the old gas and change the oil/water separator filter before I started the engine for the first time. Fuel pump loosing prime?

Just wondering if these symptoms seem familiar. Obviously, it would be nice to have instant engine access while sailing, for those sphincter-tightening moments. (I've been sailing small boats with no engine at all up to this point, but now there's bigger more expensive things to break!)

[toddster]

Finally got a chance to snap a couple of pics of the exhaust, behind the bulkhead. Sorry for poor quality - can't actually put my head in there, just pointed the phone down there:




(And yes, the wiring is an issue for another day. I think the 12V is stable enough to wait until the haul-out and the shore-power... well we just don't use that for the time being.)

The PVC pipe runs slightly downward (on her lines) to the stern through-hull. The small swim-fin may be the problem - it was obviously made to fit another boat.

[lat 64]

Toddster,
You're right, that looks like a Bayliner swim fin.
Wow PVC exhaust! Are you the only one?

My real offering here is: Do you think you may be using cold-start techniques for starting a warm engine?
I thought not. Oh well, Maybe the fuel is getting stirred up in the float bowl with water and gunk.
Have you taken the carb off and cleaned it?
It's not that big of a deal, but if you've never done a carb before, get a motor-head buddy to come to the boat to help. Just remember to take it apart over a basin to collect the tiny bits that fall out. Then the motor-head buddy can put them back in in the right place. You may ruin the "paper" gasket so be prepared with a new one., The set up for carbs is somewhere on this site.

Russ

[Gordo]

. The small swim-fin may be the problem - it was obviously made to fit another boat.

Well said my friend, you knew we were all gonna get onto that wagon

your system looks very different than mine (mine is waterlift), so I'm not sure what I'm looking at. The "standpipe" system can't backflow? It looks like it would easily flow back once the engine was stopped, at least whatever was in the pipe at the time. I'm just useing your thread to learn more...hope that's ok

[toddster]

Well, based on this diagram that I found through Google books

It looks as if it's possible that water could backflow to the engine if the inner tube corroded. However, it seems as if that would happen whether or not we were motoring or sailing. And I don't see how adding an anti-siphon loop would help this situation. In fact, if at all possible, one would want the water to siphon back out of the chamber when not in use, to avoid corrosion.

Will go back and look at fuel systems again when next I get an opportunity.

[toddster]

This seems to be "my" exhaust system thread, so I thought I'd bump it up. I got tired of sanding the bottom this afternoon, and was clearing out the sail locker. And I started looking at this exhaust system again. (Continuing to procrastinate on the sanding.)

From the standpipe, there is a short piece of rubber hose, leading to about 5-feet of PVC pipe that someone has tried to bend-to-fit with a torch or something. (see pic above) After that, another 2-foot or so piece of rubber hose leads to the through-hull. Not finding exhaust pipe in the Moyer catalog, I'm wondering what a "normal" system looks like? This PVC really gets in the way in the locker. I'm thinking that a one-piece rubber hose fastened to the side of the compartment might be a good "upgrade" when I get to organizing the locker. Anybody have specs or a source for such hose? Or the temperature range it might experience?

[Mo]

Todd,
Do you think you could get us some pics of the whole thing or put a light and video camera below the cockpit so we can see what is there. What type boat do you have?

Edit: I removed my sketch because I saw that Joe had put a great one in post number 9