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Oops, bad engine flush!

xoomer

xoomer

Jet Boat Junkie
Messages
240
Reaction score
163
Points
142
Location
Cape Coral, Florida
Boat Make
Yamaha
Year
2014
Boat Model
SX
Boat Length
24
Today I finished installing my "tow valves"--what an ordeal--and then proceeded to test them out. I started the engine, turned on the water, and everything seemed to be okay but I decided to see if there were any leaks. No problem in the engine compartment so I decided I should open the clean-out hatch since I had been working in there also. The problem was that I forgot that when I opened the hatch that it would kill the engine. So, the engine stopped but the water continued to flow through the flush hose into the engine until I was able to start the engine again--only a matter of a few seconds.

I started the engine up right away and it ran as it normally does so I doubt there was any damage but does anyone know for sure how long would the water have to run with the engine off to cause serious damage--a few seconds, a few minutes, or longer?
 
Almost instantly..... Hydrolock is not something pleasant to hear and I would think if you heard no difference in the engine before/after you would be ok.... Hydrolock has a tendency to stop the motor as well, so if it is still running, sounds good to me........That being said, if there are any members here with more experience with hydrolock, please chime in!!!

Good Luck!
 
Hydrolock should have been evident if it had occurred.

What about checking the oil for water?
 
Bruce said:
Hydrolock should have been evident if it had occurred.

What about checking the oil for water?
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I didn't think about that but I'm going back to the boat tomorrow so I will check the oil. From what I'm reading about hydrolock it will kill the engine so I'm assuming that didn't happen in this case. One post I saw about jetskis said to pull the spark plugs and turn the engine over to blow out any water but since I ran the engine for 5-10 minutes after the problem I don't see how that would help.
 
Nah, you're fine. The hose isn't gonna fill up the whole exhaust that fast man. It'll take a few minutes. Not many, but a few.
 
IMHO it would take at least a few minutes of running water to fill up the water boxes enough to get into the engines. You should be fine.
 
you will know if you have hydrolock.. when you get hydrolock water gets on top of the piston,, water does not compress like air does when the pistion goes up.. since it does not compress that means something else has to give...something breaks.. you will know.. I had a inboard that hydrolocked a few years ago.. It locked up so hard that it wouldn't turn over with the plugs out and a big breaker bar on the front.
 
I had the same experience a few years ago, trying to multi task while flushing the engine, opened the hatch to clean it out then suddenly running around to turn the hose off, scratching my head afterwards wondering if I just ruined an engine even though it started right up and sounded normal.

Like others have stated if the water wasn't running for at least a few minutes, not seconds, while the engine was off you should be fine. It can't hurt to check the oil for water but I wouldn't make a trip to the boat just to do that. If something broke you would have found out soon after you restarted the engine, or tried to anyway.

I'm not sure how the water routes when the flush ports are used but the water box for each engine will hold at least a gallon of water, then there is a bladder (looks similar to a whooping cushion) integrated into each cooling system too that will hold a half to a full quart of water plus the capacity of all the hoses. I got hands on experience with all of this last season when I installed a fish/depth finder transducer near the stock transducer both of which are only accessible through the clean out hatch. If the water has to fill all those things first a few seconds won't matter at all and May amount to less water than you would blow out of the engine at the end of a boating day.
 
You might want to pull out the spark plugs, pull off the lanyard, and crank the engine. If there is any water in the cylinder's this will clear it out. I would imagine that you are probably okay but this is easy enough to do
 
No worries there, the entire exhaust system has to fill with water for it to get back in the engine, as others have stated you caught it in plenty of time
.
 
Thanks guys for all the replies...I can sleep a bit better tonight...:)
 
I did this same oops while winterizing last fall. It was about 8 seconds of hose on and engine off. As soon as I realized it, everything went into slowmo as I reached for the shutoff on the hose. Engine started back up fine and no water detectable in the oil so I figure I'll be good to go this spring. I might do an extra oil change just to be extra safe though.
 
About 3AM one morning, the house security alarm went off while we were all asleep. I sprang from the bed, grabbed the gun from my secure location (had kids in the house), grabbed the kids from their beds and into my bedroom with the wife, flipped my all lights on switch, and shut down the alarm. Of course, the alarm captures the phone line back then and you can't use the line until the security company calls to see if your ok. I managed to check the doors and windows, seeing the front door standing wide open. It was very windy, so I assumed it wasn't closed and locked before. But the security company called about then, and to abbreviate where possible, suffice it to say, that after all was known to be secure and I had a moment to chat with the monitor company, they told me that from the time of the alarm until I silenced it...was only 10 seconds! So go back and read what all I did in 10 seconds! I guess I could have said you didn't hurt the engine, but then that wouldn't be me! It is amazing what kind of heroics you perform when your assholes and elbows to shut down a hose or start an engine!!! Bet it wasn't running on the hose without the engine for even 5 seconds! But I am not sure that you have to fill the water box (waterlock) to fill the exhaust on the boats. The flush hose enters the cooling loop in one of the upper legs of a "Y", and doesn't go back to the waterbox. Water does fill it from the exhaust and some certainly runs out backwards, but the flush hose is direct into the engine and exhaust cooling. Whether it has to fill the water box or not, I doubt you could completely fill the exhaust section of the exhaust up to where it spills into the valve train in less than a minute or so on the average hose. Now don't take that to mean that you can't hydrolock an engine running WOT on the lake! Because if you kill and engine and keep going on the remaining engine, you will and certainly MUCH faster. We have seen that reported a few times. Bottom line, if it started back up and ran, your ok.
 
Bottom line if you hydrolock an engine you'll know it instantly. Water doesn't compress! Best thing you can do is run your engines for a while and keep an eye on your oil. If your engine didn't seize and it ran fine then you're good.
 
I've done this before....no worries! I'm not even sure a garden hose has the pressure necessary to backfill the exhaust! That would be an interesting test for someone to perform! My bet is not a chance in hell it could!

I went water skiing one day, and had a friend drive my boat. So I'm back there and he keeps taking off, and I can't get up. I ask him...are you throttling up BOTH engines dude? He says "Yup!" So I'm scratching my head, getting exhausted and say I'll try one more time (slalom). And this time I watch carefully and see only one jet wash.....

I say "DUDE...you are only throttling up ONE ENGINE!!!"
He says "no way...I'm pushing both throttles up!!!!"
I say "did you start BOTH ENGINES?"
"uh.....whoops....." (he was used to single engine boats)

Suffice to say, we tried like 4-5 times to get me up on one engine and the non-running engine never got any water into it. Imagine the water pressure that was coming from that as compared to a hose.

Not to say it couldn't happen.....but my bet is on a normal pressure hose....no way.
 
xoomer said:
Thanks guys for all the replies...I can sleep a bit better tonight...:)
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I recommend that you take the boat out this weekend and run the crap out of her....you know, just to be sure! ;)
 
Julian said:
I've done this before....no worries! I'm not even sure a garden hose has the pressure necessary to backfill the exhaust! That would be an interesting test for someone to perform! My bet is not a chance in hell it could!

I went water skiing one day, and had a friend drive my boat. So I'm back there and he keeps taking off, and I can't get up. I ask him...are you throttling up BOTH engines dude? He says "Yup!" So I'm scratching my head, getting exhausted and say I'll try one more time (slalom). And this time I watch carefully and see only one jet wash.....

I say "DUDE...you are only throttling up ONE ENGINE!!!"
He says "no way...I'm pushing both throttles up!!!!"
I say "did you start BOTH ENGINES?"
"uh.....whoops....." (he was used to single engine boats)

Suffice to say, we tried like 4-5 times to get me up on one engine and the non-running engine never got any water into it. Imagine the water pressure that was coming from that as compared to a hose.

Not to say it couldn't happen.....but my bet is on a normal pressure hose....no way.
Click to expand...

I've thought of, and been worried about this same scenario. Your post helps ease my nerves a bit. I always tell people if one engine dies then put the throttles in neutral and start the dead engine first before taking off. New(er) drivers can get a little overwhelmed so I'm glad to hear that it will take more than a couple of false starts to hydro lock it.
 
jetboater4life said:
I've thought of, and been worried about this same scenario. Your post helps ease my nerves a bit. I always tell people if one engine dies then put the throttles in neutral and start the dead engine first before taking off. New(er) drivers can get a little overwhelmed so I'm glad to hear that it will take more than a couple of false starts to hydro lock it.
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My guess is that it takes lots of pressure, and lots of water to fill the entire exhaust section up and force water into the exhaust valves. You just don't get that kind of pressure on the hose and many things would have to happen to do it. And as Julian found out, even the low speed attempt to pull up a skier with an engine not running, didn't seem to cause an issue either. I am guessing, but I suspect you can't get to fast trying to pull a slalom skier up on one engine. But have an engine die at cruising speed and not shut down...well, that is where the rub starts to leave a mark.
 
I did the same thing once...no issues...however, I did pray a bit before I cranked the engine over...here's my sign...
 
To really be safe you shouldn't crank the motor at all if you think there is a chance of water in the system. Remove the plugs first and crank it a few times to blow any water out. The put the plugs back in and try to start. Most starters aren't strong enough to bend anything but if a cylinder fires while another cylinder has water it can do damage.
 
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