View Full Version : hydrolock / water in cylinders

05-11-2011, 12:40 AM
Just wanted to share my latest experience with my new to me 05 xlv. Bought the boat in the fall with only 38 hrs on it and have used it for about a month now and have the hrs up to 63. Beautiful boat in damn near show room condition.

Saturday i noticed my starter sticking. if you played with it enough it would finally turn the motor over. Ended up getting stranded on the lake sunday and needed a tow in as i thought my starter was shot as it couldn't turn the motor.

After pulling from the water and getting back to the house i noticed my oil was very milky and approx 2 quarts high. All was perfect on friday night when i checked fluids. something had happened during an outing on saturday.

Went to the local mechanic and he advised me that i was probably hydrolocked from having to much weight in the boat and water rushing up thru the exhaust and flooding the cylinder. Recommended to take the boat home, pull the plugs, spin the starter to push out water, change plugs and oil and all should be fine. He was correct on the hydrolock but not on how the water got in.

Tonight i started the boat to circulate and change oil again to remove remainder of water which was in the oil and the starter was stuck again. I again pulled plugs and found water in the passenger side cylinders. Hoping i just didn't get it all out last night, i ran again on the fake lake. after 5 min of run time shut it down and pulled the plug again to check. Sure enough more water in cylinder #4 (passenger side back of boat).

Got to thinking of how it got in and came to the website here. Found the below thread in service and repair titled "boat motor cylinders filling with water" by walb0244.

Got to thinking and understanding how things work with the exhaust and decided to remove the passenger side riser and exhaust manifold (pretty simple removal). Did a water test on both and sure enough found a leak in the manifold right above the cylinder 4 position. Ordered a new manifold tonight and will install when it gets here. Total bill is around $400 for the manifold, gaskets, and a few oil changes to flush the water from the crankcase. Sucks but could have been worse so I'm grateful.

Mechanic was partially right by pointing me to the exhaust area instead of the starter. Not sure if his theory of the boat being sunk to deep and water rushing in is accurate but will always be in the back of my mind now. it may have caused the initial crack as we were trying to learn to surf saturday morning and our water temp is only 60. The slow speed, big wave offset to the damaged side and a lot of sudden stops may have pushed cold water up past my flappers and caused a stress crack, who knows.

Just wanted to thank everyone and express how great this forum is. I've learned so much and its my #1 resource for any issues with my boat. Great ideas also for misc mods.


05-11-2011, 12:45 AM
A little extra lean to the boat isn't going to be a problem at all IMO. Glad to hear you found the issue before it turned into a bigger one! What lake do you ride on?

05-11-2011, 01:07 AM
Lake Manawa over in council bluffs. Little to much boat for this lake but the deal was to good to pass up. Look me up if you're ever in the area.

05-11-2011, 01:34 PM
Never thought about this happening. I find it highly unlikely, the water level in relation to the muffler would have to be above the bottom of the muffler , then your motor would have to be shut off. I guess this could happen if you are loaded down to the rub rail when at a stop on the ipsilateral engine side. The muffler is fairly high and I would think you would have to have water coming into your boat before this would occur. .02

05-11-2011, 03:05 PM
Not a mechanic, but thought it was all about the pressure. If you had a pressure leak in the manifold, then water could get to the cylinder. I've seen a few boats with rubrail and vents under the water (vents sealed off) to the point of touching the sunpad (extra bilge pumps). Crazy stuff and I would never condone it anywhere.

I wonder how well the flapper plays a role?

05-11-2011, 04:01 PM
my guess is that the weighting of the boat was not any relation to the issue. For some reason a random crack occured in the waterjacket of the mainfold. Just glad it was found early. I'm going to take it easy on the boat for a few outings and keep an eye on the oil condition. I'll give an update when the new manifold shows up and gets installed.

05-11-2011, 04:07 PM
I have the gravity 3 ballast system in my Outback V and I add an additional 1200lb when sufing so that is 2400lb in my boat plus the passengers.

I never once had any issues with water getting in due to having too much weight in the boat.

05-11-2011, 10:33 PM
I agree with the other posts, I'd check your flapers make sure they are closing properly, also when surfing really try to avoid sudden stops and or sudden engine shut downs.

Was this the first time out this year? If so my thoughts are water was left I. The exhaust over winter and caused a stress crack, your putting Friday caused the stress crack to become a fracture. Then it started leaking at the end of the day and Sunday it got bad enough to take in water and create your problem.

Another tip is even when your rider is done after there sets cruise up slow let the engine have a minute to pump that cold lake water threw and cool off before just shutting it off also

05-13-2011, 01:45 AM
They run Jeep engines under water with no problem if they have an air intake snorkel. You may have more of a back pressure issue than hydrolock. You probably has a part that went bad.

05-13-2011, 03:42 PM
I've had it in the water for a month and put around 14 hrs on the boat already for the year. Like i said, my guess is that its a random crack in the exhaust manifold. I only run 400 lb bags on each rear corner so its never really been that deep in the water. that emiminates the theory of the water pushing in to the block thru the flappers due to being to deep. It was the cracked manifold let the water in the cylinder which caused the hydrolock. New manifold shows up mid next week so i'll get it installed and issues should be gone.

05-18-2011, 10:41 AM
got the new manifold yesterday and installed last night. Going to start it tonight to get the oil cycled to try to absorb any remaining water that may be thru the block. I'll do another oil change after that. Planning on pulling the plugs one more time after running on the fake lake to see if there is any new water showing up. If no water in the cylinders i'm going to claim a victory. All in all not a hard repair, just was lucky enough to find it early before any major damage could happen.