Attention Gear Heads. Hydrolock

[bruceb58]

I wonder why this affects some engines but not all? I have a 2014 R5 with the VP 380 and have chopped the throttle many times for various reasons with no ill effects. Now that I have read this I will probably think about it next time though. A couple weeks ago we met up with some friends that we saw beached on the river so I pushed our R5 up on the beach right next to them. They were beached in an area right next to a no wake zone. It was right where everyone comes down off plane so we were taking pretty big waves because we have a lot of really large cruisers on the St Croix river and it was really busy that day. As were were sitting there with the waves hitting the stern of the boat and even up over the swim platform I thought about this post but when it came time to leave the boat fired right up without any issues.

Did you have the drive tilted up? That will make a huge difference so that the wave surge doesn't get forced up past the risers.

[Snowman8]

I wonder why this affects some engines but not all? I have a 2014 R5 with the VP 380 and have chopped the throttle many times for various reasons with no ill effects. Now that I have read this I will probably think about it next time though. A couple weeks ago we met up with some friends that we saw beached on the river so I pushed our R5 up on the beach right next to them. They were beached in an area right next to a no wake zone. It was right where everyone comes down off plane so we were taking pretty big waves because we have a lot of really large cruisers on the St Croix river and it was really busy that day. As were were sitting there with the waves hitting the stern of the boat and even up over the swim platform I thought about this post but when it came time to leave the boat fired right up without any issues.

Did you have the drive tilted up? That will make a huge difference so that the wave surge doesn't get forced up past the risers.

It was probably trimmed up maybe half way, the water was 5-6’ deep at the stern of the boat so I wasn’t all the way up. I would guess that most of the people that have had their engines hydro lock by cutting the throttle at high speeds have been trimmed down.

[buzzy54]

I bought a new 2019 Cobalt 220S with a Volvo Penta V6-280 in the spring of 2019. Engine hydrolocked within the first two weeks. Great mechanic at our marina kept digging until he found a faulty thermostat in the engine. Found a piece of metal in the thermostat that was preventing it from operating correctly.
Thought we were all good but a few weeks ago it did it again. We've been driving boats for 40 years and never had this problem. We know not to stop short and have the water rush up the back of the boat.
Mechanics didn't find anything just got it up and running again.
The two times it has happened we had it out for a short run--maybe 10 mins versus other longer runs. Not sure if there is a correlation.
Boat is stored in a hoist well out of the water
Any input would be very helpful

[Big Block Power]

Yea the tstat would have nothing to do with a hydrolock. It's messed up forsure sorry.

[AsLan7]

I bought a new 2019 Cobalt 220S with a Volvo Penta V6-280 in the spring of 2019. Engine hydrolocked within the first two weeks. Great mechanic at our marina kept digging until he found a faulty thermostat in the engine. Found a piece of metal in the thermostat that was preventing it from operating correctly.
Thought we were all good but a few weeks ago it did it again. We've been driving boats for 40 years and never had this problem. We know not to stop short and have the water rush up the back of the boat.
Mechanics didn't find anything just got it up and running again.
The two times it has happened we had it out for a short run--maybe 10 mins versus other longer runs. Not sure if there is a correlation.
Boat is stored in a hoist well out of the water
Any input would be very helpful

.
Hey B54. So glad you found us!

I believe this is the first I've heard of the V6 having this issue on the forum...especially since most six cylinder engines have exhaust routed through the prop. Thru hull exhaust just doesn't sound that good with a six. Did someone add thru hull exhaust to your 220? Most of the hydrolock issues have been with later Cobalt models equipped with V8 VP's.

Thermostat is a separate issue.

And welcome aboard mate.

.

[2023BlackR8SURF]

Just bought a 2023 R8 Surf with the 430 Volvo in it. Took it for a test drive Saturday with the sales guy. They didn't tighten down the Bimini so I was on plane, went to neutral cause I was immediately worried the top was coming off. The wave crashed into the back of the boat and hydro locked it. All is well now after spark plug replacement, multiple oil changes, but I have never seen this happen to any boat. Been boating for 30 plus years. Was told by the dealer that this was a bigger issue with the 2020 models and 2021 models. Supposedly the riser has been adjusted to try to resolve this issue but seems they would come up with a better design. Needless to say, I will no longer be going from on plane to neutral ever. Also have to watch it when putting it on a lift. Learning experience for me. Love the boat thought.

[Krob1114]

I guess we've been lucky. Before reading threads here on hydolock, I never worried about the wave coming up on the back swim deck. Now we are taking measures to stop it, turning away for the wake or slowing down slowly.

[dsthomas]

The wave coming into the back of the boat causing hydrolock puzzles me... It must have to happen at high speed and I believe other things probably are happening in conjunction... we had a whole season with our 2022 R8 surf, it has a huge wave and if you don't turn immediately after pulling the throttle back it overlaps into the aft portion of the boat. I would think if it's a simple matter of JUST the wave they would have hundreds of hydro locking R4, 6, 8 surf boats???? I'm thinking there is something else that occurs in conjunction with that? I never go from on plane to neutral and we pull the throttle back relatively slowly, I'm just saying if it was something as simple as a wave I feel like this would be way more prevalent to the point they'd have to issue a recall of some sort?

[billk2632]

The likely hood of hydro lock has a lot do to with the engine installation. There are specific specifications as to how low the engine can be installed in relation to the water line and how high the exhaust risers are - some engines have spacers between the manifold and riser for this specific reason. Also, inboard ski/wake boats usually have some type of flapper on the exhaust. The exhaust risers have to be a certain level above the water line. Also, some marine engines have exhaust flappers installed in the exhaust, basically a one way flapper valve that will prevent water from running back in through the exhaust (I don't think VP engines have flappers, I know my Mercruisers (4.3 and 5.0's did). Hydro lock can occur in situations where the is not enough exhaust pressure to keep water from running back up through the exhaust AND you have either a following sea or a wake (from quickly pulling back the throttle). I could see where make a sharp turn in a wake boat and killing the throttle could bring the wake back into the boat and cause hydro lock - at that point the engine is at idle and there is not enough exhaust pressure to keep water from running back in through the exahaust.. It is not just limited to inboard / sterndrives, even an outboard can hydro lock under certain conditions. The other thing is to recognize it if it happens - if you try to start a hydro locked engine, it is likely to bend valves and/or connecting rods because water will not compress.

[dsthomas]

Thats great great info thank you. I really feel for those that have had this happen and I'll do all the things recommended to keep it from happening to me, but it sounds like it can happen from pretty much normal use if you get caught up in the right circumstances and sometimes it sounds like it just happens. This just seems like something that should have been handled by the marine industry years ago. Or am miss understanding and this is a very rare issue. Essentially the marine industry is saying "here's your boat, and oh by the way, avoid any large waves because that might ruin the engine". I might of thought twice before purchasing. ;0)

[AsLan7]

Just bought a 2023 R8 Surf with the 430 Volvo in it. Took it for a test drive Saturday with the sales guy. They didn't tighten down the Bimini so I was on plane, went to neutral cause I was immediately worried the top was coming off. The wave crashed into the back of the boat and hydro locked it. All is well now after spark plug replacement, multiple oil changes, but I have never seen this happen to any boat. Been boating for 30 plus years. Was told by the dealer that this was a bigger issue with the 2020 models and 2021 models. Supposedly the riser has been adjusted to try to resolve this issue but seems they would come up with a better design. Needless to say, I will no longer be going from on plane to neutral ever. Also have to watch it when putting it on a lift. Learning experience for me. Love the boat thought.

.
Hey 2023BR8S.....so glad you found us my friend. Sorry to hear about your hydro lock woes. We have certainly seen more of these issues with the late 2018 thru 2023 surf models vs the earlier Cobalts. Blame it on Bu.

Any pics of your R8?
And welcome aboard mate!

.

[Big Block Power]

I guess we've been lucky. Before reading threads here on hydolock, I never worried about the wave coming up on the back swim deck. Now we are taking measures to stop it, turning away for the wake or slowing down slowly.

You don't have to worry with your 240!
Not enough valve over lap.

[Big Block Power]

Just bought a 2023 R8 Surf with the 430 Volvo in it. Took it for a test drive Saturday with the sales guy. They didn't tighten down the Bimini so I was on plane, went to neutral cause I was immediately worried the top was coming off. The wave crashed into the back of the boat and hydro locked it. All is well now after spark plug replacement, multiple oil changes, but I have never seen this happen to any boat. Been boating for 30 plus years. Was told by the dealer that this was a bigger issue with the 2020 models and 2021 models. Supposedly the riser has been adjusted to try to resolve this issue but seems they would come up with a better design. Needless to say, I will no longer be going from on plane to neutral ever. Also have to watch it when putting it on a lift. Learning experience for me. Love the boat thought.

.
Hey 2023BR8S.....so glad you found us my friend. Sorry to hear about your hydro lock woes. We have certainly seen more of these issues with the late 2018 thru 2023 models vs the earlier Cobalts. Blame it on Bu.

Any pics of your R8?
And welcome aboard mate!

.

Another reason Cobalt should run Mercury power with the b4 surf drive. Solves all issues. Vp need to add flappers and Cobalt needs to adjust the risers. Bad bad bad. I would be pissed. #gomerc!

[Krob1114]

Just bought a 2023 R8 Surf with the 430 Volvo in it. Took it for a test drive Saturday with the sales guy. They didn't tighten down the Bimini so I was on plane, went to neutral cause I was immediately worried the top was coming off. The wave crashed into the back of the boat and hydro locked it. All is well now after spark plug replacement, multiple oil changes, but I have never seen this happen to any boat. Been boating for 30 plus years. Was told by the dealer that this was a bigger issue with the 2020 models and 2021 models. Supposedly the riser has been adjusted to try to resolve this issue but seems they would come up with a better design. Needless to say, I will no longer be going from on plane to neutral ever. Also have to watch it when putting it on a lift. Learning experience for me. Love the boat thought.

.
Hey 2023BR8S.....so glad you found us my friend. Sorry to hear about your hydro lock woes. We have certainly seen more of these issues with the late 2018 thru 2023 models vs the earlier Cobalts. Blame it on Bu.

Any pics of your R8?
And welcome aboard mate!

.

Another reason Cobalt should run Mercury power with the b4 surf drive. Solves all issues. Vp need to add flappers and Cobalt needs to adjust the risers. Bad bad bad. I would be pissed. #gomerc!

13 years of VP with no expence but oil and filter changes.

[billk2632]

Hydrolock is nothing new, it's been a problem for decades with marine engines. At one time or another every marine engine manufacture has had their engines hydrolock. It's usually not a particular manufacture, but more the design of the boat and engine installation and / or how it is used. Wake boats that have 1000's of LBS of ballast pushing the stern down or a fishing boat that routinely backs down on a fish in a following sea or the guy who routinely beaches his boat in an area where waves are rolling in on the stern. Flappers like in Mercruisers can help, but they are not foolproof and usually cause other problems eventually. I would bet in the cases of the Cobalts are mainly surf models and most experienced hydrolock when the ballasts were being used and there was a quick stop to pickup a wake boarder and the stern wave rolled into the back of the boat while the engine was at ide or even shutoff.

I personally have seen:
A Correct Ski boat - hydrolocked due do making a sharp turns at speed to pickup a skier and shutting the engine off.
An old Grady White with a Yammaha outboard -- this boat had a low transom, they were backing down on a fish and brough the engine to idle in a following sea, water ran in through the exhaust and locked the motor.
Kolher generator in a SeaRay 300DA - Hydrolocked due to overcranking with no start, lift muffler filled with water and eventually ran water back into the engine.

Was aware of this issue when I bought my SeaRay:
SeaRay 310's, 330's from circa 1999-2000 with v-drives - exhaust routing to the lift mufflers wash too high and could allow water to run back into the engine when engine was shutoff and allow water vapor to be drawn back into the engine while running at low speed.

It's just something to be aware of - I've had sterndrive and inboard boats for years, have put thousands of hours on them and personally have never had an issue with hydrolock, but if I had an R Surf and really used it for wake surfing, I would definitely pay attention.