Hydrolock after accidental shutdown

[JR IN JAX]

My Daughter's new boat left them stranded mid-river in front of Renegades just before dark on the 4th. The starter would just click so they called me to drive down and give the a tow in. I had my S-I-L try to pry the flywheel around before I came, which he was barely able to do. He took it to the shop [the Merc 150 4 stroke is only 2 months old]. The shop was able to spin the flywheel a couple of times and it cranked. They determined that My S-I-L must have hit the key with his knee and it hydro-locked the engine. Has anyone ever heard of this before? I might understand if it was my Grandsport when I had the 15" mid 2.5, but this is a 20" mid.

They love the engine and boat and this is the first trouble with it.

[RSWORDS]

I've heard of it on small engines on big pontoons.

The Enertia of the boat moving forward at speed spins the motor backwards effectively turning the exhaust into the intake.

[rock]

Just dealt with it yesterday. Guy brings in 4 stroke 9.9 Merc that would not pull start. Motor seemed locked up until I pulled the top plug and gas ran out of cylinder. Told him to not leave fuel connected cuz if the boat sat in sun the tank would pressurize and force fuel past needle and flood cylinder. First time I seen anything like it. You would think the tank vent would prevent this but somehow it did hydrolock.

Rock

[RSWORDS]

Just dealt with it yesterday. Guy brings in 4 stroke 9.9 Merc that would not pull start. Motor seemed locked up until I pulled the top plug and gas ran out of cylinder. Told him to not leave fuel connected cuz if the boat sat in sun the tank would pressurize and force fuel past needle and flood cylinder. First time I seen anything like it. You would think the tank vent would prevent this but somehow it did hydrolock.

Rock

The new tanks dont vent until a certain psi.

That reason is also why the now use those stupid demand valves

[lbhsbz]

How's that possible?...wouldn't the lower unit just ratchet?

[nitro_rat]

Not familiar with the 4 strokes but the late model merc 2.5 lowers don't ratchet...

[JR IN JAX]

Thanks everyone for the advice. I am going to suggest him to position the driver's seat to make the key switch less prone to being bumped.

[Merc 2.5]

Just dealt with it yesterday. Guy brings in 4 stroke 9.9 Merc that would not pull start. Motor seemed locked up until I pulled the top plug and gas ran out of cylinder. Told him to not leave fuel connected cuz if the boat sat in sun the tank would pressurize and force fuel past needle and flood cylinder. First time I seen anything like it. You would think the tank vent would prevent this but somehow it did hydrolock.

Rock

My pressure washer hydrolocks if it dies or I cut it off with water on. Cant pull start till water off. Only thing I've dealt with like that

[rochelle howell]

My pressure washer hydrolocks if it dies or I cut it off with water on. Cant pull start till water off. Only thing I've dealt with like that
You should be able to start your pressure washer without turning water off if you squeeze the trigger.
This unloads the pump.
Works for mine.
Was sold to me as "won't restart when it warms up" Got a pretty nice one for next to nothing.

[flabum1017]

Ha! we go from engine filling with water to engine filling with gas to pressure washer won't budge............... Hey, I had an intestinal blockage once..... needed a lot of Mylanta and an enema to clear it..... :rolleyes::leaving:

[rochelle howell]

What could possibly be next?

[SS Minnow]

What could possibly be next?
How do I wire it to start in gear?

[rock]

Ha! we go from engine filling with water :rolleyes::leaving:

Totally misunderstood. So when he accidentally hit the key the motor ingested water? I understand the wake following the boat cuz I have nearly swamped a few of em. Hard to imagine it sucked in enough water to lock motor and with just a couple turns of the flywheel purged enough to start.

Rock