Did a little research on Hydrolock

I was recently talking to a buddy about hydro/hydralocking. After going offroading and seeing two vehicle die in large puddles i decided to do a little research. I was sceptical that the starter had enough strength to bend a rod or blow a head gasket. Im sharing what i have found.


When off-roading through water the biggest fear we all have is hydro-lock.

Hydrolock (short for either hydraulic lock or hydrostatic lock) is a condition of an internal combustion engine in which an incompressible liquid has been introduced into its cylinder(s), resulting in the immobilization of the engine's pistons. The liquid causing this malfunction is often water. Internal combustion engines must compress air to work efficiently and this works because gases can be compressed. Liquids do not compress so if a volume of liquid greater than the volume of the combustion chamber at its minimum (top of the piston's stroke) enters the combustion chamber then the piston cannot complete its travel. Either the engine must stop rotating or something must give. The result is often a bent connecting rod or sometimes a cracked cylinder head or block.

True hydrolock causes damage as soon as the engine stops. When driving through water, if the engine ingests enough water it will instantaneously stop often causing a loud clunk. (bent rod/cracked block). The damage is from having an engine turning several thousand rpms and suddenly stopping because the fluid does not compress.

In my research I have found that it is a common myth that trying to start a hydrolocked vehicle can cause damage. The damage is usually done by the engine suddenly stopping from non compressible fluid in the cylinder while running. The damage is done before trying to start the engine.

From experience, I have seen vehicles hydraulically locked and attempting to start the vehicle has not damaged anything. A toyota celica came to my fathers shop and wouldn’t start. Just a loud click. After we tested the starter and starter solenoid we dug deeper and found the owner had put wayyyyyy too much oil in the vehicle causing hydraulic locking. We drained 5 qts of oil and checked the level and it was just over the full mark. The lady had been putting a quart of oil in the car everytime she got gas because her husband told her to check it at every fill up. She misunderstood. Then one day she got gas and put a qt of oil in the car and it wouldnt start, not even turn over. With countless tries to start the engine there was no internal damage. She has had no problems and is still driving the car after we drained the oil and emptied the oil from the cylinders.


There is hope for a truck if there is only enough water to cause combustion to stop not hydraulic locking. The best way to tell is if the truck starts to die slowly… not instantly. The water causes the gas to not atomize and combust properly.

Have your offroading buddy pull you out
Remove the spark plugs and crank the engine over to blow out any water.
If you luck out and can get the vehicle running again, go home and change the oil in case any water may have made it into the case.

 

Good info! I was wondering that myself, since it was my first time off roading like that and having those 2 guys pretty much eat it.

 

haha like your avatar there MHS. looks like were from the same area.

 

does pulling the plugs and cranking really work? any videos anywhere of that happening...to lazy to search youtube

 

Yeah, i'm from Coos bay..currently stationed down in SoCal right now. Gonna be up your way at the end of december though!

I'm pretty sure it does...I think that jeep that had problems on that run today might have done that...i'm not sure though. Never stuck around to find out. But never had any first hand experience myself.

 

nice small right up rolland. cool meeting u today!

 

it works. i did it on my old k5 once when i got too much water in the intake.

 

Chris4x4???

 

Pulling the plugs and cranking does work, It also shoots the water out FAST. Anyone who went on the run with us remember that red jeep? Hes a buddy of mine, he hydrolocked his motor when it was stock, so we towed it home, pull the plugs and cranked the motor over. It shot water out A LOT OF IT.

 

http://www.youtube.com/watch?v=8l3EXIm0AHo

 

the big thing i was surprised about is that it has been proven that trying to start a hydrolocked car wont bend a rod or damage the engine. The starter is strong but not strong enough to break anything. The damage is actually caused by the engine running and the water locking it up hard.

The best way is to take the plugs out and crank it, clean the plugs and it will start. change the oil too as water probably got in it.

 

Change the Oil twice, my buddy changed his oil after that, and we pulled the dip stick and it was still milky. drained it again and the oil was milky.

 

I'll have to disagree with this....

Damage may not necessarily be caused immediately upon hydrolocking.

It's not a myth...... and I'll try to explain it like this:
Imagine you have 6 cylinders. When attempting to start the engine (with starter), at some point - the spark plugs will fire on the cylinders in the upstroke. When those cylinders fire - it forces the other cylinders into their compression stroke. If there is any water in those cylinders while its' trying to compress the water, that's where the damage is caused. You can have water in only ONE cylinder to cause major damage - while all the other cylinders can fire up as normal....when that one cylinder reaches the compression stroke, the damage can be done. Atleast, that's how I understand it.

And yes....removing air filter & getting as much water out of the intake as possible, removing all plugs from the cylinders. Spray WD40 in the cylinders (to help displace the water). Crank the engine over and watch the water come flying out in a myst spray. Keep cranking the engine over until the spray is clean. Spray more WD-40 in each cylinder. Put spark plugs back in and try to start. It's smoke like a chimney for a while.
This also works if you roll your vehicle and you get oil in the cylinders.

 

That does make sense, why risk it whether its a myth or not. just pull the plugs and cross your fingers the damage didnt happen the first time the water locked the engine...

 

thanx i'll keep that in mind!

 

I did the remove the spark plugs thing on our jet ski when it sank overnight on the beach (we take it out of the water now lol). It worked great and started right up with the same plugs. That is a two stroke though.

 

Random question:

Im assuming the deckplate mod INCREASES the chances of this. Has anyone had any problems out of the deckplate mod with water in your intake?

 

Good thread BTW. and an even better write-up

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You put the deckplate in before wet conditions. And if sealed properly it should not be a problem.

 

i have the deckplate mod and dont worry about water getting in. the deckplate hole is right in front of the headlight housing (on my 02) so i dont see how much if any water would get around it. the only thing that i could think of if you go through a super deep whole and submerge it but at that point your introuble already and should have a snorkle. i keep mine open during rain, and when i take it to the car wash and its still running. but afwrestler is right, if your worried about it just screw the deckplate in before wet conditions.