What does it take to hydrolock?

[WIDTIO]

So me and my roommates have been debating on what it takes to actually hydro lock a motor.

I've heard that if you are wheelin' in deep water and your tail pipe is submerged in water and you kill your engine (ie shut off or stall) youll be hydrolocked.In what circumstances could this be true, or is it always true.

Just curious for the future.

BTW this is me over the summer.

 

[Ozwynn]

you have to get water in the intake. more than once I was my tail pipe was submerged and I stalled the engine.....

 

[WIDTIO]

you have to get water in the intake. more than once I was my tail pipe was submerged and I stalled the engine.....

Good to know. However, I've heard that if you stall, sometimes the engine can actually vacuum and pull water from the tailpipe into the cylinders. Is this possible or just a theory?

 

[Ozwynn]

I have heard that aswell but I do not think it is possible with a stock motor

 

[Big Jim M]

Good to know. However, I've heard that if you stall, sometimes the engine can actually vacuum and pull water from the tailpipe into the cylinders. Is this possible or just a theory?

Like you wrote...in theory it IS possible.. It would take a very short exhaust pipe and even more this and that! All I have ever HEARD of had the hydro come into the cylinder thru the intake system.

Take note! If you ever have your engine stop while in deep water...don't try to restart it! It will only get worse and worse, trying to turn it over.
Big JIm

 

[stegomon]

hmmmm i have ha water in 2 engines....one i just spun the engine over with the starter for a few minutes and vrooom...was a great day...then the last one one was a little bit of water and yup....2 bent piston rods

 

[srteach]

Hydro lock is getting enough water into the cylinders to cause the cylinder to hit and compress the water. This can only happen if there is more water (volume wise) than there is space when the piston is at TDC (Top Dead Center).
It is easier to get water into the cylinders through vacuum (intake) than through pressure (exhaust).If you hydro a motor, you have stopped the piston movement when the rod and crankshaft were still in motion. Bent rod is usually the result, sometimes a broken piston.

Big Jim and BDAB are correct.

What does it take? 4 liquid ounces or more in ONE cylinder will hydro most stock motors. 1 liquid ounce can kill some motors.

 

[wahlstrom1]

If you suck water in and it stalls or starts making noise, get towed out. Then pull the plugs and crank it over to clear the water out. Hydrolocking a motor is a quick way to empty your wallet.....

 

[stegomon]

i was lucky....the bill on fixing my truck was only $100

 

[fangotango306]

i did this yesterday and pushed my truck out and pulled plugs and blew out the cylinders but, another thing to watch for is the oil pan will fill with water too, and so will the axle unless you extend the crap out of the vent line. my clutch was also slipping for a while after we got it running. water was up to the bottom of my seats, luckily i dont have carpet. a snorkel is in the works now.

 

[Gotta_gofast]

Actually, its still a good idea to change the differential fluid when the axle is submerged even if the vent tube was still above water. Reason is, warm fluid is cooled rapidly by the water. This in turn creates a vacuum and can sip a little water through the seals. How much water gets in depends on how hard you were running your truck (to create heat) before hand, how worn your seals are, how cold the water, and quick you submerge the axles.

Since I regularly tow a boat in the summer time, I make it a habit to change the diff fluid once or twice a year because towing a boat puts a little more stress on the ring and pinion gears creating more heat. Then I'm dipping the truck right into the water to load/unload my boat.

 

[UrbanRedneckKid]

Good to know. However, I've heard that if you stall, sometimes the engine can actually vacuum and pull water from the tailpipe into the cylinders. Is this possible or just a theory?

It is very possible, if the water in your exhaust is up to the manifolds.

It's called "scavaging", it has to do with both intake and exhaust valves partially open at the same time. The air leaving the cylinder aids in starting to pull the fresh air into the cylinder also vice versa. Also has to do with exhaust "pulses", and how headers work to create more power.
*very summed up explaination.

So yes, just before every intake stroke the exhaust does suck in.

Also on another simpler note, if water is up to the valves, and the exhaust valve is in the open position. the water could go in.

 

[bobbywalter]

It is very possible, if the water in your exhaust is up to the manifolds.

It's called "scavaging", it has to do with both intake and exhaust valves partially open at the same time. The air leaving the cylinder aids in starting to pull the fresh air into the cylinder also vice versa. Also has to do with exhaust "pulses", and how headers work to create more power.
*very summed up explaination.

So yes, just before every intake stroke the exhaust does suck in.

Also on another simpler note, if water is up to the valves, and the exhaust valve is in the open position. the water could go in.

most oem exausts have enough bends to prevent this.....














but. oil, thats a sneaky one and i have seen that eat quite a few engines. too many. if you have a well worn engine and flopped on its side where it has a tire or two off the ground and is allowed to sit like that for an exended perion of time its a good idea to pull the low side plugs and crank it a bit before powering it up for the recovery.