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Old 03-25-2009, 05:59 PM   #3
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Ok, with the question of hydrolock on alot of people's minds ALOT, i thought i would make a Quick Thread on Informational Facts:

HydroLock Definition:

In automotive terminology, a hydrolock (short for hydraulic lock) is the immobilization of an engine's pistons by a liquid (usually water, hence the prefix "hydro-"). Hydrolocking occurs when liquid fills a cylinder on the intake stroke and, due to the incompressibility of a liquid, makes the compression stroke impossible. This, in turn, prevents the entire engine from turning, and can cause significant engine damage if one attempts to forcibly turn over or start the engine. Typically, connecting rods will be bent, making the engine uneconomical to repair.


It is relatively common when driving through floods, either where the water is above the level of the air intake or the vehicle's speed is excessive, creating a tall bow wave.

Hydrolocking is often a concern when consumers modify their engines with aftermarket intake systems (e.g. Cold air intake). A cold air intake typically locates the filter near the bottom of the engine compartment to gain access to colder air, which can also increase its chances of ingesting water should it be submerged.

Another reason for it to occur is in the event of the head gasket cracking or "blowing", which causes the radiator coolant to mix inside the combustion chamber.


Regardless of the cause, treatment is the same. Removal of the spark plugs will allow access to the combustion chamber. By inserting an irrigation syringe fitted with a flexible plastic tube on the end, you can suck out the liquid that infiltrated the combustion chamber. Once all the fluid is removed, the chamber should be sprayed with a liberal coating of a water displacing lubricant such as WD40[citation needed], and allowed to sit until the remaining water has evaporated. Once the water or coolant has been removed, inspect the combustion chamber for rust. The best option would be to remove the head, but a borescope or small flashlight and mirror will also work. Light surface rust will be normal, but if you see any heavy corrosion, it should be gently removed, and vacuumed out of the chamber. After inspection, pour a tablespoon of assembly lube (such as Marvel Mystery Oil) or clean engine oil into each combustion chamber. Attach a socket to the crankshaft, and slowly rotate the engine through a few revolutions. (Make sure that you turn the engine in the proper direction, see a service manual for proper rotation direction.) If you hear any clanking, or harsh scraping, you should bring the engine to a competent mechanic. After verifying that the remaining systems are free of water (electrical, fuel delivery, air intake, distributor, etc.), re-install the spark plugs and wires, and attempt to start the engine.

Courtesy of Wikipedia


Hydrostatic lock, hydraulic lock or hydrolock occurs when liquids, typically water, enter an engine cylinder. This can occur from a coolant, oil or fuel leak, but the chief cause is drawing water into the engine through the air induction system (airbox & filter, ducting, throttle body or carburetor, intake manifold). Internal combustion engines (spark or compression ignition) operating on a two-stroke or four-stroke cycle must employ a compression stroke to compress the charge (usually an air/fuel mixture). Liquids are incompressible; the presence of a liquid in the engine cylinder during the compression stroke generates destructively high cylinder pressures.

Abnormally high cylinder pressures can bend and break pistons, piston pins, connecting rods, crankshafts and ruin bearings and can crack or break cylinder heads and engine blocks. Small amounts of liquids may pass through an engine cycle without damage, but volumes exceeding 40cc (1.4 fluid ounces, <3 tablespoons) will cause many engines to develop cylinder pressures well in excess of 1000psi. A larger volume of water, up to the combustion chamber volume (usually 60cc to 100cc), will generate increasingly high cylinder pressure during the completion of the compression stroke. Volumes of water which exceed the combustion chamber volume will "stop" a running engine through true hydrostatic lock. Something expensive always bends or breaks when this happens.

Hydrolock may occur while the engine is running, the work of the compression stroke being supplied by engine's rotational inertia. Or a liquid may leak into the cylinder while the engine is being stored; the work of the compression stroke will be supplied by the starter motor.

Hydrolock is not a new problem, but it only affected certain applications. Older American made cars, particularly with V-configuration engines, often employed an air intake location which was high in the engine compartment. Because of the reduced tendency of these older American cars to hydrolock, it has not been in the forefront of design consideration and is not a household term.

Most newer, fuel injected cars have the air intake located low in the engine compartment. The objective of this low air intake is to draw cool air into the engine. Unfortunately, when driving through sufficiently deep standing or splashing water, engine vacuum from the intake stroke will suck water into the engine, particularly if the intake is submerged.

The cost to repair hydrolock damage begins at about $1000.00, and only goes sky high from there. Repair bills in excess of $35,000 have been reported in high-end passenger cars. Racing engines can cost twice that amount. Many new cars have been recognized as having poor designs to prevent hydrolock. Even some Four-Wheel-Drive pickup trucks and SUV's have been identified as having particularly high incidence rates of hydrolock. Manufacturers' warranties do not cover hydrolock engine damage, stating that the cause of operator error. One SUV manufacturer states the maximum vehicle speed through standing water to be 5 mph; hydrolock occurring at speeds in excess of 5 mph is judged to be operator error. The repair may be covered by a vehicle's Collision/Comprehensive insurance.

Don't take our word for the causes and consequences of hydrolock. To the left are links to authoritative websites and individual tales of woe.

Courtesy of

AEM has a Bypass Valve in production, here is excerpt from their site about the AEM Bypass Valve:

AEM is in the process of including diagrams in its Cold Air Induction System (CAS) instructions for Air Bypass Valve placement. In the mean time, if you receive a system without this information and are unsure as to where the Air Bypass Valve installs on your CAS, please contact AEM customer service at (310) 484-2322, extension 300 and we will provide information on proper placement of the valve.

Generally, the Air Bypass Valve installs along the upper section of the induction pipe, close to the throttle body. Do NOT install it too close to the Inlet Air Temp sensor, and NEVER install an air bypass valve in between a throttle body and Mass Air Flow sensor (MAF). Be sure to check for clearance for the width of the Air Bypass Valve during installation, and to use the provided template that comes with your Air Bypass Valve to remove the proper amount of material from the induction pipe.

NEVER use an Air Bypass Valve on a forced induction vehicle as it will damage the valve and could lead to engine damage.


SO, with that said, there isnt a Logical place to install the Bypass valve in the duratec intake system...

Best tip for avoding hydrolock is to drive smart, and drive safe.

If it seems too deep, then dont drive threw it, also throttle control, If you have to go threw a deep puddle or one that'll create alot of water under the front of the car, drive into it with enough momentum to allow you to lift the throttle and allow the engine as little vaccumm as possible to avoid sucking up water.

I hope this helps people in the informative facts and information on Hydrolock.

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