After seeing several forum posts and receiving many emails asking about performance intakes and sucking in water I decided to write this bog, because I wanted to get this cleared up for everyone with questions.

Water is everywhere, as our planet is covered in it. There is water in the air. When you are driving your car down the road you are sucking in water. It may be water vapor but it is still water and harmless to your engine.

Open element filters in either short ram intakes or cold air intakes have water come in contact with them by splashing puddles or rain. With air passing through the filter the water gets vaporized (evaporates) and gets consumed by the engine during the combustion process. This process is like the hand dryers in a washroom that blow air across your hands to dry them. The water enters your intake as vapor which is safe for your engine.

There are several companies that sell water injection systems for combustion engines. The water cools the fuel air mixture resulting in less chance for engine detonation. This is helpful for forced induction engines running higher boost levels to control detonation and get more power.

The only time you will experience water damage/engine destruction is when the intake in your car creates a seal with a water source, as in complete submersion. The engine creates suction from the air pumping movement thus pulling more water into the intake towards the engine. This becomes a problem when the water gets to the cylinders and the crankshaft tries to move the piston up. Water does not compress like air and causes the piston to stop and catastrophe occurs. This is called hydro-lock, which is when the cylinder is too full of water and the piston moves against it effectively preventing, or “locking” the engine from further movement. The result of hydro-lock is bent connecting rods, broken pistons, etc. It is not pretty.

Hydrolock Damage

Cold air intakes normally get the bad rap for sucking up water and hydro-locking engines. You would have to move your vehicle into large water mass, like a very deep puddle and submerge your air filter for this to occur. If you live in a climate that has lots of standing water or floods on a regular basis a cold air intake is probably not the best choice. Short ram intakes normally have the filter situated up higher in the engine bay near the throttle body. The chances of water being deep enough to cause a seal and suck in water are pretty low. You would need the water to be higher that the filter location in the engine bay. This also applies to the stock intake airbox. If you see water cresting over the top of your hood you have more problems than water getting into your engine.

Sure fire defense against water in your intake

If you want an aftermarket intake and you are paranoid about hydro-locking your engine there is a solution. The sure fire way to avoid water getting into your engine is an intake snorkel. Most have the air pickup at the highest point on the vehicle to give you the best chance when fording a river.

Mazda BT-50 crossing a small creek

The best advice I can give is to steer clear of deep standing water if you have a performance intake installed in your Mazda. If you are not sure how deep the puddle or standing water is go around it.


6 Replies to “Hydrolock”

  1. Great post Derrick. I’ve neglected looking at CAI because of the high amount of H2O we get here in Vancouver. Glad to know I can purchase the CAI for my wife’s car and not worry about hydro-locking!

  2. You literally have to plow through a lot of water to get hydrolock to happen. Under normal driving, if you get the filter will get wet and that immediately changes the amount of air getting, the ECU will see that from the MAF and put the car into a limp mode to protect the car before any real damage can happen. I drive my CX-7 semi-regularly through 2 feet of water (it floods in my area during the rainy season), I’ve done it with both a SRI and the stock intake with no problems, but I was crawling through the water and not stirring things up too much.

  3. Brilliant post Derrick. I have a 1993 BMW 320 i Auto Coupe, and by accident I poured in a lot of engine oil. I changed the fuel pump relay as when I connected it, the relay seemed to be “STUCK ON” causing a discharge of PETROL/OIL from seemingly under the engine, flooding the whole road. The mechanic had a look and said something about the PISTON could this be PISTON HYDROLOCK?…Can that make your engine a write off????…Saying it was dead!!!…Had 3 weeks of using the M3(lookalike)….Can you fix the engine?

    Help Please….


  4. Very Informative Post Derrick, never really understood Hydro-Lock until now. I’m currently running the SRI on my 2.5 and contemplating on this new CAI. Although I find myself when the opportunity presents it during rainy days I like to run through low level puddles that are about 4-6 deep just to make a splash around me for fun. But I know if I go CAI have to be more cautious. But since it’s interchangeable to a SRI I will only run it on rainy days. But who am I to complain about rain, I live in sunny So*Cal!

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