Engine Heeltoe Explains Universal Fit Blogging

Will a Cold Air Intake Suck Up Water and Hydrolock My Engine?

A performance intake system is one of the first things people buy to improve the performance of their cars. For the most, the “cold-air” class of intake is preferred as it is known to bring in denser, cooler air than “short rams” for the maximum gain in power. Oftentimes these cars are daily use, and it also comes up fairly often that cold-air intakes are questioned for use in rainy or wet areas because of the risk of engine damage.

A recent email from a customer asks it all:

“I understand that heat soak is possible with short ram & can slow me down, but the possibility of hydrolocking on a brand new car [with a cold-air intake] doesn’t sound very appealing to me. All my friends have very conflicting opinions on this & I’m basically caught up in the middle!”

Before we get to the response, I’ll explain a little about the reason for the concern.

Why are CAIs a concern?

Cold-air intakes (CAIs) work by placing the air inlet down behind the bumper cover, away from the engine bay where hot air accumulates. Because the air filter is low and closer to the ground, there is a concern that it might suck up water, and hydrolock the engine.

In a very brief explanation, hydrolocking is a catastrophic condition where water enters the engine’s cylinder. This is a problem because engines operate by creating an air-tight cylinder to compress gas and control combustion. Water is non-compressable, so if the cylinder on the compression stroke is full of water it will break the engine. Most commonly, the connecting rod will bend or break, and most likely cause the piston to break or tweak inside the bore causing it to get jammed (or locked). Hence the term hyrdolock. So, one should definitely avoid sucking water into the engine!

So how real are the risks?

Our reply puts it in real, honest terms:

“The hydrolocking issue with cold-air intakes has been blown out of proportion. While it is a real possibility, the chances of you actually encountering that scenario are very slim. Unless your daily commute involves fording small creeks or pools, that is.

“In all seriousness, you would have to be driving through deep water, fully submerging the filter, for this to be a real threat. You’d also have to apply common sense and not drive through floods. We would not hesitate to use cold air in a place where it rains heavily all the time (we have a store in the Portland, we know rain). You do need to be mindful that if you’re driving through a freakishly deep puddle, it might be time to re-evaluate your route.”

It’s a deep concern

In a cold air system where the filter is placed near the ground, the amount of water that is required to submerge the filter is usually 8-10 inches or more. Hold a tape measure up to your leg to see how deep that is. You would not likely drive through water this deep, and so you really should not have an issue if you can avoid driving in such deep waters.

Furthermore, the engine is going to want to stall if it tries to suck up water. The deeper you go, you might find that more throttle is needed to push through the river, but more than that you are just going to ingest more water. If you are driving through water and the engine starts bogging, don’t floor it. Shut it down!

But, I’m a special case…

The next argument made is typically regarding special cases where the filters aren’t just lower to the ground because of the CAI, it’s “really really” low because the car is lowered a lot as well.

“My car is really low though…the water would not need to be really deep for me to have an issue then?”

Well, how much lower than the next car is yours? My car is lowered 2″ and yours is lowered 3.5″ That means if my car is “safe” in 8″ of water, yours is only “safe” to 6.5″? the point is the same. Whether the car is stock height, or lowered 3″ isn’t the point. The point is, try not to drive through water deeper than you would walk through in rain boots.

But, aside from the issue of driving a car at an unsafe ride-height, this argument can also be made about water being just a little bit deeper than you might think. In other words, the false judgment of how deep the water is causing issues more than the filter being a little lower to the ground because of your static stance life.

The best rule of thumb is if you cannot see or tell how deep the water is, avoid it. Go around or go another way. There are possibly times when you have no choice, but that would not preclude you from having an issue even in a completely stock car. At the end of the day, floods cause issues for cars. A cold air intake is not likely to work against you dramatically.

Keep your splash shields and fender liners

Are your fender liners and splash shields in place? They should be. If they are, this won’t get you out of the flooding issue because those shields aren’t water-tight. But with them, the filter is going to be pretty well protected from splashing water.

It can happen that the filter may get WET, but not actually suck up water. The filter, if installed properly on the car, is covered in the front by the bumper, and the bottom and sides by a splash shield. If you remove the splash shields from your car (or they are torn off by scraping along the ground or poorly fitting wheels), it is highly recommended not to install a cold air intake.

Without splash shields, the filter will be exposed to water and will surely become saturated in rain. This will not cause a hydrolock, but the saturation of the filter will not allow air to pass through. Without air, the engine will suffocate and stall the engine. Aside from the fact that driving with the filter exposed so close to the road will dramatically accelerate dirt accumulation and generally lead to poor performance.

So to sum it up

  • Driving with a cold-air intake in the rain will not cause your engine to hydrolock.
  • Driving with a coil-air intake without splash shields and fender lines will cause you problems.
  • If you aren’t able to avoid driving through water deeper than 6-8 inches deep, a cold-air probably isn’t for you.
  • Don’t lower your car too much and then worry about performance concerns, because the low-life and the #gridlife are mutually exclusive.