Should You Pressure Wash Your Car Truck or SUVs Engine Bay

Okay. So we just washed the exterior of the vehicle. The question lies, should we pressure wash the engine bay?

Hey friends, it's Len here from 1A Auto. If you have a question on whether or not you should be pressure washing your engine compartment, I wanted to go over a couple things you should think about. Let's get into it. So if you look under your hood, you're gonna see three major components. You're gonna see mechanical, right? You have your engine block, you have the components that are mounted to it. They all have gaskets in between. If any of those gaskets are dry and brittle or even weak in any way, you could potentially force water in between the two and cause issues. You're also gonna have hydraulic units such as maybe your transmission, you're gonna have your oil, you're gonna have power steering fluid, coolant, and the list goes on. Most of these units have to have a certain type of lubricity to them or a lubricant to them. If you were to contaminate that fluid with something such as pressurized water, obviously it's not gonna be able to lubricate critical engine parts the way that it should. Also, you're gonna have a whole lot of electronic components, especially in newer vehicles. Every one of those electronic components is gonna have a connector that leads to it with some wiring, right? If you force water in between that component and the connector itself, you have a great possibility for getting corrosion or buildup or even electrical resistance inside the system. And you could cause very bad damage. And you're probably gonna notice some pretty weird stuff. Let's get a little bit more into this though.

So on this video, I'm gonna show you all sorts of different vehicles, but mainly every vehicle is gonna have a break master cylinder. If I was to spray water at this under high pressure, just to get off this little bit of dirt, is there a possibility I can get water under there and contaminate my brake fluid? Yeah. Would that be a safety issue? Yeah, absolutely. We also have our battery here. A lot of batteries have caps on the top. These are for vents. If I was to spray, once again, you can imagine what's going to happen. Is that battery going to be any good if I mess up the acidity on the inside there? Probably not. I'm gonna keep moving because this is all dirty. What's this? Let's take a look right under here. It's covered, but I wouldn't say it's airtight or even pressure watertight. If I was to spray any water inside here, you can imagine what might happen to any of these electronic components. This right here is a critical microprocessor for your vehicle. You can either have a PCM or an ECU, or generally both actually. And they're gonna be located in different areas. Why are they right out in the open where they're susceptible to rain and everything like that? Well, because maybe a little bit of rain water that might be splashing up coming through under the hood or through the radiator, or even from the bottom more than likely is not gonna soak this to the point where the electrical connector is gonna get water in there. You have your mass air flow sensor right here, critical component, spray that down. I want it to be nice and clean. Underneath there as an air filter, more than likely I'm not gonna get very much water on that air filter because it is sealed pretty good. So we're not really necessarily worried about that. But if we're talking about air filters and you moved over to other side of the vehicle, generally behind the passenger side right here on a lot of vehicles, you'll have a cabin air filter. Sometimes it's located along the top of the engine compartment right here, or even maybe behind the glove box. If it is behind this area right there, and I force water in there, your cabin air filter is going to be wet and something that's wet that dries slowly, is gonna eventually get mold or even other types of spores in there. So is that a safety issue? I would definitely say that's a safety issue.

Other things things you wanna think about down along here, you're going to see you have your alternator. I'm spraying that because it's all dusty, right? Well, that's probably not a great idea. Yeah, I'm cleaning it up and it's going to look great, but there's stuff inside there that needs to be able to function properly. And it's not supposed to be sprayed directly with water like this would be. There are of course other issues that you might run into if you were spraying electrical connectors, because there's a whole bunch of different things. There's gonna be sensors, there's gonna be actuators, there's gonna be computers. There's all sorts of things inside your engine compartment that you just should not force water into.

Now in all honesty, it's really not even a good idea to pressure wash older vehicles because if you look underneath the air filter area, you're gonna see right back here where your distributor cap is. Distributor caps are very susceptible to water damage, mainly because of the seal that goes along the bottom of the base. Moisture can get up inside there and if it does, it'll make it so you're not getting any spark coming from your electrode in the center and going out to your spark plug wires, which of course is part of your ignition system. What you might notice if you get water inside there is probably a misfire of some sort. You'll probably get a check engine light. And even in some cases, your vehicle might not even start. Also since we just lifted up the air filter, you're gonna see that there should be a seal right about here. And then of course, one underneath that plate as well. If I was spraying directly underneath this area, is there a possibility I can get water in between this? Yeah, especially if these were loose. If I get water in where the air is supposed to be getting drawn into the engine, obviously I'm not gonna get the proper combustion that I need to to run the engine. So more than likely the engine is either once again gonna misfire or even not start.

Now, I'm looking down along the side of this engine and something that I wanted to mention is you definitely don't wanna wash your engine in any way if the engine is hot. You have your exhaust manifolds here. If anything's hot or generally if things are hot, they expand. So this metal would be expanded. And then let's say you go ahead and you wash it down and you just spray it for an extended period of time, cooling it very rapidly. If you cool something that was very hot, rapidly, more than likely it's gonna crack or break in some way in which case you probably see a crack along here or along pretty much one of the bends generally. And you might also get issues with your O2 sensors.

So now if you're looking up along the top of your engine, you're gonna see your valve covers and more than likely they're probably pretty dirty. So you'd want to clean those down as well. The problem with that is you're gonna have your oil cap usually on it. And the oil cap just has a little seal under there. That seal isn't necessarily supposed to have water being sprayed at it under pressure. So if water happened to seep by it's gonna make its way right inside your crankcase in with the engine oil, and you can imagine what that would do to the engine.

Some vehicles will actually have covers over some of their integral parts. This right here is a coilover, the spark plugs are gonna be located in the engine just underneath this. Obviously you can tell that it's less likely to get moisture issues on something like this, rather than that distributor that I showed you a second ago. But of course there is still an electrical connector that if you force water into it's gonna cause an issue.

Okay, so we're gonna say we decided not to use this pressure washer here. That's great. We decided to maybe use a regular hose. Even using a regular hose, you could still potentially get water inside of those electrical items. So once again, just be super careful, be very careful for electrical and especially hydraulic. If you get water inside your braking system, your oil, your transmission fluid, you're gonna have major issues. Once again, water inside your electrical system as well is not a good thing. You're probably gonna get some engine light codes on, maybe a traction light, maybe an ABS light, your car might start doing some really fluky things. If you're gonna clean down your engine, just kind of do it with very low pressure, make sure your engine is cool, and just kind of clean the areas that you feel as though you need to.

All right. So if you like the video, make sure you smash on that like button for me, it would mean the world. If you learned something or if you got something to say, please leave it in the comment section. I love to hear from you. While you're at it, why don't you go ahead and subscribe and ring the bell that way there you can be kept up with all of our latest content. Thanks.
Man: Thanks for watching. Visit 1aauto.com for quality auto parts shipped to your door, the place for DIY auto repair. And if you enjoy this video, please click the subscribe button.