I went offroading last week and got a fair amount of dirt (I will call it, since it it now dry) in the engine bay. I spent the better part of an hour underneath the 4Runner, getting it out of the nooks and crannies down there. I want to use a pressure washer on the engine bay as well, but I DON'T want to have any water-related issues. I remembered reading on here about a guy that pressure washed his engine and afterwards had a bunch of codes pop up, and had to take off the plenum, take spark plugs out, and blow the holes out with compressed air. Now, I'd like to avoid that if possible. I know not to spray directly onto the air filter area (the two pieces connect side-by-side with the crack vertical, right?) or the alternator, or any obvious electrical connections. Basically, I just want to know how to safely clean this thing, and what areas are off-limits and will give me less headache. Better to do it while the engine is running or off (I wouldn't do it after it's been running for a long time, in order to minimize the "shock" to the block / head). I've read a lot of conflicting information when I Googled it, so I figured I'd ask!
Pressure Washing Engine Bay
- Thread starter Koko4
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JamesDean91
New member
I have the motor running and don't spray directly at any major components kinda do a bunch of sprays quick by.
shootmymime
New member
you shouldnt worry about quenching shock, the metal is not anywhere close to above the austenitic region temperature for recrystallization. nor will there be that rapid of a thermal change.
drive it to the car wash and spray it down.
Ive only had problems once with getting water into the spark plug wells out of the 60 ish times ive washed my engine. like you said stay away from the alternator and the spark plug boots with direct pressure.
because you have been in mud and dirt you will have a film of dirt layer you wont be able to get off unless you scrub it. or you can spray the motor down with tire shine. that stuff gets under the dirt and will lift it off so the next time you wash it no more dirt marks or stains. when mine is dirty i just spray away, stay about 1-1.5 ft away from where your spraying and you will be fine.
engine can be running or off. i like off because the fan blades spray water everywhere and gets water all over me.
drive it to the car wash and spray it down.
Ive only had problems once with getting water into the spark plug wells out of the 60 ish times ive washed my engine. like you said stay away from the alternator and the spark plug boots with direct pressure.
because you have been in mud and dirt you will have a film of dirt layer you wont be able to get off unless you scrub it. or you can spray the motor down with tire shine. that stuff gets under the dirt and will lift it off so the next time you wash it no more dirt marks or stains. when mine is dirty i just spray away, stay about 1-1.5 ft away from where your spraying and you will be fine.
engine can be running or off. i like off because the fan blades spray water everywhere and gets water all over me.
Last edited:
AZ4Running
New member
I have pressure washed my 4runners engine bat many times like 5 times in the past few months and did not have any issues. Engine NOT running and dont soak the alternator or fuse boxes and you will be fine. I am a mechanic and have to pressure was engine bays all the time and i have never had an issue as long as it is done right.
