Pressure washing the engine is a 
Pressure wash question
Thread Starter
Melting Slicks
Joined: Mar 2003
Posts: 2,532
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From: Willow Springs Ca.
Pressure wash question
Going to clean my engine. Will Simple Green everything then pressure wash it. I remember reading on here sometime ago that there is one area that you should not hit with the pressure washer. Anyone know?
Drifting
Joined: Mar 2017
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From: Long Island New York
Lots of areas you shouldn't hit....
The intake is not watertight, fuse box area, alternator.
I use very rarely, just a garden hose mist and a mild degreaser. Pressure washer maybe the under body and that's it.
The intake is not watertight, fuse box area, alternator.
I use very rarely, just a garden hose mist and a mild degreaser. Pressure washer maybe the under body and that's it.
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I would not use a pressure washer on the engine. If you need to use water, a garden hose with a gentle spray should work just fine. Others may have used a pressure washer and had no problems, but I prefer to be cautious.
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I know there are many who suggest you can pressure wash the entire engine and engine bay, but there are too many potential pitfalls for me. It's almost like the battery question of whether the AGM battery is needed. Many people have used regular batteries for years with no problems but others have had the battery leak that damaged wire harnesses, the Throttle Actuator Control or Power-train Control Modules, or the vacuum lines for the A/C. To me, many of these same areas (especially the TAC or PCM) can be affected by high pressure water spray.
Hopefully all goes well for you if you do pressure wash, and it does make your engine and bay look good.
Hopefully all goes well for you if you do pressure wash, and it does make your engine and bay look good.
Team Owner
Joined: Aug 2003
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From: Scottsdale AZ
Simple green half strength on a warm engine- avoid the belts . . .use a soft bristle brush to loosen caked on stuff- bag the alternator and the fuse block... use a regular garden sprayer to rinse things off and let it dry for awhile without starting until things are generally dry - - use a towel to mop up standing water. If you want to go nuts with a high pressure sprayer underneath the car and in the wheel wells and barrels of the wheel fine- but suggest you not use high pressure on the engine.
While you're at it- it might be a good time to direct the pressure from the hose from inside the engine compartment forward on the radiator to try and blow out bugs and crud.
I also have used tire foam on the plastic parts-- avoid the belts on the front of the engine-- and then use a damp wash cloth to even things out.
Good luck-
While you're at it- it might be a good time to direct the pressure from the hose from inside the engine compartment forward on the radiator to try and blow out bugs and crud.
I also have used tire foam on the plastic parts-- avoid the belts on the front of the engine-- and then use a damp wash cloth to even things out.
Good luck-
Last edited by CQRT; Aug 8, 2018 at 06:25 PM.
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From: Erlanger, Kentucky
I use full strength Simple Green in the engine bay several times along with pressure washing. I use low pressure around any electrical components and stay away from the alternator. Any areas with caked on dirt or grease, I will go with high pressure but sparingly. I have done this at least 3 times on my Z06 and have never had any problems. I will wipe down as much excess water as I can then go for a drive to evaporate any pooled water.
Team Owner
Joined: May 2001
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From: Western NY
Just a thought.....if you use something like Simple Green, and a soft bristle brush, followed by a rinse with the garden hose, every once in a while, you WON'T have to deal with "caked on grease", that requires "high pressure washing" to clean it off.....
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From: Erlanger, Kentucky
I have had several cars over the years and have used Simple Green and a pressure washer and not had any problems. But, you need to use good judgement on where you can hit with high pressure. Areas like the side of the block, the oil pan area, etc. are quite safe. Electronic components, wiring, plastica you want to be gentle and use low pressure (garden hose) or not directly hit with any water.
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You guys who have used pressure washers......what nozzle were you using out of curiosity. I will be doing this to my engine bay shortly with a sealed partially assembled motor, just to clean up some not so meticulous previous owner cleanliness.