Safe to pressure wash engine bay?

Celco

Veteran Member
Joined
Feb 7, 2005
Location
Warren, MI 48092
TDI
2002 Golf 4dr ALH 5-speed
I just picked up a 2002 Golf TDI 5-speed with ALH. The PO took off the plastic shield to show off the engine and get a look at everything. Everything looks good, but dirty! Just the normal engine grime and build up on the front of the engine especially near the front and near the injectors and glow plug area.

Wondering what the deal with pressure washing a diesel engine is? Can you do it as long as you are not blasting away on electronics? Any components to stay away from? Is there a good protocol to follow (leaving the engine running? Warmed engine?). Any good products to spray down first and soak to act as a solvent and loosen some of the grime up? Any products to spray down after to treat, protect, and keep cleaner longer?

Thanks for the info
 

nord

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Mar 5, 2010
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Southern Tier NY
TDI
All turned back to VW. Now a 2017 Hundai Tuscon. Not a single squalk in 10k miles.
Within reason go ahead. Be mindful of twelve year old electrical wires and connections. Don't force water into the fuel or induction systems. Use a degreaser from your local auto parts store on a warm engine first as it will greatly reduce your time and effort.
 

FlyTDI Guy

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Nov 3, 2001
Location
PNW
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'01 Jetta GLS
While some may, I wouldn't hit things with a lot of water pressure. I've done mine multiple times and only needed some degreaser/cleaner and light hose spray/rinse. I've used "orange" and "green" type cleaners along with A/P degreaser. All work well. I usually pick a nice hot day, belly pan off and liberally spray cleaner on all trouble spots. Let it work for a few minutes then re-spray as needed. Again, let it work for a while then rinse lightly but thoroughly.

I have one of those multi-pattern hose nozzles so I use a fine/mist setting. Not much pressure yet enough water volume to do the job. Let things dry out and check results. Repeat as needed.

The key is not introducing water into the electrical connections, air intake tract or even transmission vents, etc. Being a bit mindful of those, you shouldn't have any problems. I'm not one who would risk full pressure-washer pressures though. They are just not needed to do the job.
 

ffemtp

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Dec 9, 2008
Location
SE WI
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2001 Jetta GLS TDI Deceased 11/2012, 2004 Jetta GL TDI Sold, 2012 Jetta TDI (Retruned to VW), 2004 Jetta TDI GLS 5spd
All good tips, everyone. I have my own 2 cents to add.....

Pick a nice warm day, and leave the hood up, belly pan off, etc for a couple hours to allow it to dry out afterward. I usually do mine with hose pressure only, as the blast from a power washer just isn't needed, and not a good idea for reasons that are obvious. I spray mine down that way several times a summer. Never had a problem...
 

Jesus Is Lord

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Jan 24, 2014
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Hersey, MI
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2005 Passat TDI Wagon 144,000 2003 Eurovan VR6 2007 Touareg V10 TDI 158,000
My dad pressure washed the engine bay of a chrysler mini van and afterward it would not start, the ecu was shorted out.
 

TDI smile

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Edmonton, Alberta (b4 BC - LOWER MAINLAND = Chilli
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2002 TDI (ALH) with 513,000 km. First Owner and very happy... No Problems, never left us stranded on the Highway. Average useage is about between under 4 ltr. and 5 ltr. Normal longdistance travel: 4.1/100
A few month ago I saw my GURU doing a Power Wash to one of his customers engine bays. I was surprised, but he does that a lot, but I just keep it clean, without POWER WASHING.
 

40X40

Experienced
Joined
Feb 12, 2006
Location
Kansas City area, MO
TDI
2013 Passat SEL Premium
There is 'power washing' with the nozzle 3 inches from the car and there is the same thing with the nozzle a foot or more away from the car. Use the latter. Lower pressure will allow you to get closer and with higher pressure you need to back away a bit.

Use discretion.

Bill
 

Corsair

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Joined
Aug 17, 2003
Location
Weedsport, New York
TDI
2002 Jetta GLS TDI 5M
Lots of opinions, here's mine...
The under hood area is designed to get wet- water comes through the radiator etc. when driving in the rain. Like some of the above, I'll generally agree that a pressure washer could be used, if you didn't get too close to sensitive areas with it. But, also similar to the above, my bottom line recommendation would be- don't use a pressure washer. You can get into trouble with it, because the various connections weren't designed to withstand pressure washer type "assaults". Perhaps more importantly, you just don't need to do that. Standard engine degreaser on a warm engine, and a garden hose sprayer will get it clean. Might take more than one session if it's grimy- I'd prefer that to blasting with a pressure washer.

Be careful with "simple green" cleaner- I've read that it attacks aluminum.
 

phaser

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Apr 18, 2004
Location
Oregon
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2004 Jetta PD - 490k
Be careful with "simple green" cleaner- I've read that it attacks aluminum.
The Simple Green for aircraft is safe, but the others products as noted below come with advice about limiting contact time.

Aircrafts - Is Simple Green All-Purpose Cleaner safe for cleaning aircraft?

Simple Green manufactures a product specifically designed for use on aircraft — Extreme Simple Green Aircraft & Precision Cleaner. This product was initially developed for use in the aircraft industry and extensive testing shows it to be safe for use on aluminum, plastics, rubber, and high tech alloys, in both normal and extreme temperatures and stress conditions. Extreme Simple Green passed a variety of aircraft industry tests. Testing has been performed by Scientific Materials International, Inc. and is available upon request.
Aluminum - Is it safe to use Simple Green All-Purpose Cleaner on aluminum?
When used with caution and according to the instructions, Simple Green All-Purpose Cleaner has been safely and successfully used to clean aluminum. Simple Green All-Purpose Cleaner, Crystal Simple Green Industrial Cleaner & Degreaser, and Simple Green Pressure Washer Concentrates have been used on aircraft, automotive, industrial and consumer aluminum items for over 20 years. However, caution and common sense must be used: aluminum is a soft metal that easily corrodes with unprotected exposure to water. The aqueous-base and alkalinity of Simple Green All-Purpose Cleaner can accelerate the corrosion process. Therefore, contact times for unprotected or unpainted aluminum surfaces should be kept as brief as the job will allow - never for more than 10 minutes.
]http://industrial.simplegreen.com/ind_solutions_faqs.php?search_query=aluminum&search=Search

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ffemtp

Veteran Member
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Dec 9, 2008
Location
SE WI
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2001 Jetta GLS TDI Deceased 11/2012, 2004 Jetta GL TDI Sold, 2012 Jetta TDI (Retruned to VW), 2004 Jetta TDI GLS 5spd
Is there any information about Castrol Super Clean being safe? Or Purple Power? I think they are similar products.
 

BKmetz

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Staff member
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Sep 25, 1997
Location
Illinois
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2015 Passat, titanium beige, 6MT
I bought a pressure washer this spring (electric 2000 PSI). I've washed the car several times but not the engine yet. I use a variable PSI nozzle when washing the car.

All the you tube videos on power washing engines show the wand 1ft away or more from the engine. USE COMMON SENSE: You can get as close as you want to the head, block, engine mounts, transmission, inner fenders, suspension, etc. Back off around most plastic, rubber, and electrical connectors, and stay the hell away from insulation like under the hood. A power washer can blow right through foil insulation also. Thicker plastic like mud guards, inner fender liners, etc, are thick and should be OK.

When my engine gets dirty enough to use the pressure washer I will use the variable PSI wand to wet the engine, then the foaming nozzle with degreaser to soap up the engine, then the variable wand to rinse.

:)
 

rotarykid

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Apr 27, 2003
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Piedmont of N.C. & the plains of Colorado
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1997 Passat TDI White,99.5 Blue Jetta TDI
I use tire clean or similar at the car wash. then a few seconds of soap but with some distance so as not to apply too much force to seals around sensitive areas. Then high pressure wax with that same distance to protect the now clean aluminum and hoses....

If you take care around the sensitive areas a pressure wash of the engine and engine bay should not be a problem...........................
 

Super T

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Sep 6, 2008
Location
Alberta, Canada
TDI
2001 Jetta TDI
I totally pressure wash my engine all the time. There's not a hell of a lot to hurt under there. Be careful around the air box and the battery. And naturally any preexisting problems could be troublesome when introduced to high pressure water. But if under your hood is in good shape go hard.
 

jveccs

Member
Joined
Jul 6, 2014
Location
New York
TDI
2001 Jetta
Cover the transmission vent tube (under airbox) with tinfoil. I had trouble shifting after I pressure washed my pup. Also a good idea to grease up the moving shifter mechanicanism after everything is dry
 

burpod

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cape cod, ma
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82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
i've pressure washed my engine bays many, many times. as others have mentioned, don't be an idiot and point the nozzle right at electrical connections, alternator, right into the transmission holes and you're fine. never had a problem. use common sense
 

Caddy 16v

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I fly that 61 in heli logging operations, actually the company is based in your neighborhood in White City.
It can sling load 10,000lbs with the right amount of fuel, originally this one was flying in England for British International but got imported last year. Now instead of retiring it gets to logg 8h a day. ☺
 

new tdi guy

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Mar 20, 2023
Location
Anza california
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Alh
Within reason go ahead. Be mindful of twelve year old electrical wires and connections. Don't force water into the fuel or induction systems. Use a degreaser from your local auto parts store on a warm engine first as it will greatly reduce your time and effort.
I have a very dirty engine and I need to get a clean So that I can assure myself that the oil leak has stopped but the entire engine is caked with dirt oil stuff like that I figured if I put bags around the important components then it would be safer to use but I've never pressure washed before It needs to be done because previous owner neglected the engine completely
 

TornadoRed

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Aug 3, 2003
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West Des Moines (formerly St Paul)
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I pressure-wash whenever the engine gets too dirty. Never resulted in any problems.
 

454k30

Veteran Member
Joined
Feb 20, 2006
Location
Long Beach, CA
TDI
2002 Jetta
The front of the engine bay I usually attack with soapy water, simple green, a number of different sized scrub and old paint brushes, and then rinse down with a garden hose. I try not to use a pressure washer as they force too much water into places. I'm a bit hypocritical though as when it comes to the back side of the engine, I heavily spray that with simple green and then blast it with a pressure washer. After that I try to towel dry as much as I can (which also shows the spots I missed) and then go for a drive to get everything dried out. Oh, I should mention that I pull the skid plate for this too. When it's dry I go over all of the black plastic and rubber with some black finish restorer. The engine bay looks very good after all that.
 

jimbote

Certified Volkswagen Nut
Joined
Jul 10, 2006
Location
spiral arm, milky way (aka central NC)
TDI
Tacoma 4x4 converted to TDI
Blasted the crap out of dozens and dozens of Mk4 engine bays with zero problems. Just don't spray the alternator directly. All the mission critical connectors have very good sealing and water entry is extremely difficult unless you focus the nozzle directly into a connector seam. I use carwash tire soak followed by high pressure soap then rinse. Always with the engine running. Works wonders on the bay. Will be doing one tomorrow.
 
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