GL Class (X164) 2007-2012: GL320CDI, GL420CDI, GL450, GL550

Cleaning engine with low pressure garden hose and degreaser

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Old 05-21-2019, 03:27 PM
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2009 GL450 SOLD / 2011 GL550 SOLD / 2013 GL450 current daily
Cleaning engine with low pressure garden hose and degreaser

I want to clean up the very dirty engine bay on a 2011 GL550 I just purchased so it can be clean and so I can visually see any issues.

This is what I plan to do, are there any other suggestions for a GL550 specific engine?

- Run cold engine for a couple of minutes to warm up grease/oil/dirt on engine.
- Remove plastic cover and air filter housings.
- plug up exposed inlets from where air filter housings were removed.
- put plastic bag over alternator.
- put plastic bag over ECM
- Put plastic bag over MAF
- 1) Spray engine with degreaser.
- 2) scrub with brush.
- 3) hose down with low pressure water from garden house. Do not use pressure washer.
- repeat 1-3 if still dirty.
- blow off excess water with air compressor or use leaf blower if you don't have air compressor.

Old 05-23-2019, 03:51 AM
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Mercedes Benz 2007 GL450 , 2012 BMW 528i
I would consider disconnecting negative battery terminal too
Old 05-24-2019, 09:02 AM
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alx
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Originally Posted by mrathell
I want to clean up the very dirty engine bay on a 2011 GL550 I just purchased so it can be clean and so I can visually see any issues.

This is what I plan to do, are there any other suggestions for a GL550 specific engine?

- Run cold engine for a couple of minutes to warm up grease/oil/dirt on engine.
- Remove plastic cover and air filter housings.
- plug up exposed inlets from where air filter housings were removed.
- put plastic bag over alternator.
- put plastic bag over ECM
- Put plastic bag over MAF
- 1) Spray engine with degreaser.
- 2) scrub with brush.
- 3) hose down with low pressure water from garden house. Do not use pressure washer.
- repeat 1-3 if still dirty.
- blow off excess water with air compressor or use leaf blower if you don't have air compressor.
move away from the hose and do not even think about doing what you just wrote.
Old 05-24-2019, 02:03 PM
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'07 S65 '05 SL65 '07 GL450 '03 SL55 (sold)
Don't use a water hose in the engine compartment

Congrats on your new GL! I realize you want to get the engine cleaned up. And all over youtube there are folks who have done what you're proposing, but the real problem is introducing water into the engine compartment with a water hose. The sheer number of electrical connections that plug into each other and electrical connections that plug into components can really lead to a lot of corrosion problems in the future. There is absolutely nothing more frustrating than an electrical problem, and worse, an intermittent electrical problem. I have only had two electrical corrosion problems on my '07 GL450. Most recently was a headlight electrical connector that was corroded. I swapped bulbs, igniters, ballasts and then went to the electrical connector - which was corroded. And I don't wash my engine with a water hose. Have owned it since new. However, I'm currently replacing the forward and rear SAM modules on my father's 2001 S430 due to water damage. I just ordered yesterday the front SAM, rear SAM and a couple other components from water damage from previous owner. I'm getting it sorted out, but my father was scared to drive the car because of the intermittent electrical problems. Not trying to scare you or anyone else, but I just hate water anywhere near any electrical connections.

This is what I do to clean up the engine:
- I start by using an air hose with compressor to remove lose dust and debris. If you don't have an air compressor, no worries.
-Then I take off the covers and and any other easily removed plastic components and clean them up with soapy water and a rag. Wipe them down and allow to dry. Btw, the rear cover is a little tricky to reinstall if you've never done it before. It requires getting the cover part over the MAF completely sealed onto the MAF and the rest of the cover prongs seated properly to ensure the back clip near the MAF properly seats onto the rear of the cover.
-Cover the MAF with a plastic bag.
-With damp rags from the bucket, I clean up the various engine bay components and engine bay by hand as best I can. I typically get about four or five damp rags ready to go from the bucket, clean up components/bay, then rinse in bucket and start again. The key is to ensure the rag is barely damp - just enough to remove debris from the engine but definitely not "wet."
-I follow up with my air hose to get rid of any debris my rags had removed.
-My secret to a clean engine/compartment: I get 3-4 cans of CRC Electrical Cleaner to get to places I cannot reach. It's safe on all electrical connectors and plastics. If this is the first engine cleaning, you may need to get more. You can buy them locally at the auto parts store for about $10/each for an 11oz or you can get them on Amazon for less than $5/each. Sure, it's more expensive to use the electrical cleaner, but the savings in potential electrical problems in the future is priceless. The electrical cleaner actually does a decent job of removing some dirt in places you cannot reach as well.
-On the heavily soiled parts of the engine (sides/underneath) I've used brake cleaner to loosen the debris, then wiped down with damp rag. I do not let the brake cleaner come near any electrical components at all. I actually don't spray it on any areas where there are gaskets or rubber parts either. But, if the brake cleaner did come near an electrical connection, I immediately follow up with a spraying of electrical cleaner.
-Complete the cleaning by going over the engine with my air hose.

Again, this is just what I do to ensure no water gets near the electrical connectors. Good luck.


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