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Guest Message by DevFuse

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Cleaning - Engine Compartment

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10 replies to this topic

#1 GaryW


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Posted 20 June 2006 - 10:19 AM

The engine compartment on my 2000 Forester is rather cruddy. I see some corrosion and my belief is the sucker should get a good cleaning. I bet there is still some salt/grime in there from the winter months. Nasty.

This may be a noobish question to ask ... but.

Whats the proper method to keep an engine clean and prevent corrosion? Just a regular old hose and water? Should I use an engine degreaser spray instead? Something else? What about water and electrical components?

Thanks in advance..

#2 fnlyfnd


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Posted 20 June 2006 - 10:44 AM

Heat up the engine for a few minutes. Some people say let it run incase you hit something sensitive, since you'll know right away. I turn mine off and just avoid blasting the electrical compontents directly. Your engine bay gets soaked when it rains so it can handle the water, just not a direct blast in the alternator, coil, connections... I use simple grean or engine brite, any good degreaser should work fine.

#3 Setright


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Posted 20 June 2006 - 10:49 AM

Get some small plastic bags and rubber bands to seal:

Brake fluid reservoir, alternator, dipsticks, ABS pump <-expensive part to bust, power steering fluid reservoir. Disconnect the negative battery terminal.

Rinse engine, spray with diluted engine degrease, leave for ten minutes, agitate with a small (1 inch) paint brush, rinse off. Let dry, remove bags, hook up battery.


#4 dj3stripes


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Posted 20 June 2006 - 07:08 PM

thank you for the thorough answer, i had this same question a few weeks back but the answer i got wasn't nearly as plotted out as yours, thanks for helping us newbs.:headbang:

#5 forester2002s


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Posted 20 June 2006 - 07:53 PM

I have seen people at the local DIY car-wash, with their hood up, and spraying the 'foamy' wash into their engine, and then rinsing it off with the high-pressure wand.

I have been tempted to try this myself, but I have never plucked up the courage.

Is this safe?

#6 daehttub2000


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Posted 20 June 2006 - 10:53 PM

I’ve been doing the following for years to keep my engine compartments bright and tidy without any problems. I followed friends’ advice when I started noticing how the insane amount of Chicago winter road salt started showing up in my engine compartment. It’s also nice to be able to do quick visual fluid level checks without opening all those darn caps…

  • Find a manual car wash with a low pressure engine cleaner/degreaser option. This usually means that they’ve done stuff to meet environmental laws. They’re usually not that tough to find in car crazy big cities.
  • First thing in the morning take a short drive to the car wash. Gets the engine just warm enough but not too hot. Sometimes I’d wash my car first before hitting the engine compartment if I thought the engine was too hot.
  • Quick rinse with plain water to blow out the accumulated loose gunk.
  • Apply low pressure engine cleaner (yes I’ve used the foamy high pressure stuff at times but was careful to not soak the alternator and other delicate bits. Probably not a very bright thing to do…)
  • Depending upon how dirty the engine compartment was, I’d either wait a bit before giving the engine compartment a good rinse. I’d also make sure to rinse off any overspray that got on the car.
  • I’d start the engine right away and put in a good drive to heat up the engine again and completely dry out the engine compartment.

I might be committing a few car care sins though. If you want to do a really precise and careful engine wash, here’s a nice write up I found at Answerbag.com (Google “car wash engine compartment”):

Many car, truck and RV owners spend hours cleaning and waxing the exterior of their rigs, but do not give any more attention to things under the hood beyond checking the fluids periodically. There are many reasons why it is important to clean the engine and its surroundings routinely. A clean and tidy engine compartment makes it much easier to detect oil and fluid leaks, damaged or worn drive belts and rust or battery corrosion before they lead to more serious damage. And if things really get out of hand, the dirt could provide fuel for an engine fire.

Cleaning the engine compartment is not that difficult and unless you are a perfectionist or plan to enter the vehicle in Concours d'Elegance competition, it does not require much elbow grease.

First, warm up the engine for a few minutes. This will help soften the grease and crud. However, do not let the engine get hot. Never spray water on a hot engine since sudden temperature changes can cause serious damage. Also you can get serious burns from hot engine parts.

Next, cover critical parts of engine with plastic bags and rubber band to protect them from water and other liquids. Either cover the air intake and filter or remove it and cover the opening. Protect electrical components like distributor, coil and fuse box. Use rubber bands to seal the bags around the components. Check the oil filler cap, the power steering filler cap, oil dip stick, etc. to make sure they are tight.

After everything is sealed up, spray the engine, accessories and surrounding components with a high quality non-petroleum-based degreaser that will not harm the paint. After letting the degreaser work for about five minutes, use a soft brush, a paint brush works well, to loosen up the crud. Respray with degreaser and rebrush if grease and grunge remains.

When the entire engine and engine compartment looks pretty clean, rinse with lots of water from your garden hose. If you can, hook up to a hot water tap since hot water will do an even better job. Better yet, do the job at a do-it-yourself car wash which usually has higher pressure hot water and is set up to handle the dirty water in a more environmentally friendly way. Even though the degreaser may not contaminate the ground, the nasty stuff washed off can get into the groundwater supply and do harm. Many car washes have equipment specifically for cleaning engines. If you want to use a degreaser that you know is safe, I only use the facility to rinse with plain, hot water. Clean the engine first and wash the vehicle after cleaning the engine compartment making sure all overspray of the degreaser is removed. Since all degreasers will remove wax, plan on rewaxing after cleaning the engine compartment.

Once the engine and compartment is clean, immediately remove all plastic bags and rubber bands. Dry standing water and aluminum parts with a soft cotton towel. Start the engine and let it to warm up to dry the rest of the engine as well as evaporate any moisture that may have collected in electric parts. If you do not start the engine immediately, often moisture will seep inside parts and it now will take a long time for things to dry out. If this occurs, use an ordinary hair dry to heat ignition systemparts like distributor and coil.

Once everything is dry and has completely cooled, you may want to coat hoses, weatherstripping, shields, gaskets and other rubber parts with a rubber protectant. However, do not use it on rubber belts since it could cause them to slip.

#7 a97obw


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Posted 21 June 2006 - 12:48 AM

I'd limit the use of the degreaser chemicals to only the metal parts in the engine compartment....simply because all of the hoses and other rubber components have a coating of protectant like cosmoline that is there for a reason, and you'd better price the cost of replacement A/C hoses before you clean them with degreaser.:eek:

#8 Kilroy


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Posted 21 June 2006 - 03:58 AM

Mine is nice and shiny....but that's because I had a power steering hose come off and fluid was everywhere. I had to clean it all off. :-p

#9 kimokalihi


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Posted 21 June 2006 - 04:23 AM

Alright, here's what they do at the dealership where I used to work as a lot attendant. This is what the detailer does to EVERY car and I did it too and they never had problems.

Take a bottle of degreaser(they got special chemicals that I've never seen sold in any stores and they get them from a chemical truck that goes around to all the dealerships)and they spray the entire engine down with a spray bottle of this green liquid. It comes in a big 5 gallon bucket that has a pouring spout and it's concentrate and you can mix tons of gallons of this stuff with it. It's pretty thick, almost as thick as jelly but a bit more oozy and you put a little bit in a spray bottle and fill the 90% that's left with water.

Let it sit for a few mins and then they take a gas powered pressure washer and blast the whole engine down. It looks brand new when you're done. The chemicals they use at the dealership are amazing!

We would do all sorts of things with this stuff. We'd do the whole engine bay and all the little cracks, the underside of the hood, wheel wells, any drip stains from door handles or lines in the exterior where previous washes had run dirty water and stained the paint. It would work wonders. I just can't remember what it was called, it was almost a year ago.

They also had this other stuff called SAR(something like sealant adhesive remover)and that stuff was nuts. It would burn your skin and eat through rubber. Used it to get scuff marks off interior stuff and rubber off the bumpers by the wheels from the road. Stuff you would scrub on for hours and not make any headway would come right off in a second with this stuff.

They have a chemical for everything. Bug stuff that would get bugs off that would NOT come off no matter what you did, would just come right off with a effortless wipe of a rag after spraying this bug removed off.

Anways, we never had a single problem or complaint with electrical and I've done it to my truck countless times and it's a fuel injected 2.4 22RE toyota pickup.

We would do it on a brand new 2006 mazda RX8 or a Lincoln Navigator, never hurt a thing! But if you mess something up, don't go crying to me because I'm just telling you what the dealerships do with their cars to get them looking new again! They use acid on your windows to remove water marks! If you let that stuff on there more than a few seconds it can really damage the glass and if you let it touch the paint...oooh!

#10 GaryW


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Posted 21 June 2006 - 11:20 AM

Thanks for the very detailed responses.

The process seems quite straight forward. I'll check my local manual car wash and see if they have an engine degreaser option.

I admit, I haven't kept the engine very clean in the past 6 years and well.. it shows. I have some rust/corrosion in the engine. Salt is nasty stuff.


#11 skizix


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Posted 22 June 2006 - 05:18 AM

I can be good to have a bottle of compressed air (dust-off, etc.) with a tiny hose (a la wd40) to concentrate the spray, handy, especially if you're doing this away from your driveway. The reason: if you soak the harness connectors to the injector(s) (easy to do), they will short out, and that cylinder(s) will miss, causing the car to run like absolute crap. Blast out the connector to dry it, and drive away happy. Letting it sit will obviously dry it out as well, obviously, but it can take a while.

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