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How to (properly) wash engine bay?

8K views 33 replies 24 participants last post by  g20driver82 
#1 ·
Hi there, I want to wash my p11's engine bay, its been pretty grime-y since I got it. Someone advised me that I can just go to my car wash open the engine bay and use their degreaser and hose is down. They advised me to keep the car running just in case (what?!). I have read that the engine be should be cold. I have also read that it should be warm. Some have suggested that if i do this I need to cover up the distributor cap and alternator to avoid getting them wet. Also, I have read that you can just use something like simple green and go over the engine bay with a rag. I really want to get the sludge off the VC and down in the nooks and crannies though. Also, I have an open air filter so I assume I cant just spray down my engine bay, sounds like suicide IMO. I guess it just depends on the vehicle, I know with new cars everything is already covered up with plastic so cleaning the engine bay isn't much on an issue.

What has worked for you guys? What do you suggest? Your opinions are much appreciated, thanks.
 
#2 ·
got this advice from CrimsonRockett

CrimsonRockett said:
The first(and most obvious) thing to do is disconnect both battery terminals.

Second, cover your alternator with a bag or something. I never actually do, but it's good to prevent water from getting in there.

Remove your spark plug wires from the valve cover and completely seal off the holes with paper towels or something to prevent water from getting in there. You could leave your spark plug wires on, but water likes to seep through. So, I'd remove and plug the holes just to be safe.

Other than that, you should be golden.

After hosing down the engine bay, i'd recommend letting it air dry overnight. Or, if you have a compressor/air nozzle, dry it up as much as you can before reconnecting the battery.

I buy that heavy duty(industrial strength) degreaser from Sam's Club. It's a purple 1-gallon jug. Cost about $5. Pour some into a spray bottle, lightly "mist" or spray your engine bay down with water, then the degreaser. Use a tooth brush(or any other brush) that isn't too thick/hard and start brushing everything you can reach.

If you only want to make it look good from up top, it should take you less than an hour. If you really want everything cleaned off, it'll take 2-3 hours.


I recommend doing the entire thing. It makes everything easier to work on. I personally can't stand working on "dirty" cars(full of grease/sludge/crap). The cleaner I keep my cars, the easier they are to work on.
 
#3 ·
good advice ^

disconnect the battery cable and cover teh relay boxes and alternator etc with plastic bags first.

regular spray cans of engine degreaser from the auto store are very effective.

make sure to put a protectant (303, tire shine, etc) on the rubber and plastic parts afterward, and don't let the degreaser sit too long on your hoses before you rinse.

next time you do a tuneup and replace the valve cover gasket, spray the valve cover with caliper paint or engine enamel for a cleaner look.

peace
 
#9 ·
i just did mine saturday....

i covered the batt with a plastic bag, along with the air filter, then covered all elec components with aluminum foil, & then sprayed the SHIT outta my bay with some autozone degreaser, scrubeed heavily soiled areas, (around the PS res) then rinsed, then sprayed the rest of the can , then rinsed, then sprayed half a can of the Gunk degreeaser scrubbed again, then rinsed, & then hit all hoses/rubber/black plastic with seom Turtle wax Back to black.....


ill get pics up tonight
 
#10 ·
i just cover my alt. and cone filter with 2 grocery bags and pressure wash it at a do it yourself place with their engine cleaner.ive done this at least 7-8 times and never had a problem....sometimes i leave the car running sometimes i dont. i dont really go crazy though...my main concern is just getting any oil from the head and dirt buildup and cleaning the rear firewall. i basically avoid the entire cone filter/ alternator area. something you can do when your bay is already pretty clean....just pollen and typical dirt.
 
#11 ·
Simple green & use a pressure washer. The benefits of a pressure washer is very obviously high pressure but with low volume of water. I've personally never covered my alternator nor disconnected the battery. I've cleaned my engine/bay several times like this without issue. Then again I avoid the alternator. The nice thing with a pressure washer is that you can adjust the spray pattern width and you have pinpoint control where/what you're spraying. Key thing is don't point & spray continuiously at one one spot. Fan the spray back & forth. If you're engine bay is super dirty/greasy (from years of built up oil/rust proofing spray) it may take a few repeat applications of your choice of cleaning product.
 
#13 ·
i just did mine last week. the purple castrol degreaser ruined the paint on my coilovers. i bagged my distributor and air filter/maf. left battery connected and alternator untouched. engine was warm and i pressure washed the whole bay. the results were amazing in only 5 minutes. pressure washer is the key. you can really avoid alot of unnecessary scrubbing.
 
#17 ·
^ how do you figure
 
#20 ·
Don't know what he said before the edit, but it's definitely the same car/engine bay.

Nothing was modified/painted at all. It was just washed.

Same valve cover. Same everything.

That car was purchased from the original owner(woman). She didn't bother having the valve cover gasket replaced. So, that's a good 10+ years of oil slowly leaking out.
 
#25 ·
Sorry to revive an old thread, I'm doing this this weekend, I read everywhere to cover the alternator but my alternator is very dirty from oil leaking from the cover gasket over the years. What's the best approach to clean the alternator, cover and then wipe separately or just spray away as slimlou suggested above?
 
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