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View Full Version : best method to clean engine bay?


everlast
06-15-2006, 01:44 PM
Well, I'm ready to start some more serious work under the hood of my 88 325i.. but the car has been thoroughly undercoated every year of its life.

You can imagine the grime under the hood. I changed the low beams a few days ago and the covers were so dirty my hands were black in 30 seconds.

My first thought bothers me a little: go to a spray wash booth with a few bottles of engine cleaner. Coat the stuff on, use the brush to loosen it.

Then gently spray it off in the booth. At least it saves my driveway. Morally though, that's pretty nasty.

I would of course clean the brush up with spray nine, etc.. but thats a lot of petroleum products going down the drain. I can't think of any other way of doing it really.

I'm not worried about water under the hood.

Any other suggestions? What about those natural orange cleaners? They are supposed to be more environmently friendly I hear.

paul christians
06-15-2006, 02:07 PM
there is a couple of ways for this,how bad is it for one,use spray9 for 1,or any engine shampo will work,tools to us,an old toothbrash a soft wirebrash VERY SOFT one at that and a power washer,and don us armerall on hoes at all.........

everlast
06-15-2006, 02:24 PM
No armor all or anything would be used.. I'm not trying to make it look pretty, I'm trying to make it grime free so I can change the rad / timing belt / water pump without getting filthy.

paul christians
06-15-2006, 02:33 PM
^^^that cool man,and I under stand that now,but this good to do any ways....

1BADRIDE
06-15-2006, 03:04 PM
...an old toothbrash a soft wirebrash VERY SOFT one at that and a power washer,and don us armerall on hoes at all.........

Did the hoes get mad? *angel* :D

crusher
06-15-2006, 04:01 PM
Just water it down, seal the electrical bits and spry some of that CNC orange scent engine cleaner.. Works all the time for me

Axxe
06-15-2006, 04:34 PM
Castrol Super Clean + brush + powerwash. Works like a charm.

calegrant
06-16-2006, 02:43 AM
Whats with everyone saying powerwash? Sure you're not going to spray straight on at anything sensative but it's still risky. I used spray nine and water on my motor when I bought it. It just requires a lot of time to get it looking clean and then whenever you give your car a detail rinse off the motor to remove and light dirt.

djcontra
06-16-2006, 03:29 AM
Someone on here (maybe randy) told me about this method once before...

Step 1: Drive the car
Step 2: Park the car, and cover up electricals with plastic bags
Step 3: While the engine is still warm, spray 'Simple Green' or any other degreaser of your choice liberally all over the engine
Step 4: Wait a few hours, or overnight if possible
Step 5: Power wash the heck out of the engine bay the next morning. Should look great afterwards!

Repeat if needed but usually that does it for me. Might as well clean your door jams and the like at the same time too *th-up*

Step 6 (optional): Spray some WD-40 on a rag and wipe down all of the plastic parts to make em shine :)

NOTORIOUS VR
06-16-2006, 04:01 AM
you shouldn't have to cover anything with plastic... just spray the whole engine bay down with a powerwasher...

engines and anything in the engine bay is waterproof... unless u have broken electrical connections to start with, then water in u'r engine bay is the least of u'r problems...

I haven't found any engine degreaser to be that effective on rust proofing/ undercoating, especially if there's lots of it and/or it's been on there for a while...

Although I've heard that varsol/thinner works well... not 100% sure about that tho...

Also after using any solvant, spray everything down with WD-40 or some form of penetrating oil to prevent the plastics/rubber from cracking.

djcontra
06-16-2006, 04:36 AM
you shouldn't have to cover anything with plastic... just spray the whole engine bay down with a powerwasher...

engines and anything in the engine bay is waterproof... unless u have broken electrical connections to start with, then water in u'r engine bay is the least of u'r problems...


There are two design issues with the E36 engine bay which may be present on other bmw's as well which is why I suggest covering up things with plastic. The first is the wiper tray drainage holes can get clogged and end up channelling water into the ECU compartment, damaging the ECU. The second is that water is notorious for ending up in the spark plug cylinder cavities causing a short in one or more of the ignition coils when firing. To prevent this, one should cover those holes (with the coils out) before spraying. The plastic cover which goes ontop of those electricals doesn't provide enough shielding from the elements I find.

everlast
06-16-2006, 10:53 AM
One of my problems is that I don't want to have a thinner or tough chemicals running down my driveway, hence the suggestion of using the spray booth. Also, without any money in it, the spray booths sometimes still squirt a little water with little pressure, which might be good.

Anyway, I'm going to try this tonight, so I'll take before and after shots and let you all know how it went.

Edit: and thanks for all the feedback!

NOTORIOUS VR
06-16-2006, 12:41 PM
There are two design issues with the E36 engine bay which may be present on other bmw's as well which is why I suggest covering up things with plastic. The first is the wiper tray drainage holes can get clogged and end up channelling water into the ECU compartment, damaging the ECU. The second is that water is notorious for ending up in the spark plug cylinder cavities causing a short in one or more of the ignition coils when firing. To prevent this, one should cover those holes (with the coils out) before spraying. The plastic cover which goes ontop of those electricals doesn't provide enough shielding from the elements I find.

That's totally understandable.... VW's have the same issue with their rain trays...

but if that's the case, you should make sure it unclogged, and take care not to blast the rain tray *th-up*

As for the spark plug holes, that's pretty shitty, although I guess there's not much u can do about it because the rubber around the COP's get's hard from all the heat they see.... you could always just remove the COP's, and use compressed air to remove any water that gets in there after the wash *wiggle*

paul christians
06-16-2006, 04:57 PM
go with the way I said to go man........I done it many times on peoples cars back in the day when I had a detail shop..........

everlast
06-16-2006, 11:04 PM
Well, i emptied a can of the spray on citrus stuff as a start tonight. It worked pretty good, but didn't get a lot of corners, etc. I'll go at it with a brush (which I bought and it broke right away) and some of the castrol stuff which I found I had already bought. My basement is like the CT auto isle. :P

Edit: I forgot to get pics of the before.. In any case, I can see that the whole underhood is cosmolined still. Damnit.

Jordan
06-17-2006, 12:09 AM
100% pure Castrol Superclean and a stiff bristled plastic brush with scrub off cosmoline pretty easily. Combine with a pressure washer for best results.

You do NOT have to cover anything in a e30 engine compartment. Just don't be a retard. If you are using a garden hose keep water from directly hitting the spark plug area, the distributer cap, and the the fuse box if your lid doesn't seal as it should.

If you are using a pressure washer its pretty hard to blast any significant amount of water into any problem areas. High pressure low volume...

everlast
06-17-2006, 01:18 PM
I agree on the water points. I'll get another brush and try tomorrow to get the perfectly smooth yellow crud to come off.