View Full Version : Cleaning the engine bay

10-01-2005, 08:25 AM
Anyone know anything about cleaning the engine bay?
My mechanic said it would be fine to hose it if I put a plastic bag over the alternator and make sure the sparkplugs are sealed up.
I tried it after great reluctance (with much caution). No problems what-so-ever.

So, any chemicals to get the greasy shit off the innerbody? What have you guys tried?

Dr Tweak
10-01-2005, 08:27 AM
First spray a bottle of engine degreaser all over it, let it sit for a few minutes, then spray it off.


10-01-2005, 09:09 AM
YAY for new englanders. Wicked good!

10-01-2005, 10:33 AM
If you know where to find your fuse boxes, alternator, spark plugs and rotor you should be fine. Pretty much everything else is relatively well-sealed. And I'm fairly sure you know where to find just about everything in your engine bay.

Fast and hard rule number one -- no pressurized water if you're not sure exactly what you're doing.

Two: No petroleum-based degreasers, they'll eat the rubber and plastics. Those types of degreasers are meant for when you're taking the engine apart and don't have to worry about non-metal bits.

Three: when using citrus-based degreasers, don't let them sit on polished or anodized aluminum as they will stain or etch the finish.

Four: elbow grease is always a safer means of cleaning than harsh chemicals or harsh tools. The Meguiar's Extra cleaner I used is safe enough it's actually meant for cleaning rubber, plastic and uphosterly as well as engines.

I wrote this detail how-to during a debate on a detailing site over how to safely clean the alternator. It was mostly to compare techniques, but I haven't found anyone who's pointed out any errors -- just the occasional preference for steam cleaning, of which I'm a little wary given it's ability to introduce moisture into electronics without you knowing.

This applies to a 1990 Toyota Celica GT with an inline 2.2L four-cylinder engine that had never previously been cleaned to my knowledge but wasn't in terrible shape. However, I only did the top half of the engine due to a persistent leak in the power steering fluid pump -- it's so slow I've been trying for years to get a bottle of stopleak into it, but power steering fluid makes an incredibly large mess with small amounts.

I should also note I have a major advantage in that the tap water in my region is collected from rain-fed rivers, meaning in a dust-free environment it dries spot-free.

aluminum foil
Meguiar's Extra cleaner
shop rags
long-handled scrubbing brush
wire brush
Silvo metal polish
Mother's Back-to-Black
Black Magic anti-static dashboard protectant
cloth diapers

Ran the engine for about five minutes, let it get to the point where I could still put my hand on it.

Covered the alternator, fuse boxes, alarm computer, and sparkplugs with foil completely. Draped foil over the distributor as best I could. The stock air intake in my Celica is actually a CAI, so it didn't need covering.

Lightly rinsed the engine with a spray from the hose, then scrubbed at the more disgusting areas with the long-handled brush to loosen the grime. Rinsed again, gave the engine a quick scrub, then liberally sprayed the compartment with Extra and let it soak for 10 minutes.

From there it was elbow grease and banged-up knuckles, scrubbing at stuck-on grime with either the scrub brush or the toothbrush, depending on how tight the crevice was. Discovered how effective Extra remains, even when the brush is black. For lightly soiled areas, used a shop rag wet with Extra to wipe down, including the various hoses and plastic covers.

Lightly rinsed the compartment with the garden hose again, then used the shop rags to wipe it down, particularly concentrating on areas where water could pool. On the 5SFE, watch between the manifold and the head.

Unwrapped the covered pieces and went at them with a shop rag, again wet with Extra, then wiped them down with a water-damp rag to rinse. This was the safest method I could find to use on the alternator. The shop rags are rough-textured for some cleaning power, but won't sling droplets like a brush.

Wire brush was used on certain aluminum or iron parts to deal with rust/oxidation, then Silvo applied with a shop rag to smooth and protect. Three months later, the aluminum heat shield over the manifold is still silky smooth. My alternator is painted, so a similar treatment could not be used on it, unfortunately, though I did lightly go over it with the wire brush during the Extra wipe-down.

Next step was treating all rubber and plastic with Mothers B2B on a cloth diaper -- though I kind of regret that now, knowing the long-term effects of B2B. Penultimate step was to dress all the rubber and plastic with Black Magic's anti-static dashboard protectant, which will help repel dust instead of attracting it like most protectants. (Next time, both steps will be covered by one application of Meguair's Vinyl and Rubber cleaner/conditioner, which is a spray and forget product that works incredibly well and doesn't collect dust.)

Finally, I went inside and bandaged the various gashes, scrapes and cuts I'd inflicted on my hands.