Engine bay cleaning is a fairly simple job, but there are some things to be aware of and some cheaper (and yet more effective) way of getting a sparkle under the hood.
Step 1) What you need:
- Engine Degreaser (5 Star Lubricants - Heavy-Duty Degreaser goes the furtherest & is the cheapest)
- Masking tape (the 3M range is better - Don't buy cheap tape as it will undo all your hard work)
- Scrap plastic sheet (shopping bags are ideal)
- a Bag-O-Dry-Rags
Step 2) Where to start:
The first thing to do should be the protection of electrical items in the bay. Distributors, spark plugs, open relays & electrical connectors hate getting wet.
We'll start with the spark plugs. On a 4AGE (4AGZE & 4AGTE) remove the centre spark plug cover. Pop out the spark plug leads. This should take 6 small (10mm) bolts and some careful persuasion to get out from behind the belt cover on the left. Very carefully stuff the valley between the cams with rags around the spark plugs, but leave the spark plugs in. Do not remove the spark plugs, as it's better to have wet sparklers than a watery grave for the pistons. Stuff a shopping bag on top of the rags to seal them from the water and tape down if necessary. Replace the cover temporarily (just put a couple of bolts back in by hand) & tape up around the edges. Replace the spark plug leads and tape up around them. If you don't do this step you'll end up with a TwinCam Sea & it's a long, hard process of mopping up. If you'd prefer to remove the spark plug leads make sure you tape up the connectors on the dizzy & the spark plugs well. On 4AFC (& maybe the 4AFE) motors there is no cover, just a lip around the spark plug leads. These lips work well, but tape them to the cam covers just in case.
Next is the Dizzy. These things really hate water so out with another shopping bag or 2 and mummify the distributor and it's leads and tape up to seal any openings. You should leave the base of the distributor (where it attached to the motor) exposed as this will no doubt be oily & dirty, but seal & tape the bag tight before the cap. Also mummify the coil, these guys don't mind water so much but it's better to be safe.
The relay & fuse box should be covered with a shopping bag & taped up. Again this area can get a little wet, but it's not advisable. Also tape up the top of the brake & clutch master cylinders reservoirs.
Anyone with an open pod filter like mine will have to (yes you guessed it) wrap it in plastic bag and tape it up.
This should be it for the protective side but check that there aren't any openings into air intakes or other exposed filters (like oil breathers) & tape them up.
Step 3) The fun part:
Make sure the engine is off & cold. Apply the degreaser liberally to all of the bay unless otherwise stared by the manufacturer. The 5 Star degreaser is based on kero (I think) & says it's not recommended on polished aluminum so just use car wash on any aluminum surfaces including the cam covers. Let it sit for 5 minutes. Pay special attention to the greasy, oily & really dirty areas, these may have to have a second, third or 10th go. If you have a build up of grease (ie around the CV joints), scarp it off with a blunt stick but be careful not to damage anything. Raising the front of your car will be help to get under the engine, but please use car stands cross members & bumpers will make a real mess of your face if they fall on you.
Step 4) The wet part:
Finally we get to play. Use a garden hose with plenty of pressure or a high pressure cleaner on it's lowest setting. With pressure cleaners you can do a lot of damage so beware. They can cut hoses, wires & damage fragile parts so use the minimum of pressure & stand back. You will get wet doing this so wear clothes that you don't mind getting grease, oil & dirt on. Ok, go nuts, drown the thing, within reason. Don't put any pressure on the taped areas or they'll blow off.
Step 5) Blow dry:
If you have access to an air compressor, lucky you. Just remember that air pressure can damage just like water pressure. Use a regulator on the line & turn it down low or stand back & gingerly coax water from out of those hard to get places. The rest of us will have to use rags & some elbow grease. Stuff dry rags into the pockets of water & wipe over all accessible surfaces. Careful not to damage or unplug anything. Drying will take ages so after you've removed the surface water leave the hood up & in a sunny position.
Step 6) Remove all evidence:
Remove the shopping bags slowly from the dizzy, coil & fuse box, trying not to get any standing water on the item in question. Take a rag & wipe over these items with something like Windex spayed onto the rag NOT the item. Don't use water, Doh!! Finally remove the spark plug cover, take the bag out (watch for standing water & try to keep it in the bag) & then the rags. If you did manage to get water down near the sparklers just mop it up with dry rags. Replace the cover & spark plugs (don't do the bolts up too tight).
Step 7) Shield your eyes:
Now you should have a gleaming engine bay. You may want to polish some bare alloy or stainless steel parts. If these can be removed easily do so. Grab some metal polish on a a dry rag (Autosol) and rub, rub, rub. Wipe off with another clean dry rag & replace all parts. Check the entire bay for loose wires, hoses & anything else. Start the car & run it standing for a little while (5 mins) to get the engine up to normal operating temp. If it misfires or runs rough at all stop it immediately & check the spark plugs & dizzy for water. You can damage the electronics if these have water in or around them.
Done. Go to your nearest show & shine and dazzle the crowds.