In need of washing the engine compartment on my S500 1997, what should I watch out for in terms of getting it wet? Thanks

 

This may be more than you want to know.

I have pressure washed engines for decades. Recently I did my 1996 S320. I have found that you must always cover the alternator with a towel to keep direct water spray out. A cloth towel works best as you can wrap it around the alternator and when it gets wet it gets heavy and holds in place to keep any spray out. Plastic bags are blown off with the water pressure. Any exposed electrical connection boxes should also be cover/wraped with a wet towel as well as anything else you think a blast of water may harm. Wear your old clothing because when the spray hits some areas you will get a back splash and you "will" get wet. I use a commercial coin car wash because there will be a puddle of gunk and black debris on the ground after your done. Your driveway will be a mess. I start with the coin car wash low pressure engine degreaser spray to remove oil and grease. You can also use the can spray engine degreaser. Let it set for a a minute or two. Then switch to soap and start spraying the engine block and engine{the degreaser should have helped to cool the block down by now}. The spray will blast off all the gunk. Spray close to areas that have not critical parts and back off over areas of cable's etc. Stick the wand down and in all area's then to the side areas and work to the frame area and fenders. Avoid the hood insulation. I get on my knees or even spray a spot clean and lay down to spray the under engine area and wheel area's. Switch to rinse and start at the top and spray rinse all the soap off just the water spray all over until the soap is rinsed. Use the spray wax selection at the end for a spot free dry.

REMOVE THE PROTECTION TOWELS! Now before you start it let it sit for about 10 to 15 minutes. The warm engine block will help to dry the engine area. I take a gas leaf blower {you can use an electric if there is a plug available} and blow all the water off the engine and engine area and all connector's and plug's etc. to aid in a quick dry and to get water out of any area's that can cause hard starting or rough idle until fully dry. I find this works best for trouble free engine washing. The dryer the better before starting. If you have exposed spark plug area's on the block water will short the plug until all the water in the recessed plug area dries, as with many engines. BE CAREFUL that you do not break the white plastic vacuum tubing or accidentally unplug a connector or something when poking the spray wand around. If you do pull something off you will think the water has caused a problem when in fact only a vacuum tube was pulled off or broken.

Good luck...

 

I did find after my years with marine engines, that spraying of WD-40 or CRC-56 to all electrical connections and bolts after washing would not hurt.

In our county a lot of salt is used in the roads during the winter causing corrosion - not only to the sheet metal - but also to the electrical connections.

Spraying of WD-40 after throrough washing the salt away will prevent corrosion in connectors and fuse boxes.