Joel Griffith

Hello,
The underside of my 928 has a lot of oil residue from an oil leak that I recently fixed. I want to clean this area but am worried about harming the factory polymer undercoating. I have heard suggestions of everything from detergent to easy-off oven cleaner which I have used on another vehicle and works really well for stubborn grease.Has anyone had the underside steam cleaned and if so will this harm the undercoating?
Thanks.
Joel

Paul D

Joel - I've never used steam, but I have used Simple Green (full strength) and a soft nylon bristle brush to clean the entire undercarriage, engine and compartment, with excellent results. Good luck.

dr bob

I'll second Paul's recommendation on the detergent method, and suggest that you stay away from real steam-cleaning. True steam cleaning removes the undercoating, and also like to take paint off.

There are spray degreasers, like Gunk's Engine Brite product, that are solvent and detergent based. I used these in the engine bay and stained the paint there, so I recommend that you stay away from these if you are at any risk of getting contact with the paint.

In addition to the Simple Green method, there are citrus degreasers that work amazingly well and cut down on phosphate pollution at the end of the driveway. Castrol (I think..) has one that's pretty good, or buy a no-name from Home Depot. Either way, it's a spray on, soak, hose off cleanup of oil residue.

You'll soon be aware that engine oil does in fact soften the factory cosmoline or whatever it is coating that protects the bottom of the car. Aggressive use of the hose (or pressure washer at the car wash) may loosen areas of that stuff and take you quickly to painted metal or raw aluminum. Use appropriate caution when spraying.


A clean engine and undercarriage make it a snap to locate any new leaks that might spring up, and also make it easier to justify sliding uncer there to do any regular maintenance. Squeezing the dr into a set of michelin-man coveralls for a slide under a dirty car... naw, I don't go for it. Clean is the way to go!


Cheers!

Joel Griffith

Thanks guys!
Joel

JKelly

I would like to ask a question that relates to this topic and maybe it will be read. When you use Simple Green or citrus cleaners to clean the engine, is it necessary to protect any certain part or parts from the cleaner and/or water or do you just soak everything down with the cleaner, scrub, and rinse? I to have a tad bit of oil to clean off.
Thanks

dr bob

My figgerin' is that the bottom of the car is pretty waterproof as it comes from the factory. Except for possible damage to a specific finish like the undercoating or paint, I'm pretty free with stuff I use under there.


For the top of the engine, you probably want to shield the distributors, and use a minimum amount of water. Avoid hi-pressure sprays that force water into places where it shouldn't be, like electrical and ignition parts. No solvent=based stuff on the engine if you treasure the paint on the cam covers and manifold either. Learned that the hard way!


All that said, I also have a little environmental concern. I've been using Engine Brite for as long as I can remember, but didn't read the fine print on the can until I had spots on the manifold paint. Nothing about the spots of course.


But it does say to use it only where you can catch the runoff and separate the oil residue, etc. My street drains directly to the ocean via a local storm channel, so that pretty much put a halt to using that stuff in the driveway. There are plenty of industrial chems on the market that will do the job, but not many that I'd be willing to swim with or drink. Moral- use the mildest friendliest stuff you can find. Simple Green comes from a company headquartered down the road from me in Seal Beach, and claims it to be friendly with no phosphates that pollute the water. I'd start off with that and see how it looks. If you still need more, try the citrus stuff. I'd save the solvent-based stuff for a last-resort effort, and try to corral any runoff.

Just a thought...


dr bob

lives too close to the ocean, gets all the uphill stuff, etc.

JKelly

Dr. Bob,

I moved from Dana Point 1 1/2 years ago. The local storm drain was (and probably still is) causing a lot of concern for people who frequented Salt Creek Beach, which also is a very popular surfing spot.

Thank you for your advice.

Paul D

If your engine has not been cleaded and or degreased in a long time and there is heavy gooey sludge that needs to be removed the initial cleaning will be long and tedious. I used both nylon and brass tooth brushes to get into the hard to reach places (new appreciation for my dental hygenist). At the time of my initial cleaning I was replacing my radiator so I had much of the ancillary equipment removed (A/C compressor, accessory belts, hoses, Timimg belt covers) which made cleaning easier. Subsequent cleanings (1 or 2 a year) are much simpler, just spray Simple Green liberally and hose off. You should avoid getting any degreaser into the alternator (you'll degrease and unsealed bearings) and the distributor (I cover with aluminum foil). I also remove the intake tubes (plastic ones) and air filter box, cover air intake inlet with aluminum foil (even use rubber bands to hold foil in place). When it comes time to rinse with a gardenhose be extra careful around the intake and distributor. You may want to get a long turkey baster to remove any water in the "V" and when everthing is dry squirt the throttle linkage with some WD-40. Hope this helps.

Joel Griffith

Thanks!
Joel