2006 XK8 with 58,500 miles....

Last Sunday afternoon I had a hell of a time cleaning off a greasy, grimy black substance from the lower body molding of my wife's car. It ran from the front wheel well all the way down the side of the car to the rear wheel well and rear fender, mostly on the drivers side but also on the passenger side as well. I had to break out my trusty can of polishing compound and even then the substance just wanted to spread around on the surface of the paint as I worked on it with a multitude of damp rags and compound. I spent over two hours working on this grime before I finally got it all off the paint. Then I went back in the house and chewed my wife out for not paying attention to what she was driving through on the roads. She rebutted me and claimed that she had not driven through any marked construction zones since I had last washed the car about ten days previously....

The car is dirty again as a result of being driven in the rain we've had off and on this week. Not to the filthy degree it was last weekend, but dirtier than usual after being driven in the rain, particularly in the left front wheel well area. This morning I remembered that my research prior to purchasing this car right at a year ago showed that the right front shock was replaced in January 2007 at less than 5,200 miles due to leakage. I realize that I need to jack the car up and pull the front wheels to get a good look and I'll do that as soon as I can get the car away from my wife long enough. But in the meantime, I have some questions:

1. Are these shocks known for frequent failure?

2. When they leak, do they throw the black greasy grime I've described above?

3. When they leak, does the car begin to make front-end noises during braking or turns or any other time when the shock may be under heavy stress?

4. What other components under the hood could leak fluid, drip to the front wheels, and potentially cause this mess? I've checked the brake fluid reservoir - it is full and looks normal.


Thanks for any suggestions you can provide. I surely hope this was just a nasty case of sticky winter road grime, but at this point I do not know....

 

Jon,

I'm looking forward to the video of that little exchange - it should be dynamite!

The possible sources of greasy residue from the vehicle which could accumulate like that are:

1. power steering fluid
2. transmission fluid
3. brake fluid
4. engine oil
5. grease from a failed bearing seal
6. oil from a failed shocker

The only one of these likely to be anywhere near black would be engine oil although anything oily would soon pick up road dirt.

Unless you can see anymore of the residue around suspension or steering components when you remove the road wheel, it seems more likely to be something spilled on the road that she's driven through which has then been sprayed along the side by the rotation of the front wheel.

Graham

 

Thanks, Graham. I hope you're right that the substance is just greasy road debris. Some of our roads were sprayed last Thursday and Friday with brine due to the icy mix that fell on Friday afternoon and evening, but brine does not make the mess that this stuff did....

I'll report more this weekend once I have the car up on jack stands and the front wheels off....

Sorry, no spousal confrontation video available (thank goodness)....

 

A simple but also plausible possibility, since it has happened to me on occasion as well, is when you last dressed the tires with whatever product you use, sometimes it either doesn't fully dry and then sprays all along the side rockers (and is quite black) and then mixes with whatever road grime comes up and produces a slimy, greasy mess. And/or if you were overly generous with spraying the tires and some got on the inner liner, it will continue to spray for some time. It's not a scientific explanation but I don't believe leaking shocks would produce as much spray as you're describing, and when I've had leaking shocks on other cars, it seeps out of the piston and barely dribbles down, not enough to wash down the rockers. Good luck in your search.

 

I'm going to lean more towards joint sealant or perhaps the emulsifier that is under the asphalt, and when driving through potholes and/or pavement thats broken up, can reveal it. I get the same semi-hard product on the very bottom of the chassis. Since its asphalt based, (at least on mine) it breaks down and comes off easier w/ a degreaser, brake cleaner, etc. A paint cleaner takes forever to 'wear' it down.

 

Thanks for the additional input, guys. By the way, I never dress the tires. I simply scrub them clean with a soft brush using soap and water after I've cleaned that wheel....

I plan to get the car in the air tomorrow. I'll report what I find. I hope it is indeed nothing but particularly nasty road grime....

 

Update:

Washed the car this morning, then took a good look underneath. No obvious signs of fluid leakage from any component. My conclusion is that this stuff is indeed some sort of nasty, greasy road debris that was picked up primarily by the left-side tires and slung all over the lower body molding. I wish I could break out my pressure washer and go after it but I'm not willing to risk creating a limp mode situation with overspray into the engine bay. I've managed to clean the vast majority of this stuff from the paint and underside with old-fashioned manual scrubbing using rags, brushes, soap, and water. Future car washes along with my wife's driving in the rain should eventually break down whatever residue is left clinging to the underside and wheel wells. I'll watch the affected areas to see how they react over the next couple of weeks, but I do not expect any further grime-slinging by the wheels and tires. We'll see....

In more than 40 years of washing vehicles I've never encountered anything this difficult to remove from a painted surface other than freshly-poured tar. This stuff was greasier and more fluid than that. Whatever my wife ran through, I hope she never does it again....

 

Jon,

It sounds like a real pain to clean off but I'm pleased to hear it was no leak on the vehicle that caused it or, from your description, any physical damage to the vehicle resulted from the incident.

Graham

 

If it is that difficult to get off then it sounds to me like perhaps the car was driven on a street that had recently been recoated with asphalt or a seal coat. This happened to me once with another car and it had to lie on my back on the driveway and use a variety of materials and solvents to get the stuff off. Not only did it line the wheel wells (never did totally remove that) but it coated the paint to varying degrees along the underside below the door line. I found what worked well was some very thin liquid wax/polish from Mother's (I think). I have heard that using WD-40 also works well to remove stuff like this.


Doug

 

+1 on the WD 40 thats what we use during paving operations. Diesel fuel will aslo work on larger areas. Jim

 

This has to be a first - a recommendation for something WD40 will work on!

Graham

 

If I see any additional grime spots, you can bet that I'll be testing the WD-40 approach....

 

There are bug and tar removers available at good auto parts stores. The ingredient is kerosene. This will not hurt paint and takes off all manner of grease and tar.

 

I had a can of DuPont bug-and-tar remover (circa 1985) somewhere in the garage. Thus far I have not been able to find it. Perhaps I finally used it all up, threw it away, and neglected to put it on my supplies replenishment list....

 

Hot-to-the-touch vegetable oil removes thin smears of tar like water removes mud.