Ken,

How big are the spots?  Do they occur more in cold weather?  Hot weather?  Damp conditions?  Short trips?  Long trips?

I had a '95 Golf turbo diesel for 8 years, and and tiny black spots on the rear hatch happened from time to time - usually from driving around town rather than the highway, and worse in cold and damp weather.  That was my first experience with a diesel, and they worried me, but they were identified as soot trapped in moisture and deposited.  

One thing that helped was an exhaust extension that was turned down, so the exhaust was more likely to hit the ground or be carried away from the vehicle by the air stream under it.  Another was a change in muffler.  But the best cure was when lower-sulfur diesel fuel became available here - then the soot problem was really lessened.

Does your customer buy low-sulfur or ultra-low sulphur diesel?

James
Ottawa, ON

> Date: Fri, 22 Aug 2014 09:27:42 -0400
> From: kenwilfy@COMCAST.NET
> Subject: Advice about black oil on back of diesel Vanagon
> To: vanagon@GERRY.VANAGON.COM
> 
> OK, here is the deal.  A white 82 diesel Westy.  It has a relatively low
> mileage 1.9l NA engine in it and a rebuilt fuel pump with all new
> injectors.  The customer is complaining about "black oil" spots on his
> back hatch.  The engine isn't leaking or using oil.  I am thinking that
> it is soot from the exhaust and that there is really no way to make it
> stop, but I thought I would ask the list if anyone has any advice on
> this one for me.  I would appreciate it.  The van runs and drives fine
> otherwise.  If it wasn't white it would probably not be that much of an
> issue.  Really pristine example of an 82 Westy though.
> 
> --
> Thanks,
> Ken Wilford
> John 3:16
> www.vanagain.com
> Phone: 856-327-4936
> Fax: 856-327-2242