And found this black slime. Do I have a bacteria problem? Should I check the Pre-filter?
I believe those are asphaltenes; they occur naturally in diesel fuel. And they are the primary reason you don't want to leave the fuel filter unchanged for too long. I got busy or distracted for quite a while once and ended up with about 50K on my filter. There was 1/16" of asphaltenes on the filter; it wasn't passing fuel very well.
Here's a good description of the problem:
Fuel School: Asphaltene's and Plugged Fuel Filters
Answer is additives and Amsoil has an excellent additive to solve this.
Ken
How many miles were on that filter?
12K-15K
I'm going to be changing it a lot sooner!
Excellent write-up you found. Thanks.
I submit that even if you use aditives that the filter will turn black. The answer is change the filter on a regular basis. I change mine every 15 to 20k, but if I had a 3rd gen it would be more often.
When I bought my truck it had 10K on it, and the stock filter and 3 years of use. The filter was nasty like that one. Since then I have put 30K on the filter (I have 3 and a psi gauge) and never had a spec of the asphaltenes and have used Amsoil Diesel Concentrate on every tank, it must work!
My truck is no longer my DD, so the fuel is sitting a lot longer so I plan to check the filter every 5K to see if its asphaltening up.
:-laf
Yes sounds like another satisfied fuel snake oil user :-laf
Quite satisfied. . fuel lubricity is huge! And my filters stay asphaltene clean with it, without they don't.