Dear JB,   
    My 1999 Chevrolet Silverado has a knocking noise when I first start it in the morning.  This first began happening when the truck had about 15,000 miles on it, so I took it to my dealer and asked them to fix it.  They told me it was carbon build up around the piston rings and blamed me for not driving it hard enough!  They also performed some sort of internal engine cleaning, which helped, but now it is out of  warranty  and I'm a little unsure what to do next.  Help!
Signed,
(Sounds) Like A Rock

Dear Rocky,
    I hope misery does love company because you have plenty of it with this problem. What you are describing is soon to be GM's largest and perhaps most expensive issue ever.  Depending who you listen to it is either a defective piston skirt design or a defective piston ring design which allows carbon to build up in the ring grooves.  Since engine

decarbonization makes the problem go away you would think that it is the latter, but who cares anyway since fixing the problem will require new pistons!  The good news is that you can live with the knocking noise and apparently no further harm will be done; however, I suspect most customers who just dropped thirty to fifty thousand dollars on a new GM truck aren't really in the mood to do that.  For the time being just keep spending the seventy-five or so dollars on the decarbonization until this thing is resolved.

Dear JB
    Does this sound possible?  I have a 1993 Ford Tempo that recently died due to a defective fuel pump.  This is the fourth pump in two years.  Now my mechanic is advising me to let him install a new (not used) fuel tank, because he thinks that it is rusting inside and ruining the pump.  Is he pulling my leg?
Signed,
Pumping Iron?

Dear Pumping,
    It is not only possible, but he is most certainly right!  I have seen many vehicles exhibit this same condition with repeated fuel pump failures because of rusty tanks.  You might legitimately ask what makes them rust since you never put water in them, but you might be surprised by the answer - sometimes it is caused by the car's owner!  Have you ever succumbed to the temptation to add a bottle of some

super-duper fuel injector cleaner to you fuel?  If so, then you may have inadvertently set in motion an irreversible chain of events which ultimately led to your fuel tank's demise!  Metal fuel tanks are galvanized inside and out to keep them from rusting, but some fuel system cleaners are so harsh that they actually begin removing the coating from inside your tank.  The first pump is then destroyed by this metal coating as it is flushed through it and subsequent pumps are later destroyed by the rust which is now forming on the bare metal of the tank.  So go ahead, Pumpy, let that mechanic of yours

install a new tank and put this problem behind you.

JB can be seen each Thursday morning on WDEF-TV News 12's Morning Show at 7:30 A.M. where he answers your car questions.  He can also be heard Saturday Mornings 7-9 on Talk Radio 102.3 FM on the Saturday Morning Garage.  He spends the rest of his time taking advantage of helpless motorists at North Shore Auto Repair in Chattanooga.  E-mail JB at jeepster1515@yahoo.com to have your car care question answered in this column. 

JB can be seen each Thursday morning on WDEF-TV News 12's Morning Show at 7:30 A.M. where he answers your car questions.  He can also be heard Saturday Mornings 7-9 on Talk Radio 102.3 FM on the Saturday Morning Garage.  He spends the rest of his time taking advantage of helpless motorists at North Shore Auto Repair in Chattanooga.  E-mail JB at jeepster1515@yahoo.com to have your car care question answered in this column.