In Vehicle Chemical Cleaning Of Fuel System Options

[Ryan H]

I was just reading the new post in the Fuel System Forum about the difference between in vehicle chemical cleaning and out of vehicle flow testing and ultrasonic cleaning. I would just like to shed some light on the diesel end of things.

I've been a diesel fuel injection technician of over 11 years and have seen a shift towards in vehicle chemical cleaning to resolve any fuel related drivability issues. As stated in the previously mentioned post,

http://thompsonautolabs.com/forums/index.p...view=getnewpost

I believe that in vehicle chemical cleaning should be left for preventative maintenance only. I want to focus strictly on injectors as the cause of concern and will leave injection pumps out of this for the moment.

I guess it all starts with the saying a little bit of knowledge is a bad thing. Customers and some technicians hear about the great benefits of chemical cleaning and how it can improve engine operation and fuel economy in a gas engine so why not diesel? I've heard many times of techs solving injector issues on diesel by running them through this cleaning process. The problem is a diesel fuel system is very different from non direct injected gas systems. Injectors in a gas system may be exposed to around 60 psi of fuel pressure and live happily in the intake manifold. On the other hand diesel injectors are exposed to between 15,000 and 28,000 psi and have to endure life in the combustion chamber. Unlike gas injectors, diesel fuel injectors are a wear item of the engine. Their nozzles will wear out around 150,000 miles in an automotive application. What I mean by wear out is that the nozzle seat will get pounded out and start to leak (this is more noticeable in common rail systems), also the holes of the nozzle will erode and start to over fuel. Finally the opening pressure of the injector will fall and the nozzle will open out of time. Now cleaning my appear to fix the issue but will not restore any of the above concerns.

Injectors are a silent killer and the number one reason for diesel engine failure. No matter what the make they all have to same issues regarding the nozzle. Think of diesel injectors like copper spark plugs in a gasoline engine, your engine still might be running after 100,000 miles but would you just clean them and put them back into service?