Walnut Blasting

What is carbon buildup?

Carbon buildup is a problem on most modern engines with direct injection. Direct injected engines inject fuel directly into the combustion chamber. For years prior to direct injection, fuel was injected into the intake manifold before the intake valves. This helped keep the valves clean as the fuel flowed past the intake valves which had a “cleaning effect”.

During the combustion process on direct injection engines, not all of the cylinder pressure is utilized in the combustion chamber. A small percentage of that pressure pushes past the piston rings into the crankcase (where the engine oil is). While this is completely normal, the pressure has to be vented back into the intake manifold or it would cause external oil leaks. The heat combined with the oil vapours (positive crankcase pressure) stick to the valves causing buildup over time.

This buildup can affect airflow past the valves and have a negative effect on engine efficiency causing things like a reduced power, rough running, and misfires upon startup. A rough or misfiring engine can cause damage to the catalytic converter(s) which are very expensive to service or replace.

Intake valve carbon cleaning

To complete an intake valve carbon cleaning service, the intake manifold must be removed to gain access to the cylinder head intake ports. Once removed, you must carefully protect any openings left from the intake removal to ensure solvents/media does not enter any unwanted areas.

Chemicals/brushing vs. walnut blasting

Carbon buildup is typically cleaned in one of two ways.

One method is soaking the buildup with harsh chemicals and manually removing the carbon with various tools and brushes. This method is obviously not ideal for the technician’s health or the environment, plus it is a longer (more expensive) process.

Our preferred method is to use ground walnut shell media with a walnut baster to clean the ports. We use an adapter that fits directly into the intake port. The blaster tip goes into the adaptor along with a vacuum hose (which is used to vacuum out the wasted walnut media, keeping the mess to a minimum).

Some manual carbon removal is still required but no chemicals are used at all. Walnut media is safe for the components in your engine as the media is softer than aluminum and steel, thus leaving no evidence!

Walnut blasting cost

Walnut blasting costs vary depending on the time spent cleaning, but it’s roughly between $40-65 per cylinder (typically $160-260 for a 4 cylinder engine, unless its an extreme case!) PLUS the time to remove and reinstall your intake manifold.

Total cost depends on your vehicle make, model, and engine. Contact us for accurate pricing!

We recommend completing a carbon cleaning every 80-100,000 km as a preventive maintenance service.