This article will cover how to clean carbon build-up from direct injection engines using a walnut sheel blaster. You can apply this technique to all direct injection engines.
In this demonstration, we will be using a 2004 Hyundai 2.4-liter engine. This engine is out of the vehicle, so access is greatly improved. (sorry you will have to suffer dealing with the air filter and various other obstacles).
If you suspect carbon build-up, use an ATS Inspection Camera to view the back of the intake valves. It rotates 360° to allow a full view, no other boroscope or inspection camera does that.
The walnut blasting device we will be using is from the world-renowned Harbor Freight Company. This device is a very affordable tool. Some walnut shell blasters (factory type) can run as high as $1800.00.
We are also using media purchased at Harbor Freight (in this case we are using a FINE grain media). Pictured here is the adaptor (and filling funnel and scoop) used to introduce the media blown into the cylinder head swirl chamber. Also shown is the media spraying nozzle.
NOTE: the spray nozzle always remains in the closed position when not in use.
You will also need a good shop vacuum. Larger with good filtration to keep dust out of the air. Don't forget to wear eye, hand, ear and respiratory protection. ALWAYS WORK SAFE WITH ALL SAFETY GEAR!!!
You will need an air compressor capable of producing 100 PSI. and reasonably large tank (at least thirty gallon).
Begin by opening the filling port at the top of the blaster canister.
NOTE: BE VERY CAREFUL WHEN OPENING THE BLASTER CANISTER! BE ABSULUTELY SURE THERE IS NO PRESSURE IN THE CANISTER! EVEN A SMALL AMOUT OF PRESSURE CAN CAUSE THE UNSCREWD TOP TO BLOW OFF! HITTING YOU IN THE FACE A PLASTERING YOUR BRAINS ON THE CEILING!! Be sure to release all the pressure first using the pressure release valve!
Fill the canister about 3/4 full with media. Leave some space for the compressed air.
Be sure to close the media storage bag after filling the canister. Even a little bit of moisture will affect the media (makes it clump up like cat litter, not good).
Refit the canister fill top.
NOTE: Do not over tighten and risk pushing out the rubber seal.
Pictured here are the inlet water trap and valves for the media blasting canister.
NOTE: ALL valves must remain closed until ready for use!
Connect air supply.
NOTE: air supply must reach a minimum of 90psi. and remain constant.
Open the air supply valve first.
Drain any water that may have been trapped in the line.
Here’s what pressure on the gauges will look lik e before you begin.
Next open the lower tank siphon hose.
Next open the feed hose valve for the media blasting nozzle.
Shown here, is the control valve for the media blasting spraying nozzle.
Next, place the adaptor into the swirl chamber of the cylinder head (intake side).
NOTE: in some cases, the adapter will be smaller than the port it is being inserted into. If you begin to blast with an air gap around the adapter, a lot of “blow back” will occur! This will be very messy and you will probably cry!!!
We fashioned a nice grommet to seal the adapter to the cylinder head. You can do this too. Use your imagination!! The idea is to seal off the chamber so the media goes into the cylinder and not in your face.
BEFORE!!!!!!!!! ANY!!!!!! BLASTING BEGINS, BE ABSOLUTELY SURE THE INTAKE AND EXHAUST VALVES ARE CLOSED!!!!!!!! USING YOUR FLASHLIGHT (AND MIRROR, IF NECESSARY), LOOK INTO THE CYLINDER HEAD AND VISUALLY CHECK THE VALVES ARE CLOSED. DON’T BE THE GUY THAT FILLS UP THE CYLINDER WITH WALNUT SHELLS!!!!!!!!!!!!!!!!!
Now connect the shop vac.
Insert the adapter into the swirl chamber.
With the nozzle valve still closed, insert the nozzle through the adapter and into the swirl chamber.
You are now READY to blast.
BEFORE YOU BLAST, TURN ON THE VACUUM CLEANER (SHOP VAC).
OK, slowly open the blasting nozzle. Do not “bury” the nozzle into any thick gunk inside the swirl chamber. Work in short blasts. Typically, ten to fifteen seconds at a time. Work the nozzle in and out and around in a circle to clean as much surface area as possible (per blast). Close the nozzle valve and allow the vacuum to run for a few more seconds. This will clear the swirl chamber. NEVER PULL THE NOZZLE OUT OF THE ADAPTER WITH THE SUPPLY VALVE OPEN! YOU WILL BE GREATLY DISAPPOINTED.
As shown in the picture below, we have drawn a line around the end of the nozzle to let us know when the end of the nozzle is coming up. This will help prevent pulling it out too far and getting a face full of media.
After you have blasted the valves a few times inspect your work. The job is complete when the valves look nice and clean, as shown in the picture below.