WE all love a clean engine, right? The problem with modern vehicles is that their powertrains have many electronic control modules, actuators, switches and a vast number of connectors. And none of those components like water. Spraying these delicate electric components with jets of H2O or steam will most likely result in a non-starting engine at best and, in a worst-case scenario, expensive repairs.
That’s why you’ll see disclaimer boards at car washes that state that engine cleaning is at the owner’s risk. Advancement in powertrain complexity calls for a change in cleaning technology, which is why there’s now an alternative – dry-ice cleaning.
The Basics
Dry ice in the form of small pellets (1,5 and 3,0 mm for automotive use) is loaded in a specialised machine and fired at the dirty object at speeds of up to 360 km/h. Compressed air at about 6,0 bar is the driving force behind the pellets (see Polarjet 600) and the low temperature of dry ice (approximately -78 degrees Celsius) freezes the dirt on impact and dislodges it from the surface.
The process of easing the adhesion force of the dirt is enhanced by the kinetic energy of the dry ice and the fact that the coefficient of expansion of the offending material is different to that of the carrier material. The biggest advantage of using dry ice is that it sublimates – it changes from a solid to gaseous state (CO2) without entering a liquid phase – and therefore poses no risk to the engine’s electronics.
The Test
To put the technology to the test, we asked Hans Kaiser, the sole importer of Polarjet machines, to treat the engine of a 2007 Toyota Prado 4,0-litre V6, which had undergone many off-road excursions but not many engine-bay cleanings, to a “dry clean”. To remove seven years of dirt and grime without water was going to be a difficult task. Hans connected a portable, diesel-powered compressor with a dehumidifier unit to the Polarjet machine filled with dry-ice pellets … and pressed the button.
In little over an hour, 12 kg of dry ice was used to clean the engine thoroughly. Thanks to the non-abrasive nature of the process, there was no damage to the vehicle. Most of the dirt and grime dropped to the floor and a rag (or compressed air) took care of the rest. When the task was completed, the engine started promptly.
Conclusion
The test proved that it is quite possible to clean a modern engine without the risk of incurring water-related damage. At about R1 200 per cleanse, the downside is cost; the equipment is pricey and scarce. However, as the public’s awareness of the benefits of this technology grows, the costs of “dry cleaning” should come down.
Top tips for engine cleaning
- Follow a top-down approach.
- Use as little water as possible.
- Use engine cleaner on a small brush to dislodge stubborn dirt and grime.
- Wipe down with a clean cloth.
- Check all engine fluid levels and condition of piping while you’re at it.
- After cleaning, apply a product that protects the components and repels dust (Hans uses Swissvax Motor Shine).