Fifty years ago, engine rebuilders primarily dealt with cast iron materials, labour cost were much less, and disposing the cleaning solutions was simple. Not so today, wet cleaning still plays a key role in today’s engine rebuilding process and will continue for the un-seeable future. The major changes for engine rebuilders and wet cleaning is the mass introduction of aluminium components and the onset of tighter restrictions on hazardous waste.
Engine rebuilders have been using aggressive, harsh caustic chemicals to strip away paints, carbons and heavy soiled cast iron materials for many years. Engine rebuilders have gravitated away from the older style vats, or hot cleaning tanks towards faster more efficient spray washer cabinets and ultra-sonic cleaners. After thousands and thousands of miles of driving most engines are covered with oil, grease, paint, rust, road salt and other crusty items.
There’s no single wet cleaning process that is right for both cast iron and aluminium applications. Aluminium is much softer and porous than cast iron and is at risk to harsh cleaning solutions. Cast iron on the other hand can survive almost any harsh caustic chemical you throw its way. Clean bare aluminium quickly forms a surface layer of aluminium oxide that stops further oxidation, and the colour is the same as the base metal so there is no change in appearance or colour. Most customers want a bright, like-new finish on their aluminium heads and blocks so it’s important you use a cleaning process that can do just that.
If you attempt to clean an aluminium head in a caustic charged spray washer cabinet you will be very disappointed. Harsh chemicals such as caustic will turn the aluminium black.
There are lots of ways to clean blocks and heads and different shops use different cleaning techniques for different reasons. If you’re building performance engines and working primarily with new castings, you shouldn’t have to deal with much grease and grime. So, you could most likely get by with one spray washer cabinet with a chemical designed for both cast iron and aluminium. In contrast if you are cleaning both cast iron and aluminium components from daily drivers then the preferred method by most rebuilder shops is to use a dedicated wet cleaning process for each type of metal. That is one spray washer cabinet for cast iron only, and a second spray washer cabinet for all the aluminium and all the cast iron post machining operations. Final cleaning wash operations includes removing cutting oils, honing oils, and machining chips.
The wet cleaning process should require the least amount of labour to complete, the less manual labour it takes to clean the parts, the better. Besides, most cleaning is a dirty job that nobody likes doing. It’s never appreciated until it breaks. Standard spray washer cabinets are manufactured regardless of the components being cleaned inside these cabinets, they all require a non-foaming chemical with a built-in rust inhibitor. Otherwise with no rust inhibitors your wet cleaning investment will be short lived and guaranteed to rust out quickly.
Owning these labour-saving spray washer cabinets also involves learning your environmental responsibilities. It doesn’t take a chemist to know that dumping all the used chemicals and sludge down the drain might be restricted, and illegal. You need to have a plan for when, not if, the local inspector someday wants to know what you do with all your hazardous waste. Most cleaning equipment suppliers and AERA can assist you with finding resources to assist with this.
Because these wet cleaning cabinets can evaporate several litres of water per day they will require a water source for refilling purposes. AXE Equipment emphasizes that you need not use fresh water to refill these tanks. Your best replenish source is capturing your used rinse water and recycle it back through the spray washer cabinet. There are many different sizes of water recycling rinse booth that can help you recycle your old rinse water and in some cases eliminating the drain in the cleaning area. Your local inspector will love it!
When looking for a new wet cleaning cabinet there can be other features and options but the basic requirements are:
- Heat
- Non-foaming chemical with a rust inhibitor
- Turntable and rotation
- Water pressure and flow
- Filter screen
- Steam vent
Make sure to ask yourself, “Do I want a gas heated machine or an electric heated machine?” Both have their benefits. Gas heated machines cost more up front, however the gas heated machines can cost up to 20% less to operate. Gas heated machines will also require much less electrical energy, and they will burn hotter then electric heated machines thereby heating up faster, and having faster heat recovery time.
On the other hand, electric heated machines provide ease of set up as no gas line or no gas venting is required. They can provide a bit less maintenance as you have less moving parts such as gas valves, blower motors, etc. All these cabinet washers and hot tanks require electrical power and they can be purchased in single phase power or three phase power. Be careful selecting as some can require high amperage requirements, so before you purchase ask about the electrical requirements.
Without a good efficient cleaning process, you can’t even begin to do a thorough job of inspecting dirty parts for cracks. Even porosity leaks in aluminium heads and blocks can be masked if there’s a heavy layer of gunk on the casting. You also don’t want to gum up and contaminate your shop equipment while you’re machining the castings. In short, wet cleaning can be a boring and dull process. But, you’ll never miss what you never had, and once you have an efficient wet cleaning process it then becomes really important.
*Written by Perry Crabb for Engine Professional magaine
