Cleaning Carbies and Pistons

If you are a karting or motor bike fan, or a backyard mower mechanic then it’s likely that you’ll know the pain of old fuel that has turned into varnish.  Bet you wear the same despondent look when you see a blackened piston.

For the home mechanic, this is probably the most useful function of an ultrasonic cleaner – to clean out that gunked up carbie.  The great thing is that it can do the job without resorting to those seriously caustic solvents.

Even so, there are still two schools of thought on what additive to use in the ultrasonic tank.  You guessed it – green vs more aggressive.  We caution against using substances that will require the operator to put on the protective clothing and respirator and hold their breath.

Option 1 – More Aggressive

In the industry, we know of guys who still swear by the caustic products, which is fine as long as they tell us that they are using them before we pay a visit.

If they are using CT14 (generally marketed as truck or bilge wash) then this is a safe option.  The safety data sheet on CT14 says that it is non-flammable and in other respects pretty inoffensive.  Of course, you won’t want to drink it, but otherwise it’s about as safe as you can find, while still giving good results.  For carbies, half a cup in a 12 litre tank is as much as you need.  When last we checked, you could get a 5 litre concentrate at Supercheap Auto for a touch under $40.  Similar price from Repco.  As long as the tank is heated adequately (around 70C+), it should only take about 15 minutes to clean a dirty carbie, more or less.  A hint though – it can take quite a while to get the tank up to that temperature.  We would recommend using the cleaning function as well as the heater, and put the lid on.  That way you won’t be waiting around twiddling your thumbs.   Brett, our customer in the engine reconditioning business, recommends giving it a good blow out with compressed air after cleaning, just to make sure the gunk has come off and been sent to keeper.

For pistons, he says it might take a couple of hours to get them clean, especially the top – really bad ones can be left to soak in CT14 overnight – the next morning you should find the carbon has softened and the ultrasonic will have an easier job of finishing it off.

Back to the ‘not so gentle’ products – some are also flammable. Cool.  Because the flash point can be lowered after using an ultrsonic cleaner. Now we have the worst of both worlds.  It is worth noting very prominently, that flammable products do NOT belong in an ultrasonic cleaner, whether heated or not.  If you must use these products, then do yourself, and your loved ones, a favour.  Soak the carbie or piston in a tank well away from the ultrasonic.  Only after the substance has evaporated off, or has been thoroughly rinsed off, should you place the item in the ultrasonic for the next stage of cleaning.  High powered cleaning at 60C in an ultrasonic is a formula for pyrotechnics, not safety.

A very popular solvent is good old acetone, found in almost every woman’s survival kit.  As gossip girl will happily tell – acetone is great to remove nail polish.  It is also seriously flammable stuff.  Play it safe.  Wait until the acetone evaporates off the piston or carbie before placing in the ultrasonic tank for the perfect clean.

Option 2 – Go the Green. 

Now, the green alternative is to try products that are kinder to people and to the environment when the cleaning is over.  On our list of more environmentally (and people) friendly products are Simple Green and Kenco SHIFT-IT Heavy Duty Cleaner.  Simple Green is very popular in the USA where it is widely available.  It’s a biodegradable product that can be bought on the internet from the Australian distributor (shipped from Adelaide).  We have also seen it at Bunnings and Blackwoods – so it might be worth a trip down to your local store (or check them on line), to save on freight by picking it up when you buy your other hardware staples.  NB. There is a range of Simple Green cleaning products – you want the industrial strength cleaner.

Simple Green ships as a concentrate, so one bottle goes a long way.  We have customers who are very big in reconditioning carbies who swear by it.  At the other end of the spectrum we have an elderly customer painstakingly restoring his beloved vintage roadster in WA, who is likewise a big fan of Simple Green for its effectiveness and for its reputation for safety.

The Kenco product does not appear to be as widely used by our customers – perhaps it is just less well known.  Anyway, Paul the grubhunter uses it to good effect, and is a big supporter of both its effect and kindness to worker and environment.  You can get it at the regular auto product stores – about $12 for a 750ml spray bottle – although larger bottles (up to 5L) are also available.

As with many of these cleaning tasks, there is no magic formula for the time the cleaning job will take.  Let yourself be guided by common sense.  Time in the cleaner is a function of 5 factors:

  1. Power of the machine (ie Watts)
  2. Frequency of your ultrasonic (lower frequency (typically 20-25kHz) has more ‘oomph’, but not so good for detail – eg blind holes and thread vs higher frequency (40-45kHz) which is better for fine detail and more consistent across a surface and better for gentle cleaning results)
  3. Temperature – as a general rule, 60C will be the best operating temperature for an ultrasonic cleaner, although this temperature is too hot for some materials.  Be aware that at 60C evaporation can be faster than you might think.  So keep an eye on the fluid level in the tank and always top up fluids as required (Think SAFE.  Turn unit off and disconnect from power first).  Please do not even THINK of putting a flammable product in an ultrasonic and running the unit at 60C.  The cavitation effect helps to lower the ignition point of fluids – don’t say you weren’t warned!
  4. Amount of Dirty Gear you place in the ultrasonic tank.  The higher the surface area to be cleaned, the slower will be the result.  and
  5. Type of Contamination what is on it – eg burned carbon vs light soiling.

So, you need to be flexible and keep an eye on how it is going.   Just remove the item for examination about every 10-15 minutes, so that you know when it’s done, and you can move on to your next subject for cleaning.  That approach will also help you to maintain the correct fluid level in the tank, so you don’t damage the ultrasonic or the heater in the process.

NB. Simple Green needs to be used carefully with aluminium products, as it may cause oxidation if contact is extended.  Remove item from the solution as soon as it is cleaned, and ensure that all traces of Simple Green are rinsed thoroughly off your carbie.  If you see evidence of aluminium oxide you can remove it with an aluminium polish like Autosol or Briteshine.

Dual Frequency or Intello-Cleaning.  If you are using an ultrasonic with dual frequencies, we would suggest running it first on low frequency for 30 minutes to blast the heavy duty crud.  Examine the item after first cycle and extend low frequency cleaning to continue ‘blast mode’, or switch to high frequency operation to ensure that fine detail areas are covered.  Adjust cleaning based on the cleaning result you experience.

If you are using an Intelloclean or similar sweep style ultrasonic cleaner the process is simple.  Select your sweep function and leave the machine to cycle through low and high frequencies for about 30 minutes.  You can also use the Turbo function, but go easy if the item you are cleaning is a soft alloy.  Examine the item and repeat as necessary.

If you remember that an ultrasonic cleaner of 100W will take 10 hours to consume a kW/hr of electricity, and that kWhr still only costs about 27cents, it is a very cheap cleaning process.  Add say 25 cents of Simple Green or Kenco liquid to the tank and you are looking at petty cash indeed.  HINT: Try the shooter’s tip – use a Pyrex beaker or jug to hold your parts inside the basket of the ultrasonic’s tank.  That way you can ration the Simple Green/Kenco or caustic brew to just treat the carbie or piston while the rest of the tank is filled with tap water. A final caution – no flammable items in the ultrasonic tank.

  1. Always turn machine off before removing item from tank for inspection.  Never permit fingers, hands, or any other body part to enter the liquid of the tank while the ultrasonic cleaner is operating.  Damage to living tissue will result, even if you cannot see it.
  2. A little reality check.  There are some videos on you tube that show a dirty motor going in, and, hey presto!  a brand new looking motor emerges.  We find these a bit deceptive, as they imply that an ultrasonic cleaner will clean and polish and restore a motor to brand new condition on their own.  There is often no indication of how long the motor has been worked on, how powerful the ultrasonic cleaner, and what, if any, sort of additive or solvent is used in the video.  An ultrasonic cleaner will clean, but carboned metal normally requires an additive to help break it down.  And polishing – well just like with jewellery – this is an additional process.  Once an item is clean it can then be polished.
Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)

Best Frequency for an Ultrasonic Cleaner

We’ve often been asked ‘what is the best frequency?’ for a customer who is in the market for an ultrasonic cleaner.

Like many things in life, there is no simple black and white answer.  It’s like asking a vehicle salesman whether it’s better to buy a truck or a car.  Both will get you from A to B, but the best solution depends on the individual’s situation.  For instance, a furniture removalist will find a truck more useful, whereas a real estate agent would definitely find a car more appropriate – especially when it comes to parking in busy shopping centres!


Early ultrasonic cleaners tended to be in the low frequency range – roughly 15 – 25 kHz.  Their wave patterns meant that they were very good at ‘blasting’ heavy contamination off metallic objects with plane surfaces.  But, they were not very good at cleaning items with fine detail (such as apertures, threads and blind holes), nor did they give consistent cleaning results across a surface, unless the object was moved about inside the tank during the cycle.  Lower frequencies were also found to have an impact on softer materials being cleaned.

More modern cleaners tend to deliver frequencies in the upper range – between 40 – 45 kHz.  The wave pattern of these cleaners results in a more gentle and more thorough cleaning result, so they usually have no effect, even on softer metals.  Often there is no need to adjust an item’s placement in the ultrasonic tank to ensure all surfaces are properly cleaned, which means a faster result with less labour. The higher frequency wave pattern also has a better cleaning effect on parts with fine detail (eg the apertures, threads and blind holes that the lower frequency cleaners do not clean well).  However, the trade-off is that higher frequency cleaners will not always have enough ‘grunt’ to remove the heaviest contamination, so it will take longer to properly clean some items, or the machine will need to be more powerful, or some additive will be needed – in some cases all three!

Cleaning requirements, materials and situations vary.  So, operators cannot always get by with a single frequency solution.  In summary:

Low Frequencies – ‘blast’ effect, especially for plane surfaces, but can be hit and miss unless object is adjusted inside tank, and poor for fine detail.  Not good for softer materials.

High Frequencies – gentle consistent cleaning across a variety of surfaces and good for fine detail. Suitable for even soft metals. Not ideal for heavy contamination.

The Solution – Dual Frequency Control

So, how can we overcome the shortfalls of low and high frequency wave patterns in ultrasonic cleaning?

Not every heavily contaminated item has a plane surface.  Often these parts are designed with flanges, apertures and threads to connect to other parts.  Sometimes these items are weighty, and are awkward to adjust inside the tank.  For other items, such as surgical instruments, patient care and infection control policy dictates that instruments need to be perfectly clean, before moving on to the sterilisation procedure.

Dual frequency ultrasonic cleaners combine the advantages of the high and low frequency wave patterns in a single unit.  They significantly reduce capital cost and the footprint required to accommodate the equipment.  ‘Space’ was the final frontier for Startrek, but the lack of it is equally important in today’s clinic or workshop facility.  The better designs feature options to switch between high and low frequencies and to select a range of power settings.  This provides substantially greater control over the cleaning environment than less sophisticated machines, and ultimately leads to a better cleaning outcome.

Dual frequency ultrasonic cleaners allow the operator to clean items in a multi stage process, that minimises cleaning time, staff intervention and the need for additives.

As a general rule, dual frequency ultrasonic cleaning will be conducted as follows:

Stage 1. Use the low frequency ultrasonic cleaner setting to dislodge gross matter and heavy contamination.  Unless material is soft or delicate, use full power and complete a 30 minute cycle.  Remove basket from tank and examine objects.  If heavy contamination remains, repeat process – NB Removal of basket and examination of objects will adjust position of cleaning object – aiding in cleaning consistency.

Stage 2. Use high frequency ultrasonic cleaner setting to address fine detail cleaning and to ensure cleaning result is thorough across all surfaces.  Set for additional 30 minutes cleaning cycle and examine object to ensure desired result is achieved.

Note: For surgical instruments, refer to practice procedure manual and ensure that at start of day tank is degassed and unit’s working condition confirmed, using the foil test.

Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)

Setting Up Your Ultrasonic Cleaner

OK.  You’ve bought your new ultrasonic cleaner and you want to know how to set it up.  There’s a trick to doing most things – and this is no exception.  A little time spent following a procedure could save you a lot of money!

Protecting Your Investment

Inspect the box for damage before opening it.  If outside shows any sign of rough treatment during transport, take photos – they might be needed to show the supplier or freight company for a claim.

  1. Take more photos of the unit and anything inside the box if they have been damaged in transit.  Take a clear image of the unit’s serial number.
  2. Inspect contents. Take particular note of the tax invoice and the unit’s user manual/operations guide.  Often the items supplied will be specified in the user manual.  Check you have them all.  If not, contact the supplier ASAP and ask for anything that seems to be missing.
  3. Tax Invoice  A valid tax invoice will show GST included in the sale, the supplier’s Australian Business Number (ABN) and address in Australia.  The tax invoice is a valuable document which should be kept safe and produced (or copied) if you ever have any warranty issues.   Some sellers on Ebay will provide a tax invoice which is generated through their system.  As long as the document meets the requirements set out in the New Tax System (GST legislation) it doesn’t matter what it looks like.  This contrasts with invoices/shipping documents that make no mention of the words tax invoice, GST included in the purchase and the supplier’s ABN.  We recommend caution if dealing with a supplier who ships cleaners without a valid tax invoice, because it is extremely unlikely that you are dealing with a registered Australian business who can be forced to adhere to Australian consumer protection laws.

Product Safety and Compliance

Once you know you have everything that’s supposed to be included, you can move on further.  The next step is about checking your unit is safe for you and your staff.

  1. Check the power lead provided with the unit has an approved Australian/New Zealand style plug – sometimes suppliers will provide one that fits in the socket, but it does not have the insulation on the top pins (normally black).  Plugs without visible insulation on the top two pins are the ‘old style’ which ceased being approved for sale in the late 1990s.
  2. Check for C Tick label.  Electrical equipment needs a C Tick label to identify the authorised supplier and to show that the supplier can prove the device meets Australian/NZ EMC requirements.  By law ALL ultrasonic cleaners sold in Australia and New Zealand must have this label, whether imported or manufactured locally.  They also require the supplier’s electrical code (usually a number starting with letter N or V, representing the state the company is registered in).   NB If the unit does not have a C Tick and the supplier’s electrical code, then it is illegal for sale in Australia and New Zealand and it may also be unsafe.  Contact your local Department of Fair Trading and request a refund from the supplier.
  3. Check power supply.  Most quality units will be manufactured for 240Volt mains supply.   Many units will state 220 or 230 Volts, or some range between these.  The closer to 240 Volts the better.   If the unit is labelled less than 220 Volts its working life can be much less than one made for 240.  NB Do NOT attempt to use a device made for US power supply (110 Volts).  Return it f or replacement or refund.
  4. Use a surge protector. Even robust commercial ultrasonic cleaners can fail due to power surges.  Like computers, these days, ultrasonic cleaners all have electronic components which can easily burn out when power spikes occur.  We recommend taking sensible precautions, like using a quality surge protector at all times and to remove the device from the power outlet during electrical storms,  or when you are absent from the workplace..

User/Operating Manual

Most suppliers will provide a user or operating manual.  Manuals from quality suppliers units will be in plain English that the average person can understand.  Often the manual will also specify the unit’s warranty and support arrangements.   We recommend against items that must be sent overseas for warranty service.  The following points are obvious, but we’ve all seen the line – if all else fails read the manual.

  1. BEFORE you connect the unit to the power supply, or attempting to use it ensure that you read the manual and understand it.
  2. Follow the instructions in the manual.  If you don’t, often the manufacturer’s warranty will not apply.  It could be an expensive mistake.

Next Step

After you have set up your machine as per supplier’s user manual, you should immediately test its function.   Run a simple foil test to satisfy yourself you have a true ultrasonic cleaner, not a dud.  If the machine fails the test contact the supplier and have it replaced/get a credit.


  1. EMC is Electro Magnetic Compatibility. When a product shows the C Tick symbol it tells the consumer that the supplier has proven that the device meets the Australian/New Zealand regulations for EMC.  A product that does not meet EMC rules may interfere with radio and other communications, including devices such as pace makers and other sensitive life saving equipment.
  2. The supplier’s code (usually a number starting with letter N or V) on an electrical product tells the consumer that the supplier has tested the device for compliance with the Australian/New Zealand regulations for electrical safety.  The CE label often seen on electrical products has not value in Australian/NZ.  It is easily confused with an almost identical CE label which represents Chinese Export.
Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)