Chronic Overheating

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Learn how to fix the root cause of your problem. Many people have engine overheating problems, and struggle to find the cause. There’s no loss of coolant, and it runs fine until they need more power, eg hook up the caravan, climb a steep range, or up the cruising speed a bit.

Very commonly, before they speak to us, they have spent several thousand dollars, on thermostats, water pumps, fan hubs, big core radiators and hoses…and it still overheats.

Finding the root cause of the problem

Reduce engine friction, overheating toyotaAs with a lot of problems, our approach to finding the root cause in this case, is simple. Get everything clean first. Sounds far too simple, but often that’s all you really need to do.

Few people realize that the engine oil plays a major role in cooling. If your oil gets dirty very quickly, it can be a pointer to your problem. The black soot in your oil absorbs heat readily, but tends to retain it, rather than disperse it. Sludge can easily result, which insulates against heat transfer, and reduces the flow of cooling oil. Carbon deposits form (unchecked by the dirty oil), and wherever it forms (eg under the piston skirts), it also acts as insulation against heat dissipation.

Problem Correction

This problem can be easily corrected. Simply run the engine at a fast idle with clean oil, treated with Flushing Oil Concentrate (FOC) for 30-45 minutes, and bring the entire oil wetted side of the engine back to pristine cleanliness. This removes carbon from around sticking piston rings, top lands & skirts. All sludge that constricts oil galleries, oil pumps and oil coolers is removed to allow the oil to do its important cooling job.

Cooling System Treatment

With the cooling system itself, there are situations where the typical glycol type coolant additives can cause sludgy deposits. Mineral scale is also a common problem, and even the thinnest deposits through the cooling ducts in the radiator, engine block and cylinder head will prevent efficient cooling.

Just add RMI-25 cooling system treatment to your existing coolant. RMI-25 cleans, desludges and descales the entire cooling system…while you drive! It lubricates water pumps and better preserves hoses, seals and O-rings. It can easily cool overheating systems by 10 deg C and more!

Remember, water is a superior coolant to glycol, so provides additional cooling benefits to glycol, and is a lot cheaper. If you need antifreeze, you will require a small amount of glycol, but for most Australians, RMI-25 and water is recommended. Importantly for the environment, it is non-toxic and biodegradable.

“Waterless Coolants” are usually based on glycol alone, without any water.  They offer a very high boiling point, but are less efficient at cooling than water, and to that end are more a “bandaid” approach.

High Temperatures

For high ambient temperatures, or high engine load applications, AW10 Antiwear is also recommended to reduce friction, wear and heat build up at highly loaded parts. AW10 is also useful for reducing operating temperature in transmissions, differentials, hydraulics, etc.

Engine Overheating


Datsun SD25 Diesel.

For 4 years, Allan Dickson had been unable to solve an overheating problem. Despite flushing the cooling system, and fitting a larger radiator, it would always boil up the Toowoomba Range. After using FOC, it gets up the range at 70 kph (instead of 40-50 kph) without overheating. One of the functions of oil is to cool, and if flow is restricted, overheating results.

Landcruiser 1HZ Diesel (1994)

Hi Jimmy, I would like to say thank you for the extra bit of engine oil flush. I ran the flush thru the old girl with 9 litres of clean oil for 30 mins as directed. Well over 11 litres of black gunk came out. I was totally blown away by the sludge in the bottom of the Drain Pan. I’ve added a couple of pics for your website and feel free to use my above testimony of the result. I must say my Family were impressed and will more than likely be placing an order themselves.

Once again thanks Mate. (Evan Yates)

Nissan 4.2TD Patrol

 (Peter Simms, HUMPTYDOO NT).  Originally never ran hot, but in recent years it had become a problem. Peter had spent thousands of $$$ replacing radiators, clutch fan hubs, thermostats, chemical cleaning, etc, etc…all to no benefit, as nothing solved his overheating. In fact over the last 3 years, it just got worse & worse. The temp gauge would sit 3-4mm above the ½ way mark. Every time it ran hot, the air conditioner would cut out. After doing a web search, and finding reports of solving this problem, Peter finally tried the Flushing Oil Concentrate & Cleanpower pack. The overheating problem was immediately solved. Now at 110kph uphill, towing the quad bike trailer, and the temp stays cool. Peter also reports that after his first flush, the new oil was amber clean on the dipstick. Normally it went black straight away.

Nissan Patrol2.8L TD

I used the Flush to your instructions, and couldn’t believe the sludge that came out!! The motor is now running a lot smoother and staying much cooler under heavy loads now, eg towing my 2 tonne horse float. Fuel consumption has also improved, but it is too early to confirm the figures yet. Les White, Heartland Real Estate GIN GIN.

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