Cooling

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Just because it’s an oldie, it doesn’t have to overheat! Here’s our take on what upgrades and tweaks are available to help a classic car cope with modern traffic

Preserving the components that make up a vehicle is in many cases down to maintaining their temperature. In the case of an engine, it’s either water or air-cooled, but the temperature of the oil is also important. Similarly, a gearbox and axle also need some means of controlling the temperature of the oil inside.

Cooling upgrades are not solely for modified classics. Take an air-cooled VW campervan, for instance. Its standard engine isn’t designed to be able to cruise along a motorway at 70mph all day long, unlike a more modern vehicle. However, with a few modifications, such as an external oil cooler and a larger sump, it can withstand longer journeys.

The range of upgrades that are available to help improve the cooling capability of an engine, gearbox or similar component range in price and effectiveness. At the budget end of the scale, painting rocker covers, tinware, radiators and coolant pipework black helps with heat absorption and takes the heat away from the engine. Ducting can help to channel more air to the radiator. Exhaust manifolds can be wrapped in insulation bandage and heatshields can protect opencone air filters from drawing air off hot components – useful to help prevent fuel evaporation too.

System upgrades

Most of the components that make up an engine’s cooling system can be uprated to help improve its cooling capabilities. Starting at the header or expansion tank (if fitted), an alloy tank can dissipate heat better than one made from stainless steel or plastic. If an engine has been highly modified, such as a turbo or supercharger conversion, then a standard header tank may not be sufficient to cope with the increases in coolant temperature.

Made-to-measure and universal header tanks are available through specialists such as Bailey Motorsport, Forge Motorsport and AH Fabrications. In some cases, the new header tank uses the existing mounting points, otherwise, new mounts may need to be fitted or fabricated.

The coolant hoses between the radiator, engine and heater are usually a black rubber type that’s effective at absorbing heat. Aftermarket silicone hoses are stronger and look better, but they do not offer a greater cooling capability over standard black rubber. However, as Alex Harrhy at Forge Motorsport explains, “The main function of an uprated silicone coolant hose is to provide better longevity over a rubber equivalent. Over time, and after heat cycling, standard hoses can mechanical fan with an electric alternative offers many advantages including: increased airflow whilst idling – a must for those long traffic queues in summer; mechanical fans consume power, much like a water pump, so changing to an electric fan can reduce the load on your engine, increasing performance and MPG.”

As well as their range of retrofit conversions, Revotec has a range of off-the-shelf fans from 4-inch to 16.5-inch diameters, with adjustable controllers and universal mounts to replace existing OE electric fans or mechanical type with modern, high efficiency, higher output, types. This can either be as an upgrade to an existing system or a replacement for a prohibitively expensive or out-of-production OE component.

Why use water?

There are some alternatives to the traditional antifreeze-based engine coolants, such as Evans Waterless Coolant. This doesn’t operate under pressure, unlike antifreeze-based engine coolant, so there’s less strain on the hoses, connections and the radiator. To use it, all traces of coolant and water need to be removed by filling the engine’s cooling system with a prep fluid, before draining it and then adding Evans Waterless coolant and bleeding the system. The only disadvantage with this coolant is that it cannot be topped up with water, so it’s wise to carry a container with some Waterless coolant, just in case, and its seeping characteristics means the system has to be fluid tight.

Oil cooling

Engine oil accounts for around a quarter of the unit’s cooling. Oil temperature of the engine and transmission is critical – if it gets too hot, it becomes too thin and loses its effectiveness at lubricating any bearings and other internal components.

A modified engine will inevitably put greater demands on the lubricant and potentially raise its temperature. An oil cooler helps here, which might be cooled by airflow if it’s mounted near the front of the vehicle, engine coolant, or a fan (e.g. on an air-cooled Beetle). Just like a radiator for the engine coolant, an oil cooler works in the same way for the engine oil but if you don’t need one then don’t fit one as over cooling can be just as detrimental.

The oil inside the gearbox and axle can be cooled via cooling fins. These fins are found on the casing of the gearbox or diff. Aftermarket casings are available, replacing the standard casing on a differential for instance, for one with cooling fins. Again, for normal road use it’s not needed unless it’s an auto doing towing.

More cool tips

The methods adopted for cooling often require some lateral thinking. Keeping the heat away is one solution, with the use of heatshields and insulation bandages (e.g. wrapping an exhaust manifold). The aforementioned ducting to help direct airflow into an area, or draw hot air out can help, along with vents to allow air to rise and escape. Experimentation and testing is often the best approach, so arm yourself with an infrared thermometer and start measuring the temperature of components.

Don’t forget the basics

Classic cars didn’t break down when they were new so there’s little excuse in 2018… and much of the hot and bothered problems experienced by owners stem from simply neglect

1. Regularly check the hoses for ageing and bulging past its clips which can cut into the hose. Are they soft to squeeze or rock solid? Either way, replace them

2. Is the fan belt (or alternator drive belt) in good order? Always carry a spare as replacements can be hard to find for many classics – especially on a Sunday afternoon!

3. Thermostats aren’t open and shut cases! They constantly operate to regulate temperature and do wear out. A new ’stat can work wonders for your cooling system

4. On the other hand, don’t be tempted to run without one installed as, on many engines, its sheer presence becomes part of the system’s flow and if removed can create dangerous hotspots

5. Same with the rad cap; inspect its seal for deterioration and replace if required. Consult a specialist or manual as, in many cases, their pressure ratings may have been altered during a car’s production run and a later spec cap may help

6. Engines like nothing more than fresh clean water mixed with the right percentage of anti-freeze. Forget the name, in fact it does improve cooling properties in all weathers

7. Spent anti-freeze can lead to furred up water ways; you can buy special flushes to remove a lot of the nasty old gunk

8. You can also purchase additives that makes the water ‘wetter’ and improve coolant performance; may just tip the balance in your favour on mildly overheating engines

9. Seemingly incurable hot running can be due to a poor engine tune with incorrect ignition timing and too weak a fuel mixture. If it can’t be adjusted out, then a worn distributor or carburettor (try SU Burlen and Webcon for modern replacements) will have to be changed

10. Last, but by no means least, if your engine starts to run hot, you can take the heat off it significantly (but not you and any passengers) by turning the heater to ‘hot’ and the fan full blast. It may just get you home…

Useful contacts

2Spec 01564 779010 http://www.2specgroup.co.uk

AH Fabrications 01432 354704 http://www.ahfabrications.com

Bailey Motorsport 01954 230725 http://www.baileymotorsport.co.uk

Demon Tweeks 01978 663000 http://www.demon-tweeks.co.uk

Forge Motorsport 01452 380999 http://www.forgemotorsport.co.uk

Mike Satur 01782 373547 http://www.mikesatur.com

NAR Group LTD 01604 684850 nargroup.com

Revotec 01491 824424 http://www.revotec.com

Silicon Hoses 0845 8385364 http://www.siliconhoses.com