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Classic cooling systems can often struggle to cope with modern driving conditions, especially when temperatures start to rise. We look at what upgrades are available to keep things cool.
About cooling upgrades. We look at what’s available to keep underbonnet temperatures under control.
F ollowing the opening of the first section of the M1 in 1959, a steady stream of overheated vehicles was towed off the motorway with clouds of steam billowing out from underneath their bonnets. This sad state of affairs was mainly due to the majority of mass-produced cars built during the pre-motorway age having a poorly designed cooling system that was simply unable to cope with extended periods of flat out motoring.
Cars powered by a side valve engine usually had a nonpressurised thermo-syphon system based on the principle of natural convection to feed coolant from the engine into the radiator rather than a mechanical water pump. Long stints of fast running or sitting in a traffic jam would often cause engines cooled in this manner to rapidly overheat and eventually seize up.
To keep engine temperatures under control in a sidevalve powered upright Ford Popular, Aquaplane produced an after market mechanical water pump that could be fitted to the Ford’s 1172cc top hose to assist coolant to circulate around the system more efficiently. In those early motorway days even cars with a mechanical water pump fitted as standard regularly boiled over when driven hard.
Hot water expands at a rapid rate and rises as its density decreases. Excessive heat drawn away from the engine into the circulating coolant is referred to as heat load. As manufacturers introduced new models with lower bonnet lines, engineers were required to design engines with powerful water pumps to propel greater volumes of hot coolant through the radiator to reduce the heat load. The faster an internal combustion engine warms up, the more efficient it becomes and back in the days of black and white telly a popular (and cheap) upgrade to ensure an engine warmed up quickly on a cold and frosty morning was to place a piece of cardboard in front of the radiator grille.
Forgetting to remove a temporary blind like this would often result in the engine boiling over. A more permanent solution was to fit a specially tailored radiator blind, which could be raised and lowered from inside the car by pulling a cord located under the dashboard.
Today there’s an impressive range of far more sophisticated ways to upgrade a classic cooling system rather than using a bit of old cardboard. Some of these upgrades are relatively cheap and easy to install, while others are more expensive. Following is a selection of popular aftermarket cooling upgrades currently available to stop classics getting too hot under the collar.
HIGH PERFORMAN CE RADIATORS
Upgrading the cooling system by fitting an aluminium radiator offers a larger cooling area over a standard radiator. Specialist suppliers are able to manufacture custom-made aluminium
radiators and Rimmer Brothers can supply one suitable to fit an MGB for £550.
Specialist firms are able to refurbish leaking brass radiators by soldering in a new core and its worth enquiring if the number of tubes in a replacement core can be increased to aid cooling.
Whatever type of radiator is fitted to your classic, make sure the pressure rating of the cap is correct for the car’s cooling system, especially if a high performance radiator has been fitted rather than a standard one.
These work on the same principle as a radiator by forcing cold air through tiny pipes filled with hot lubricating oil diverted off the engine’s main oil gallery. Usually fitted alongside the car’s coolant radiator, oil coolers can often be too efficient in very cold weather and may have to be blanked off.
Performance cars fitted with a turbocharger may benefit by having a larger or even a water-cooled intercooler fitted.
Moulded rubber radiator and heater hoses can degrade over time and finding replacements for some classics can be almost impossible. Thankfully, specialists such as Classic Silicone Hoses (01530 230971) are able to supply hose kits for a large range of classic vehicles and hoses are available in various colours, including satin black.
Silicone hoses are more hard wearing than cheaper rubber equivalents (which may not be available any longer) and when fitting a set of replacement silicon hoses, it’s always a good idea to invest in a new set of good quality worm-style stainless steel screw clips.
ELECTRIC WATER PUMPS
Increasing the size of a radiator’s core is an efficient way to reduce the coolant’s heat load. However, it may be necessary to fit an uprated water pump to avoid any cavitation (bubbling) in the coolant at high revs. Replacing a mechanical water pump with a high flow capacity electrically driven unit has the advantage of running at a speed independent to the engine. An electric pump can also be set to run constantly or through a controller to make it switch on at a set temperature.
The ideal operating temperature for an internal combustion engine to work at its maximum efficiency is between 92 and 95°C . Fitting a thermostat that opens at a different temperature to the one installed will make the car run hotter or cooler to suit the ambient temperature and operating conditions. Swapping a thermostat for one that opens slightly earlier is an easy fix to make and engine run cooler, especially in very hot weather.
This special formulation of fluid contains no oxygen or minerals and used properly waterless coolant, which has a boiling point of 180°C, helps eliminate corrosion. The ability to work at such high temperature prevents
hot spots of steam developing in high performance engines. Another benefit for using waterless coolant is that it allows the cooling system to run at a lower pressure, which in turn reduces the stress on components.
Waterless coolants also contain a special blend of anti-freeze and can be used in temperatures as low as - 40°C. When swapping over to waterless coolant, a special fluid has to be used to ‘clean’ the system out and neutralise any remaining H O, which makes it 2 best to switch over to waterless coolant during a major engine rebuild. For more information about the long-term benefits of using waterless coolants, visit www.evenscoolant.co.uk.
Not so much an upgrade, but the concentration of the coolant in a car’s radiator should be periodically checked with a hydrometer to ensure the ratio of water (preferably de-ionised) and anti-freeze is maintained at the correct percentage.
Modern anti-freeze is made up of 96 per cent ethylene glycol and four per cent corrosion inhibitor. When topping up a cooling system, it’s important to know what type of anti-freeze to use. Cars built before 1998 usually require a silicate-free anti-freeze, while those built after that date require a 50/50 coolant mix using ‘organic acid technology’, or OAT for short. OAT anti-freeze is usually orange in colour, while the silicate-free coolant suitable for classic engines is usually red or green.
Despite being matched to a decent sized radiator, the fan sucking cold air into the engine bay may not be able to cope in very hot weather. Viscous coupled thermostatic fans can break down and some owners even bolt the mechanism up so they work continuously. This defeats the object of having a fan that only runs when it’s needed and a worthwhile upgrade is to fit a thermostatically controlled electric fan. These can be adjusted to operate at a range of different temperatures and are relatively easy for a DIY owner to fit. Revotec (01491 824424) stock a large range of kits suitable for classic cars, and can be fitted along with grilles and ducts to help keep the engine bay cool.
GAUGES AND SENSORS
A lot of classics didn’t have a coolant temperature gauge as standard and installing an aftermarket gauge will provide information in advance if things start to get too hot under the bonnet. Extra gauges to show water and oil temperature can be installed in a neat binnacle under the dash and are relatively easy to plumb in and wire up. Rather than add an extra dial to a classic’s interior, some owners may prefer to wire up an underbonnet temperature sensor that can be set to sound a warning buzzer or a lamp if the coolant temperature starts to head north.
Adding a small amount of proprietary coolant additive such as Water Wetter to the anti-freeze mix is a chemical way to help reduce the temperature of the coolant by up to 20°C. Water Wetter has better heat transfer properties than off-the shelf glycol-based anti-freeze and adding a small dose will also help to reduce the formation of rust and corrosion in the radiator and associated waterways.
A number of classics, such as the V8-powered Triumph Stag, gained an unenviable reputation for overheating. Over the years specialist suppliers have developed a wide range of upgrades and improvements to help eliminate the problems that caused the Stag’s V8 engine to brew up. However, before deciding to drastically upgrade a classic cooling system, it’s a good idea to do a bit of simple maintenance first. All the old coolant should be drained out and the system back flushed to remove any muck and sediment from the waterways to see if this improves matters.
Cars fitting with an automatic transmission may have a heat exchanger built inside the radiator to cool the transmission fluid. Leaks will allow anti-freeze to contaminate the transmission fluid, so consider fitting a separate oil cooler for the auto box. Keeping a car’s cooling system in good order is the key and if the temperature gauge starts to climb there are plenty of upgrades available to help a hot engine maintain its cool.
Thermostatic controlled electric fans can be positioned to either suck or blow incoming air through the radiator.
Bonnet vents and louvres help keep temperatures in the engine bay down but can be very expensive to retrofit.
Waterless coolant doesn’t contain any oxygen or minerals and has a much higher boiling point than normal coolant.
A cold air feed direct to the carbs will aid engine efficiency. Alloy radiators are able to disperse extra heat quickly.
Silicone hose kits usually include new stainless steel clips.
An alloy header tank can be much bigger than the original.
Performance engines require a huge amount of cooling and fitting extra electric fans will stop boil ups on the track.
When adding anti-freeze, make sure it’s the correct type.
The Stag’s V8 was notorious for overheating but fitting a larger radiator is one way to keep the temperature down.
Finding space to fit uprated cooling parts can be an issue.
Silicone hoses are available in a selection of bright colours.