Warm weather and summertime brings out thousands of collector cars and special interest vehicles to cruise nights and car shows across our country. It also brings its own type of mechanical problems — ones that new-car owners seldom have to deal with.

Some of the problems are fairly obvious, although they can take considerable time to fix. These problems are ones that involve rubber parts — everything from door gaskets to heater hoses. Replacing some items such as body gaskets are inconvenient fixes but necessary to prevent moisture from getting where it shouldn’t and rust from starting to form.

Other parts, such as coolant hoses and engine seals, need more immediate attention or you may be stranded on the side of the road. There are a few mechanical problems that pop up with older vehicles that are related to modern fuels; one of these is the addition of alcohol to the fuel.

Alcohol acts as a great cleaning agent, loosening gum deposits and grime from the inside of fuel tanks and lines. Vehicles that have been driven all the time usually don’t have a lot of deposits, but vehicles that have been sitting for months or years usually do. The loosened deposits are usually caught in the fuel filter and plug it. A shortage of power during acceleration, stalling, and hard starting are all symptoms that can be caused by a plugged fuel filter.

The other fuel problem is pinging caused by detonation or pre-ignition. Cars of the ’50s, ’60s and early ’70s had relatively high compression engines. If the engine-cylinder pressures became too high the fuel could ignite by itself before the sparkplug could ignite it and the fuel would burn in an uncontrolled manner (called detonation). This caused even higher pressures in the cylinder and violent vibrations that would break pistons, piston rings, and even crack cylinder heads.

We hear it as a rattling sound, usually called ‘Pinging.’ Pre-ignition is similar to detonation but the fuel is started burning prematurely by something hot inside the cylinder. It could be a piece of carbon, an overheated sparkplug electrode, or even a part of a failing head gasket. Pre-ignition causes violent vibrations inside the engine just like detonation does, so the two are often confused.

Repairing a pre-ignition problem can involve engine disassembly to remove carbon or failing head gaskets. Detonation problems can be prevented by changing ignition timing. Both of these types of problems can be reduced by using a high-octane fuel and maintaining a good engine-cooling system.

Octane is a rating indicating the ability of the fuel to withstand self-ignition due to pressure — the higher the octane number, the higher the pressure. Premium fuels back in the ’60s and ’70s could have an octane number of 95 or higher. Today, premium fuels are usually in the 91 octane range. There are octane boosters you can add to the fuel, but these are often unstable and designed more for racing vehicles where the fuel will be used right away.

The best way to deal with pinging problems are to increase engine cooling so hot spots don’t form in the engine cylinders and retard ignition timing to lower cylinder pressures. Be careful to not retard ignition timing too far or it will cause the engine to overheat.

Reducing the amount of time the fuel has to self-ignite will help reduce pinging. Revving the engine higher sooner, using transmission and axle gearing so there is less load on the engine, and avoiding large throttle openings during acceleration are some of the ways of reducing pinging.

Modern cars can also ping if the octane rating of the fuel is too low for driving conditions, but computer controls sense the vibrations and change ignition timing to reduce it before engine damage can occur.

Mazda, with their new SkyActiv engine, has the highest compression ratio of any production car and they have used modern technology to direct fuel injector spray into a special pocket in the top of the piston. The fuel burns in this concentrated area and there is not enough fuel elsewhere for detonation to occur, even with the high compression ratio. Mazda can even run this engine on regular fuel with an 87 octane rating!

For classic-car drivers, using premium fuel, ensuring the engine cooling system is operating at peak efficiency, and having the ignition system reworked so there is less initial timing advance are a good start to reducing pinging problems.