As today’s high-pressure, high-temperature cooling systems operate under high internal stress, even in winter, these notes apply all year long. The extra thermal loads of the hot days of summer and autumn driving just add to their heavy job.
In the old days, all antifreeze was basically the same green “Prestone” type, and most cooling system components were made of metal — all except the rubber hoses. The radiators had brass expansion tanks and copper-finned cooling tubes; all the basic components (water pump, thermostat, pulleys) were made of metal. Radiators could be “rodded out” or even “re-cored” to extend their lives. Typical internal temperatures were around 180°F and pressure was limited to about 15 pounds.
This all began to change in the 1980’s with the impact of emission controls: engines needed to warm up faster and sustain higher temperatures for more efficient combustion. Cost controls imposed an ever-increasing amount of plastic in place of metal. Water pumps acquired plastic impellers, thermostats became electronically regulated devices housed in plastic, and radiators and their attachments became recycled plastic and aluminum. All of these components are designed to be replaced, rather than “reconditioned.” The days of re-cored radiators and rebuilt water pumps are over. At the same time, operating temperatures rose to 240°F and pressures to 29 psi. More plastic, but also more stress.
These tips will help you deal with these newer cooling systems and other key points about your car. If observed, these systems will have a happy, extended life, and so will your car.
- Always use the blue-colored BMW/Mini coolant, and mix it 50/50 with soft or distilled water. Cooling systems should be drained and refilled every two years. This coolant, one of four color-coded types, is “organic acid technology.” Not easy to find at parts stores, you can obtain it at H&B or any BMW or Mini dealer
- Keep an eye on the flat, ribbed “serpentine” engine belts and their tensioners. These belts are usually good for 50,000-60,000 miles, but can shred suddenly if not checked during services. They show a tell-tale segmentation of the ribs on the inside surface just before they let go. Unlike the old, skinny “V” belts, these newer type can tangle up in the fan blades and wreak havoc when they break, so it’s important to replace them ahead of time. While they’re off is a good time to check the plastic tensioner pulleys. These look rather like plastic roller skate wheels, and have ball bearings which eventually wear out. When they do, they can fly off the engine and cause the same damage as shredding belts. If you hear a metallic squeaking sound, especially during the first few seconds after starting, this could be from worn tensioner pulley bearings.
- The plastic components should be replaced sometime between 8 years/80,000 miles and 10 years/100,000 miles.
The parts typically include the radiator, its plastic expansion tank, the front engine hoses (which have plastic joints and fittings), the plastic-housed thermostat, and the plastic-vaned water pump. When available, H&B installs a stainless-steel-vaned water pump.
- Always treat coolant loss, and especially overheating, seriously. If in doubt, stop the car and have it towed. We have seen numerous instances of serious engine damage caused by not being alert to the seriousness of this issue. You do not want to find out how much a replacement engine for your BMW or Mini costs.
- Notes about Oil
We expect that, in today's electronically laden cars, the driver would get timely information about some of these basics. But it ain't necessarily so. Some BMWs and many Minis have no information inside the car about the oil level. This is an important omission in this era of underhood mysteries, especially if your car uses some oil between services. Low oil levels account for a lot of the engine problems second to coolant loss. We're happy to advise how and how often to check the oil level, and which oil might work best for you.
- Notes about Tires
Though most BMWs after model year 2000 have tire pressure sensors (the Mini ones are super-sensitive), they tell you nothing about tire wear. And the latest wide tire sizes often wear out on the inside where it's hard to see. Extended service intervals mean we check the tread less often; and when we do, we see a lot of bald ones. Be sure and do that annual safety check, which gives close attention to tire wear and aging.
- Notes about Brakes
BMWs and Minis use a thickness sensor in two of the eight brake pads on each car. These sensors wear down along with the brake pad friction material, until they eventually trigger a dash warning to replace the brake pads. This warning should be taken seriously: metal-to-metal brakes do a poor job of stopping the car. If you're thinking of taking a trip and haven't checked the brakes in the past several months, it's a good idea to do so.