Repairs are inevitable when it comes to owning a classic, but an unexpected roadside breakdown is a great way to spoil a fun day driving. To set yourself up for more enjoyment and less time waiting for a tow, we asked the Hagerty Forums last week to tell us what parts most commonly failed and left them stranded. We took the responses and created this list of items to keep an eye on before you hit the open road.
Alternator or generator
Your car can function without an alternator, but not forever. Even basic electrical systems for 1960s cars consume electricity for the ignition system, and without a source like an alternator or generator replenishing the battery, your car is just a ticking clock before you are on the side of the road in need of electrical attention. Common failure points are the electrical connectors that tie the alternator to the electrical system, as well as the internal diodes themselves. Unfortunately, this is typically a part where failure comes with no warning. If you have an uncommon car without easily replaceable parts, it might be worth carrying a spare if you regularly drive outside of tow range.
We have to admit, we saw this one coming. Fuel pumps are at the top of our staff’s list of part failures. Loss of fuel pressure ends a Sunday drive in short order. If the engine doesn’t have the fuel in the carburetor or fuel injection system, it can’t properly meter the fuel into the intake—thus no combustion. If you are relying on a decades-old mechanical pump, it is time to consider a replacement or possibly an upgrade to an electric pump. Each style has its own set of benefits and drawbacks to consider, so be sure to do your research on your specific car (or carburetor) to make sure you are setting yourself up for success. Nobody likes a flood.
The second-most important pump on most engines, the water pump keeps things from melting down—literally. An internal combustion engine like a small-block Chevy V-8 is around 18 percent thermally efficient, meaning of the potential energy in the liquid fuel, only 18 percent of it is turned into useful work. The remainder is lost in the form of heat. Lots of heat. Big radiators do nothing without coolant flow, and it doesn’t take long at higher than normal temps for problems to crop up with most engines.
Air-cooled folks, despite operating without liquid coolant, don’t avoid the problem completely either. Corvairs, vintage Porsches, and Beetles, still need some type of fan to force cooling air over the engine. Think of that as a water pump in this scenario.
Check for leaks and any play in the water pump shaft. If you have a mechanical fan you can test the bearings or bushings of a regular pump by trying to rock the fan of a non-running engine. Any movement should be treated as grounds to at least start planning for a replacement. Major play should convince you to order parts or call a mechanic. By then it’s not a question of if, but when you will witness your car overheating.
Broken connectors, worn wires, or failed switches happen. Sadly, sometimes they happen in places that can leave you stranded. A thorough inspection of the wiring harness can suss out many issues that are lying in wait to ruin your long-awaited drive. If there are issues that arise while on the road, inspect the system with your handy multimeter and see if it is one of two failures: something getting current that shouldn’t, or something not getting current that should. There are some roadside electrical workarounds to at least get you home before you can properly repair as issues. If not handled properly, such electrical problems have the potential to burn your classic to the ground. Not good.
Out of gas
Seriously. Readers brought this up as something happens that a lot more often than you’d think. If you are still trusting a 30-year-old (or older) fuel gauge, you are gambling and might not even know it. Small amounts of varnish from dried up fuel can easily cause the float or sensor of the fuel level sending unit to stick or otherwise malfunction, the same goes for a bad ground wire.. We can assure you your car does not magically get better gas mileage in the last quarter tank of gas. That gauge is stuck, not going down slower than usual because of your gentle throttle application.
Something we missed? Be sure to leave it in a comment below, and if you want to have your opinion and feedback included in next week’s Answer of the Week, weigh on this week’s Question of the Week in the Hagerty Forums.