Here's another handy guide from Just Kampers! This one covers some of the most common reasons that our air-cooled Volkswagen break down, and how you can prevent them.
We've been part of the VW community here in the UK since 1989, and have driven countless classic VWs right around Britain, Europe, and the USA, so we've spent a decent amount of time making unexpected stops at the roadside!
This guide has been put together based on our own experience, and we hope it will help you to avoid breaking down in your air-cooled VW so you can spend more time enjoying it and less time repairing it.
Ten Common Causes of Mechanical Breakdown in Air-Cooled VWs, and How to Avoid Them
Here are 10 of the more common reasons that classic Volkswagens break down, and what you can do to avoid them.
Scroll through the list at your leisure, or use the links below to jump straight to section you're most interested in.
• Fuel Issues
• V-Belts
• Broken Cables
• Ignition Issues
• Spark Plugs
• Tyres
• Oil (or lack of it!)
• Brakes & Brake Fluid
• Wheel Bearings
• Electrical Issues
Download This Guide for Free
You can click here to download this guide as a printer-friendly PDF, which you can print out and keep in your garage or glovebox!
Fuel Issues
Fuel can go bad, with modern ethanol-based fuels having a shelf life of less than 12 months, which can cause problems if you don’t use your classic VW that often. These modern fuels also absorb moisture, and can then damage fuel lines, fuel pumps, and carburettors.
Your fuel filter can also get clogged up with impurities and ‘stuff’ which blocks fuel flow. If this keeps happening, check your fuel tank to see if the ‘stuff’ is coming from there.
V-Belts
Your engine’s V-belt drives the cooling fan, as well as the dynamo or alternator for electrical power, so it’s pretty important!
Because they work so hard, they can become loose or break, which is why we recommend carrying a spare and the tools you’ll need to replace it.
You can quickly check if your V-belt needs to be adjusted by taking hold of it half way between the upper and lower pulley, and twisting the flat 'back' edge towards you. It should twist a quarter of a turn, so that the flat face is now pointing towards you, but shouldn't really go further than that. If it'll twist past that point, you'll need to adjust the V-belt.
To adjust your v-belt, you'll need a socket, and a c-spanner. This is a specialised tool which lets you hold the dynamo or alternator pulley in place while you loosen the central bolt with the socket, so that the pulley doesn't turn while you're trying to undo the bolt.
With the bolt off, you can remove the top pulley (carefully, so you don't drop shims everywhere), and then move some of the shims from behind the pulley to be in front of it. One or two should be enough, but you can repeat the 'quarter turn' test to make sure it's the right tightness before bolting the top pulley back on.
If the V-belt does break, your engine will still run. However, you won’t have any cooling and your vehicle battery won’t be charging either, so you’ll quite quickly lose power to your lights and indicators. If this happens, find somewhere to pull over safely and you should be able to fit a replacement V-belt using your emergency breakdown kit.
Alternatively, if you're unable to replace your broken V-belt, you may need to call out a recovery service - easily done if you've got vehilcle cover with Just Kampers Insurance!
Broken Cables
Accelerator, brake, and clutch cables seem to break at the most inconvenient moments possible. If they do break, it’s likely that you’ll need to replace more than just the cable, too, as the fittings tend to fall off around the same time.
Keep an eye on the condition of your cables, and make a note of when they were last changed. In our experience, carrying a set of spare cables seems to mean you’re less likely to need them!
Ignition Issues
Keep an eye on your distributor cap, as it’s often overlooked but is vitally important. Cracks or damage to the cap can let moisture in, which will play havoc with your engine. Luckily they’re easy to replace and inexpensive.
Under the distributor cap, the rotor arm can also become damaged. At 3500 RPM, a 2-hour motorway journey will have that rotor spinning 400,000 times, so it needs to be in good shape! Check that the metal surface on the end of the rotor arm is clean and not corroded, and that there’s no damage to the rest of the unit.
The points are another vital part of your air-cooled engine which can cause problems. Check that the points gap is correct and adjust it if necessary. The majority of air-cooled engines need a points gap of 0.4mm (0.016 inches).
Spark Plugs
Your spark plugs can tell you a lot about how your engine is running. Take them out, and look at the electrode.
If it’s black and sooty, your engine is running too rich. Check whether the choke has stuck on, or if the choke wire has come loose.
If it’s gone grey or white, your engine is running too lean. Is the air filter blocked? If you’ve got a twin-port engine, has the manifold boot split?
Tyres
Take a good look at your tyres, and check that they’re in good condition, with no cuts or damage, good tread depth, and correctly inflated.
If you do get a flat, you’re usually better off writing off a tyre by driving slowly to a safe place to change it, than to risk jacking your vehicle up in an unsafe location.
Oil (or lack of it!)
You should check your engine oil regularly, and pay attention to the level, condition, and colour of it.
If the level is rising, then don’t run the engine. It’s possible that the diaphragm in the fuel pump has perished and fuel is getting into the oil, which is why the level is rising.
If the oil is really dark, or feels gritty between your fingers, then it’s time for an oil change.
Brakes & Brake Fluid
If you feel like something is wrong with your brakes, then find somewhere safe to stop and call for breakdown assistance.
Brake fluid can weep from the seals, and you can sometimes see the brake fluid on the wheels or brake backing plates. This can massively impact how effective your brakes are, and make your vehicle unsafe to drive until the brake fluid is topped up and the leaky seals replaced.
Sometimes brakes can bind or stick on, which causes a lot of heat to build up. This can then boil the brake fluid, and render it useless. Again, this makes your vehicle unsafe to drive until the problem is resolved and the brake fluid levels topped up.
Wheel Bearings
A wheel bearing which is too loose or too tight can quickly produce a lot of heat, melting the grease packed around the bearings and causing it to drip out. Without this grease, the issues caused by the wheel bearing being too loose or too tight will become worse, which can cause damage to other components around it.
Electrical Issues
Bad earth connections are a common problem on older vehicles of all makes, which can lead to problems starting or running your engine. Check that the different earth cables are in good condition and securely connected.
You’ll also want to check the fuse boards for loose fuses, and ensure that you’ve not had any rodents chewing away at electrical cables, especially if you’ve stored your vehicle away for a few months.
Get a PDF of this guide for free
If you can found this info useful, you can click here to download this guide as a printer-friendly PDF. View it on your mobile it print a copy to stash away in your glovebox, to help you keep your VW on the road and ready for adventure.
