Hyundai SUV Range

If the engine is not getting hot and the temperature gauge is reading normal, it’s difficult to see how the coolant could be boiling. Perhaps what you’re seeing is the coolant in the overflow bottle bubbling, which can appear as though it’s boiling. But the reality might be that you have a leaking cylinder head gasket.

When that happens, gasses from the combustion process can escape into the engine’s coolant system and appear as bubbles in the overflow system. And to the observer, that can look very much like boiling coolant.

Either way, you need to find a good workshop that can check this stuff and figure out what’s really going on. Only then can you diagnose the root problem and tackle it.

This model Hyundai i40 had two different automatic transmissions depending on which engine was fitted. If you have the petrol engine, the transmission will be a conventional torque converter six-speed automatic. However, if your car has the turbo-diesel engine, the transmission will be a seven-speed dual-clutch unit. At which point things change.

These dual-clutch units (and not just Hyundai’s) have shown themselves to be a bit under-engineered in some respects. And when they start to develop wear in the clutch packs, they can definitely start to behave poorly including rough shifting, shuddering when moving off and other problems.

But either way, you are going to need the services of a transmission specialist to determine what’s wrong. Even if you have the conventional automatic version, you might still find it has serious internal wear or failures, but only a detailed diagnosis will tell you the whole story.

On the other hand, you might be lucky and simply have a transmission with low fluid level that will be restored to health by a top up of that fluid. You’ll still need to find from where it’s escaping, however, as this is a sealed system and should not lose fluid over time.

Most Hyundai engines with a rubber timing belt require belt changes every 100,000km. Stretching this interval is pushing your luck as a failed belt will destroy the rest of the engine. With that in mind, you’re already over that limit by about 10,000km, so a change sooner rather than later is in order.

The car will, indeed, drive perfectly even with an old timing belt. Until it doesn’t. At which point you have an engine bay full of junk and a big engine replacement bill coming your way.