Hyundai Reviews

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.

There are many reasons this could happen, and they could be mechanical or electrical. An engine that revs freely with no load on it, but goes weak at the knees when a load is placed on it, could be suffering from poor fuel supply, a faulty ignition system, internal wear, a blocked exhaust or even a worn driveline that is creating excess friction. You could even have a seized brake or something equally fundamental going on.

But it’s also true that the car’s computer can send the engine into what’s called limp-home mode if it detects a serious problem. Limp-home mode limits the amount of power the engine can make or how fast it can rev, as a means of protecting it against further, more serious damage. Perhaps that’s what’s going on here. Certainly the symptoms match that diagnosis. The best advice is to have the car electronically scanned to see what fault codes are thrown up by the computer. Only then do you have a decent starting point on where to look for the root problem.