Holden Problems

I think you’re on the right track by concentrating on the information being conveyed by the crank-angle sensor. But the problem is more likely to be a stretched timing chain rather than a dud sensor. The V6 engine in your Colorado is notorious for this problem and, when it happens, it throws the camshafts out of synch with the crankshaft. When the crank-angle sensor and the camshaft-angle sensor can’t agree that the positions of the crankshaft and camshafts relative to each other are correct, the problems start.

This lack of synchronisation is one of the things the crank-angle sensor is paid to look for and why it’s limiting engine speed or not allowing the engine to start at all. By clearing the fault code and disconnecting the crank-angle sensor, you’re stopping the error information being sent to the ECU and the ute starts first time (it’s probably taking a camshaft-angle reference when it can’t find the crank-angle information).

The old M20 four-speed transmission wasn’t exactly a sophisticated piece of equipment, but it was a pretty tough thing. In any case, this sounds more like a clutch problem. Wear or damage in the clutch can cause all sorts of difficult shifting, and the big clue here is that it will do so only when the engine is running, not when it’s switched off.

You may find it’s a case of poorly adjusted shift linkages or a damaged shifter, but all the signs point to a broken clutch.

This is one of those 'how long is a piece of string' questions. It all depends on where the oil leak is coming from and what is involved in fixing it. If it’s a simple loose fitting that can be tightened in a minute or two, then it won’t cost much. But if the leak is coming from a gasket that requires the entire engine to be removed and disassembled to replace, then the cost will be much, much more.

Oil and coolant leaks can emanate from a huge number of locations on a modern engine, Sometimes just finding the source can take longer than actually fixing it. The best approach is to thoroughly clean the engine of all oil and gunk, and then drive it and keep checking until the oil reappears and track it back to the source.

There are literally hundreds of things that can cause a check-engine light in a modern, computer-controlled car. A problem with the ignition, fuel system, emissions-control system, air-intake, lubrication, cooling and much, much more can cause this light to illuminate.

The best way to proceed is to have the vehicle electronically scanned. That way, the computer can tell the mechanic where the problem is and, hopefully, precisely what’s causing the check-engine light to flicker on.

For the record, however, a common fault with the V6 engine in this series of Commodores is a stretched timing chain that the computer interprets as incorrect valve timing (which it is). Plenty of owners of this model have discovered this as the cause of their check-engine light.

The first conclusion many mechanics will arrive at is that the engine’s head gasket has blown, allowing the oil and coolant to mix. Have a look at the dipstick. If the engine oil is milky, then this is a very real possibility. Perhaps when the cylinder head was replaced, the gasket has not sealed properly.

But if the oil cooler was replaced because it was leaking into the radiator (which is pretty common) then you might find that the oil you’re still seeing is just residual oil from the previous failure, and not a problem at all. Even so, it would be wise to replace the coolant and flush the system to try to eradicate all traces of the old oil.

A workshop can perform a chemical-based test to see if the head gasket is leaking. It’s worth the relatively small cost to rule this out and begin to look elsewhere.

The most problematic of the Cruze transmissions were the six-speed automatic fitted to Cruzes built between 2011 and 2013. Holden actually instituted a special repair program for owners of these cars and extended the warranty period on those that had been repaired under the terms of that program.

The 2015 car you’re looking at should not have these problems, but the Cruze itself was plague by a long list of other faults including oil and coolant leaks, overheating, cracked cylinder heads and more. To be fair, the later the build date, the less likely the problems were to occur, but any Cruze needs a careful, independent inspection before money changes hands.

The starter motor would be a very good place to start looking for the problem. If the battery checks out (and that presumes you’ve load tested it, not just run a voltmeter across its terminals) and the addition of a second jump battery only just turned the engine over, then, the starter motor is a likely suspect.

But don’t forget things like a poor earth somewhere on the car or a dodgy ignition or starter button. Once the engine is running, check the power going into the battery. You should be looking at between 13.2 and 14.5 volts going into the battery with the engine running if the alternator is pulling its weight.

Just because the battery indicator is showing green, does not mean categorically that it’s in good health. It can produce a surface charge that might show 12 volts with no load on it, but can fall to its knees when you load it up with the starter motor.

Rather than the new battery causing the headlights and wipers to come on, this sounds more like the lights and wipers were already playing up, coming on randomly for no reason, and killing the original battery when your back was turned.

This is a relatively common problem and can usually be traced back to the car’s body computer. If the computer starts to act up, it can switch on various things including lights and wipers, even though the car is locked in the driveway and the key is in your kitchen.

Try an auto electrician who is a bit more familiar with modern body computer set-ups, but in the meantime, there’s a quick trick you can try that might stop the car misbehaving. Disconnect the car’s battery and leave it overnight before reconnecting it. This can sometimes be enough to reset the body computer and the problem will go away. Beware, though, this fix might be temporary and may return some weeks or months later.