Holden Problems

If your diagnosis is correct, the problem will be with the either sensor that detects the temperature of the coolant, the computer that creates the signal to open, the wiring that carries the message or the thermostat itself. An auto electrician should be able to sort this out by testing the components one by one until the dud one reveals itself.

But there’s another possibility in cars like this one with a thermostat that lives in a plastic housing. Over time and repeated heat cycles, the plastic can degrade and fail internally. At that point, the actual thermostat mechanism can move sideways and jam against the housing, effectively preventing it from opening., At that point the engine can overheat. Don’t rule that out until the condition of the housing has been checked.

Just because you can’t see where coolant is escaping, doesn’t mean it isn’t. Equally, a lack of milky oil in the sump does not guarantee that the problem is not a head gasket-related one. Even an external leak from a hose or fitting can be hard to track down as the hot coolant evaporates before you have time to find the witness mark or the coolant drips on the garage floor.

Your best bet is to have the car’s cooling system pressure tested. A mechanic will pressurise the system and leave it for a period of time. If the system holds pressure, that’s a good sign that there’s no leaking. If it loses pressure, you have a problem somewhere in the closed-loop cooling system. That could indicate a problem with a radiator, hose, water pump, head gasket or even a split bore or cracked cylinder head.

But there’s one other check to make that might save you a lot of time and hassle. Takle a close look at the car’s overflow tank. This is also called the expansion tank and is designed to catch coolant as it expands (through engine heat) before allowing that extra coolant to return to the engine as the car cools down at the end of the trip. If this tank is leaking (even from a tiny crack) coolant that expands into it will be lost and the cooling system will appear to be continually losing coolant.

This is not an uncommon problem with the head unit in a lot of makes and models. Like any other computer-driven piece of equipment, they have a finite lifespan and, once they’re done, they’re usually done for good. That’s why the dealer would be recommending to replace the unit rather than tyring to fix the one you have.

What a lot of people do is that this opportunity to upgrade to a newer, better head unit with better sound, better connectivity and more up to date apps. There’s loads of choice in the aftermarket and you can spend as little or as much as you want. Many owners also use this as a chance to upgrade speakers and perhaps add a sub-woofer or extra amplifier for much better sound. And you’re right; if the original unit died, a replacement of the same type may well have the same problems.

This is really backwards, isn’t it? The ice warning is designed to alert the driver to road conditions cold enough for ice to form and cause a skidding risk. But in your case, the opposite is happening and the car thinks it’s freezing outside whenever the temperature creeps up to 28. This would make most mechanics think that the temperature sensor that reads the ambient temperature has gone haywire and is telling the onboard computer lies.

Either that, or the vehicle is selecting the ice and snow driving mode on its own behalf, and that’s what’s limiting your engine speed. That wouldn’t be dependent on the ambient temperature reaching 28 degrees, however. But if the ice and snow driving mode is part of the problem, you could have a faulty switch or even a problem with the car’s body computer. An auto electrician is your best bet.

Plenty of owners of this make and model have experienced similar frustrations with the rotary dial not selecting two- and four-wheel-drive promptly and accurately. It’s possibly down to a switch (the rotary dial itself) that has developed wear or play in its mechanism and simply isn’t as accurate as it once was. But it’s also worth checking the electronics that control the shift function, as a glitch might have the system trying to select something other than what’s showing on the dial.

This is a classic case of electronics taking over a mechanical function (early 4WDs had a simple, mechanical lever to switch between two and four-wheel-drive) and not being as good at it. This function, when you think about it, is an incredibly important one for this type of vehicle and might mean the difference between getting out of a bog-hole and not. Many owners would welcome the return of the purely mechanical lever, but that’s not the direction car design is travelling.

This could simply be a case of the engine’s idle speed being set too low. If that’s the case, even though it’s firing on all four cylinders, it can feel rough and lumpy as though there’s something major wrong. Then, as you increase the revs, the engine smooths out and feels normal again. Even a worn or broken engine mount can amplify vibrations at idle, as can an exhaust leak.

A good mechanic will be able to tell you quickly whether this is the case or if, in fact, the engine really is dropping a cylinder at idle. If the latter is the case, you may have a dud spark plug, ignition wire, sensor or even a blocked or dirty fuel filter. Again, most mechanics won’t have a problem tracking this one down.

You could have an engine problem that is causing the vehicle to lose power. The cause of this could literally be a thousand different things. An electronic scan of the vehicle might shed some light on the root cause of the problem, and most mechanics would carry out such a scan before doing anything else.

If the engine is not at fault, you might find the problem can be traced to a transmission that is not shifting gear properly or is slipping, or perhaps even something as simple as a dragging brake or poorly adjusted park-brake. But before you hit the workshop, you can check simple things like the condition of the engine’s air filter to make sure there’s no obvious cause. If your car is a turbocharged model, check the plastic trunking that carries the boost from the turbo to the engine’s intake. This trunking can split or fall off, leading to a loss of boost pressure and, therefore, performance.

A common cause of overheating can be a failed head gasket which allows the coolant to be consumed by the engine. When this happens, soon there’s not enough coolant remaining to cool the engine and the car overheats.

But it may not be as serious as that. You could simply have a stuck thermostat. This is the component that prevents coolant flowing around the engine when it’s first started, forcing the engine to warm up faster. Then, as the engine gets warmer, the thermostat starts to open to allow the coolant to flow through the engine and do its job, maintaining the correct running temperature in the process.

Other possible causes for overheating include incorrect ignition timing, a slipping fan belt, non-functioning cooling fans, a collapsed radiator hose, blocked radiator, a worn water pump and many others. A good mechanic should be able to make a diagnosis and tackle the problem from there.

For a start, you might find it’s neither of those things causing the noise. You may have a worn tyre, poor wheel alignment or a faulty brake, to name just a few possibilities. That said, both your suspects are likely contributors to this type of noise.

In any case, there’s a simple way to tell whether a noise is coming from the driveline (engine and transmission) or from one of the wheel bearings. Drive the car at whatever speed is necessary to make the noise appear. If it gets louder as you apply throttle, there’s a good chance it’s driveline related.

But now, with the car still making the offending noise, drop the transmission into neutral (where it’s safe to do so, of course) and let the vehicle coast. This takes all the stress off the driveline and the engine should return to idle. If the noise is still present, then you have a wheel bearing or other problem linked to the wheels, brakes or axles, but not the engine or gearbox.

This is actually quite normal and nothing to be concerned about. If the engine temperature is high enough, the computer will continue to run the cooling fan even though the ignition has been turned off. This helps keep the temperature from spiking when the vehicle stops and is turned off.

Even though this only really lowers the temperature of the coolant in the radiator (not in the actual engine) it also helps to maintain a constant, safe temperature if you restart the car soon after shutting it down.

That said, the fan should only continue running for a couple of minutes at most after you’ve turned the car off. Any longer and you might have a problem with the circuits that power and control the electric fan.