How to break your shiny new SUV

A lot of people think their new SUV is tantamount to indestructible. 
Nothing could be further from the truth.
This report is presented in the hope you'll learn how easy it is to cost yourself thousands of dollars in repair costs ... and then hopefully not do these things. Alternatively, if you're feeling generous and want to fight poverty in the service department, knock yourself out.

If you don't have time to watch the report, the six ways are:

  1. Put petrol in a diesel SUV, or vice-versa (one of these is far worse than the other)
  2. Leave the 4WD lock engaged and drive on a high-traction surface
  3. Suck water into the air intake during a water crossing
  4. Suck water into driveline components during water crossings
  5. Block your radiator with mud and overheat the engine
  6. Neglect to drive your diesel SUV on the highway often enough, and destroy the exhaust particle filter

The service department will, of course, be overjoyed if you do these things, even unwittingly. It's up to you.

VIDEO TRANSCRIPT

Have you ever wanted to break your shiny new SUV? It’s a lot easier than you think

Thanks for joining me in the great Australian cultural void. If you’ve ever wanted to break your seemingly robust new SUV, this report is exactly what you’ve been looking for. These are the top six ways to generate thousands in additional service department revenue… all without breaking a sweat.

See also:

Mis-fuelling is a disaster. Complacency at this point - or just not focussing on the job at hand - opens the door to a very expensive mistake. Especially in an unfamiliar vehicle 

Mis-fuelling is a disaster. Complacency at this point - or just not focussing on the job at hand - opens the door to a very expensive mistake. Especially in an unfamiliar vehicle 

1: Getting the fuel horribly wrong

Putting the wrong fuel in your SUV is an excellent way to do break your budget. There are two permutations obviously, you could put petrol or gasoline in a diesel powered SUV or vice versa.

Have a guess which one of these is worse?

If you just answered gasoline/ petrol in a diesel powered SUV… congratulations! Go to the top of the class.

So let’s deal with the other case first:

Diesel in a petrol SUV

If you put diesel in a petrol powered SUV, this is going to be something like, a thousand dollars worth of mistake at the bowser. What happens basically is, they’ll have to clean everything up but no substantial damage will be done to your fuel systems so that will be a painful enough lesson you’ll know not to do it again. 

But if you really want to do this properly and generate several thousand dollars in service department revenue, you should put gasoline (petrol) in a diesel powered SUV.

Petrol in a diesel SUV

People think this problem has something to do with the way the fuel combusts in the engine but, au contraire, it actually happens a lot further upstream. The problems all occur inside the fuel delivery system itself. At the core of this problem is complexity. Everything in a modern direct-injected diesel fuel system (forward of the driver) is basically expensive and complex.

A modern diesel direct injected fuel system is a miracle of precision engineering. Here’s what happens though if you get gasoline mixed up with that diesel. As it gets delivered from the tank and goes further downstream towards the engine, eventually it will encounter the high pressure fuel pumps. These are amazing devices that ramp up the pressure in the fuel line up to around 2000 atmospheres. So, in order to do that, they need to be driven mechanically off the engine; they’re full of harden surfaces and high precision mechanical parts. 

Those magic high pressure pumps also rely on the lubricating properties of diesel fuel to remain viable. If you put petrol in there, obviously what happens is: the lubrication goes away in a heartbeat. All those hardened surfaces start to fall apart. Metal filings and other fragments appear in the fuel system and get delivered downstream where they encounter the next miracle of modern fuel delivery engineering: the piezoelectric fuel injectors.

Getting the fuel wrong once wreaks havoc on some of the vehicle's most expensive components - especially in a diesel

Getting the fuel wrong once wreaks havoc on some of the vehicle's most expensive components - especially in a diesel

Injectors for dummies

Piezoelectric injectors are amazing devices that deliver precise volumes of fuel at staggeringly precise windows in the time domain relative to the motion of the pistons and the combustion cycle. 

Unfortunately, they have no tolerance whatsoever for any contamination in the fuel. They have a stroke at the drop of a hat and if the pump falls apart, guess what happens to those injectors? They’re cactus too. This repair will cost you between five and ten thousand dollars…

You’ll have to sit down next to the defibrillator at the service department before they deliver the bad news. It’s that confronting.

Of course, you’ll also have to dispose of the contaminated fuel and in these environmentally responsible times, that has to be done at considerable expense. A shandy of petrol and diesel is not all that useful for most jobs. I guess if you’re an arsonist or a terrorist, you could make use of it. It’s probably okay for hillbilly napalm as well. But for internal combustion, not so useful.

Mis-fuelling your SUV… one of the text book ways to keep your service department afloat.

More on fuel: Octane rating - huh? >>

Subaru SUVs have symmetrical AWD - ie, AWD all the time. Most other SUVs are either on-demand AWD or (in the cheap seats) just front-drivers

Subaru SUVs have symmetrical AWD - ie, AWD all the time. Most other SUVs are either on-demand AWD or (in the cheap seats) just front-drivers

2: Forgetting to unlock the AWD drivetrain

First-time SUV buyers often decide to rekindle their connection with the great outdoors so the kids can bitch and moan about not having WiFi or television.

So, what happens there is, you drive down some dirt road and you might decide, perhaps because there’s a big pool of mud in front of you, to lock the centre diff.

Good idea.

One of the really interesting things about AWD SUVs (Subaru excepted - they're always in AWD), is that most of them spend the majority of their lives as FWD and they wait until wheel spin occurs to transmit drive to the rear. This is what so-called 'on-demand AWD' is.

So that’s fair enough: if you’re driving down some dirt track though and you some mud in front, you might choose to reach down and nudge the 4WD LOCK button. That’s a great idea because it will synchronise the front and rear propshafts and basically double your tractive effort; twice as much chance of getting through that slippery stuff unscathed. So that’s good.

What’s not so good however, is forgetting to unlock that centre diff afterwards - especially if you drive back on a high traction surface, like bitumen or concrete.

Judicious use of the 4WD lock button can get you out of trouble, but leaving it on is a disaster

Judicious use of the 4WD lock button can get you out of trouble, but leaving it on is a disaster

The problem with that of course is geometry. When you’re driving on a twisty road, you might not think about it that often, but all four wheels are travelling on slightly different paths and that means all four wheels are travelling at slightly different speeds.

If you go back upstream in the driveline that means the front propshaft and the rear prop shaft, if they’re locked up, want to turn at different rates. But that mechanical lock that you engaged previously, it prevents them from doing that. So I guess there are two potential consequences there. 

If the traction is not all that high, what will happen is the tyres will scrub and they will wear out quickly because that’s just a whole bunch of abrasion that you could have avoided. You’ll be contributing disproportionately to the profits of Dunlop, Bridgestone, Goodyear, Kumho, Pirelli ... whichever.

 A better scenario (for the service department at least) is that you will break the weakest link in the drivetrain. Whatever that is, it is under immense stress if you are forcing those shafts into synchronising when they really want to drive at different rates. So ultimately of course you’ll end up with a mechanical failure there. Something goes bang. Your forward progress halts. You need to get the vehicle towed, they sit you down, they say ‘Hey, defibrillator just over there … here’s what this is going to cost’.

So, good safety tip, if you want to avoid that, always remember to unlock the centre diff before you get back on a high traction surface.

Which kind of SUV should you buy? Hardcore SUV or light-duty SUV >>

This kind of water crossing is quite safe - but falling into a hole and submerging the air intake can destroy your engine in a fraction of a second

This kind of water crossing is quite safe - but falling into a hole and submerging the air intake can destroy your engine in a fraction of a second

3: Going 100% hydraulic in the drink

On this whole communing with nature business with your SUV:

Sooner or later you are going to come face-to-face with a water crossing. And that’s kind of exciting, I guess.

It gets really exciting if it’s deeper than you think and you poke the nose of the vehicle a lot deeper than the manufacturer ever anticipated a rational person would poke it.

Only two things go in an engine: fuel and air. The air is sucked basically from the leading edge of the forward part of the engine compartments. Unfortunately, if you park that leading edge under the water, the engine has no alternative but to suck water instead of air. 

Water and air both have fascinating physical properties: one of the salient differences is, of course, that water is incompressible whereas air is compressible. In fact, the whole principal of operation of an internal combustion engine is the compressibility of the air/fuel mixture.

So what happens there: if your engine sucks water, it gets into the inlet manifold, it sucks down the inlet runner, it goes into the combustion chamber. If your engine is doing, say, 2000rpm, that doesn’t seem that high until you realise that it’s 33 revolutions every second. That piston is rocketing up and down inside its bore… even at mundane revs.

If it happens to slam into a tsunami of incompressible water, it will stop much more rapidly than the manufacturer ever anticipated. This will cause a catastrophic failure of several expensive internal engine components. You will probably bend or break the crankshaft; the conrods will be cactus as well, and your engine is basically going to be scrap metal in a heartbeat … actually, in less than a heartbeat. 

So the hot tip there is: if you want to generate all of that revenue for the service department, at a water crossing, never walk through first and confirm that the water is below the maximum permitted wading depth, which, incidentally, is in the owners’ manual.

What a pity more people don’t read it.

The hard core off-road blue singlet driving brigade actually have a colloquialism for this problem, should it occur while you're driving. They call it, aptly enough, a hydraulic. 

4: Sucking it with your powertrain

Parking in the drink - perhaps because you get stuck - can force water into your powertrain's most expensive hardware

Parking in the drink - perhaps because you get stuck - can force water into your powertrain's most expensive hardware

While we're detaining ourselves momentarily with all that fun you could have in your SUV using water, let’s think about all those expensive driveline components 'down there'.

I’m talking about gearboxes, differentials, transfer cases… things like that. These are essentially metal casings full of high precision components. They’ve also got lubricating oil inside them and the rest of the space is filled up with air. 

Air’s an interesting substance, because as those driveline components heats up, the air heats up inside the gearbox, or whatever, and it expands. This is why engineers don’t seal gearboxes and differentials. They leave them with breathers in place. If they were sealed, what would happen is, as the air pressure built up inside the gearbox, as a result of thermal expansion, the gearbox would start to pump its lubricating oil out past the seals that are designed to keep the oil in around the rotating shafts that come out.

So these vents (or 'breathers') do an absolutely essential job in terms of retaining the lubricating oil that those mechanical components need.

If you manage to park in the water for any length of time, because, for example, you get stuck, here’s what happens:

The water quenches the gearbox, the transfer case, the differential, whatever. It starts to cool down. The air inside correspondingly starts to cool down, as well, and it forms a partial vacuum. The vents, the breathers … they start to suck, which is what they’re designed to do. Unfortunately though, they suck water because the component is submerged and that is not what they are designed to suck.

Water and oil don’t mix but when you churn them up inside a gearbox or a differential, they form a kind of cool looking cappuccino-coloured emulsion which is quite attractive but not very good for lubrication. 

So if it’s ten months or something until you next scheduled service is due, that cappuccino-coloured emulsion is churning away inside some of the most expensive mechanical widgets in your SUV. This will, of course, shorten the life of those parts significantly.

If you want to avoid that kind of nightmare repair bill, it’s pretty simple. Go to the service department after you’ve done this kind of thing; tell them you’ve been parked in the water and ask them to change the oil in the gearbox, the differential’s transfer case and whatever else is vulnerable to that kind of breather abuse.

Driving through mud: Fun. Baking it into your radiator and overheating on the freeway ... you'll need Mastercard for that...

Driving through mud: Fun. Baking it into your radiator and overheating on the freeway ... you'll need Mastercard for that...

5: Mud-packed overheating: here's how

The final thing that is really good for destroying your SUV in the great outdoors, communing with nature, is plain old mud.

Don't get me wrong: your SUV is designed to drive through a bit of mud, that’s fine. Mud’s not really going to hurt it in some sort of acute way, however, before you get back on the bitumen and ramp up to highway speeds, it’s a fantastic idea to have a look at the radiator because it’s easy to clog the bottom third of the radiator with mud. 

And when you get out on the highway, and you’re starting to battle a bit of aerodynamic drag on a hot day, you’re pressing the vehicle up against a hill, battling gravity, as well, suddenly you need all of the cooling capacity that that radiator can muster. Not much good if the bottom third of it is clogged with mud. You will, of course, be exceptionally popular with the service department if you fail to heed this advice.

Because here’s what happens: When you don’t have enough cooling capacity, the coolant inside the engine heats up and heats up and heats up. Eventually it vaporises despite the pressurisation of the cooling system. It turns to steam. This will blow a radiator hose rapidly. It’s a great way to seize your engine, it’s a great way to blow your head gasket. It’s also a fantastic way to crack your cylinder head … or if you’re extremely lucky, you might tick all three of those boxes.

The service department will be overjoyed if that’s the case.

Obviously, the replacement bill for an average new SUV engine is going to be ten to fifteen thousand dollars which is going to keep the dealer principal’s children in private school education for the foreseeable next few terms. 

Diesels with DPFs need this kind of driving to keep the particle filter healthy - and if not the repair bill is huge

Diesels with DPFs need this kind of driving to keep the particle filter healthy - and if not the repair bill is huge

6: How to celebrate a real black mass 

Of course, you need not commune with nature to generate thousands in additional revenue for the service department.

You can do it in the city as well, especially if your vehicle is diesel. Diesel SUVs have particle filters (DPFs) which are a great idea because they trap microscopic particles of soot.

Soot is bad for human health which is a kind of medical euphemism, which means: soot gives you cancer. So that’s bad. 

A diesel particle filter is an expensive component to replace - but a regular trip up the highway and back each fortnight will generally keep yours in good health

A diesel particle filter is an expensive component to replace - but a regular trip up the highway and back each fortnight will generally keep yours in good health

The particle filters in diesel exhausts are very clever things. If you do what the owners manual suggests and get out onto the highway regularly, they don’t need maintenance and they last the life of the vehicle.

When it detects that light duty highway driving, the engine control computer turns the particle filter into a de facto furnace and it burns those trapped soot particles into a parallel dimension where they can do no further harm to human beings. So that’s good.

Unfortunately, if you don't do that kind of driving ever… if all you do is drive out of your driveway and drive down to the local shops, the particle filter will never burn off into a parallel dimension those trapped particles, and the filter will become clogged. 

When this happens, of course, they sit you down and they tell you that the replacement cost is going to be five-to-seven thousand bucks, thank you very much. Ouch.

I note a certain potential owner- inspired backlash against particle filters. I don’t know what’s worth really, a five-to-seven thousand dollar bill or the diagnosis down the track in fifteen or twenty years, whatever, that you or one of your kids has cancer. 

Get out of town and onto the freeway once a fortnight to keep the DPF healthy

Get out of town and onto the freeway once a fortnight to keep the DPF healthy

I guess I’d take the five-to-seven thousand dollar bill.

But you know what? They aren’t the only options.

All you’ve got to do to prevent this donation to the service department, is get in your SUV and get out onto the freeway, drive for half an hour, park your backside somewhere, drink a nice coffee, somewhere with a view of the ocean then turn around and come back.

You’ve only got to do it once every fortnight. 

There are, of course, many more creative ways to damage that shiny new SUV. This is by no means a comprehensive list. But I think in terms of return on investment and simplicity, you’d agree these six are the best.

If you want to tackle the pernicious problem of poverty in the service department, these six are the easiest ways to get that job done. 

Alternatively, I guess you could just choose to be a greedy bastard and keep all of that cash for yourself.

It’s entirely up to you.

Petrol versus diesel >>

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