Model differences and other things I’ve learned when researching the 2003-2009 Kia Sorento

What sounds simple enough soon starts getting entertaining. I’d been asked “which Sorento is the best for…” questions more than a few times now, so I’ve decided to publish all that I know about them as there’s more than a few subtle and not-so-subtle differences between the models.

As ever, this is what I’ve found and what has worked for me. Do not take it as bible and do your own research. Please also feel free to tell me that I’m both an idiot and wrong by correcting my mistakes where you find them – I’m sure there’ll be some. Otherwise, hope this helps!

General

The vehicle comes in two major flavours – pre-facelift and facelift models. Pre-facelift ran from launch in 2003 to mid 2006, with the so-called facelift models becoming available in late 2006 until the end of the run. As such, you can get a 56-plate facelift model or simply a late-registered pre-facelift on an 07 if you’re unlucky.

Facelift cars have orange-coloured indicators in the headlamp cluster, pre-facelift cars do not.

Trim levels are poverty-spec XE < XS < XSE < XT < Titan with all the options ticked.

It is not a car-derived cross-over and has a discreet chassis with a body on top, much like a classic Land Rover. It has independent front suspension with a solid live rear axle and either a part- or full-time four wheel drive system complete with a discrete two-speed transfer case, giving a proper low-range for off-road use.

Diesel engine

No, it’s not a Mercedes engine like your mate told you. Honestly! Much digging has revealed the following:

The Kia A-series 2.5 CRDi engine for both pre-facelift and facelift vehicles is a re-labelled Hyundai D4CB, which in turn is a manufactured-under-license Mitsubishi 4D56.

Pre-facelift models get common-rail injection and a standard turbo, producing a factory-stated 138BHP and 253lb/ft of torque.

By slapping on a variable-geometry turbocharger to the facelift models, these figures increase to 168BHP and 289lb/ft respectively. Add an after-market remap and these facelift engines are good for 200+BHP and a nose-and-a-half over 310lb/ft of torque, making a superb tow car.

The pre-facelift vehicles have their coolant reservoir to the right of the engine bay on the bulkhead whereas the VGT-equipped facelift models have it between the engine and radiator. Also, it would appear that the facelift-model engine covers have the CDRi moniker painted red. Other than that, there’s not a lot within the engine bay to distinguish the two.

EGRs can block up on low-load, low-rev vehicles – taking them for a good hoon down the motorway is good for them. EGR delete is easy simply by blocking off the EGR pipe.

The cooling system on this thing is nothing short of epic. If you overheat it, you’re doing it wrong! The rad stretches from the bash plate below the front bumper all the way to the top of the engine compartment and it has a proper viscous-coupled engine-driven fan drawing air through it. I’m assuming this is to cope with the one American with the 3.8 v6 auto hauling half a house across the Mojave in the wrong gear. Nonetheless, it’s a pleasant state of affairs!

The diesel has a generously sized oil-to-water heat exchanger positioned on the right-hand side (viewed from inside the vehicle) of the engine block, ensuring that oil temperatures should stay within, at most, 15 degrees of water temperature.

Oil cooler

Oil-to-water heat exchanger on the side of the engine block

The A/C condenser is of a similar size and mounted in front of the engine rad, and pleasantly it has its own electric fan mounted up front to push air through the condenser when things are not hot enough for the main engine fan to have engaged. Nicely done.

According to this document, pre-facelift and facelift vehicles use 10W30 oil. Pre-facelift specifies oil complying to API CF-4, facelift vehicles should use oil complying to ACEA B4.

Manual gearboxes

To the best of my knowledge, the manual ‘box has been the same throughout the manufacturing run. If someone can let me know the make and model and if this assertion is correct I would be most grateful!

Automatic gearboxes

The Sorento has been fitted with two auto boxes: MY2003 and early 2004 vehicles had a four-speed Borg-Warner box, whilst all vehicles beyond mid2004 had a much-improved, Jatco- (Nissan-) derived five-speed with “tiptronic”-style manual override. Whilst there was nothing intrinsically bad with the old Borg-Warner auto, it was a very old-school gearbox and often felt a bit stodgy.

The five-speed (Hyundai designation A5SR1 or A5SR2, or Jatco RE5R05A) is altogether more useful and, as anyone who’s towed a decent-size trailer for any period of time will tell you, the extra ratio and manual override come in very useful. It also seems to be quite robust considering that it gets used in other medium-sized vehicles as well as sporty things such as Nissan’s 350Z.

The five-speed must, according to various service manuals, use Kia Red-1 ATF. As far as I can work out, you’d have more luck finding unicorn blood than this fabled hydraulic fluid and even many Kia dealers (incorrectly) recommend using bogo Dexron-III. Working on the principle that it is a re-labelled Jatco/Nissan box, I’m also going to assume that it would use the same fluid. This is a bit of a leap as they may use different friction materials (but I don’t believe so, as an auto trans rebuild parts list has the same friction and steel packs listed for both the Hyundai and Jatco transmissions). So, if you think my logic follows so far, I reckon the box can safely use Nissan Matic-J, Matic-S (superceded Matic-J) or any other fluid that meets Matic-[J/S] or Kia Red-1 specifications (such as Hyundai Matic-J) or indeed anything that meets the JASO 1A spec.

There’s an interesting point of view about this on the Club Frontier forum here.

As ever, on your own head be it, but its worked for me thus far 🙂

Transfer Box

For the UK, there were two boxes available, both running from 2003 to 2009.

No models have a centre differential – they are either two-wheel drive only (!) (option in the US), switchable part-time 4×4 like a 1950s Land Rover or a marginally-clever-yet-weak-sounding torque-on-demand system by Borg Warner.

Switchable 2×4 / 4×4

XE models had selectable four-wheel drive and came equipped with a Borg Warner “Shift-On-The-Fly” box that had an epicyclic geartrain providing a 1:1 high and 1:2.48 low range, plus a dog clutch that would engage the front prop shaft in 4×4 mode.

It’s also worth mentioning that the 2×4 models have a pneumatically-operated free-wheeling front axle (Kia’s mnemonic is CADS – Center Axle Disconnect System), meaning the front wheels don’t have to stir the diff or turn the prop shaft when in 2×4 mode – a very neat little addition. It has a pneumatic actuator on the front diff and a dedicated pump to run it. The same trick is used on Mitsubishi’s Shogun (Pajero) and Shogun Sport (Challenger), and seems like a really nice idea.

Note that like any other switchable 2/4 wheel drive system, 4×4 mode should not be used on grippy surfaces due to the lack of a centre differential.

Full time 4×4 / Torque On Demand

Models above the XE (XS, XSE, XT, Titan) came equipped with a similar Borg Warner box, but this time using an electronic “Torque-on-demand” or TOD system (some Kia material refers to it as “active torque transfer” or ATT). Sensors similar to those used on ABS systems read the front and rear output shaft speeds and, based on the speed difference, road speed, throttle position and other factors, would apply a varying current to the ToD electro-magnetic clutch, allowing anywhere from a 0:100 to 50:50 front:rear power split.

Whilst this system can do some cool things (for example automatically engaging front-wheel-drive if you stand on the throttle from rest to eliminate wheel spin) it is highly intolerant of differences in tyre size. Because of this, fitting new tyres to one axle – even if they are of the same make as those on the other – can cause the system to engage (typically 10 to 20%). This causes heat generation in the transfer case, clutch wear, unnecessary load on the axles, tyre scrubbing and a loss of fuel efficiency.

As such, people have come up with a way of temporarily off-lining the ToD system, allowing for a true 2×4 mode or 4×4 high without setting transmission computer errors – googling “Sorento Super Locker” is left as an exercise for the reader 🙂

As a design choice, I’d much rather have seen them put in a real open differential that could take the majority of the load for the majority of the time, and then have the ToD clutch over it allowing it to become a locking or partially-locking diff as required. That would have been expensive, however, and probably overkill for the market at which this vehicle is aimed.

In other markets, notably the US, the Sorento was also offered with a single-speed two-wheel-drive transfer case; about which regrettably I have no information. It also sounds utterly pointless!
Correction – the two-wheel drive version deletes the transfer case altogether, instead substituting a stub-prop and bearing carrier to extend the main transmission’s output shaft to within reach of the rear prop. It also looks as if the main gearbox has a different tailstock on it. I still think this is pointless in a vehicle like this 🙂

sorento_2wd_vs_4wd

 

Lubrication for the transfer box appears to be Dexron-III ATF. The handbook states no volume for this but claims instead that it is “fill-for-life”, whatever the hell that means.

Rear axle

Pre-facelift models appear to have been available with either a standard open or a limited-slip differential on the rear.

Post-facelift models that incorporate ESP into the ABS system (recognisable by the “ESP off” button next to the range selector) have only an open rear diff as the limited slip action would adversely effect the discrete braking action of the ESP’s yaw correction mechanism.

That being said, the electronic traction control will get you out of a two-wheels-floating crossaxle, albeit with much less dignified “grabby” approach than the LSD would.

One chap has successfully attached some kind of air locker to his Sorento (see the YouTube vid here), but until I get hold of an axle I can pull to bits, from the information I have it’s most likely it was an ARB locker, part number RD156 that was used. In the video he says its modified – quite what modifications were required however I’m unsure. Take this last para as complete speculation until I can prove it and have a spare £1K to throw at ARB!

One final and very important note is that this particular model suffers from a design flaw in the upper trailing arm brackets on the rear axle. Long story short, somebody forgot to design in any  drain holes at the base of the brackets, allowing them to retain water and consequently corrode through both the brackets themselves and the upper surface of the axle tubes.

Obviously this is not a good thing, however Kia will modify your brackets for free by cleaning them up, drilling a couple of drain holes in the lower corners and then re-rustproofing the axle. They will also repair or replace the axel casing itself if it is beyond economic repair. All is done at Kia’s expense, but only until the end of March 2016. If you have one of these vehicles and you don’t have drain holes in your upper axel brackets, now’s the time to get them modified!

See the Sorento forums here for more info.

A note on deep water

Alas, there are places where corners have been cut, and there is a reason that Kia say that the maximum wading depth is only to the middle of the wheel: the wheel bearings are not watertight as they are on more grown up 4x4s. I’m sure it can wade far deeper, but you’d want to re-pack the bearings with fresh grease not too long afterwards! I’m willing to consider any wading potential as emergency use only.

ABS, EBD, ETC, ESP

ABS (ant-lock braking) and EBD (electronic brake-force distribution) is standard across the range. EBD simply uses the two rear ABS circuits to prevent the rear wheels locking prematurely, and from the looks of it can actually increase the amount of braking available to the vehicle when compared with a load-sensing mechanical proportioning valve.

Post-facelift, everything other than the poverty-spec XE gets ETC (electronic traction control) and ESP (electronic stability programme), but as such the LSD on the rear axle is deleted (see above).

The ABS ECU sends an “ABS active” signal to the TOD control unit when the ABS or ESP system activates, ensuring the driveline is in a known state to enable wheels to brake independently without shock-loading the transmission.

Incidentally, the ABS system seems to be very on-road oriented and doesn’t work well in the rough stuff, most notably when attempting to do a controlled descent in reverse. Just beware of it and how it can misbehave.

As a personal opinion, if you have the choice, get a vehicle with ESP. It can do some amazing things that no driver can do no matter how much they claim they can (can you operate four brake pedals simultaneously? No, thought not!) and it might save your life one day.

Wheels, tyres and suspension

XE, XS get 16″ alloys, XT appears to get 17″ alloys while the range-topping Titan gets 18″, which IMHO is pointless on a 4×4. If your Sorento never sees mud, however…

Tyres are, from the factory, 245/70R16, 245/65R17 or 245/60R18 depending on the wheel size. It would appear you can’t go too much taller than this otherwise you end up rubbing on the wheel arch inners or chassis rails when on full lock.

Old Man Emu do a spring replacement kit to give enough clearance to fit 32″ tyres. Never tried it, can’t comment on it, but it looks cool 😀

Brakes

Discs all round, decent, bitey and generally unchanged over the vehicle’s life.

Part numbers for aftermarket replacements are shown in the tables at the end of this post.

Interior

Poverty-spec XE gets a grey cloth interior. XS gets grey leather, XT and Titan get black leather.

XE gets manual air-con, XS, XT and Titan all get automatic climate control.

Post-facelift cars have silver-accented rings around the otherwise barren instrument cluster.

Known failure points

Early (2003/2004) All vehicles have been known to suffer sever corrosion around the rear axle’s upper trailing arm mounts, causing them to sheer off. There was a recall for this, but it would appear many vehicles missed the update. When buying an early vehicle, even if it has had the service bulletin work completed, check the trailing arm mounts on the top of the axle.

Rear axles also appear to be susceptible to internal failure, either due to pinion gear bearings or diff carrier bearings failing. This is rather circumstantial again, but may be down to bad servicing: According to the service manual, when refilling the oil, the vehicle needs to be on quite a steep incline in order for the correct amount of oil to be added. This has to be the only vehicle I know of where the level plug on the axle case does not indicate the correct level of fluid!

Another entertaining one is down to seized splines on the front prop. If you have a motorway-cruiser that you’ve just bought for off-roading, remove the props and check the splines on the prop shafts as when you venture off road for the first time and the body is subjected to some twist, the front prop is unable to change length due to the seized splines. In extreme cases this can crack the transfer case.

Like most off-roaders that are used on-road, UJs seem to be neglected and consequently cause failures.

Diesel engines are reasonably bomb-proof with the exception of the timing chain. It’s a simplex chain (!) and for whatever reason this hasn’t been addressed. If the vehicle’s been well serviced, it’ll probably last the life of the car. If not, well, probably better to get them (there are three – crank-to-oil-pump, crank-to-high-pressure-fuel-pump, fuel-pump-to-cams) changed around 100,000 miles along with the tensioners and guides. Aftermarket kits seem to be in the £150 range, but getting it fitted is quite a job.

The V6 engines also suffer similar timing chain issues even though it’s a very stout-looking triplex affair as the guides fail, causing the chain to slap and rattle on cold starts and eventually causing a catastrophic failure.

Not really a failure so much as maintenance; EGR systems can choke up, causing the EGR valve or the recirc pipe to get blocked with sooty debris. Usually an easy fix.

I’ve seen circumstantial evidence that the manual 5-speed gearbox can be a bit weak, but I have no empirical data for that.

Over a seven year run, that’s actually not-half bad!

Useful measures and parts

These parts are all for a 2007 UK-spec 2.5CRDi with the variable geometry turbo.

ItemQuantitySpecification
Diesel Engine Oil~6lACEA B4, 10w30
Automatic Transmission Fluid10lKia Red-1 / Nissan Matic-J or Matic-S / fluid meeting JASO 1A
Transfer case1.42lDexron-III
Front and Rear diffs (open-type)~0.9lAPI GL-5 (SAE90)
Power steering~1.3lDexron-III
Brake fluid0.35lDOT-3 or DOT-4
Fuel80lLow-sulphur diesel
ItemManufacturerPart numberNotes
Oil filterBlueprintADG02121
Engine air filterMannC3033
Engine air filterFiaamPA7453
Engine air filterFramCA9525Nasty, nasty - have a personal dislike of Fram filters...
Engine air filterKnecht / MahleLX 1955
Engine air filterPurfluxA1218
Engine air filterTecnocarA2178
Cabin air filterCroslandC40413P-2Two filters per pack - both are required...
Cabin air filterHyundai, Bosch971332E910
Cabin air filterMann, HengstCU2214-2
Cabin air filterKnechtLA444/S
Front brake padsEBCDP61557Green stuff
Front brake padsEBCDP1557Ultimax
Rear brake padsEBCDP1559Ultimax
Front brake discsEBCD1720Standard disc
Rear brake discsEBCD1779Standard disc

Any further information that I find I’ll add as I go along, but that’s mostly it for now!

8 thoughts on “Model differences and other things I’ve learned when researching the 2003-2009 Kia Sorento

  1. Philip Spicer

    Read your report and brilliant knowledge of the sorento.
    We are thinking of buying a Sorrento to tow a twin axle caravan with weight of 17.45 kg and they recommend that you have 85% towing weight. So picking your brains which Sorrento would you recommend to buy, I hav a £6000 budget. I would appreciate any help you can give me as I am totally confused with all the cars that I have been looking at & told would be suitable.
    Many thanks

  2. Harry Post author

    Hi Philip,

    OK, disclaimer first – I’m an amateur, and while I think my maths and engineering are valid, please know that ultimately the decision is yours and you must be sure you understand the decisions you take and I can’t be held responsible for that. That said, I shall try and help if I can 🙂

    The 85% rule is a very good rule of thumb, i.e. the trailer you’re towing should, at most, represent 85% of the mass of the tow vehicle. The Mk.I Sorento has a kerb weight of approximately 2050KG for the 2.5CRDi variants, hence 2050 x 0.85 = 1742.5kg – just below the mass of your caravan. It is rated for towing up to 2800kg in CDRi form, but obviously you’re massively exceeding that magic 85%. Reading between the lines (and this is just my opinion), the 85% figure gives a comfortable, easily-managed tow weight, so you should be OK.

    The pre-facelift vehicles (before model-year 2007) had the option of self-levelling rear suspension. I only tow trailers filled with random bits of car around the place and hence this wasn’t really of any great issue to me, however I can imagine it being quite a boon for a caravan. The SLS option was a purely hydraulic thing accomplished by clever rear dampers that incorporated the self-levelling mechanism. They are, therefore, expensive to replace but from third party accounts are very good at what they do.

    Mine is a 2007-model-year vehicle and hence came with very ordinary springs and dampers. They were also, at 110,000 miles, very tired. The whole vehicle sat a good inch or so lower than many I’ve seen and the front dampers were a joke. I forked out for a set of ARB’s Old Man Emu springs and dampers for it – they’re made for use in the Australian Outback and hence are more than capable of dealing with a heavy trailer being towed over a rutted field. This is classed as a modification as it changes the vehicle’s spring rate and damping dynamics, but my insurers didn’t raise my premium when I informed them of it.

    Also remember that the Mark I Sorento (Pre-2010) was of body-on-frame Land Rover Defender / LandCruiser-esque construction. The later vehicles (2010 onwards) are based on the Hyundai Santa-Fe platform, hence much lighter, less sturdy, no low-range transfer gearbox etc.

    I’d avoid the very early auto gearboxes: the 2005-onwards Nissan-derrived auto is way better, and offers torque converter lock-up in second, third, fourth and fifth when in manual mode. Also, the manual mode locks the transmission into that gear unless you overspeed or come to a complete stop, so it’s very pleasant when dragging something heavy through uppy-downy countryside. The diesel engines also have an electronically operated butterfly valve in the air intake that closes when in a low gear in overrun to aid in engine braking, which is a nice touch.

    If you want sure-footedness over fuel economy, I would recommend going for one of the models fitted with torque-on-demand 4×4, i.e. the XS, XT or Titan. Having four-wheel-drive kick in automagically and progressively when pulling out of a slippery incline is very pleasant and requires no driver involvement at all.

    Finally, regarding budget, you can get a stonking lower-spec, lower-milage newer vehicle for that or a higher-mileage, higer-spec one. Mine’s done 125,000 miles now and you’d barely recognise the fact.

    When buying, check the auto gearbox is snappy in its shifts (it shouldn’t slob around on the first-second shift, for example) and test the gearshift when the engine is up to full working temperature and at various throttle positions (light, medium, heavy and flat out). The speed of the one-two shift should be the same no matter what load it is under. The second gear clutch pack is the one that get a kicking if the vehicle’s been used for heavy towing for much of its life. Check the rear axle upper radius arm brackets: they should have had a modification done to them (a hole drilled to allow water to drain). If this hasn’t been done and / or heavy corrosion is present on the brackets, walk away: should the brackets fail then you, your car and your caravan may be going to visit somewhere picturesque in a very undignified and uncontrolled manner :-/ Also, the rust can perforate the axle case and allow water ingress or oil leaks, both of which usually lead to a toasted rear axle.

    The vehicle should drive very smoothly with no clonks, thunks or bangs from either the suspension or the drivetrain. Wind the front windows down, turn the steering to full lock, put it in reverse, hold it on the brakes just hard enough to keep it stopped then add a small amount of throttle. Let it reverse for a good few feet and feel and listen for any clunk-clunk noises as the wheels rotate. If there are, you’ll need new CVs at the front. Not a major job, but get some money knocked off. Only usually the ToD-equipped vehicles that suffer from this as the part-time 4×4’s CVs are never under load.

    Finally, check that the hand brake works, especially if it’s an auto. People insist on not using it and as a consequence the mechanisms can sieze or the drums corrode.

    If you have any further questions, don’t hesitate to ask 🙂

  3. Tommy Tennant

    could you please tell me what transfer box is in my 2009 sorento as i have looked at one but the 2 electrical fittings on mine are a grey round and a black round fitting. The one i was looking at has a round and a rectangular fitting. Are these transfer boxes compatible with each other or are they entirely different. also can you give me the Borg Warner number of my box so i can get the parts i require
    Kind regards
    Tommy

  4. hugh costello

    brilliant post harry , are there any diagrammes for making a diy switch to control the TOD SYSTEM

  5. Jennifer McCann

    I’m not quite sure when this was written but its very interesting. I have a question. I own a 2007 XS and the front prop shaft seized and was removed. Is there an alternative prop shaft I could replace it with, as the Kia ones are very expensive?

  6. Harry Post author

    Hello,
    Mine suffered exactly that fate – although I’d greased it when I first had it, it was really too far gone and soon got back to clonking and squeaking… I had a remanufactured one suppled to me by Wilson Driveshafts in Nottingham (http://www.wilsondriveshafts.co.uk) – they can attempt to recondition your existing one, however as the splines on mine were well and truly bound up I elected for a complete replacement. ~£200 inc VAT if I remember correctly.
    Cheers,
    Harry

  7. Harry Post author

    I seem to recall there being a set on the interwebs somewhere – if I find it I’ll add it to the post, however I don’t believe its something that would defeat a thorough googling 🙂

  8. Harry Post author

    Sorry – can’t really advise for anything other than that which I have direct experience. There will be differences between the ToD box (present on UK XS and XT trims) and the selectable 4×4 box (XE trim) as one couples the front prop with an electromagnetic clutch under computer control (‘permanent’ 4×4 XS and XT), the other with an engaged / disengaged (non-progressive) dog clutch under manual control (XE).

Leave a Reply

Your email address will not be published. Required fields are marked *