Isuzu Dmax problems; where does it fall short?

I’ve been a Toyota fan for a long time. They make great vehicles, and I’d happily own most of their range.

That said, our replacement 4WD from the 80 Series Land Cruiser was an Isuzu Dmax; a step in a very different direction. If you want to know how much the total build cost, you can read about it here – Dmax build cost.

I’ve had the Dmax for nearly 6 years now, and clocked up about 95, 000km in it. They are a great vehicle, with a solid foundation, great engine and reputable gearbox (if you get the auto) and good quality gear used overall. If you want the full review, check this out – Isuzu Dmax review after 4 years.

However, I’m not brand biased, or so attached to it that I fail to mention its shortcomings, and every single 4WD out there has at least a couple. Sometimes their owners will acknowledge it, but more often than not they don’t!

If you are looking for Isuzu D’max problems, then you’ve come to the right place. Please note most of what is raised here are also Isuzu MUX problems, which are basically a wagon version of the Dmax. 

Please note this post is my opinion only, and its up to you to do your own, independent research. I’m more than happy to share my opinion, but don’t base your decisions off them without doing extensive research elsewhere.

Frills and fancy bits

There’s no doubt that the D-max lacks in the fancy bits department. If you want a Ute that has all the bells and whistles, a Dmax is not it. They are a bit agricultural, truck like if you will, and that’s exactly what a select portion of the market wants.

I couldn’t care less about chrome bits, fancy dash boards, leather seats, lights that come on when you unlock the car and the long list of other things that some people find important. I wanted a solid vehicle, with vinyl floors that could be taken away with minimal fuss and relative comfort.

Being the SX version (base model) our Dmax has a similar interior to that of a 15 year old vehicle, and that’s OK with me. It might not be for you.

I will mention that the new shape (2020 onwards) Dmax and MUX have had a major upgrade in the frills and fancy department, which is great to see.

Power

At 130kw at the engine, and 380NM of torque, the Dmax is not leading the market here either. It’s got enough power to be reasonable, and a lot if you are used to some of the older diesel 4WD’s, but its got nothing on  other Utes like the Ford Ranger, Ford Raptor or V6 Volkswagen Amarok.

If you are towing anything heavier than 2.5 tonne (which you probably shouldn’t be with a Dmax anyway) you are going to feel it, substantially. You will not be able to sit on 100km/h when there are hills at all around; it just won’t happen.

Our Dmax has bigger tyres, a big ute canopy and a fair bit of weight, and you feel it towing a camper trailer around the 1.5 tonne mark. We’ve just recently gone and bought a Lifestyle Reconn R2 Hypercamper which is about 2.3 tonnes loaded and you really notice it!

It will sit on 100 most of the time, but it has to work hard to do so. Of course, there are lots of options when it comes to improving power and the 4JJ1 motor is extremely popular for getting huge power figures from with reliability remaining largely unchanged.

The 4JJ engine is widely regarded as one of the best on the market today, and is used in a wide range of applications from light trucks through to the Dmax and BT50, boat motors and you can even get conversion kits to put them into Patrols now.

There are limited 4JJ1 engine problems, and they tend to be reasonably cheap to repair as needed.

Weak CV’s

Independent front suspension vehicles are notorious for breaking CV’s, especially when a lift is fitted. Dmax lift kit problems are always going to be accentuated because of this, and you need to be careful going too high.

The Dmax CV’s seem to be at a disadvantage from the factory though, with the differential sitting slightly further back than it other vehicles, and this puts more stress on them to start off with.

Some people have broken CV’s with factory tyres and no lift. Touch wood, I’ve had no issues with bigger tyres and a 30mm lift kit, but I drive it as carefully as possible and have installed a diff drop kit.

The thing to remember is that if your wheel comes off the ground and lands hard when the tyre is spinning your chances of breaking a CV increase hugely. I know a number of people who’ve hammered their vehicles and not broken anything, so maybe its part luck/driver ability too.

That, and don’t hop the vehicle; as soon as it starts to bounce, stop and re-think what you are doing. Keep bouncing the front end and you’ll end up in broken CV territory very quickly.

Weak tie rods

If you see a broken Dmax on the side of a 4WD track, there’s a pretty high chance the two front wheels are pointing inwards towards each other. This is because the tie rods on the steering rack are not very strong, and have a habit of bending/breaking.

Again, this happens when you are 4WDing and giving it a bit too much. I’ve seen a few cases of this, but again know plenty of people who give them a lot of work and have never had a problem (and neither have I). A bit of mechanical sympathy goes a long way.

I’ve just recently seen much heavier duty options which sleeve the thread to prevent this, and will be keeping an eye out on it, and driving with care.

Early differential failures

I have read of a surprising number of Dmax’s with rear differentials that have failed before 80,000km. Apparently there was a batch of ring and pinion gears that were made with poor hardening properties, and the gears essentially chop out and become a pile of metal shavings in the bottom of your differential.

Mine will be getting checked shortly with a camera through the oil fill hole, and I wouldn’t be surprised to see damage. (EDIT – all good so far!), but we have replaced the whole lot with a Harrop Elocker.

Not good enough Isuzu; absolutely no leg to stand on in your defence. I don’t know how many of these have been covered by warranty, but often by the time you reach those sort of kilometres the warranty is long gone.

Cracked inner guards

Update – I’ve just heard that Bannister Law is investigating the Dmax and MUX cracked inner guards.

EDIT – We’ve just noticed some cracking on our battery mount, that is attached to the inner guards (and not a removable part). You can read more about it in the link above.

This point is possibly the most major concern with the Dmax and MUX. A number of Dmax’s and MUX’s (I’ve seen about 200 online) end up with the inner guard cracking, above the front wheels. This seems to stem from vehicles that spend a lot of time on rough roads, have heavy bull bars and winches mounted and that stick out a long way.

That said, I’ve also seen it on Dmax’s and MUX’s that have no bull bar, or even the factory aluminium or steel bull bar, and those that have done limited, or no off road work.

The repair is not pleasant; it requires the engine to be removed, and the cracks welded up or inner panels replaced, but there’s no guarantee it won’t happen again. 

I did read from an Isuzu technician that it is caused by soft body mounts that wear out and are not replaced often enough, and have seen a number of them cracking at the front, so keep an eye on it. Apparently this is something all dealerships are required to check and rectify on a regular basis now.

Also, I’m told that there was a mishap in the manufacturing facility where high tensile steel was stamped incorrectly for the guard panels, and used anyway. Obviously this is more susceptible to fatigue and is more likely to crack.

We’ve gone with the lightest full size steel bull bar I could find, opted not to install a second battery under the bonnet (which I reckon is a daft place to put one anyway!) and will keep an eye on the body mounts regularly.

EDIT – we had our Dmax body mounts replaced under warranty at 60,000km after the front two were showing signs of cracking and sagging badly.

I’ve also seen a lot of people installing Colorado body mounts, which are apparently more solid, but as to whether this makes the actual issue any better or not, I couldn’t say. If the steel is incorrect, its not going to fix that, and Isuzu would certainly have a greater leg to stand on if you did end up with cracking.

Leaking rear main seals

Early on, there were a number of Dmax’s that had rear main seals replaced under warranty. I was told that the robot applying the sealant to the seal was missing a small portion of the seal for a huge number of vehicles. I’ve not had mine leak so far, and hope it stays that way!

Open rear diff

The Isuzu Dmax is one of the few 4WD’s on the market that doesn’t come with a diff lock, or an LSD as a factory fitted install. Instead, it comes with traction control only (which most vehicles also come with). It works OK, but isn’t as good as some other variants on the market.

A rear diff lock makes a big difference in these, and I suspect we will end up with one down the track. 

The hands free sucks

If there is one thing that is a total and utter flop on my model Dmax (2012 – 2016) its the hands free. It is absolutely useless. You can adjust the settings, but its just terrible.

Who ever has the bad luck of trying to talk to you on the other end of the call will have major issues hearing what you say. Of course, you can rip the dash out and replace the head unit, which is what we will be doing soon.

For me, this is not the biggest issue in the world (and I knew about it when I bought the car) as I don’t use it too often to make or receive calls, but if you were using it for business purposes it’d be the first thing you would rip out and replace.

Turbo failures on DPF Dmax’s

I specifically bought the older version Dmax. I could have paid the same price for a brand new one, but opted for the last of the pre DPF models.

The reasoning was simple; a DPF (or DPD as Isuzu calls them) is just another thing to go wrong, and I know Isuzu have issues with them in their trucks (despite being one of the better DPF’s on the market today). If you have had DPF issues, Bannister Law is looking into it!

At the time of purchase, I’d heard of a couple of turbo’s going on the newer model with the DPF, and since then I have heard of a huge number. Every week there are a couple posted online about turbo’s that start to wail like a police or ambulance siren, or put the vehicle into limp mode.

These are being replaced under warranty, but it takes time and means you are without a car for a while, and some people are on their third or fourth turbo’s!

Isuzu Dmax DPF problems

In terms of engine reliability, an EGR and a DPF are not a great idea. Of course, they’ve come about in order to meet environmental emission regulations, so they are here to stay.

Isuzu have done an amazing job with their DPF’s in general (compared to many other brands), but I am still seeing some DPF (or DPD) problems on Dmax’s and MUX’s. A few people have had theirs replaced (and realistically they are a consumable) earlier than they should have.

If you are finding the DPF burns are happening much closer together, you may have a problem. One of the most important things to get right with a motor running a DPF is the right oil; if you run non DPF suitable oil it will block the DPF in no time, and you’ll have all sorts of issues.

Limit the number of short trips you do and the DPF will be much happier too.

As these get a bit older, I’m seeing more complaints about the DPF in Isuzu Dmax and MUX vehicles. Sometimes its the DPF itself, an other times its the sensor. Realistically, if you have a DPF you should consider it a consumable, which is a shame as they aren’t cheap.

Aircon failures

The 2012 – 2020 Isuzu Dmax’s have a very bad habit of cracking the evaporator at the end of a rigid pipe that goes through your firewall, which releases the cooling gas, and results in you needing to have the entire dash removed, and the evaporator replaced. I’m told that the new evaporators being fitted are a different design, but there are a number of people who are onto their 4th evaporator, which is pretty poor.

I have seen people installing P clamps onto the firewall to stop the pipe from moving and cracking, and there seems to be a relationship with extensive off road use. 

These are also damaged easily by anyone working in the engine bay with a number of people saying during battery changes, or even if someone just leans on it the pipe will crack and leak your gas out.

Our Dmax had the aircon fail just recently, and cost $1400 to be fixed (which I did get covered by warranty). Keen to know more? Check this out – Dmax Evaporator Failure.

What’s gone wrong with our Dmax?

So far, I’m reasonably pleased with my Dmax, but having only done around 80,000km its not really a huge form of evidence just yet. It’s certainly not been trouble free, and it would be interesting to compare this to a Hilux to see if they are actually any better.

The Dmax turbo was replaced when it was first delivered to me (faulty waste gate actuator), and I had the transfer case seal on the rear weep, which was replaced under warranty, and kept leaking (we are on seal #4 now, which seems to be holding).

I’m fairly confident the first 3 seals that were installed were not done properly (pushed too far in). You can read more about that here; Dmax leaking transfer case seal.

I’ve had the rear differential pinion seal replaced under warranty as it was leaking, and the 4 front body mounts that were cracking and deforming.

The next issue was a leak from the front differential, in the 4WD actuator assembly, and its booked to go in to be repaired. EDIT – this has stopped leaking, is still full and will be monitored. If its leaked, and is still full without being topped up it must have originally been over filled?!

Our next issue was the aircon failure, which resulted in the evaporator being replaced for about $1400, and we’ve since had the battery support crack, which Isuzu have been fairly helpful with so far (but its not repaired yet).

Beyond the above though, these are solid vehicles. I’ve been on various Facebook pages of different makes and models, and the Isuzu 4WD pages seems to have very, very little issues overall.

Those that are made a point of are not major (like Ford Ranger engine failures, for example, which are posted on the Facebook page just about every week!).

We’ve also fitted a transmission cooler to care for our Automatic Transmission, after the temperatures were getting a bit too hot for my happiness, but this is not uncommon for a lot of new 4WD’s that are working hard.

The Isuzu Dmax Automatic Transmission prior to 2017 seems to be bullet proof, with the 6 speed ones (prior to the new shape in 2021) having a few more issues, but still being reasonable overall.

Overall

If this post comes across as saying the Dmax’s are not a good vehicle, I apologise. This is not the case; they are good vehicles with a few little flaws (on the whole) that can be easily worked around. There’s no perfect vehicle out there, and plenty of other rigs have a lot more, worse issues.

I feel that there’s a lot of people who don’t share the issues they have with their 4WD’s, and when its put together openly and honestly it probably looks a bit daunting, but there are many other vehicles with much worse runs than this!

Would I buy another one? Sure. Would I look at alternatives? Absolutely. The game is always changing, and there’s no perfect 4WD for everyone out there. Overall though, I’m pleased with the vehicle, and it is serving us well. We will have this for at least another 5 years, so lets see how it goes by the end of it. We’ve got some big plans which will see it used a lot more shortly too.

Have you got a Dmax? Have you had any issues with it? Let me know below!

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