Dmax inner guard cracking; ours finally gave in

If you own an Isuzu Dmax, and haven’t heard of the inner guard cracking issue before you’ve probably not spent too much time online.

It’s one of the well documented Isuzu Dmax failure points that happens to models between 2013 and 2020 (before the new shape), and takes the form of cracks in various places in the engine bay, along the inner guards.

This has long been my biggest concern with our 2016 Isuzu Dmax, and if I’m honest, every time I open the bonnet I’m waiting to see them appear.

Inner guards on the Dmax
Every time I open the bonnet I’m waiting to see cracks

What causes the Dmax cracks?

There’s been a lot of debate online about the exact cause of the cracking. It’s happened in vehicles with heavy bull bars, with factory aluminium bull bars, and those that had no bull bars at all.

I’ve seen it happen on vehicles with good condition body mounts, and often with body mounts that have cracked and deformed.

Our very own Dmax had the body mounts replaced under warranty at about 60,000km, because they were cracking and deformed, and I pushed hard as I didn’t want any chance of inner guard cracking.

Body mounts replaced
I got our damaged body mounts replaced under warranty

A lot of people are installing Colorado body mounts, which are heavier duty, but I don’t think that this helps with the cracking; you want to absorb and cancel the vibrations, not install heavier ones that can do the opposite.

I was also told that there was an incorrect type of steel used in some of the inner guards, which was stamped incorrectly and fatigued much easier than the correct grade of steel.

What ever it is that causes the cracking isn’t good, as the repair is expensive, time consuming and not guaranteed.

How are the cracks repaired?

Depending on how bad the cracks are, I’ve seen panel beaters cut out and replace portions of the panel, or just weld supports in. Some of the earlier repairs though required the entire engine to be removed, with the inner guards replaced.

Originally these were like for like replacements, and the chances of it happening again were just as high as before. I’m not sure whether Isuzu has changed the design on the new inner guards that they install, but a repair is not something you want to be dealing with.

It’s worth noting that Bannister Law have come out looking for those affected by DPF and inner guard cracking, as they are ‘looking into it’.

Our Dmax cracked

I try to pop the bonnet on our Dmax at least a couple of times a week when we are travelling around Australia, and more depending on how its being used.

After 3 amazing nights at Memory Cove in the Lincoln National Park, I popped the bonnet up to check all was OK, and my eyes very quickly noticed a crack. Great. It’s finally happened!

Closer inspection revealed that a crack had started, and gone around a spot weld, and continued up a little on the bracket that supports the battery from moving side to side. The track out to Memory Cove is quite rough, but I have no doubt that this was just the needle that broke the camels back.

Slowly heading into Memory Cove
The track to Memory Cove is fairly rough and slow

Fortunately, it appeared that the actual inner guard was OK, and it was just the bracket that attaches to the inner guard that was damaged. I did wonder where the crack would go to, and what other stresses it would pass on being cracked.

Cracking on the Dmax
A small crack from the spot weld on the battery bracket

We drove back into town, and I thought I’d call in at Isuzu in Port Lincoln unannounced, to see what they had to say about it. They did the service a week prior, and were quite helpful, and I wanted to get the ball rolling.

They asked me to come back the next morning so they could put it on the hoist and take photos, and I agreed. The next day, I detached the camper trailer in Supercheap Auto’s car park next door, and they took the Dmax for about 20 minutes to take photos and have a good look.

The service manager came back and said they couldn’t find any other cracking, but they’d lodge a technical case with Isuzu Australia, and let them know we were on the road and heading across towards Adelaide, and that we’d hear from them.

It’s been a month since then, and I’ve not noticed any further change in the cracking, and am still waiting for Isuzu to get back to me. I’ll update this with any progress (or lack of it) as it happens.

I’d like them to repair it, but given its out of warranty, and has quite a few modifications I’m not going to hold my breathe. I’ll call in at a few panel beaters otherwise, and get their thoughts. For now, our lap of Australia continues.

EDIT #1 – After a few months of not hearing anything, I rang Isuzu in Port Lincoln, who gave me the technical case number that was lodged, but said I’d have to get another dealer to lodge a new case in order for them to work on it. How does that work, when its already been done, and when we are on the road?

I also put my name down on the Bannister Law class action, and had a call from them. They wanted to know if the Dmax had any modifications as they are doing a survey, and of course ours is.

I will ring Isuzu head office again and get them to sort it out; I’m not going to hop from dealer to dealer and wait weeks to get it sorted.

EDIT # 2  – Essendon Isuzu (ironically the place I originally purchased the vehicle) have picked up the case, and were really helpful in organising the approval for works, and getting it quoted up. Shannon in particular was really good to deal with, and worked hard to keep things rolling.

It’s been approved for repair, but they want to replace both inner guards, the body mounts and the radiator support panel, which is basically the entire front end panelling on the vehicle, and they’ve quoted 3 weeks to do this.

The idea was to try and get it repaired in Melbourne as we called through, but time’s slipped away and we don’t have 3 weeks to get it repaired down here, so will have to organise it (or something else), further along out leg.

I’ve been monitoring the crack, and its now about 15mm long (from the original 5mm), but doesn’t seem to be growing any further now that its hit the corner, which is good.

I’m pleased its all been approved, and understand these things take time. I’m having a harder time trying to work out how we’ll survive without our vehicle for 3 weeks while it gets repaired!

EDIT # 3 – We kept monitoring the crack in Queensland, and trying to book the vehicle in advance at an Isuzu Dealer, but they all wanted to see the vehicle in person, which made it very difficult. T

hen, on our drive out to Stanage Bay we lost our aircon, and 5 minutes from camp the fault lights came on, so I got out to have a look.

What I found is the thing of nightmares; a massive crack in the passenger inner guard running from near the battery towards the radiator, up the guard itself, and around 130mm long.

This is what the aircon hose is attached to, which has caused it to fracture. Our repair options have now been dramatically pushed forwards!

What about you?

Have you had inner guard cracking on your Isuzu Dmax? What did you do about it?

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  1. Hey Paul,

    Thanks for the update, and I hope it goes favourably for you. I get the impression that these repairs are being done with less red tape today, and I can’t help but wonder if that might be due to the class action investigation.

    IUA have been really helpful, and decent towards me, and if you get a response you aren’t happy with, I’d suggest you speak to them directly. I can’t see how them, or you servicing it would have prevented the cracks, unless the body mounts are bad, and haven’t been picked up.

    All the best mate

  2. Paul FitzGerald says:

    Hi Aaron, just an update on this from my last post. Put my 2014 (with 15mm crack) into the local dealer for assessment and reporting to Isuzu Aust. IA came back wanting all my service invoices from day dot up to my current 147,000km. I have done a number of the more recent services myself as they are relatively simple, so responded as such. Guessing they are going to reject my case for not having all my servicing done professionally. Have asked the dealer to query IA on what causes the cracking, as I can’t see it would be related to any servicing issues as such given it’s a structural issue. Be interesting if they specifically respond to the question.

  3. Hi Simon,

    Good to hear it’s been repaired. If it’s still wearing tyres badly, I’d go and see a decent tyre aligner, like Pedders suspension.

    Maybe something is bent or misaligned

    All the best

  4. Hey Tom,

    Sounds like a right old shambles, and total pain in the backside. Sorry it didn’t go nearly as smoothly as it should have.

    So far IUA have been very helpful towards us, and I get the impression they’re fighting any claims relating to cracking much less these days, probably due to pioneers like yourself!

    What vehicle are you using now? Are you happy with it?

    All the best

  5. Simon De Masson says:

    Hi, going through this problem as we speak. 2015 DMax with 345.000 on the clock . Had it assessed and about to collect it tomorrow with full repair under warranty. All it cost me was a guard that hit a small stump .
    My problem is wheel alignment. I’ve had spacers put in when getting new shocks but still scrubbing Tyers . Has been lifted , Maybe that’s the problem although it was scrubbing before the lift ?

  6. Hi There,

    I may have posted here before in detail, but yeah. Similiar story but Isuzu wouldn’t cover and we settled out of court after a year of heartache and being lied to and hung up on by Isuzu Ute Australia. My air con went as well after the repair and once the radiator support panel and inner guards came off it was also riddled with cracks. I initiated the class action through bannister law but due to signing NDA I can’t be the lead plaintiff. Im really sorry to hear it’s now happened to someone else but the problem is rife. Isuzu Ute Australia are masters in marketing and sponsoring all the right influences, YouTubers, influenzas- whatever you want to call them. You’re right about the Colorado body mounts too. Have all the info as I needed two engineers reports for the lemon of a car. 5 years old and needed $20,000 worth of failures. Serviced on time every time and treated like my baby which it was. Good luck and if you need any info let me know.

  7. Hey Harry,

    Shame. It’s not a nice feeling to see the cracking! I’d speak to Isuzu ASAP. We too have been quite happy with them in general, and most of the dealers have been pretty good too. It’s a shame your local one hasn’t been up to scratch. I don’t suppose you can use anyone else?

    What was the warranty respray for? Peeling, or other issues?

    All the best

  8. Harry Dil says:

    Have just found our is starting to crack as well, 2015 MUX.

    Only discovered as it was going in for a warranty respray.

    Not sure if I should tell Isuzu now or just leave it!

    TBH Isuzu Australia have been really helpful and had no real issue, it’s been the local dealer who has been woeful.

  9. Hey Paul,

    Sorry to hear mate. It’s super common, and I’d be surprised if your body mounts are in good condition. I’d have a chat to your local Isuzu Dealer, and see what they say; its a known fault, and there’s a chance it will be covered with good will, or you might have to try and fight hard for it.

    All the best

  10. Paul FitzGerald says:

    Hi Aaron,
    Recently watched something on YouTube which mentioned the cracking issue so popped the bonnet on my Dec 2014 build D-Max to see a 15mm downward crack on the driver’s side just back from the bracket where yours cracked on the passenger side. Unsure how long it’s been there but will check further including the condition of the mounts.
    Thanks for detailing your experience.

  11. Hey Mark,

    I assume you mean the newest models, with the different motor, and vastly updated interior. I have yet to hear anything, and I’d be very surprised if they did, given how much Isuzu would have spent on repairing the older versions already (and its still ongoing).

    All the best

  12. Does the new dmax suffer the same guard cracking problems?

  13. Hey Christie,

    Sorry to hear that. Normally Isuzu organise the repair; it shouldn’t be up to you to organise.

    We had a panel shop near Melbourne quote on ours, but might have to find someone else further north. We still haven’t had it repaired yet.

    I’d just keep hunting for shops that will take it on, or go back to Isuzu head office and see what they can arrange. They’re normally very helpful

    All the best

  14. Christie jackson says:

    I have a 2018 Isuzu d max with extensive inner Gard cracking I have been dealing with Isuzu since October 2022 with everything been approved to fix but no one wanting to deal with it any advice