Dmax inner guard cracking

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 a well documented Dmax problem 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.

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 #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.

I’d like them to repair it, but given its out of warranty, and has a larger battery installed 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.

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

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  1. 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

  2. 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