Isuzu DMax MUX body & inner guard crack

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Danno
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Re: Isuzu DMax MUX body & inner guard crack

Post by Danno »

All were affected mate, some were ok some were not its a bit of a lottery. Most cracked within 20000k's even if not used off road but some held out to much later.
My advice? buy something else, you'll always be worried about it and checking.
Cheers
Dan
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bazzz_
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Joined: Sat Jan 11, 2020 10:47 pm

Re: Isuzu DMax MUX body & inner guard crack

Post by bazzz_ »

Danno wrote:All were affected mate, some were ok some were not its a bit of a lottery. Most cracked within 20000k's even if not used off road but some held out to much later.
My advice? buy something else, you'll always be worried about it and checking.
thanks mate, that's true, along with the odd axle housing crack as well. It is unfortunate otherwise a dmax would be the pick of the dual cab utes.
ano42553
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Joined: Tue Oct 06, 2020 5:27 pm

Re: Isuzu DMax MUX body & inner guard crack

Post by ano42553 »

Here we have another one 2017 dmax space cab 84 km all the fruit and cracked right engine bay centre above right wheel has done no offroad at all , it hasn't even been on the dirt or crazy roads yet
mydmax
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Re: Isuzu DMax MUX body & inner guard crack

Post by mydmax »

ano42553
Way back I mentioned a possible cause and no one has investigated to my knowledge. I consider, IF, that is IF the body mounts are not in pressure/tension equilibrium then they hold the body hard one way from the chassis position. That would mean one side of either the rear or front mounts is either compressed or opened. In the front bolts were loosened and a gap appears above the rubbers while sitting on level ground, it would indicate the chassis is trying to drag the bodywork downward and the weakest panels begin to crack. Seeing you mentioned ALL the fruit I suppose that is a bullbar too and possibly winch. That WILL have some effect on the chassis at the front. Alternatively, with front mounts tight, loosen the rearmost body mounts and so if a gap appears above or below, it all depends on how the mount is made as to where the stress will reveal itself. If you find loosening at either end allows a clearance to show, then you probably know the cause and can correct it or allow for it before repairs are done. Just my opinion, but there has to be a reason with some vehicles, it was all vehicles then all would crack.
goody59
Posts: 110
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Location: Wollert ((Melbourne outer northern suburb)

Re: Isuzu DMax MUX body & inner guard crack

Post by goody59 »

mydmax wrote: Wed Oct 07, 2020 5:10 pm ano42553
Way back I mentioned a possible cause and no one has investigated to my knowledge. I consider, IF, that is IF the body mounts are not in pressure/tension equilibrium then they hold the body hard one way from the chassis position. That would mean one side of either the rear or front mounts is either compressed or opened. In the front bolts were loosened and a gap appears above the rubbers while sitting on level ground, it would indicate the chassis is trying to drag the bodywork downward and the weakest panels begin to crack. Seeing you mentioned ALL the fruit I suppose that is a bullbar too and possibly winch. That WILL have some effect on the chassis at the front. Alternatively, with front mounts tight, loosen the rearmost body mounts and so if a gap appears above or below, it all depends on how the mount is made as to where the stress will reveal itself. If you find loosening at either end allows a clearance to show, then you probably know the cause and can correct it or allow for it before repairs are done. Just my opinion, but there has to be a reason with some vehicles, it was all vehicles then all would crack.
Hi Dmax,
I like what you are saying re body mount being a possible cause. How would you correct it, body washers to take up that gap if a gap became apparent? I have done something in my Dmax that I had done on my last Nissan Terrano II. That is add a brace from the battery clamp bolt closest to the motor and the brace goes over the battery to an outer guard mounting bolt. I have the oem 10inch battery but that is enough weight to get the battery tray stressing the inner guard in my opinion. Amplified with a bigger and heavier battery or even more so with two batteries mounted end on end. It is just a theory too, no proof. I know of a guy in another group, that suspects it a metal composition issue, ie brittle metal cracking. It could be all three of these theories. The resulting crack is not good news for any owner. I am happy to avoid the cracking anyway possible. Chassis are designed to twist and along with cabin mounts, could be the issue causing cracks. Everything is trying to twist and something has got to give.
mydmax
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Joined: Sat Oct 12, 2013 8:36 pm

Re: Isuzu DMax MUX body & inner guard crack

Post by mydmax »

Goody
I agree a metallurgy issue may be present too. My point is, if the chassis and body are not in passive equilibrium then they are already under stress. That means the weakest bit, the bodywork is stressed because the chassis won't give much. Loosening to find out and appropriately packing the gap with spacers so the bolts are tight at that rest point, has to be beneficial IF the problem is present.
goody59
Posts: 110
Joined: Fri Apr 25, 2014 2:12 pm
Location: Wollert ((Melbourne outer northern suburb)

Re: Isuzu DMax MUX body & inner guard crack

Post by goody59 »

mydmax wrote: Wed Oct 07, 2020 8:44 pm Goody
I agree a metallurgy issue may be present too. My point is, if the chassis and body are not in passive equilibrium then they are already under stress. That means the weakest bit, the bodywork is stressed because the chassis won't give much. Loosening to find out and appropriately packing the gap with spacers so the bolts are tight at that rest point, has to be beneficial IF the problem is present.
Agreed!
goody59
Posts: 110
Joined: Fri Apr 25, 2014 2:12 pm
Location: Wollert ((Melbourne outer northern suburb)

Re: Isuzu DMax MUX body & inner guard crack

Post by goody59 »

mydmax wrote: Wed Oct 07, 2020 8:44 pm Goody
I agree a metallurgy issue may be present too. My point is, if the chassis and body are not in passive equilibrium then they are already under stress. That means the weakest bit, the bodywork is stressed because the chassis won't give much. Loosening to find out and appropriately packing the gap with spacers so the bolts are tight at that rest point, has to be beneficial IF the problem is present.
Hi mydmax.
Well I thought I would try out what you suggested regarding forces on the body that involved a twisting of body v chassis by loosening the front two body mounts off and seeing if they were under stress. They both loosened off evenly and a uniform gap remained in between the mounts indicating to me they were not stressed or stressing the body. I repeated this with the two rear body mounts and they too showed no signs of being stressed and maintained an even gap. There was nothing from this exercise to suggest that the body was clamped down to chassis stressing the body or chassis. It appeared as one would expect and nothing showed up out of the ordinary. Thanks for suggestion. I believe it to be metallurgy related and the possibility that the battery mounting may be contributing to the problem. The crack is most common on the battery side of the engine bay I believe. I did a poll on a FB group for Dmaxes and at about 80 or so owners without inner guard issues there were 7 that had inner guard cracking but owners were not expanding on if there was known causes or how they delt with the cracks as in warranty, insurance or just attempts to repair. I would hate to expand the small poll result to the number of Isuzu inner guard cracks in owners guars across all of Australia's owners.
mydmax
Posts: 1704
Joined: Sat Oct 12, 2013 8:36 pm

Re: Isuzu DMax MUX body & inner guard crack

Post by mydmax »

Goody
Did you closely inspect the relative compression of all upper and lower rubbers while tight the bolt is tight. Any sleeve divider/tube/load bearing tube, inside which proportionately distributes load to the mounts may be pulled one way from a neutral central position and inducing a stress by having the rubber one side squashed more than the other. Of course allow for initial natural weight of body compression and go from there. Any gap may appear internally where a crush tube against a washer is positioned. ie, although factory, if too short for the situation it will pull the body down when tight. Just a theory. I used to have to set uni shafts to run by mounts being in equilibrium so uni life was good but the unit could move because of other forces. it is just a possible. My dealer wouldn't like me to go unbolting MUX and Dmax bodies to find out. They get a bit funny about it for some reason.
goody59
Posts: 110
Joined: Fri Apr 25, 2014 2:12 pm
Location: Wollert ((Melbourne outer northern suburb)

Re: Isuzu DMax MUX body & inner guard crack

Post by goody59 »

mydmax wrote: Wed Oct 14, 2020 4:38 pm Goody
Did you closely inspect the relative compression of all upper and lower rubbers while tight the bolt is tight. Any sleeve divider/tube/load bearing tube, inside which proportionately distributes load to the mounts may be pulled one way from a neutral central position and inducing a stress by having the rubber one side squashed more than the other. Of course allow for initial natural weight of body compression and go from there. Any gap may appear internally where a crush tube against a washer is positioned. ie, although factory, if too short for the situation it will pull the body down when tight. Just a theory. I used to have to set uni shafts to run by mounts being in equilibrium so uni life was good but the unit could move because of other forces. it is just a possible. My dealer wouldn't like me to go unbolting MUX and Dmax bodies to find out. They get a bit funny about it for some reason.
I didn't go into the detail you describe above and as a layman probably didn't do the exercise justice. It was just a matter of me undoing the bolts up front one at a time and getting a feel of there was any tension there of a 'twist' under stress. It was about all I was trying to observe with an untrained eye. It felt to me that there was even release of mount undoing bolt and repeated other side at front then retensioning bolt. They pulled down evenly in my untrained opinion. It was repeated at the rear mounts of my spacecab. I probably achieved nothing but thought I would give it a crack to see if there was any tension observed, again with an untrained eye and mind. You would have made different trained observations I am sure.
Oh well, so far no cracking inner guards but I am aware an I do look when bonnet is up. I do not have my second battery under bonnet. I will just keep an eye on things as best as I can.
Thanks for your input mydmax, it is informative and comming from a well qualified owner, it holds interest for me too.
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