Power Steering Bracket Bolt Broke off - 3rd time unlucky

[gomulletgo]

Gidday all,

Quick post before I go out to try and fix my truck (Isuzu Bighorn UBS55)

My Road going bighorn has just had it's power steer / air con belts go loose, then a while later the steering got very heavy at low revs, on closer inspection the power steering pump is really loose and appears to have broken the mounting bolt that holds the power steering bracket to the engine block.

Now this is the 3rd time I've seen this fault on the 2.8ltr 4JB1-T The first couple of times the vehicles arrived to me in that state, with the power steering loose/tied up. I thought someone must of got over enthusiastic and tightened them till breaking point.

So it's pretty obvious this is a factory fault with this model, it must have happened to some of you other guys, how did you solve it? Is there any way to avoid it happening again? Higher Tensile Bolt? What are the specs on the bolt? Thread? Length etc. ?

Thanks in advance

Edit: In my experience this fault requires removal of the radiator etc. and drilling/ EZ outing of the broken off bolt in the engine block.

[geeves]

thats now a grand total of three of these all in CHCH. Must be winter frost cracking the metal
Seriously Ive not heard of it elsewhere. Only thoughts are the rear bolt not tightened on the pump or the belts too tight. Im not sure what the standard bolt is but would expect it to have a 7 on the top of it which is roughly the same as 8.8. They are big bolts for the stress they are under.

[isuzurob]

i got a bighorn from chch aswell arrived with both the bolts broken, i have never seen it before and never had issues, normally leaving them loose makes them break

[geeves]

Only see one common factor in these 4 examples. location

[gomulletgo]

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My Road going bighorn I purchased from Nelson but it's been down here a while.

2 Local mechanics, one had never seen this issue before, another had seen it at least twice before.

For now I'll try and replace with brand new bolts from Blacks Fasteners, I considered high tensile but they may be worse? Also they may be harder to drill if they do break. The middle bolt most likely won't be replaceable as it's a threaded shaft with attached nut that gets wound through a water fitting into the block then the power steering pump slips onto more of the exposed threaded shaft then a nut tightens the power steering pump on. I expect it'd not be available from Blacks Fasteners.

[geeves]

Ive never touched those 2 bolts only ever using the other 2 for adjustment and replacement. If the other 2 were loose which could happen as the adjuster would keep the belt tight a huge strain is put on the 2 you broke due to extra leverage. I see they are marked 7. This is roughly equal to grade8.8 or class5 high tensile. For the stud you should be able to buy one but if not either threasded high tensile rod or cut the head of a bolt. Its a good idea to run a nut over the thread before installing

[gomulletgo]

Hey guys,

Just a quick update, this just happened again to my parents who just drove my road going UBS55 to CHCH. They've used bungy cords to try to give some tension to get it home. So yeh, this is the 4th time total and the 2nd time for this vehicle, just a couple of years since the last breakage, brand new bolts last time. I'll be checking against my 4JG2 to see if the bracket was improved in later models, if it wasn't I'll be looking at how I can improve it myself. It's a poor design 3 bolts in line with no bracing in any other plane. Perhaps the bracket worked better in earlier non-aircon models?

[geeves]

Still only your car 3 times plus the one rob bought from the same area with this problem. I have to wonder if they were all touched by the same mechanic

[gomulletgo]

I've got:
1x UBS55 Purchased Leithfield area - PS bracket bolts broken when I purchased
1x UBS55 Purchased Birdlings Flat area - PS bracket bolts broken when I purchased
1x UBS55 Purchased Nelson area - PS bracket bolts broken twice since I've owned it

The chances of all of these vehicles being worked on by the same mechanic are very slim. Lets not forget our local mechanic who had seen this twice before.

Quickly comparing a 4JG2 & 4JB1 engine this afternoon it looks like the later model 4JG2 does have an improvement in the bracket where it has another tab which mounts to another location which means the mount is more sturdily mounted and braced in another plane, I'll try and take some photos and supply bolt and threaded rod measurements for anyone who has the same issue.