Oh no

[BanjoPato]

Quick update,apparently the idler pulley bolt has sheared takeing everything with it.
The 2.5 diesel is non interference so hopefully if new parts arrive tomorrow & there damage we will be good to go.
I'm told the bolt is 10mm high tensile steel?????

[old Jack]

10mm HT bolts just do not randomly shear, some significant event has happen to shear the bolt off. I would asking for a more detailed explanation, the truth is a good place to start.

OJ.

[BanjoPato]

10mm HT bolts just do not randomly shear, some significant event has happen to shear the bolt off. I would asking for a more detailed explanation, the truth is a good place to start.

OJ.

Not doubting that something major happened,but short of calling him a liar I have option but to wait.

[old Jack]

Not doubting that something major happened,but short of calling him a liar I have option but to wait.

You can ask him how a 10mm HT bolt shears without calling him a liar. It is your car and you are entitled to an explanation that satisfies you. A good mechanic should be able to at least give a plausible theory. My point is bolts do not just shear and what guarantee do you have it will not happen again?

OJ.

[BanjoPato]

You can ask him how a 10mm HT bolt shears without calling him a liar. It is your car and you are entitled to an explanation that satisfies you. A good mechanic should be able to at least give a plausible theory. My point is bolts do not just shear and what guarantee do you have it will not happen again?

OJ.

Mate I did ask and he said I don't know,not being an expert like yourself I'm not sure what a plausible theory is. No doubt you would know, so let me know and I can give him your name.

[old Jack]

Mate I did ask and he said I don't know,not being an expert like yourself I'm not sure what a plausible theory is. No doubt you would know, so let me know and I can give him your name.

Don, a M10 HT bolt has a minimum breaking load of about 3,000kgs in shear and I would expect the belt to break long before an idler pulley bolt, so you can hopefully see why the questions. Surely you will want some assurances that the same won't happen again in another 68,000 kms when your Challenger will be out of warranty.

There are 2 idler pulleys fitted so are they also going to replace the other idler pulley bolt?
If 1 has failed then the other could also be fatigued (or incorrect part, incorrect assembly torque, bad batch of bolts, any number of reasons) and could be a ticking time bomb just waiting to let go.
Without seeing the broken bolt and the idler pulley I can not give an opinion on possible causes of the actual failure and even then it may not be that obvious.

OJ.

[BMN]

Mate I did ask and he said I don't know,not being an expert like yourself I'm not sure what a plausible theory is. No doubt you would know, so let me know and I can give him your name.

Don, if your able to drop through the dealer, and for your own piece of mind ask if they can save the damaged parts and run through them with you. My theory is the bolt was over tightened or damaged from day one and its finally called it quits. Otherwise as OJ is hinting at, something else has really gone wrong to cause the bolt to sheer, which if unexplained could occur again. Cant even really see how a broken belt could cause the bolt failure.
If it is just the bolt failure and as long as the bolt hole was not damaged by the failure or the dealers removing whats left of the sheered bolt, it should all be good, and just put it down to bad luck.

[Kingbrown]

Sheared ? . . . . or stripped threads I wonder.
Only about 40Nm supposed to be on the idler bolts and they may have been over-tightened.
Intetested to hear more about this failure.

[BanjoPato]

I'm yet to see the bits but it appears it won't be as simple as we hoped.
Apparently the car will run but is very rough,damaged valves suspected. Head off tomorrow.

[old Jack]

I'm yet to see the bits but it appears it won't be as simple as we hoped.
Apparently the car will run but is very rough,damaged valves suspected. Head off tomorrow.

Hi Don,

Sorry it hear it is all turning to custard on you, at least it will be fixed under warranty.
If there is valve damage, which would surprise me as I thought that these engines where a non-interference design, then even more reason to insist that both idler pulley bolts are replaced and the idler pulley's are carefully checked.
Running rough could mean the timing is out on either the timing belt or the balance belt, one assumes they have already double checked this.

OJ.

[bige]

not good
on these motors if the belt breaks the valve's that are open hit the piston
witch in turn break the rockers, pushes the cam up and snaps the cam caps
cam caps not sold seperate, requires a new head

[old Jack]

I have been doing some research on whether the engine is an interference or non-interference design.
I am not 100% sure as it seems the earlier non CRD 4D56 engines were interference and normally just snapped rockers when the timing belt failed but there are a few reports of bent valves and damaged pistons. On the CRD version reports I have read are it is a non-interferance engine and no damage is done to the engine when the belt fails. When my brothers 2011 Triton snap a timing belt after the balance shaft belt failed there was no damage to the engine valve train or pistons so the belts were just replaced so this is why I am thinking it is a non-interference engine.

Can anyone say for sure?

OJ.

[littleriver]

I have been doing some research on whether the engine is an interference or non-interference design.
I am not 100% sure as it seems the earlier non CRD 4D56 engines were interference and normally just snapped rockers when the timing belt failed but there are a few reports of bent valves and damaged pistons. On the CRD version reports I have read are it is a non-interferance engine and no damage is done to the engine when the belt fails. When my brothers 2011 Triton snap a timing belt after the balance shaft belt failed there was no damage to the engine valve train or pistons so the belts were just replaced so this is why I am thinking it is a non-interference engine.

Can anyone say for sure?

OJ.

okays just had conformation from Mitsi Tech via email - "Interferance engine for Mitsubishi PB/PC Challenger "



...

[BanjoPato]

Considering the parts I'm waiting on are exhaust valves (2) & rockers (5) I'm guessing your right.
So glad my misfortune has been informative.

[old Jack]

Hi Don,

At least the repair is under warranty but the damage to the engine upon belt failure is a worry to all of us since the belt failed at 2/3's scheduled life. This is why getting to the bottom of the real cause of the failure is important.
From my research MM had an 80,000km timing belt replacement on the earlier engines as they had higher compression ratios but one assumes the modern belts are stronger and with a lower compression ratio they\ belts are meant to have a longer life. As I stated in an earlier post, when researching failures I was seeing reports of no engine damage right through to significant engine damage hence the confusion about the engine design. LR has had MM confirm it is an interference design engine .
It appears if the belt fails at idle/low speeds then sometimes it is just belt replacement but if the belt fails at high rpm and/or high road speeds the engine damage will occur.

OJ.