Timing belt broke at 3,000 miles. Why?

The only thing I can see that would destroy a new timing belt like that in a short period of time is, if the timing belt guide plate was installed backwards.

This guide plate insures the timing belt stays on crankshaft sprocket and off the timing cover. And as you can see by it’s shape, if it’s installed backwards it’ll shred the belt.



the following is offered to the OP in case it is helpful:

  1. have you checked your state’s laws regarding warranties for work? there might be an implied or required warranty regardless of what the receipt says

  2. have you used this shop in the past? maybe semi-regularly? any indication of warranties in past work?

  3. to possibly show no actual work by the shop, what other parts were changed along with the timing belt by the shop? were OEM parts used?
    if this is the first timing belt change, and non-OEM parts were used, that should be evident by looking at those parts (if they are still OEM, then they clearly were not replaced)

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@tester that sounds promising! Could this be something that happened suddenly after the car running smoothly for 2 months? Is this something Honda would have noticed? I had them hold onto my old engine incase anyone wants to check it again.

Update: just found this article https://www.gatestechzone.com/en/news/2016-06-subaru-spacer-tool and it seems like the direction of the plate could be an issue or the distance between the belt and guide plate could cause this! Perhaps they didn’t use the spacer that they should have? Still not 100% I have a guide plate, 2012 Honda Pilot. Emailed the dealership to see if they could double check the guide plate since they had not mentioned it. Would they be able to measure it it was the right distance?

@Waterbuff yes Honda did say that the water pump appeared to be new. I actually have it in a box in my car right now as the shop asked for it in order to pursue the warranty (I am glad they agreed to do that but I have read if that works the parts manufacturer would likely only cover the cost of the part and not my $5050 engine). I should probably take pictures of everything before i hand it over to the shop.
Looking into state regulations is a great idea! Thank you! I have called the consumer protection agency that is associated with the attorney generals office a few times and hey haven’t volunteers any info about this but maybe they don’t know, I will look!

I looked at my usual sources and found no mention of that guide @Tester but like you it came to mind when considering the description of the belt failure. Other than a loose screw or bolt or as mentioned already a tool left behind nothing else comes to mind.

And the receipt seems to go into great detail to protect the shop from responsibility or even scrutiny from subsequent investigation by another shop while failing to state any specific responsibility for themselves… Awfully convenient dontchaknow.

The odds of a faulty timing belt is just about as close to zero as it can get in my opinion.

The odds of a timing belt for whatever reason “turning to dust” is less than zero.

The comments about bad gas, spark plug, etc are all bunk. Throwing the belt in the trash considering what has happened makes them look extremely guilty as it makes it seem like they’re destroying evidence so the T-belt manufacturer will be unable to point the finger if it comes to this. Bad move on their part.

Lastly, you do NOT need a new engine because the belt broke. Water under the bridge I guess… The cylinder head is simply removed, bent valves replaced as necessary, and any nicks in the piston tops smoothed out and then reassembled. Sorry I can’t be of more help and best of luck.


I couldn’t tell you how long a timing belt would last if the guide plate were installed backwards.

That’s because I’ve never installed a guide plate backwards when replacing a timing belt.


@Rod_Knox I know. Again it seems suspecious. I have probably 3 other mechanics receipts here and not one of them has a clause that they will not fix something someone else fixes. This seems like an easy way to do faulty work, say it’s not your fault and then either leave the customer with no options but to have no car while they pursue it in court. That seems insane to me.
Could timing belt cover bolts or the engine mount bolt have caused this issue? Those were removed when they sent it to Honda. Also, they did have this car all weekend without telling me abou the issue so they would have had plenty of time to fix anything they might have messed up, including maybe even putting a new water pump in if they wanted to?!

Also update to everyone apparently I can’t comment again for 18 hrs because I am a new user!! But thank you everyone and I will still be reading your responses! Pretty sure I can still update comments I have already made!

@Tester it’s 2012 Honda Pilot

I don’t see where the OP mentions the year/model of this Honda.

But every Honda I replaced the timing belt on had this guide plate.


Cover bolts and engine mount bolts are not the problem. Tester provided the likely cause.

You can see the guide plate on this Pilot crankshaft.


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Well it had seemed to me that every timing belt that I ever installed went behind a guide on the crank pulley @Tester. But I never found an exploded view of the 3.5L engine in my quick look. And improperly installing one would eventually destroy the belt.

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My Corolla has a similar guide for its timing belt, located in the area of the crank pulley, and if it was installed backwards I think this symptom could occur. It would be pretty easy to tell (for an experienced mechanic) if that happened just by looking at it before taking anything apart. So an installer’s error of some kind is probably the most likely reason. The tensioner is another major suspect. Many shops routinely install a new tensioner when they do a timing belt job. Did they install a new tensioner on your job? If there’s anything on the timing belt that locks up, that could also break the belt. On some cars the water pump is driven by the timing belt, so if the water pump locked up that could conceivably break the belt. It appears the water pump is on the timing belt loop for a 2012 Pilot, so that’s another suspect, a problematic water pump. The last likely possibility is the belt used was defective or had already reached its time expiration date. The belt has a time limit as well as a miles limit, and if that particular belt had been sitting on the shelve for 7 years already before being installed, this sort of thing might happen. Many folks here suggest that Gates timing belts are pretty good. What brand of belt did they use?

Replacing a timing belt on this engine is a pretty complicated job, spec’d at around 4 hours. If the water pump and both seals were also replaced (a common thing) it would run over 5 hours. Did they bill for that amount of time? Did they test the tensioner using a hydraulic press?


I’m about 102% certain this is all operator error.


Ironically and sadly enough . . . that is THE reason why the shop won’t own up to their mistakes

They’re incorrectly thinking it’s best to wash their hands of this mess . . . rather than make things right

But as a customer, I pay attention not only to how well a business performs its duties, but also to how they handle their mistakes

I don’t know about the rest of you guys, but I actually read reviews and write a few of my own

I’m brutally honest . . . if a business messed up, I’ll mention it. But if they went out of their way to make things right, I’ll also mention that.


Hey, what’s the “injection pump” listed in the cutaway?

The fact that weasel got rid of the evidence, yelled at you, and made that snarky threat about you know who I am tells me he’s guilty as hxxx of covering up a screw-up at the least

Know who I am? What does that mean? He has a buddy in the Govenor’s office or what. If it were me I would not let 5 grand go. AG’s office and maybe a small claims suit. I think the guy will not look good to the court.

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The more I think about and research this timing belt plate the more it seems like that is probably the cause. Other than the plate being backwards, I have read two articles now about how the spacing of the timing belt to the plate is critical and they supply a specific spacer just to make sure it is spaced correctly BECAUSE even is the spacing is slightly off t can create heat and cause premature failure!!! It seems like this would be super easy to mess up if they forgot to use the spacer or used another another method and something was off (read people use matchbooks and just random other tools as spacers to get the right spacing) Honda took out the water pump, tentioner and one other thing because the original shop needed it for the warranty. Does this mean that they now won’t be able to confirm or deny the spacing or direction of the plate? This is so frustrating!!!

I can supply photos of the things I have in the to go back for the warranty if anyone is interested

If the plate was removed to diagnose why the timing belt failed, then it can’t be determined if that caused the failure.


@Tester oh so the original shop probably took it off when they had it to look at the issue? Well I want to see this thing. I wouldn’t be surprised if the original shop just didn’t put it on at all as far as I’m concerned. Read a question online of some guy asking if he had to put it back on because he forgot and it was on his kitchen counter. I want to make sure someone has seen it recently. Anyway now I am extra fired up. Thanks for all info @Tester and everyone! I feel like I am at least on the right track
Oh I had one other question: I have heard two extremely different things from two different shops and I just want someone to tell me very clearly which thing is true
Option 1: the could NOT have been ANY internal failure before the timing belt broke because that would have been evident in the other parts they checkd: “camshaft pullies, water pump pulley, idler pulley, tensioner pulley, crank shaft pulley”. Hence we can DEFINETLY SAY that the cause of this issue was not due to an unknown internal failure
Option 2: the only way to definetly say it was not an internal failure is to have the entire engine torn apart and examined. (How in the world would they be able to tell what parts failed before or after the timing belt failure??)
Thank you