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Guest cleo

Model: 2002 Toyota Corolla

Recent work done: 2 weeks ago serpentine belt was replaced (Note, there were no problems with it or engine, the belt was just worn and needed replacing. This was done by an auto shop mechanic, not the car owner. Also note that the mechanic apparently had a difficult time tightening the belt).

Problem now (2 weeks later): Noticed the pivot bolt (holding the bracket on the serpentine belt tensioner) sheared off/broke off inside the engine block. (Note, we were just taking a look under the hood, out of curiosity, and were looking over the serpentine belt when we noticed the broken bolt.)

Questions:

1. What could have caused the pivot bolt that holds the bracket on the serpentine belt tensioner to shear off/break off inside the engine block?

2. How often do these steel pivot bolts in this location, fail on their own?

3. What is the likelihood, that this bolt failure was caused by an action that the mechanic who replaced the serpentine belt 2 weeks ago did (ie tightened the bolt too much, sheared it, etc)?

4. How would one repair this? I assume the engine needs to be pulled and the bolt will need to be drilled/tapped out? How difficult is this? What are the chances that the engine block could be damaged by attempting this?

5. Approximately how much would be reasonable for this repair to cost?

How often does a machine/auto shop mechanic typically deal with this problem? (ie is this a common problem for them to deal with?)

6. NOTE: The original mechanic, who replaced the serpentine belt 2 weeks ago, is denying that it was his fault in any way (Note: We've been using this mechanic for about 8 years and have trusted him and his work)?

Based on the timing of this bolt breaking -- it only seems logical that the TIMING of the replacement of the serpentine belt and the ACTIONS of the mechanic in doing this, are in some way, responsible for this bolt's breaking? The bolt was not broken at the time that they replaced the belt. Otherwise they would have noticed it in some way, correct?

(The only thing the mechanic said/suggested (since he wouldn't admit any fault or possible fault) was that we should look online to see if Toyota recalled pivot bolts on 2002 Corollas. He seems to think the steel bolt failed naturally. He didn't refer us to another shop that could give us a deal on removing the bolt, since they don't have the machinery/drills necessary.)

7. Any advice would be greatly appreciated. THANKS!

Which pivot bolt are you talking about - there is the main pivot point and there is a large pseudo bolt that very close by that looks like a pivot point. That pseudo nut is actually cast onto the tensioner arm. If the actual pivot point was sheared off - then the serpentine belt would be completely loose, i.e., it has fallen off the pulleys, the belt tensioner is detached from the engine.

If this was the case, then I can say with 99% certainty, this was likely from action from the mechanic. I cannot say with 100% certainty, as there is always a chance that this could have been a mechanical failure of the metal pivot point, but highly unlikely, as this is not a known issue on this generation of Corolla. The fact that the mechanic tried to push this off to a possible recall on the pivot bolt makes it more likely that he damaged it during the belt service.

Not sure why or how he ran into an issue with "tightening" the serpentine belt - as it is self-adjusting - if the mechanic tried to tighten "anything", he did something wrong.

You just relieve tension on the belt by acting on the "pseudo" nut on the belt tensioner arm by the pivot point with a long wrench. Slip the belt off, then slowly release tension on the belt tensioner. Slip new belt onto the pulleys, leaving the section by the alternator off, pull back the tensioner arm as before, slip the remaining belt on the last pulley, slowly release tension on the tensioner - your done. 10 to 15 minute job tops for a shop - typical owner, even with little to no experience could get this done in 30-60 minutes with help with a friend.

Depending on how deep the bolt that go sheared off is inside the block - might be able to use a bolt extractor without disassembling the engine. Depending on the damage, costs can be highly variable. From around a $100 to several hundreds+ dollars, if the engine needs to be pulled for machine work.

Now the case of the belt is still on the pulleys, tensioner is still on the engine - then you are perfectly fine. If you are not sure, it is possible you can post a picture of what you think is the broken pivot point. Here is a link to change the belt yourself, http://www.2carpros.com/questions/toyota-corolla-2005-toyota-corolla-drive-belt--2 - for a 2005 Corolla, but the process would be identical to the 2002 Corolla.

Here is another pic of the serpentine belt tensioner, also from a 9th gen Corolla, but would be the same for your 8th gen Corolla

So I realize this is from 2 years ago, but I have a related problem and the above diagram is quite useful to explain.

So in replacing the tensioner and belt on my 2005 corolla, on the very last step, the tensioner nut (green above) rounded over and now I can't compress the shock with a wrench. Thus I'm not quite sure how (or if) I can get the belt on. I realize this is probably my own fault. But, I'd love any ideas for making this work with out replacing the entire tensioner assembly (again). It seemed like I could push on the tensioner pulley and get a little movement. Perhaps and extra set of hands could then slip the belt on??? Some other way to compress the shock???

Thanks!

You could try a large pair of Vise-Grip pliers on what's left of the tensioner nut.

thanks, good idea, I'll give it a try

Just in case anyone in the future ever needs to know...vise grips aren't a great option. Had to remove and replace.

im no expert on this,done it once. remember the step of removeing the motor mount bolts on that side of engine to raise the engine high enough to get the long pivot bolt that goes into the block to back out and reinstall? Possible, theres clearence to drill out just 'undersized' the broke pivot bolt in the block and tapping/chaceing threads back to original size? Assumeing thats the situation. If this is the situation i wonder if engine clearence was high enough to r/r said bolt back into block correctly. Could be the mechanic use'a bigger hammer'method and bolt was somehow over stresed to eventual failure. Hope im wrong and it work out for you.

As far as the rounded off tensioning pseudo bolt goes. Maybe you can reinvent the lever...with a long piece of iron'breaker bar of some type' that can "hold" at the correct pivot points to compress the tensior shock the entire belt tensioner assembly could be r/r or the belt. 2 man job. Im shooting from the hip, im not quit shure what your situation is.

This happened to me in the middle of the road and almost got me into an accident. I had to drill a hole and use an extractor to screw it out. Here are the steps for anyone's interested.



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