Hello,
2012 Civic Base

Quick summary:
Tensioner bolt keeps breaking. 4 times within 4 months. Anyone have an idea why?

Full summary:
The original tensioner bolt broke at around 198,00 miles. (Great run). My neighbor being a hobby mechanic said he could help me replace it. We replaced the serpentine belt, one of the pulleys (think it was the water pump pulley), the tensioner, and of course the bolt. Now, at the time, I could not find the bolt at the local stores, so I ordered one from Amazon.
This bolt broke the very next day. Thinking it was just a cheap bolt, this time I picked one up from the dealer and replaced everything again. Had to replace the tensioner again as one of the pulleys dug into it and also replaced the pulley for the water pump.
This time the vehicle ran fine for about 3 months until it broke again. I was thinking it broke because my neighbor did not use a torque wrench and in my opinion, over tightened it.
This time I took the car to a mechanic shop.
He replaced everything again including the bolt from the dealer with another from the dealer. He did use a torque wrench. This would be the 4th repair.
Of course, it broke again within 3 days or so.
Any one have a clue why this would be happening?

Thanks in advance for your advice and assistance.

Joel

 

I noticed you mentioned the water pump pulley being replaced. Usually, the water pump pulley wouldn't go bad. If they thought it was related to that pulley, I would suspect an issue with the water pump seizing. An issue with the water pump ,may be the culprit.

 

The water pump pulley was replaced because it had burn marks from the belt. The original belt broke. Both mechanics looked at the water pump and they said it was good. It did spin freely, I checked that myself.

 

my suggestion, would be along the same lines. it appears that something is slowing down the belt, causing the burn marks. my suggestion is to use a timing light of sorts. (should not be a timing belt light... just a strobe). mark all the pulley's with a visible mark. and run the motor. you should visibly see the slower pully's mark visibly retard (at least at a different rate/or pattern since the light and the mark may not be timed correctly, but should still exhibit a pattern that doesn't move... this is just a guess tho as some physicists would probably tell me why that won't work ). to me, that would be a step in to finding what is your culprit. if its not anything there. verify your tensioner pulley is properly tensioned. and not creating too much force which would also cause the belt to be harder to turn and cause burns.

But, Thinking about deeper, Since you changed everything at least 3 times already. I would suggest changing out your water pump. as it seems its one of the only parts on the belt line that you haven't changed. and as the burns are actually on the water pump pulley, it was probably the issue. like there was something in your water system that gets the water pump stuck. causing the burn.

(also probably why it works until it doesn't... the thermostat hasn't opened fully to allow the water to travel through the system and get that object re-stuck.)

this is just to help you, with suggestions to help. I have never really experienced this issue myself.

 

This is the Honda Factory tensioner bolt from my 2007 Honda Civic. Does your bolt look like this one?