Timing belt skipped after two months replacement on 1999 Toyota RAV4

I have sourced following OEM parts from bestbuyaustralia.com at $150 Model :3SFE Timing belt TB138 Timing belt tensioner bearing 1350574011A Timing belt Idler roller bearing 1350363011A Front crankshaft seal 9008031022 Front camshaft seal 9031138046A Water pump & gaskets I had professional mobile mechanic fitted these parts at a cost of $450 after 2 months the car would not start. My wife called NRMA thinking it would be soothing simple. They put it down to Timing Belt. Called the mobile mechanic back and asked him to check it out. Sure enough timing belt was of the mark by 3 or 4 teeth. The issue I have is that the mechanic is blaming the belt as he has done everything by the book and the supplier is saying it’s possible that the mechanic did not have enough tension on the tensioner. Could anyone advise if it could be the belt? I did read somewhere that timing belts do not stretch. Thank you

by in Zoar, OH on August 28, 2009
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2 answers 2 comments
ANSWER by , August 28, 2009
Agree with Bret. Luckily these engines are non interference type (no damage occurs if belt breaks), insufficient tension is most likely the cause, it is a spring loaded tension that sets tension when the slackness is on the slack side of the belt it is then locked in place, the engine turned over by hand several times to recheck timing belt alignment and tension before reinstalling belt covers.
COMMENT by , August 28, 2009
Autotechpat & bretb thank you guys for your feed back, the teeth did not break off but they do have some marking where it must of rubbed on something closest to it would be the spring bracket close to the tensioner. The mechanic wants me to exercise the manufactures warranty as he knows I have bought the Kit from online. He did mention who is going to pay for it. The car was working ok prior changing the kit although it was due for a change, ticking noise and mileage. Should the mechanic re-align the existing 2 months old belt or should I purchase another one? So far it has cost me $600 and the car is still off the road. How could I tell the mechanic it is his fault when I’m not qualified to make such a judgement or should I get another mechanic involved for confirmation? What do you think? Thanks
COMMENT by , September 19, 2010
I have KIA sportage 2002 Is my suv engine is come with non interference type (no damage occurs if belt breaks) my belt in not borken just slips off the pully please advice Best Regards to you
ANSWER by , August 28, 2009
It is very unlikely that the belt was a problem. It would have to stretch or have the teeth break off, both of which would be easily proven by inspecting the belt and comparing it to a new belt. I would agree with the supplier that the tension was likely not set correctly. Was any damage done when the belt skipped? Is the mechanic going to reset the timing for you? Is he trying to charge you for the repairs?