Was standing in the driveway when someone was leaving in the Prius -- All of a sudden three or four thumps -- I guess when the ICE started -- sounded just like a slapping belt ... but no belts correct? ...... this was loud. Any ideas? We shut it off and restarted -- AC on and off ...... nothing ......... car ran fine on a trip of about 200 miles -- never another sound? I'm going to start it this evening -- it has been sitting since Friday evening -- not sure what to look for. This did not sound like any kind of valve noise -- nothing squealing.
That's surprising. It usually happens for most people in cold weather. What was the outside temperature?
That does not seem to be the case... people have had it happen in all kinds of temps. I suspect high humidity conditions.
It has been very hot - not overly humid -- car was sitting since the day before ........this start was about 1pm in the afternoon. I certainly have spotted posts regarding the knock problem -- This is a late 2011 -- I believe it was a November build ......... I thought they fixed the problem earlier. If this is what it is I understand why people get concerned.
I'm not sure what it was -- but I've never heard a notice like that on other cars with those systems. It is now due for the 10k service -- So I will mention it ... I'm hoping it will do it again.
The only time I got knocking is when the outside temp was at or below freezing. Of course, Colorado is much lower humidity than other parts of the country.
