Knocking Rear Spoiler

I have had a slight intermittent knock from the rear of my Prius for a while now, but yesterday I took the car out for the first time in ages and it has gotten worse.

Initially I always thought it was the retractable rear roller, but yesterday it would make the noise when I closed a rear door. From that I have traced it to the rear spoiler, if I lift it a little and let go it knocks from what it seems, to be on to the edge of the small vertical rear window on the tailgate.

I took off all the rear trim expecting one of the bolts holding the spoiler on to be loose, but they are all fully tight. It may be some flex in the underside of it.

Has anyone taken off the spoiler or would know if its a simple as undoing 5 nuts or is there more to it?

I am still within the 5 year warranty, but not sure if this would be covered, I don't think they could say its trim as the spoiler is part of the car.

Any advise appreciated.

 

Kind of... I took all the trim off the inside of the tailgate and checked the fixings and they were all nice and tight. Also checked the wiper motor cables etc. and everything seem tight. I managed to wedge a strip of dense foam between the underside of the spoiler and the vertical glass and it stopped the knocking..... but I still have the noise that I can hear in the car, so I think that must have been a red herring.

It is so difficult to locate. I have sat in the back of the car with my partner driving and I just can't seem to locate where it is coming from, although it does seem to be coming from the passenger side area (UK here, so Driver's side if in US) and mainly when it's cold and when the car goes over certain kind of bumps.

If I didn't love the car so much it would really get to me, so I'm not going to lose sleep over it. I may get my dealer to look at it when I take it in for its service in March.

 

I tried lightning the bolts, but they were very tight and the sound does seem to be coming from within the cabin.

 

No, mine is not persistent. I usually only every hear it going around town and just when the car hits a certain kind of bump in the road.

The only time I would hear it on the highway was if again it hit a certain kind of bump. Around town it seems to be not when the car drops into a bump, but when it is coming out. I initially thought it was the loose rear shocker mountings that some people have had fixed, but mine are rock solid.

Once the temperature warms up, the problem is goes away.

 

It definitely sounds like its in the cabin, but no amount of jumping in the car and getting it to bounce as if it's going over bumps can get the noise to start.

 

I do not have a fancy license plate frame. Like most cars in the UK it's simply stuck directly to the car with double sided tape.

I will get there one day...

 

UPDATE:
I have found the culprit and I don't know why I did think of it before.
It turned out to be the tailgate catch and I cured it by simply wrapping a small length of electrical insulation tape around the loop that the catch engages with and voila the noise is gone.
I cannot believe how different the car feels without hearing the clicking and I didn't realise how much it was doing it until it wasn't there anymore

 

Just as you open the tailgate, I guess you may call it the slam panel?

 

yes I think I did 2 turns, anymore and the catch won’t unlatch cleanly. If you do too much just try a bit less.