Water spurts out top of cistern when flushing

[Ian_S]

Hi,
I've just installed a Grohe concealed cistern. All seems good, however, when I flush the toilet a bit of water spurts out the top of what I believe is the flush valve mechanism. I've attach a photo of the part in question:



This only occurs when I press the flush button, if I reach in and manually lift up the valve with my hand this doesn't happen.

Any ideas why this is happening? Is there something I need to adjust?

 

[Ian_S]

Also, bonus point if anyone can tell me what this part is for:

 

[oldbuffer]

1. Some valves do just spurt when flushed. Provided it doesn't come out of the cistern, not a problem.
2. The parts illustrated secure the flush pipe to the cistern.

 

[Ian_S]

Thanks for the response.

1. The water shoots about 1-2 feet in the air. I can put the plastic blanking plate back over the hole on the top, but a few drops still manage to get out through as its not a water tight cover.

2. The flush pipe is already secured to the cistern, and there is no thread where the flush pipe meets the cistern to screw this part onto.