Hello
During a resent toilet replacement I had to go with a twist n set cast iron replacement Oatey flange due to the old flange on a 4" case iron pipe breaking. it brought by 4" line down to 3"At the best of times my the toilet flushes like on a airplane but the odd time my flushing action is slow or the toilet will not flush totally . The toilet is a 6.5 litre Amerian Standard Aquaforce system .
I thing my problem is sometimes the force of the flush is prevent by the new 3" line (flange ) that kills the vent action in the pipe?
Is there a flange repair kit the would fit over the outside 4" pipe that is easy to install

I don't think your Oatey is causing this problem, if it did I'd be a rich man. You may have a partially blocked vent stach that can be rodded from the roof. Rent a sewer rodder and use enough snake to reach roof top to basement floor plus 20' more. Keep the Oatey. There are flange reapir kits for broken cast flanges but you are past that point now. Just a thought but who installed the toilet?

Thanks for your reply - I was thinking as to what you are saying is the problem could be with my main vent - I installed the toilet and all went well during such - my down stairs toilet is flushing find on the same drain vent line
Its funny as I stated sometimes it works great and all of a sudden it acts up

You can find strange stuff in a vent stack. I have found plastic bags and even lids from a soup can plus an occasional dead bird, leaves, twigs and tons of rust flakes. All this stuff can cause clogs, some intermittent.

Is there some type of liquid drain (vent ) opener I can pour down my vent

I know some folks will get on the roof and run a garden hose down the vent for several minutes and they swear it works. I'd go with two 5 gallon buckets of really hot water and a big funnel. However that would do little if it's a critter.

Vexation...

If this problem occurs occasionally... could also be that the wax gasket that you used to set the toilet has squeezed out in such a manner that it is JUST partially blocking the waste line. Here, toilet flush would not necessarily be issue every time, but on occasion water would swirl around and go down slowly.

Investigate the vent as Bob is suggesting. If that doesn't improve things I think you should lift the toilet and check the wax gasket to see if it has managed to block the drain pipe a bit! Use new wax gasket and bolts to reset the toilet!


Good luck...

MARK

Well
I have completed my toilet check list
With no success
I am told that 6litre toilets are new and do not perform well
So if this is the case there is no water savings and all you have is a problem toilet by design
Warning stay away from 6litre toilets at these of now
I wish I knew before I purchanced one

Vexation... just curious here. Did you lift the toilet and check the wax gasket?

Let me know... ok?

MARK

Hello mark
I have checked the wax gasket
All is OK
??

1.6 litre flush toilets are fine nowadays... most of the kinks have been worked out by now as they are at least 10 year-old design.

All american -standard toilets Iinstall work pretty darn good.. So just has me wondering if something could be caught down the drain line or if you ended up with a bad toilet somehow?

Anyway, sorry no answer for you.

Let us know if you think we can help in future...

MARK

So if its not the toilet we could go back to that vent stack for another peek.