My Downstairs Toilet won’t flush, the sink and washer will drain fine.
The Upstairs toilet works fine along with the sing and tub drain.

What I have done so far:

Plunged the toilet, no help
Took the toilet off the floor and ran a snake through the toilet from the bottom there was nothing in it.
I Ran the hose in the drain pipe and the water continuously went down.
I also put the hose down in the drain about 5 feet and the water still sat at the same level.
I Ran the hose in the toilet and the water went through enough that the toilet didn’t fill up.
The Toilet will flush sitting on a bucket in the garage.
The toilet will flush if you loosen the bolts and tip the toilet sideways letting air in.

I only have one roof vent so I am assuming that the upstairs and downstairs toilets are both on the same vent. Even though the upstairs toilet flushes fine I went on the roof with a hose. The hose went down 15 feet before stopping (15 ft is from my eves to the ground in my raised ranch). I ran the hose for over ten minutes and the water never showed any sign of building up, it just kept going down.

I need to add that I had this same problem over a year ago, I replaced the toilet with this new one and now the same thing is happening. I already cleaned out the tiny holes under the rim and the spout on the bottom has pressure. Besides the fact that the toilet will flush when you pull the toilet up to let air in the system.

Tell us about that. Does that you ran the hose down the toilet drain?

I pulled my garden hose into the house and pushed the hose down in the drain with the toilet off about 5 feet of the hose and then turned the water on. I ran the water for over 5 minutes that way and the water level never came up any higher than normal (down a couple feet at the elbow looks like)

It's possible that the sink drain and vent could act as a WET VENT for the toilet. In this case, If the sink drain or sink vent were clogged it could cause the issue mentioned. Check the sink drain and vent... may need to cut into the pipe and snake up and down.

Mark

That's what I thought you meant.

There should not be any standing water in the toilet drain pipe. You have a blockage of some type. Snake the line. Apparently the blockage is such that is will block the flow until the water level in the pipe reaches a certain level. Then the weight of the water in the pipe will push water through the blockage.

Remove the toilet and snake the line. Blockage should not be very far away. Sink and washer probably ties into main stack, not into the toilet drain. Blockage is probably in the horizontal line between the toilet and the main stack.

Since you have had this problem for a year or more, whatever is blocking line is probably something solid, that is, it does not deteriorate in water over time.

This could be possible even if the sink right next to it drains fine?

Sporty,
Try removing the lavatory trap and then flush the toilet...