"...this is not a permanent blockage - it comes and goes."

I had one like that about a year ago, had it apart twice trying to find the problem, no luck. On the third go, I managed to get a piece of twine threaded completely through the trapway and pulled a piece of rag through. Out came a cheap BIC pen that hec been lodged in there, not thick enough to block completely but just big enough to create repeated minor blockages...well, I'm sure you get the idea.
And the snake just went right past it.

Someone suggested in a case like this...when it isn't working well, try flushing it by dumping a pail of water in the toilet. If it flushes okay, you know you're not plugged up. If you're not plugged up, that means it's a problem with your toilet not getting enough water from the tank to cause a flush.
You would then have to trouble shoot that problem.

You know, airqual, that's EXACTLY like how this reads, and a pen would cause exactly this behaviour....and the previous owners had small children.

I guess I'll try snaking it first. What you did previously, if I understand correctly, is you pushed the twine through to the cleanout or something? Did you pull down to the cleanout, or up back through the toilet? For that matter, I could use one of my extending dental mirror things, even in the water, with a flashlight to see if I can see something just inside up under, if you know what I mean.

I'm pretty sure the cleanout's directly under the toilet in question. I presume, apart from when water's running, not that much will run out of the cleanout normally? I guess I mean, is it above a trap?

CoolVT, I've tried that trick, and the water goes down fine - as I mentioned above, that used to be my trick for unblocking...so I'm liking Airqual's theory.

My wife, who's lived in n.america all her life keeps telling me this thing isn't normal, so there must be something like that described.

Here's how I managed it:

Removed tank (2-piece toilet).

Dismounted bowl section from floor

Tied heavy chunk of metal (about a 1" threaded nut) to twine and dropped it into trapway. Had to twist, turn, and shake the bowl section some to get the nut to pull the twine all the way through.

Tied rag to twine and pulled it back through. (Be sure that you leave a long piece of twine beyond the rag, so you can pull it back and forth a couple of times.)

Reassemble. Be sure that you have purchased a new wax ring before you start. If you are dealing with an older two-piece toilet, you may find that the seal between the tank and the bowl section is in bad shpe, so don't be surprised if you have to deal with that.

Another thing to check for: There ought to be a series of small holes under the bowl rim that let water in during a flush. They can get partially blocked with scale, and this will cause a weak flush. Any narrow piece of metal, like the end of a piece of coat hanger, will do to loosen and remove the scale.

Obvious stuff: Also be sure the toilet flapper valve in the bottom of the tank is opening fully during a flush. And be sure the tank is filling to the correct depth.

Good luck.

Thanks. So the pen was just trapped in the toilet part? A mirror, then, might just show me if there is something like a pen in there. Not sure what the bowl's fastened to the floor with...I'll have a look. FIL can advise me, he knows how these toilets are put together.

I've been wondering about the flushing jets round the rim - there's also a big one at the bottom of the bowl, that directs water right up the bend. That seems to flow well, although there's always a bubble of air when you flush - my wife keeps asking if that's normal.

I can see dark marks around the rim jets, our toilet brush doesn't seem to get near them. I was thinking of using a cable tie to clean them, they're stiff but still flexible, and won't scratch anything. I've also heard people suggest using CLR or similar.

So, if the water goes down fine when you pour a bucket in, why do you think it't plugged up? There are 2 basic problems that can keep a toilet from flushing correctly...something is plugged up or the toilet isn't getting enough water to flush correctly.
You say in your original note that it plugs up or stops up frequently. I assmume that you mean it doesn't flush correctly? Like I said, at a time that it doesn't flush normally, but you can make it flush with a bucket of water, then it probably isn't plugged up, but isn't getting enough water to flush properly. Airqual has given you some good hints on being sure that you have enough water going into the bowl. So first determine that you don't have a plug up and then go through the list of things that could cause you to not be getting enough water.
I had a friend years back who had the same problem. He had a company come in and dig up his sewer line and part of a leach field and they found nothing. Then someone told him to check the holes under the toilet rim, and sure enough, they were plugged up. He spend $2,000 and ended up solving his problem with a 10 cent coathanger. If you have hard water (lots of minerals) it will be much more likely to happen.

Yep, in the trapway of the bowl. You can try a mirror but don't be too surprised if there is too little light to see. Trapways can be pretty convoluted, so you may have trouble weeing all of it.

R&R on a toilet is a sometimes messy but usually fairly straightforward job. Google "toilet replacement" and you will find a dozen web pages (with illustrations) showing how it is done, so I won't go into that.

The exact symptom mine had was inability to flush solids without getting blocked. With no solids flush always looked fine. With solids and TP it started out OK but quickly stopped up. After a minute or two water level in bowl had receded to normal level. Flush-still blocked. Couple of quick blasts with a plunger-blockage goes on down the trapway. Repaeat ad infinitum. Drove me crazy.

Weeing = seeing. Heh.

I live in the Pacific Northwest (OR), have great water quality and have the same problem with both toilets (single story house). Neither is plugged up but they will frequently be very slow in the flushing department. Both are Am. Standard - 1.5 gpf/6.0 tanks. If you check the passage design under the bowl, you can see where the problem might be - mine has a series of twists and bends that would defy a NASCAR driver. We're remodeling and am going with new toilets - 4-inch flush opening and a less twisting design. We usually double flush now: initial solids flush followed by a tissue flush. This usually does the trick. Changing toilets isn't rocket science; a fairly easy DIY.

CoolVT,

My problem is EXACTLY as airqual is describing his - mine doesn't block with EVERY poo, just....errr more with mine. I'm male, maybe that's it.

Sorry for the detail. A pen or similar object would do exactly as he's describing, water past, no problem. Small poo, no problem, tp usually no prob, and it'll break up quickly. Big poo, is where it happens. Water doesn't go down, or if you're really lucky, water will go down mostly, you second flush. Bowl overflows.

Ashlander, I'm in BC and our town uses river water but it's now highly filtered and treated with very little hardness that I can see, but I've seen discolouration round the rim so will try unblocking for fun. I suspect the problem is similar to yours, poor bowl design with too tight an angle. Like I said, the toilets in Australia/NZ have a larger opening - probably 4" or 100mm and the bend is larger and simpler. Blockages hardly ever happen.

Double flushing? I'm very water conscious, even here where we throw it away (ironically, this is basically desert here, not much more than 12" of rain per annum, but we have the river.)

Almost all toilet cisterns sold in Australia are dual flush - the half button gives you half a flush for wee, full for #2.

Sorry for the bluntness. I wouldn't be double flushing myself except for this toilet being so touchy. I may well consider changing the toilet if I don't find this phantom bic pen or whatever it is.

Used a cable tie end to clean the jets which did improve the flow/circular motion somewhat - advantage of the cable tie is it won't scratch the bowl.

There did seem to be quite a lot of scale or whatever around the rim, and the cistern itself has a lot of crud in the bottom, if I flush it out I'll have to unblock the jets again.

I somehow doubt this'll solve the problem since I don't see how insufficient water will result in a genuine blockage, but we'll see.

I did look up the bend with a flashlight and mirror, but couldn't see anything. I guess a snake's next, then taking the thing apart I suppose.

I think that in your original post you just said it didn't flush well and didn't give all the symptoms. If you flush and the water level starts to rise, then it's probably a blockage. If it goes down, but doesn't go down as it should, then it could be from lack of water.
For a blockage and using a mirror... you nomally can't see the blockage from the top. You'll have to empty all the water in the tank and bowl and flip the toilet on it's side. Then you might or might not be able to see the blockage.
In my apts I have pulled out pens, tubes of toothpaste, make-up pens and combs. The craziest one was a woman's round compact. When snaked the compact would flip and the toilet would be clear for a day or two, then waste would build up on it again. With the toilet on the back lawn we ran a heavy piece of rope throught it with a rage knotted in the middle. This is the first one that I ever saw where we couldn't dislodge the obstruction. We finally figured out what it was when we took a hammer to it:-)
I thiink most of the major manufacturers are selling toilets that have been tested over and over. So, no matter what the design looks like, they usaully work. When low flows first came on the market, some of them didn't flush well and required two flushes. I've used some of the cheapest things out there in the last 10 years and have had no problems.

Six buckets of water poured rapidly, and solids are still reappearing. It has to be something thin, in the middle. Without solids there the water flows fine. A pen or similar in the middle would produce exactly these symptoms. I suspect I'll have to remove it to have any hope of seeing what it is.

I was wondering, is the obstruction likely to be in the middle and not dislodged when the bowl's removed? As long as it's gone, I'm happy I guess, but I'd prefer to see the culprit rather than just have it fall down the pipe as it's lifted off.

Sorry if I didn't explain it too well Coolvt but I couldn't think of any other way to put it - water only, fine. Cleaning the jets helped them a little and have made the water go into more of a vortex, but as I noticed this morning, it didn't help the situation.

Now if six buckets of water poured from more than a metre up - much more water than a normal flush - didn't solve it, there has to be a blockage or an incredibly bad design where stuff can build up into a perhaps wedge-shaped plug so it gets thoroughly stuck. Plunging it will dislodge it but I'm trying to get rid of the more ummm literally gross particles before putting the plunger in there.

we have 3 bathrooms. the guest bath toilet works great. the other 2 get used a lot and both had flushing issues. I finally replaced 1 and got a cheap low flow model. it works 90% of the time but does clog on occasion. the last toilet is due for replacement. flushes slow and sometimes works. we have very hard water. 25 grains. i have considered swapping toilets from the guest bath to the high use bath. why bother? leave the guest toilet alone and just buy a new toilet where it is needed. oh, all are 30yrs old, city water.

From what you are saying, it definitley does sound like something in there. Have you tried a toilet auger? The real professional models (spring cable with 2nd inner cable) normally can either break or push out any obstruction. It's probably the first thing to try before removing the toilet.
i doubt it's just going to fall out when the toilet is removed. It will most probably be wedged in the middle of the trap. If you couldn't see it from the top, you should be able to see if from the bottom.