I remember from a previous incarnation of this forum a thread about Accucraft burners and the reason why the flame is all the way into the smokebox. The story so far is that my Mortimer was running fine till one day it just stopped with no gas coming into the burner. I removed the pipe that connects the gas tank and the burner, took the jet off and there was a large ball of PTFE tape in the jet tube. That is now removed and the whole thing put back together exactly as before. The only problem is that the flame now sits right at the front of the boiler / in the firebox. When you light it there is no pop and the flame doesn't seem to want to go back up the boiler / burner tube like it used to. If you increase the gas flow the flame shoots out the front, as high as the top of the funnel (that gets your attention!!! The hairs on my hand will grow back one day soon!!) This was covered in the other forum in some detail, but I can't remember what the cause was or what the solution was. If someone can remember I would be very grateful, as I am sure it was something relatively simple to sort. Many thanks.
Accucraft burner problem
- Thread starter cheshire
- Start date
Just in case Matt (brianthesnail96) misses this topic I suggest you send him a P.M. He has recently done some research on this matter.
Hello!
The Accucraft burners are a bit prone to behaving like that anyway- that's what I was looking into. However as yours was working OK before you took it apart, it's obviously something other than the "normal" problems that is causing the issue in this case. Couple of suggestions to try though:
When you disassembled the jet assembly, did you reseal the thread on the jet when replacing it into the jet holder? It sounds to me like it's getting air in somewhere and that's the most likely cause. If you haven't done so, try a bit of PTFE (Accucraft do tend to be a bit overenthusiastic with it incidentally, I had the same problem) around the thread on the jet, or better some proper thread sealant stuff. Only needs a little bit.
The other thing to check is that the jet holder is aligned properly with the burner- it's just held in position by the gas supply pipe and on taking it apart it might well have moved. It's important that it's dead straight in the burner, i.e. the jet is pointing exactly down the flue tube. How tight the jet holder is against the back of the burner is also important- start with it pushed up dead tight, light up and see how it goes. Gradually move it back and see how you get on- the ideal position seems to vary a bit from engine to engine (and I've still not managed to get mine quite right!). It seems very "fussy" on both counts- it doesn't have to be far off to cause problems.
Let us know how you get on.
The Accucraft burners are a bit prone to behaving like that anyway- that's what I was looking into. However as yours was working OK before you took it apart, it's obviously something other than the "normal" problems that is causing the issue in this case. Couple of suggestions to try though:
When you disassembled the jet assembly, did you reseal the thread on the jet when replacing it into the jet holder? It sounds to me like it's getting air in somewhere and that's the most likely cause. If you haven't done so, try a bit of PTFE (Accucraft do tend to be a bit overenthusiastic with it incidentally, I had the same problem) around the thread on the jet, or better some proper thread sealant stuff. Only needs a little bit.
The other thing to check is that the jet holder is aligned properly with the burner- it's just held in position by the gas supply pipe and on taking it apart it might well have moved. It's important that it's dead straight in the burner, i.e. the jet is pointing exactly down the flue tube. How tight the jet holder is against the back of the burner is also important- start with it pushed up dead tight, light up and see how it goes. Gradually move it back and see how you get on- the ideal position seems to vary a bit from engine to engine (and I've still not managed to get mine quite right!). It seems very "fussy" on both counts- it doesn't have to be far off to cause problems.
Let us know how you get on.
It could just be a simple thing like too much gas. Unscrew the gas valve (regulator) and put either vaseline or silicone grease on the threads and the O ring. While you're at it blow some gas or air through the gas tank, there may be some crap on the valve seat.
You will find that you have much finer control on the gas flow after greasing the threads and it may be enough to cure your problem.
You will find that you have much finer control on the gas flow after greasing the threads and it may be enough to cure your problem.
The little rolled up "gas filter" that you removed from the jet is to help prevent blocked jets. Your initial symptoms indicate a blocked jet. Fire in the smoke box is normally due to the gas being turned up too high. I suggest you clean the jet, lubricate the gas valve and ensure you re seat the jet assembly as mentioned above and try again. Only go easy on the gas valve.
If it was a case of "too much gas" then I suspect it would have been a problem previously, unless there was a partial blockage meaning the gas was turned up higher to compensate. This is pretty much what my engine was doing when I had dissasembled the jet for cleaning and forgotten to reseal it so I'd definitely start there.
It's certainly good advice to lubricate the thread/ o- ring on the gas regulator however. They are a bit all or nothing! The thread is too coarse for fine control really.
It's certainly good advice to lubricate the thread/ o- ring on the gas regulator however. They are a bit all or nothing! The thread is too coarse for fine control really.
Valve spindle greased (silicon) as advised. Now I will have to do some testing.
Oh dear, what a nuisance , not more testing!
Not tonight but tomorrow.
Oh dear, what a nuisance , not more testing!
Not tonight but tomorrow.
