Hi all, My brother commented that he liked my Optimus 99 so I decided to find one to give him for his birthday later in the year. The one I picked was pretty filthy but seems in decent shape overall. I’ve cleaned it up, replaced the seal on the tank cap and reset the cleaning needle (the pencil eraser method with 4 clicks). I also removed the old fuel and filled up with Aspen 4. It fires up pretty nicely with good heat (enough to blue the pot rests) and turns off as it should. The only thing is it has a persistent ticking. I initially thought it was heat expansion but it doesn’t go away and varies with how open the valve is (more power faster ticks). Has anyone else experienced this? Could it be fuel supply or a worn jet? I love these old stoves but I’m by no means an expert. I have a couple of other 99’s (a flat based version and a later example) and neither of them display this quirk. The stove is running ok but I just wanted to check in with those with more experience than me. first couple of images are from the seller I bought it from. The second couple are it running with me
Ticking? A distinctive tick/click-like sound? Could you take a video of it running please The 99/8R/123R etc etc with this style/family of burner style do have a distinctive buzz/flutter/raspberry sound when they are running flat out as you'll know with your other one, is it a very different sound to this? Alec.
Thanks Alec, It’s very different to the distinctive flutter, ram-jet sound of my other 99’s (I also have a few 80’s an 8 and a Primus 71 so that sound is music to my ears!). it’s much more like a tick tick tick noise, very much like metal expanding in heat. However I’m fairly confident that isn’t the case as it continues once everything is heated up and it directly correlates to how open the valve is. I thought fur a moment it could be inconsistent fuel flow but whatever the sound is doesn’t seen to affect the level of the flame. I’ll try to take a video tomorrow
I haven’t yet, Could this cause such an issue? The stove seems to pressurise ok? I have a refurbished cap on one of my 80s which I can test on the 99 tomorrow .
@optiben80 - another thing you could try is running the stove without the cleaning needle. Process of elimination so to speak. Pharael.
I tried firing the stove up a couple of times today, both with that without the pricking needle installed and it seemed to make no difference. I also tried firing it with the cap from an 80 (I’m not at home so can’t test with a cap from one of my other 99’s) and this also yielded the same ticking noise so I’m none the wiser?!
@optiben80 - I would use a long thin screwdriver to use as a stethoscope in order to pinpoint exactly where the noise is coming from and then investigate accordingly. Pharael.
It is yes, in suspect it may be related to the fuel feed somehow. From what I can tell it sounds like it might be coming from the feeder tube or possibly the tank. I’m not certain but when it initially fires up it seems as though the flame slightly pulsates in time with the ticking (it’s subtle though so I could be wrong). I’ll attempt the screwdriver method to try to identify the source.
Wow quite the tick! Sounds like something metallic..tik then tok..up then down..my first thought is. The pressure release on the fuel cap..is there a spring in there?...pip holder bouncing? seems to hold pressure enough to sustain a decent flame tho... Second thought was the heat shield "popping" with heat and expansion but I could not see that in your video... Interesting problem. Look forward to further investigations. Scott B
