dhowe wrote:Is there any chance that I am pulling air into the system by way of the group head thermometer? I noticed a guy by the name of Howard Smith on YouTube pulling very short flushes as well and he does not appear to be having the same issue as I am.

If your thermometer was leaking, could be, but then I would think you'd see it leaking under all that pressure. Are you still having problems?

I pulled around 5-6 shots from yesterday to right now and it's happened once out of all of those. I have been doing longer flushes and maybe I just stopped that one too soon. Trying to find the sweet spot lol. I figured if the thermometer was leaking I figured I'd see water as well. I just need more practice I guess.

dhowe wrote:I figured as much. Is there any chance that I am pulling air into the system by way of the group head thermometer? I noticed a guy by the name of Howard Smith on YouTube pulling very short flushes as well and he does not appear to be having the same issue as I am.

I think that unlikely as you'd have water (or vapour) coming out when it was pressurized.. but it might be that their is a small amount of air getting into your TS somewhere

Sometimes it's difficult to see a vapor leak so what I use is a small mirror. A mirror will frost up very quickly if there's hot steam coming out of an orifice, no matter how small. You might check around the group thermometer with a mirror. You should probably also check to see if there's any air in the pump lines possibly caused by a tiny crack in a teflon hose.

The other thing about thermo stalls is like @JRising mentioned... the brew valve. If the brew valve is leaking, even slightly, it could do so in a manner that you may/may not see liquid come out of the drain. If the leak is small, it's possible that whatever water is leaking through can evaporate before it reaches the drain leaving no trace of the leak. You mentioned earlier that you saw a leak from the drain with the lever down, but it eventually stopped... it may have been an indication you saw, eventhough you don't see anything now. From the sounds of it, the machine is fairly new, (a few months?) but if the brew valve seat is damaged or overly compressed, it can leak enough to thermal stall the machine. It might do you well to pull the group head apart to check all three of the valve seats, to include the mushroom gasket to make sure it's in good shape and the fit is good. Better yet purchase the parts you need for an overhaul of the group and have them on hand when you have the time to do it.

What you're seeing certainaly doesn't sound "normal"... having a stall every so often. My machine never stalls. Then again a lot depends of course on the user routine, and possibly hardware failing. On the other hand, having to do a 10 second flush sounds excessive to avoid a thermal stall.

Here's a Quick Mill E61 drawing... your machine should be similar...

So earlier after thinking about it I went ahead and took the thermometer out and put the spare parts in it and replaced it. Maybe I over tightened the first time around. I will see what happens in the morning. The machine is around a few months old, for sure under a year though I am not certain. I will say I am not eager to take the group head apart if it is possible that it is just me causing it. I will pull the top off the machine and check the water lines after I've run it for a little while.

I will ask this question though just for my knowledge. I know there is a 45º position on the brew lever that is like a "pre wet" kind of thing. I do not use it and am under the impression that maybe some steam pressure pushes water out (maybe?). I need to do it again to be sure but the water coming out at this stage earlier was flash boiling and I left it in the 45º position for around 6 seconds. Afterwards, I went ahead and turned the pump on and it took a while for water to begin flowing again. Once again, I am very new to the E61 so please go easy on me lol.

By all means, if you're not comfortable with attacking the E61, don' t do it. Problems like you described and remedies found in replies here are best guesses on our part. Trying to look at all angles is all we're doing. One of these days, you will have to jump into the E61 to overhaul it and I think you'll find it not so intimidating once you start. No rush though, and certainly not before you're convinced about what might be causing your issues.

Many people misunderstand the mid position and "pre-wetting" and how it works on the E61. When you lift the lever from the low position, there's a range of travel up to mid-point where nothing will happen, meaning no steam or water will come out of the group. This is because the operating cam hasn't yet opened the brew valve. While you're in this area of travel, the lever can be moved freely up and down and nothing will happen. Once you start lifting a little higher, you'll start feeling some resistance on the lever, and if you move the lever even higher (without engaing the pump), then steam/water will start to flow out of the group because now the operating cam is starting to lift the brew valve and pressure in the HX starts pushing whatever is currently in the grouphead out of the group. There's a nominal amount of water, (I can't remember how much) that will come out and that water is the "pre-wetting" water. Once that water exits the group, the grouphead is, for lack of better words, empty. So... for certain, if you now lift the lever fully up and engage the pump, the pump has to refill the areas of the grouphead that is void of water before water can be seen exiting the group again. What you experienced with it taking a while before water started again is normal and expected.

Some people believe that pre-wetting begins between the low lever position and the mid-point. It actually doesn't start unless the cam opens the brew valve (without engaging the pump), which is a position just slightly higher than mid-point. For this explanation "mid-point" is the uppermost point of free travel the lever has before the cam starts opening the brew valve.

This is almost definitely just a thermosyphon stall caused by a 'too short' flush after your shot.

It's woth bearing in mind that if your looking to brew in the 93°C ish range and your causing thermosyphon stalls with a quick flush post shot your brew water temps during said shot were likely too high.

My understanding is that a thermosyphon stall comes about when water is pressurised due to it being above 100°C in a closed circuit and then the circuit becomes 'open circuit' when you flip the lever. This causes flash boiling (which generated air) withing the e61 thermosyphon loop. If you don't flush the air out it will sit at the highest point (top of the mushroom) and prevent the flow of water, causing your grouphead to cool down.

Quick fix - perform 2 back flushes, both up to full pressure.

Top Tip - You can use the technique of 'thermosyphon stall' to your advantage to reduce the temperature of your group head by lifting the lever straight up and down quickly.

I am brining the group temp to 88º and then pulling to where the group temp shows to be at 93º. I pulled a few yesterday with a long flush after the shot. Only one or two of them stalled. When I was pulling back to back shots the stall was actually very easy to catch the temps going back up rather than waiting for them to cool again.

Before pulling a shot first thing in the morning my group temp says 98-99º most of the time. I fan down to 88 and pull the shot when its coming back up. I'm getting around 93º during the shot so 91 or 92º at the puck then?

Yep if ur fanning down to 88c and pulling on the rebound at 88c??? then I'd expect to see somthing like 91.5c at around 20 seconds on the group during the shot. At puck is going to be around 1°c lower than group read out at round 20 secs.

I don't worry about that tho, just remember to pull ur shot on a rising group head, 2.5c below target brew temp and ur going to get consistent results.

FYI, if ur machine is at 98 or 99c you could have it come on a lot later and catch the machine on the way up. Prep ur basket, quick flush and pull ur shot at 2.5°c below target brew temp and ur going to get a nice flat temperature profile.

Yeah after watching your videos I tried to pull when the thermometer reads 91ºC but then I get around 96 or 97 I believe. So I have had to start at a lower temp. No clue why.