Oh, maybe. I guess that cap isn't exactly on there tight is it? And the overflow is never supposed to be full so coolant would never reach the cap. That make sense.
But if the system self-burped, what would be the point in burping it manually, like so many people do? Obviously get the big bubbles out sooner than later, but still.
Wait, you added only a half inch in 3 weeks? I think you might be just fine. The overflow is going to raise and lower by itself depending on how how the coolant is. The only way to fully tell is by adding coolant in the morning (or when the engine is fully cooled down, at least). And if it self-burps (even slightly) that would affect your half-inch in the reservoir.
I've not really kept track of how much I've added because I can tell it's still burping. I'm not too worried about it, and I monitor my temps with Torque. Maybe a half a water bottle's worth? Definitely more than you.
All I know is I'm not adding a half gallon every morning anymore and coming out to a huge puddle due to my leaking water pump.
I was loosing coolant relatively fast but my WP was 100% leaking, so I did the whole TB/WP job.
To summarize again real quick:
It never over heats, not even remotely (temps monitored via ultragauge)
I've only had to add maybe a 1/2" or so of coolant to the reservoir since the WP job 3 weeks ago. I used one of those fancy burping funnels when I added the coolant after the TB/WP job. I let it burp for a good 15 minutes, I would get a single bubble every minute or so and called it good.
I drive it about 3 to 4 days a week, maybe putting on a 100ish miles a week.
It runs excellent
Occasionally, I would get a rough idle on a cold startup that would usually last 5 seconds or so and instantly go away.
Last sunday it actually threw a misfire code on #3 cylinder, first time it ever happened. After about 10 seconds, it ran perfectly smooth and I drove it about 20 miles without a single issue or any CEL. I cleared the code right away.
Since that happened, I pulled the plugs on that side. #3 plug was loose in the cylinder? Maybe not hand tight loose but definitely not 14 ft/lbs.
Also since that happened, and I retorqued the spark plugs, the rough idle has not happened once in 3 cold start ups.
I have not had to add any more coolant to the reservoir.
I cannot see any leaks on the ground or anywhere underneath the truck.
There is "steam" coming out of the exhaust on cold start ups (usually in the 20's in the morning here). Liquid that is coming out is crystal clear (confirmed on a white towel) and tastes like dirty water (yes I tasted it!). No sweet smell or taste.
Just when I'm not sure if the amount of steam is normal, my wife starts her Highlander and "steams" about the same on a cold start up. And, every other car I see driving out of my neighborhood in WI has about the same amount of "steam".
No bubbling in the radiator/reservoir. Maybe a single bubble or two comes out of the reservoir when I shut it off.
Pistons/cylinders on # 1/3/6 all look the same (black and full of carbon). Plugs look essentially all the same.
I let it sit for 24 hours and pulled the #3 plug to see if any coolant was pooled up, using a bore scope and a flashlight, AND a long wooden cotton ear swab, the cylinder is dry.
Ok, so that wasn't short but it essentially summarized the thread so far. Leak down test should be the slam dunk whether I have a HG issue or not. I've had some really, really bad luck with cars in the past (thanks Pontiac and VW) so I'm super OCD/paranoid.
I'll know for sure on Friday.