Engineer is a wide topic that can go in many directions, as "training" to become an engineer is vastly different depending on what country you're in. So if what I write is different to your experiences it's because I'm talking about different countries. Cheers.
Firstly I'm happy with the associated title of "Engineer" being used, as for me it implies formal training. Until then your a mechanic as I'll explain.
In some cases it defines the difference in background between two roles such as Second Officer & Flight Engineer, my father was a Flight Engineer having completed a 4 year apprenticeship, to become an Aircraft Maintenance Engineer (AME), he then did the CAA Exams, while working on the specific aircraft types to gain the required experience to be eligible for a type rating and become a Licenced AME, which he did on the DC-8, 707 and others with electrical/radio extensions, some time later he became a flight engineer and flew the Convair 880, 707, L1011 & 747.
I followed in his foot steps, did my 4 year apprenticeship, did my CAA exams and spent 5 years working on the 747/767/757/737/A300B4 before getting retrenched, just before starting my 742 ground school to become Licenced. I then started flying and fortunately am now an F/O on the 742.
Now I tend to explain in my "terms" to other crew members that you could have 3 different types of people working on the aircraft at any one time, mechanics who are basically manpower, AME's (formal training and probably working to become licenced) and the LAME. Now the reason I do this is the company I work for doesn't explain that all the "engineers" working on the aircraft aren't licenced on it, therefore I find cockpit crew asking mechanics questions that should be directed at LAME's. These crew then get pissed because the guy doesn't know the answer, which leads me into my explanation, and a resounding "oh I didn't know that, how do I recognise the LAME ?"
Now back on topic, the reason I think people ask questions of pilots is that they assume pilots know every technical thing about the aircraft they fly. Now this may be true for a Cessna 152 but not your 747, there is simply too much to learn and the idea is to Aviate, Navigate, Communicate, not to get bogged down in technical details which have led to numerous crashes, and guess what? There are people specifically trained on every A/C who do know just about everything, and if not know someone who does or knows where/how to find it.
This is also the reason these days aircrew ground school is a lot less technical than some years ago, especially with the loss of the F/E who may well have been a LAME on the same A/C, as I've said a two man crew cannot afford the luxury of getting overly technical.
I'm glad I got an "old school" ground school, we did the entire F/E ground school prior to our pilot course, it took 5 weeks! Think about some of the things you read these days, courses that take less than a week, because technology has come so far, and due to the fact that technical help is just a phone call away. (SATCOM/ACARS)
So if you want to ask a question about flying a plane, ask a pilot. If you want to know something specific about a plane ask a LAME! Here's an example,
The other day we were taxiing head to head with a 744 having just landed, this -400 was taxiing for TO
and the Capt asked what the difference between the -400 LE flaps and the "classic" was, so I slipped on my AME hat and said Group A & B LE flaps are different on the -400 vs the "classic", he said "no the -400 has an extra one on each wing" which I knew but had slipped on the wrong hat.