Is this normal?

[Stu]

Whilst my car is not physically moving (see gearbox thread!), I'm turning it over for 5 minutes or so a couple of times a week.

When fully warmed up (choke right in) and idling, a significant drop in engine noise (revs) is noted when I turn on my headlights! Is this normal behaviour, or is the battery slightly too weak, wiring a bit iffy, or faulty components?

I'm just curious really.... it's not going to cause the car to stall or anything due to the idle speed.

[pbottomley]

shows the alternator is working!!! if the engine note drops the alternator is charging, if its too slow just adjust the idle speed a tiny amount.

[Stu]

Thanks!
That displays my limited (though quickly expanding!) knowledge of automotive mechanics.

I've already got the idle set so that with the drop, it's idling as one would expect/hope.

[droopsnoot]

I'd suggest you run it for longer, maybe 20 mins or so - you could be doing more harm than good.

I once bought a Viva E Coupe from a guy who'd done the same thing, only to find that the little ends went because it wasn't long enough for the oil to circulate and properly warm through. (Of course, I don't know the whole story of what he did, that's just how he described it. He could have been revving the b***s off it but not wanted to admit it).

[Stu]

Well I haven't actually timed it tbh, but I don't turn it off as soon as the needle reaches 'warm'. I let it run for a bit.

Perhaps the guy had old oil in it which couldn't flow quickly enough to where it was needed? I changed the oil only a few months back, so it should be pretty free flowing.

Hopefully it should only be a week or so 'til the car is out and about properly. That being said, I did used to drive it to work and back, which is only about 5 minutes away... probably shorter than the time I'm idling it now... perhaps I should detour in future and take a scenic route!

[droopsnoot]

Maybe - he could just have been running it for a minute or two, or rubbish oil, the little ends might even have been on the way out the start with. I don't think it's the same when you're actually driving it, though, because you're running through the rev range more - some engines have very low oil pressure at idle speed.