Odd hum from somewhere inside the engine / coil pack area

[TheMrFailz]

So I finished my timing belt job today, got everything buttoned up, and let the car idle. At first nothing other than a perfectly happy whiteblock engine, but after a few minutes I started to smell something burnt. Killed the engine, went to check and found a steady white smoke/steam coming up from behind the engine right about here:
(Note: not my image)


No big deal I figured, as there was some oil or something burning there from when my intake cam went and sprayed oil everywhere as well as from a particularly leaky oil cap. However pretty quickly I noticed that there was a new humming sound coming from the engine that wasn't a fan or anything else that is particularly common on volvos. The hum seems to be coming from one of the coil packs.

Thoughts? There doesn't seem to be anything overly wrong with it other than it's humming after the engine stops (the hum eventually stops too).

edit:

2002 2.4t V70, coil packs appear to be aftermarket ones replaced at some point.

[oragex]

How many miles? Does the humm go away if you undo the oil cap or the dipstick?

How does the belt run over the cam gears, straight in the middle without wobbling?

[abscate]

There is a coolant pipe and small hoses that run along the back (technically, right side) of the engine - if you have a leak that could be the source of steam and noise. They are fun to replace.

[TheMrFailz]

There is a coolant pipe and small hoses that run along the back (technically, right side) of the engine - if you have a leak that could be the source of steam and noise. They are fun to replace.

Smoke seems to have ceased which is good. Here's to hoping it doesn't turn out that was something important and my turbo ends up exploding.

How many miles? Does the humm go away if you undo the oil cap or the dipstick?

How does the belt run over the cam gears, straight in the middle without wobbling?

184k, belt is fine and straight. Hum doesn't go away if you undo the oil / dip. As far as I can tell it's definitely electrical.

[BlackBart]

Odvar the Volvo mechanic used to tell me "Drive it till it breaks, then you know what's wrong." But I'm just like you, I need to know... "What's that funny noise?!"

[TheMrFailz]

Odvar the Volvo mechanic used to tell me "Drive it till it breaks, then you know what's wrong." But I'm just like you, I need to know... "What's that funny noise?!"

"Local internet poster describes my entire "fix car things" experience in a single post without error."

[BlackBart]

Haha! We'll be pals.

Do you have an automotive stethoscope? They're fairly cheap. I cruise around the running engine, avoiding the dangerous spinny bits, and track down the odd lifter or cam bearing or exhaust valve or alternator bushing. It's amazing how much noise the injectors make - they're little switches, buzzing constantly.

[abscate]

A piece of hose in your ear also works, and it scares away the neighbors when they see you doing it. If the color of the hose doesn't match the car, the noise molecules won't travel as well up the hose, so get the right tool.

[BlackBart]

A 2x4 will work in a pinch......

[abscate]

Odvar the Volvo mechanic used to tell me "Drive it till it breaks, then you know what's wrong." But I'm just like you, I need to know... "What's that funny noise?!"

Im blessed with a SWMBO who will text "whir from front that goes away when I swerve- wheel bearing?" so I have parts on order before she gets home. She even diagnosed the rear UJ about 15000 before I had to do it. She is one with her machine.

She is indeed Samurai.