97 850 dash/headlights flickering only at startup. UPDATED

[Peevarino]

UPDATE!

It’s been doing the flickering a bit more often, but still only at idle, looked over a few other things, the battery to starter wire isn’t as bad as I thought once I removed a bit of the heat shrink.

Wondering if the PO had routed the serp belt the old way (less contact on alt pulley), I had a closer look. It’s routed the updated way, but when I checked tension, I realized it didn’t really have any, except I guess under load. I could move the tensioner pulley fore and aft a bit more than is probably acceptable.

So, I’ll be putting a new tensioner and belt (might as well, right?) as soon as time and shipping allows, assuming there aren’t two perfect examples at the pullapart tomorrow.

Will it solve the flickering? I hope so, but it seems like the car needs it anyway.

[misha]

It could be that voltage regulator brushes are worn out.
Diodes should be checked too and alternator tested by a specialized shop.
About serpentine belt tensioner....you shouldn't be able to move it by hand.

[Peevarino]

I’ll be pulling a couple voltage regulators out tomorrow, as well, I seem to recall a couple newer looking alternators in the few P80 cars at the yard.

[misha]

The easiest thing is to try with replacement tensioner.
If that doesn't cure it....than attack the alternator.

[Peevarino]

That’s the plan, tensioner needs replacing anyway. If the alternators’ brushes look good at the junkyard, I’m going to get them, cheap backups just in case.

I really wish I had gone to the junkyard yesterday, though, it’s almost 30 degrees colder today.

[Peevarino]

Found a properly working tensioner and pulley at the junkyard, along with a nearly new Volvo stickered Bosch alternator. The PO put in a O’Reilly reman alt at some point, so I figured get it when I can.

No time left to put tensioner in today, family time and grocery run take priority now.

I’ll report back once the tensioner is in, I may have time on my lunch break tomorrow, assuming it’s not raining.

[Peevarino]

Tried disconnecting starter to battery cable and replacing with a new, no change.

Replaced the two block to firewall ground straps, and the flickering seems to have stopped. Sadly not commuting to work at the moment, so I can’t give it a proper test drive. Maybe I’ll take it for a spin tonight or early tomorrow morning and get a better test.