Electrical issues on '84 Silverado

[woodyjim]

Hey everyone,

Was driving home the other night and noticed my headlights getting dim and then bright again. Volt meter pegging then dropping to normal. Put rebuilt alternator on last fall... any ideas? Also noticed my oil pressure guage reads 60 and wants to go higher when I goose the motor. Could this be electrical also? I'd appreciate any help.

[Palf70Step]

Sounds like the regulator, but I cannot remember if 84 they were still external regulators or integrated.

[datguysaL]

possibly your alternator is overcharging.
check your wiring, check for broken, loose connections. rubbing wires, wires rubbing on frame, make sure u got good ground connections.. etc....

as far as the the oil gauge increasing as you rev up engine, thats not electrical. thats normal. now how much its suppose to increase and the ideal PSI.. that i dont remember....

[83burban]

Ideally you would like to see at a minimum 15 psi at idle and increase the psi by 10 for every thousand rpms increased. of course, it has to do with the tolerances of bearings in a new motor and the age for an older one.

My 355 runs 30 psi hot at idle and about 60 for driving speeds

[woodyjim]

Thanks for the ideas guys, I have had some grounding issues in the past... thought I had 'em fixed but maybe not? 38burban, I'm running 60 psi at idle. Guess I thought it could be a faulty sending unit?!? This is a fairly new crate motor but I didn't think it should be that high.

[83burban]

The numbers I listed are for operating temp psi at idle and cruising. Sounds like your gauge is pegged out indicating that your oil pressure sending unit line is grounding out somewhere along the way.

[Adams74Chevy]

Years ago my father had a alternator rebuilt and it had a major overcharging issue it cooked the battery so much the vent caps on top of it blew off and splattered battery acid in that corner of the engine compartment. Definately get the alternator checked or get another it'll be cheaper than a new battery and having to clean up acid splatter and repaint the engine compartment.

[woodyjim]

OK, I'll get the alternator checked this weekend... I just replaced my battery! And I'll run down the sending unit wire and see if I can find the short.

Thanks again guys!

[woodyjim]

OK, I went to the local Auto Zone and let the guy hook up my electrical / charging system and it checked good... at first. Then I explained that I had noticed the problem when the headlights were on and we turned 'em on and repeated the test. It checked faulty. He suggested a possible internal regulator problem but also said I should check the headlight switch... something about it pulling too many amps if bad? I'm also thinking I should maybe remove the alternator for a true bench test. Any more ideas out there?

[rare86]

Make sure all grounds are clean. Battery negative main cable to block somewhere, battery negative to core support for lights (10 gauge is good) and ground from block to firewall.