sb66

Hi everyone

I noticed a flicker with the dash lights and well timed high pitch pulse when the radio is on - as well as a moody tach readout - the interference seems to keep close time with what sounds like the pulses of the motor - I was wondering if anyone else has come across that? I saw somewhere that the '85 has a tachometer filter - does that have anything to do with it? - sorry this is on a 1985 standard

any thoughts or opinions would be greatly appreciated

thanks
Sean

sb66

I should add the tach - works briefly at start up then does not - about 20minutes or so into the drive it wakes up and tries to work - a little - if that helps

billschroeder5842

Stop by the parts store ask ask one of the guys to put a meter on your battery. They can check the condition of your battery and if the alternator is putting out enough. Sounds to me like your regulator is on life support.

sb66

life support does not sound good - it is a relatively new battery - Fall 2016 - all of the other electric stuff works well - even on the dash - besides the tach

I have a couple autozones and an advanced auto I think either can run a quick test

thanks

sb66

regulator can be replaced even if it is internal correct?

billschroeder5842

Yeah, but why would you? If you regulator is shot (I'm doing surgery on my LT5 right now for a alternator swap due to a failed regulator) just get a new alternator with a warranty and swap it out.

Easy Peasy.

sb66

valid point - quite a few options for these aren't there? I noticed some went for more amps - I think ours is the 124(?)amp I saw a lot of 140 - do you know if an increase like that is fine for our c4's?

thanks again

Sean

Gibbles

If the price is not a huge difference, spring for the extra amps.

I always heard that the more power is a good thing on a computer controlled EFI engine.

And i rebuilt my stock alternator, the alternator i had suggested to me is about $240...

It's still on the list, but after tooling up for painting, and painting the car...

I spent about $10 to rebuild my alternator, it was not to difficult.
hardest thing was figuring out the holes on the side were to keep the brushes in place when assembling it (i used a piece of wire)...
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sb66

price is always a thing - I did find several 120amp in the $120-$150 range and a few reman delco's - I was not sure about

any thoughts on the remanufactured?

Gibbles

Reman is fine, there really is not much going on inside of those things.

And that was part of why i went for a "do it myself", cheapest alternator i could find was still over $100...

​​​​​​​I bought the regulator off of amazon, however i know napa carries it for a bit more...

sb66

biggest problem is finding one in stock or the part to repair - lot of cars in town this weekend for the supernat's - was really hoping to be out with it all - may sound stupid but how much of a risk to keep driving - even if it is only short distances?

sb66

this is probably yet another stupid question - but I will add it to the list - does the case style matter? I see 10si, 17si some kind of csi (that might be the tv show)

thanks

Gibbles

I would limit driving, but by all means, have fun with the car.
keep a set of jumper cables in the car.

Case type, i have noidea, i suspect they are pretty standard...
​​​​​​​my car is very early tho, one wire alternator...

sb66

thanks - I took a chance and drove for a little yesterday - too nice not to - I watched the voltage on the dash - always stayed around 14 - 14.2 when I first started it up it was closer to 14.7/.9. I turned lights, fan and radio on and it dropped to 13.9 - 14.4 then leveled off at the 14.2 area and stayed.

I am going to test a few things today if I can I think I will search to find the grounds also - could be a problem also?

I would like to be a little more sure before buying a new $160 dollar unit. (although I did find a couple of nice rebuild kits on ebay and amazon - made in the USA - for $14-$20) I may get one and put it on the shelf so it's ready just in case

thanks
Sean

bac22

I'm not sure why some where leading you down the voltage regulator route without some basic questions.

1) Yes, check all ground points. I was having similar trouble in my 96 and I think the issue was 2-fold. Bad negative post screw on the battery not make strong contact and cleaned up the ground by the battery.

2) Any chance you have an after market radio? Can't tell you how many times improper installation of after market electronics messes up a car's electrical systems.

Your voltage level on the dash is well within spec, I don't see a regulator as being the issue.

Came across this pict which I believe is ground points on an 85.

sb66

thanks - great diagram - honestly I did not watch the volts on the dash that close until they had mentioned the alternator - The radio is from what I can tell original - am/fm cassette - I will be checking and cleaning grounds before moving forward on anything else - this might be a dumb question but - should any dialectic grease be used on grounds after they are cleaned - or does that undo the very thing I am trying to do?

thanks

Sean

ctmccloskey

I woke a 1988 Corvette after a slumber of a couple years and it had all kinds of issues, mostly electrical.

I started at the battery and measured the voltage and then through the little block behind the battery where the fusible links get their power and cleaned everything there as well. I have cleaned every connector I touched, by doing this I got rid of the difference of voltages under the dash. If it supposed to have full battery voltage, it does!
I kept getting readings showing big voltage drops inside the car. I had bad ground connections and bad battery connections. After the cleaning of the fuse block my problems started to get better. Now I can read the battery voltage accurately pretty much anywhere on the car.

I have heard that you should apply a little motor oil on top of the grounds connections after they are finished. Just enough to keep it from corroding. It is supposed to be a "barrier" to protect the connection. Die electric grease is non-conductive and will stay there a while protecting the connection.

As important as your battery connection is, the ground is just as critical.

On every Ground you should see the base metal before attaching something to it. You only want one good battery ground for the whole car. C4 Corvettes have several ground straps on various parts and they too need to be clean and have no resistance to ground. My power antenna worked so-so until I cleaned the ground strap at both ends and now it works like a charm. Prior to that it had full 12-14 volt at the connector but would not work all the time.

Cleanliness is next to Godliness, especially on electrical connections!

I wish you the very best of luck with your Corvette!

sb66

thanks - I set a few hours aside today to see if I can make a dent cleaning all of those - starting with the battery

sb66

just curious would these also have the effect on the tach as well - where it does not work for about the first 20+ minutes then does after that ?

bac22

Past experience would say no, it's possible that's a separate issue, but one step at a time as the saying goes.