Thoughts on erratic alt voltage (regulator?)

[Liquid_force]

For some reason this evening I decided to basically take it WOT from the toll booth getting up to speed on the turnpike.
I noticed the battery light flicker around the 1-2 shift (close to 6k rpm). Soon after that I noticed the climate control had turned off, then I noticed the dash lights were unusually bright.

So I'm immediately thinking voltage regulator. It seemed strange to fail all at once though.

I had about 20 min left on the drive home. I was able to determine that the high voltage kicked in at 2500-3k rpm, and it would drop back to something in the "normal" range at about 1800.

Took some measurements when I got home.
At idle it was just under 13v, like 12.95-12.99. Engine off it was 12.5-12.6.
When I revved it it surged to 17v and higher.

I guess my question is do I bother trying to track down just the V reg or would I be better off just replacing the whole alt?

I have located a replacement available locally for $105, after $45 core and $35 discount code. It is a reman.

 

[stephen newberg]

You should check the battery first, if it is not very new. I was getting similar things on mine and it turned out every cell was failing, though still somewhat functional, and the battery was less than 2 years old.

pax, smn

 

[Liquid_force]

Yeah, but 17-18v is obviously not coming from the batt.

After sitting overnight I went out and checked it again this morning. Cold voltage was 12.5. Key on, 12.25. Idle voltage 13.7-13.8v. Revved it and it jumped up to more than 18v.

Called the local auto elec shop and told them the same story. Their first guess was worn brushes. They also mentioned it could be the reg, but that the brushes are usually the first thing to go.

Rebuild is $90-100 and would take a day so I'll probably just go with the reman.
I suppose I'll put a new serp on it too.

 

[luigisho]

Rebuilds and remans are a crap shoot and you may end up installing several until you get a solid performing unit. Will the rebuild shop install it or do they just want you to bring in the unit? If they do the install and warranty the work, you may end up saving yourself some extra install/removal work.

 

[stephen newberg]

The 17-18 volts can be a transient reading as the alternator tries to catch up to the battery not doing what it should. It then went down to 14-14.5 or so, right? Idle then dropped to the mid 13s, right? Next day the battery cold indicates a bit over 12. I think it is your battery, but do regard luigisho's comments about rebuilt and re-manufactured alternators if you decide to go that way. First though, if I were you and if I wanted to possibly save a lot of money and time, I would check each of the battery cells. If the end cells or 3 or more total cells test as poor to bad, the alternator is not your problem.

pax, smn

 

[Liquid_force]

Rebuild cost was w/the alt off the car.
If that was for everything I'd jump on it in a second.

 

[stephen newberg]

Ya, me too. But getting the alternator off and on is a major hassle, and if you are paying someone to do it, outright expensive. Might be smart to check out the battery completely before going to the alternator, particularly considering that the symptoms detailed fit very nicely with a failing, though not yet dead, battery.

pax, smn

 

[newshofan]

I had my alternater replaced in december. I took one look at where it was and deicided it was more than I could handle. I called around and was told by one shop four hours labor.i thought that was a lot. I called another and was told 2.5 hours and it was a motorcraft alternater. 257.99 for alternater and 162.50 for labor.I asked them afterwards if it was a PITA and they said it was. Expensive but well worth the hassle of doing it yourself.

 

[Liquid_force]

I bought this car with the understanding it would require some TLC, and the further understanding that I'd almost always get the repairs figured out myself.
Things like alts...I'm definitely going to figure out.

Regarding the replacement...honestly not as bad as some of the step-by-steps made it look.

I started by putting the front of the car on ramps. Took out the cowl on the pass side. Pulled the one large vacuum line that runs across the back of the engine down to the firewall.
From there it was just a matter of positioning myself to remove the top nut and bolt from the alt. I spent a half hr to 45 mins repeatedly getting the wrench in position only to get about 1/8 of a turn out of it. At some point during this process I remembered to disconnect batt (-). Eventually, I figured out if I stood along the pass side of the engine and basically laid over the engine compartment I could reach down my left side and get my hand on the bolt to turn it by hand. From that point it was about a minute and it was out.
If I'd figured out that procedure soon after breaking the bolt loose the hr I spent getting to that point probably could have been cut to 10-15 mins.

Jacked the rt frt enough to clear the ramp. Took off the wheel, took off the front splash guard.
Took off the little bitty splash guard blocking access to the alt.
Pulled the 3 wire connector. Removed the 10mm nut holding the output wire.
Took the belt off the tensioner and removed belt.
Took the two bottom alt bolts out which freed the alt.
It was maybe another 1/2 hr-45 min to get to that point.

It was obvious I needed to get the tie rod free from the knuckle. Had to run to advance and rent the pitman arm puller. So that step took about an hr (5-10 min if I had the tool on hand).
Got that off, turned the hub to the right moving the end link out of the way and the alt came out pretty easily.
Surprised to find a "remanufactured" label on the non-working alt. I bought the car with about 91.5k so the original obviously didn't last long.

Break time.

New (well, another reman) alt...
Tricky maneuvering it into place, but got it through in just a few mins. Two bottom bolts went in first, just hand tight.
Top bolt in, tight, bottom bolts tight. Top nut on. Vaccum hose back in place. Cowl in.
Another hr or so to that point.

Elect connector plugged in. Output wire and nut tight. Just about home.

Tq'd the tie rod castle nut to 40, the cotter pin slid right in.

Installed new serp belt -- not fun. Messed around with that for a good half hour to 45 mins. Possibly the single most difficult portion of the job.

Splash guard back on. Wheel on. Reconnected batt.
Lowered back on the ramps.

Started.
Initial voltage 14.56.
Test drove for 5-10 min. All is good.
Chk voltage again. 14.36 at idle. No chg revving to ~2k.

SHO's back in good health -- at least for now.