Ford Escape Alternator light at higher RPMs

[ab_slack]

I know the Escape is a bit outside the focus of this forum, but I am active here and I know plenty of you have experience outside RBVs.

This is a 2003 Escape with 3.0L engine.

Observed that when accelerating and vehicle downshifts that alternator light flickers and there is a noticeable dimming of the headlights and dash lights.

Put a meter on it, and while sitting parked, battery voltage was good with vehicle off. With it on it went up to 14V to 14.2V. Again that seems fine.

Pressing the gas pedal slowly, at a point above 3500rpm the voltage drops down to battery voltage (12V to 12.5V bouncing). This seems to support the other observations (battery light and dimming head lights/gauges). At the same time it seemed the engine started making am odd springy bong or boing sound about once a second. Like if a pendulum were hitting something that reverberated a bit. It wasn't louder than the engine, but a very definite tonal shift. Like revs were going up and something made them fall suddenly, but when driving there is absolutely no sensation that engine power or RPMs drop.

My thinking is that maybe the belt is slipping and grabbing but there is no squealing at all that I normally would associate with a belt. Wondering if maybe tensioner is sticking/bouncing so the belt alternately functions/slips.

I intend to replace the belt anyway, but if there is anything else I should be looking at I appreciate the input.

Thanks in advance for any thoughts.

 

[adsm08]

Your experience of the engine not revving above 3500 in park in normal. You hit the rev limiter.

As for your voltage issues, I would say the alternator is giving up the ghost. It is possible for an alternator to become weak and give out good power at idle, when demand is low, but not be able to keep up at higher RPM. The faster the engine spins the more power is needed because the injectors and coils are firing faster and the fuel pump is running harder.

I'd get a new alternator to go with that belt.

 

[Bob Ayers]

The actual reason your alternator is not charging at high RPMs is due to worn brushes. At the higher RPMs, the brushes are bouncing, loosing contact with the slip rings.

Replace the brushes, and inspect the slip rings for abnormal wear, and you will be fine.

 

[ab_slack]

Great feedback, thanks.

adsm, you know I was gonna describe it as if it were bouncing against a rev limiter, but I thought, na, can't be that cause I am pretty sure it was over that while driving. I am guess that the revs limit that low because it is park? Thank you for the clarification that it is normal. I feel much better knowing that.

 

[Road Angels]

alt

It may not be the brushs, it could be a bad front or rear altenater bearing( broken bearing cage ) causing bad brush contact, rotor is wobbling all around also causing the noise pull the belt spin the unit see if there bad

 

[tmcalavy]

Replace it soon...it's eating your battery right now.

 

[ab_slack]

Replace it soon...it's eating your battery right now.

Battery still seems good, but the alternator isn't functioning at all. Not great timing, but at least a bit of warning has helped as I was already preparing to work on it.

Unfortunately it looks like it is going to be a bear to replace. I've uncovered some good tips to help reduce the amount that needs to get taken apart first, but still it seems like it won't be an easy one.

 

[Sasquatch_Ryda]

They are a bitch to change....even on a hoist.

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[YungICY]

Sorry to hijack your thread ab_slack but I have a very similar issue that just started.



Let me give you the quick history.



Bought my truck (85 ranger 2.3) 14 months ago.



Alt light was ALWAYS on.



3 months ago the alternator and battery both went out. Replaced both.



Light still on. Know this shouldn't be with a new battery and alt I replaced the external volt regulator.



Light off.





6 weeks later alt goes out. Light never comes on. Used warranty and replace.



6 weeks later (today) driving on freeway. Gauge light comes on, all lights dim a lot. Stays like that for a minute or to then goes back to normal for a minute or two and repeats for the duration of my travels.



Any thoughts? Voltage regulator? Alternator? Wiring? Belt (which does need to be replaced)?


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[ab_slack]

I am not sure what is up with the light. I am certainly no expert, but others may chime in. Not sure what was the symptom where you knew the alternator failed the second time. Battery died and wouldn't charge?

Anyways, the most recent symptom sounds like car is running from the battery alone now. That the alternator is not supplying power. This can be caused by four things as I see it in no particular order of likely hood.


1) Alternator belt broke or slipping really bad. The slipping may occur at certain temperatures and RPMs. This should be obvious by looking (i.e. belt broken) or squealing when slipping so this probably isn't it.

2) Alternator has failed

3) Regulator/Rectifier has failed. I usually lump this with alternator as they are integral but since you said you replaced separately I list separately here.

4) Wiring or connection issues.

The most likely failure in alternator, particularly a new one is the regulator/rectifier. The alternator in itself is mechanical with wires. The mechanical stuff wears. It can go bad fast but generally shouldn't while the regulator/rectifier as semiconductor parts can get damaged much easier and in shorter periods of time.

As I understand it, typically what kills the regulator/rectifier is a bad battery that's doesn't charge up and continues to draw higher currents.

There is potential if output from alternator goes open that voltages can get too high at alternator/regulator (no place for energy to go) but this is an abstract thought and not one I have heard can happen in practice.

With the battery what kills them is not getting charged in timely manner (allowed to sit with low charge) and/or getting discharged too far. Also any kind of AC charge/draw can weaken and damage battery. So a bad alternator/regulator/rectifier can create the conditions to kill a battery.

Now you got 6 weeks after replacing the alternator the second time. Has your battery cranked the engine strong? Does the battery seem fine? If so it is probably good enough that it didn't cause alternator to fail. If it hasn't been so good it may have hurt the regulator/rectifier if that is separate from the alternator as you indicated.

If not that I tend to think there may be a wiring issue. The wire from the alternator to the battery or bad ground connection on the alternator. This isn't to say a failure in the rectifier/regulator doesn't exist now either. The connection probably may cause the failure. A loose connection, intermittent short or maybe wire broken inside the insulation which makes it seem okay but it intermittently goes open. Those are my wild guesses.

 

[YungICY]

Thank you. That was extremely informative. The battery has been cranking great on start up. I'm gonna replace the belt and check for wobble in the pulley and check the wiring. If those don't help I'll replace the regulator.



From your info. I feel like that will fix the issue. Thank you very much.


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[ab_slack]

Replaced the alternator in the Escape today and appears to have resolved the problem. It was not particularly easy but not as bad as I feared. Still took about better part of four hours not counting the clean-up. I could probably cut the time in half next time since I picked up a few tricks that weren't mentioned in what I had read.

The trick getting it out between the back of the engine and fire wall worked well enough once I gave up trying to pull it up and pushed from the bottom till I got it above the lower hose back there. One of those tricks I learned. It was pretty darned tight and I had my doubts, but it did make it.