Killing Alternators When Boosting Above 15psi | Ford Escort Owners Association (FEOA)
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Killing Alternators When Boosting Above 15psi

Discussion in 'Forced Induction & Nitrous' started by vtec-this, Jan 10, 2013.

  1. vtec-this

    vtec-this FEOA Member

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    twice now I have run over 15psi for a week or so doing a few pulls a day in my bp powered MSP.

    both times the alternator ended up dying.

    both alternators were from 91 escort gts. im hoping they failed because they are 22+ years old.

    i put in a new rebuilt alternator from parts source a couple months ago that has not given me issue yet, but i am hesitant to turn it over 15psi until i move into a new house.

    at 15psi in 3rd gear cruising at 100kmph I can mash the gas and the tires spin. seems good enough for the winter.

    i havent had a garage to work in since i sold my house in october but in march i should either be leasing a house or will have found a new house to buy and will have a place to work on the car again, so I will turn it up over 15psi again as I will have somewhere better than the side of the road to put it back together if anything breaks apart at high boost.

    still trying to figure out whats up with alternators dying though.

    Even with the new alt and pretty much ever since ive swapped the bp the lights are always dim when i first start the car. doesnt matter if i have a brand new optima red top or even my buddy's new f150 battery, they are always dim at first. even the interior i would say are 10-25% dimmer. but once the motor is revved over ~2300rpm everything brightens up as normal. just sort of been living with it for years and it never really bothered me, but I am wondering if its somehow related to the alternator dying under high boost. the car always starts up right away so its not like im lacking power or cca or reserve power etc, and it happens even when i have all lights off except for drls too so its not like im putting some massive electrical load on the alternator from having lots of lights/fans on during/after cranking. even if i start the car and let it sit there for ten mins warming up, the lights are dim the whole time. the second the rpms go over 2300 its bright like normal and stays that way until the car is turned off.

    i have more grounding straps than anyone I know all over the engine/trans to different points on the frame so i know its not the grounding, but i am curious as to what else it could be.

    does anyone on feoa have any ideas? my buddy hooked up his multimeter and performed a battery / alt voltage test as described in the haynes manual and all seems fine..

    Handling my ignition I have a megasquirt ECU, stock EGT ignitor, MSD blaster coil, stock distributor, bosch wires and colder copper plugs.
  2. vtec-this

    vtec-this FEOA Member

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    [youtube]http://www.youtube.com/watch?v=o4KmkKLyJrs[/youtube]
  3. vtec-this

    vtec-this FEOA Member

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  4. ShakeZilla19

    ShakeZilla19 My name is ^^^

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    I ran into a similar problem, while working on some dude's 03 mustang. He increased his boost by putting an ODP on his supercharger. After that, whenever he hit 6200~RPM his battery light would come on and the alternator would stop charging. He replaced battery once and the alternator 3x. I said maybe an alternator UDP would fix the issue. He got one, put it on and it solved the problem.

    I think what happens is the extra horsepower from the crank turns the alternator harder, not necessarily faster, and that causes the alt to stop chargering or in your case die altogether. If the rebuilt alt does the samething, I would try putting an UDP on it to see if it helps.
  5. vtec-this

    vtec-this FEOA Member

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    interesting that you mentioned the pulley.

    I was playing around with my idle the other day and when I slowed the motor down to the point where it was pretty much stalling, just over 400rpm I noticed a SLIGHT
    and I mean SLIGHT wobble on the crank pulley.

    When I bring it back up to normal idle i cannot notice it at all. I guess it is too minor for human eye to pick up at higher speed.

    I hit the pulley bolt with an impact and it was still there so the pulley is on tight and the wobble is still present.

    I wonder if that could also be contributing, possibly putting some "wobble" side loading into the alternator.
  6. Jeffescortlx

    Jeffescortlx FEOA Member

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    What part of the alternator is failing? Bearings? Brushes? Diode/Regulator?


    Are you using an UDP?
    It's not uncommon for an alternator to need 1200 or so RPM's to ouput it's full 14.4v.
  7. vtec-this

    vtec-this FEOA Member

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    i warmup at 1200-1500 rpm/

    its a stock 91 egt motor/pulley
  8. ShakeZilla19

    ShakeZilla19 My name is ^^^

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    Idk if the pully wobble would cause it. It's definitely odd either way. :lol:

    How is the alt. wired?
  9. Jeffescortlx

    Jeffescortlx FEOA Member

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  10. vtec-this

    vtec-this FEOA Member

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    the first one looked like a fire went on inside of it. the connection to + was also half melted.

    the second one it seemed the bearings were gone as there was play in the pulley, however the internals also looked scorched, just not as bad as the first time.

    I did not take the second one apart as I used it for my core return.

    I did a check of the new alt again last night and it looks good as good can be so at this point if nobody else is having problems I am going to conclude that the issue was either:
    a: 22 + year old alternators being run hard
    b: some sort of wiring issue that only shows its head periodically (maybe over certain bumps/vibrations a wire is grounding out?)

    either way if i have the problem again i will be sure to post back here.
  11. vtec-this

    vtec-this FEOA Member

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    ok well new updates:

    it turns out my crank pulley which i thought was in great shape certainly is not.

    I noticed that the damn wobble at low low (like 400)rpm was not going away so I removed the pulley and found some bad news.

    1. the pulley (which is essentially held together by rubber) is actually torn pretty much the whole way around. Unless you pry at it a bit, you would have no idea that the rubber has separated. Just sitting there it looks fine, but put some pressure on it and you can see the rubber is barely holding it together.

    I am assuming the reason my bolt kept coming loose was because this wobble would constantly be loosening the bolt, regardless of torque/lock tight applications.

    the wobbling pulley would then side load whatever alternator I had in the car and burn it up in short order.

    2. upon removing the pulley, I found that my crank timing belt gear is off about half a tooth, and the little rectangular key with flat end no longer resembles anything that I remember installing. It looks more like a "Z" piece from tetris game.

    3. although the key was fubar, the crank APPEARS to be OK. I guess the key is made of softer metal so the key got messed up, but the crank "keyway" i guess you would call it looks OK.

    I managed to take the little key, hammer it back into something that somewhat resembles the stock key and reinstall. New locktight, 120 foot pounds on the bolt. Start it up and she wobbles even worse than before.

    So now I am at the point where I need to locate a new crank pulley/crank timing belt gear/key.

    Trouble is, I believe the 91 EGT pulley is different than all the other years of EGT, but I am not really sure.

    Called partsource, they cant get any pulleys. Called napa, they ordered the pulley, drove all the way there, and its a damn 1.9 sohc pulley.

    Running out of ideas. there is apparently a local guy selling a whole 91 motor for ~$100, but he wont seperate the pulley.

    I figured that maybe I could look into something aftermarket, however I am not sure how the BP would react to a lightweight crank pulley and high boost.

    the other issue I have is I would prefer to order a pulley that can be used on both my 91 EGT motor and my GTR motor, however my GTR is stuffed away in storage and it would take me forever to get the damn thing out right now just to verify that it has the same crank snout as my 91 egt. Does anyone know offhand if the gtr has the same snout? I never got a pulley on it so I am not sure from pics if it is the same as my 91.

    any advice/input on where to locate pulley in gta canada would be appreciated!

    I found a few posts on CP about the crank snouts. There are apparently 3 of them-Short,Long,Large I believe, however depending on whos thread you are reading the info on them seems to vary.

    From what I understand at this point, the 89-91 1.6 miata, 91 EGT and maybe the first year or so of 1.8 miata all have the same pulley/snout, however I do not know if they have interchangeable pulleys. Mine has the 1 large bolt hole and 4 smaller 10mm bolts surrounding.

    If someone could verify or correct me that would be great because I really need to track down and order the right parts. Dont wanna take another long drive somewhere for nothin.
  12. vtec-this

    vtec-this FEOA Member

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    anyone want a nice lightweight aluminum underdrive pulley for their car?

    send me your mint condition EGT large nose crank pulley and I will send you a mint condition aluminum underdrive pulley.

    I would keep the alum pulley for myself but i hear it is not good to run high boost without a crank pulley that can dampen the vibrations, so if you are running low boost or have no turbo them PM me and we can trade.


    pm me or email [email protected]
  13. vtec-this

    vtec-this FEOA Member

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    FYI, new big nose crank pulley installed, new MPV alternator installed, back to running over 1bar. No issues so far!
  14. ShakeZilla19

    ShakeZilla19 My name is ^^^

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    Nice, glad it was something easy.

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