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Discussion Starter · #1 · (Edited)
Hey all

So I decided to hose down my engine bay. I covered a few things with a plastic bag, including the fuse box, but I didn't cover the alternator because I wasn't planning on starting the engine for a couple of days after by which time the water that got inside the alternator should have evaporated. Regrettably, the alternator has failed.

After starting the car, the battery warning light came on. Also, the alternator was making a squealing noise. See the video here to hear the sound at 1500 RPM, 1100 RPM and 800 RPM (barely makes any sound at 800 RPM).

Alternator

My battery went flat in just over an hour.

I have checked both the ACG(S) fuse (37) and alternator/fuel pump fuse (12). Both are are fine. I also disconnected the alternator power cable and let it sit overnight to allow any water that may have gotten inside to evaporate. This didn't help.

The fact that the alternator is now making a squealing noise makes me think the problem is mechanical rather than electrical but perhaps its both.

What do others think?
 

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Get a can of CRC electric parts cleaner, spray it into the alternator, then let it sit. Leave the hood open so it can air out properly. (Don't let the fumes accumulate.) That might work, but the act of turning it on while some internals were wet might have ruined the alternator. The alternator is designed to repel water that is splashed on it, but my guess is you accidentally pressure sprayed into the alternator.
 

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If it's squealing, that's usually a dead giveaway that the pulley bearing has gone bad or that something internal has locked up and isn't moving. Water shorts electrical systems - There only has to be a little to be enough to bridge rectifier diodes, and that will cause your alternator not to work properly....but the squealing tells me the same as you - that it's something mechanical. Got anyone local that rebuilds alternators? Otherwise, you might want to start looking for a replacement.
 

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Discussion Starter · #4 ·
Get a can of CRC electric parts cleaner, spray it into the alternator, then let it sit. Leave the hood open so it can air out properly. (Don't let the fumes accumulate.) That might work, but the act of turning it on while some internals were wet might have ruined the alternator. The alternator is designed to repel water that is splashed on it, but my guess is you accidentally pressure sprayed into the alternator.
Thanks for the advice. Wouldn't CRC degrease the inside of the alternator though?

Also, the weather where I am at the moment is seeing on average sunny 24 degree days. The water should have evaporated after two days.. I hope!


If it's squealing, that's usually a dead giveaway that the pulley bearing has gone bad or that something internal has locked up and isn't moving. Water shorts electrical systems - There only has to be a little to be enough to bridge rectifier diodes, and that will cause your alternator not to work properly....but the squealing tells me the same as you - that it's something mechanical. Got anyone local that rebuilds alternators? Otherwise, you might want to start looking for a replacement.
Don't you find it a bit strange though that a light garden hose could ruined a bearing?

Everything seems to be moving from the video, don't you think?

I really hope that you are not right about the alternator shorting out. Do you know if an alternator holds residual power after a car has been switched off? I am thinking perhaps it could have been holding a charge when I hosed it down.

Nah I don't know anyone and don't have time to mess about like that. I would rather just do like you said and get another one.


Thanks for your comments guys!
 

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Thanks for the advice. Wouldn't CRC degrease the inside of the alternator though?

Don't you find it a bit strange though that a light garden hose could ruined a bearing?

Everything seems to be moving from the video, don't you think?

I really hope that you are not right about the alternator shorting out. Do you know if an alternator holds residual power after a car has been switched off? I am thinking perhaps it could have been holding a charge when I hosed it down.
wince the contact cleaner might do that - the main active solvent is acetone (I use this CRC brand of contact cleaner all the time at home and at work), which will displace water and speed evaporation, and works very well to clean electronic components and connectors, etc...but it also functions really well as a degreaser.

It's unlikely that the bearing was ruined by a simple wash with a garden hose, but the wash may have knocked loose some particulates that then became contaminants inside. It's maybe not the bearing (the video sure shows it moving ok), Just keep in mind that the car is 30 years old, and that the alternator is a perishable component. It might have nothing to do with any specific problem other than age and normal wear and tear. It's too bad you don't have an automotive electrical place around that can rebuild alternators and starters - those are usually the best and least expensive way to go, rather than buying a cheap brand new alternator made in China and having it fail within the next couple years. The only things that usually go bad on an alternator are the pickup brushes and the rectifier diodes that keep your electricity all moving the same direction. Diodes are cheap and easy to replace - you prolly could do it yourself, but I've never replaced brushes on my own - you probably have to have the alternator all the way apart to replace those. Diodes are usually on a PCB either mounted directly to the outer housing (under the protective plate on the back) or just inside the housing. You might consider removing the alternator from the car and taking that plate off to have a look. It's more than possible they could stay wet in there.

As for keeping a charge after you shut down the car, an alternator cannot do that. There are no capacitors or batteries in it. The moment it stops spinning, it stops generating electricity.

I think it's more than possible that the squealing had to do with the belt being wet or damp and not making the solid contact on the pulleys that it should, and that it will go away - It's also very likely that the diodes got wet under that cover plate and ceased to function - the alternator will still work, just producing about 1/2 the power it should be because the other half goes the wrong direction when the diodes are not working. Diodes are hardy, solid state electronics - they let electricity flow in one direction, but not the other.
28840


That's a typical alternator diagram, not necessarily the same as a 'lude, but probably similar. The triangular shaped things with the bar across the tip are the electrical diagram for a diode, the triangle serving as an arrow indicating the direction of electric current, and the bar indicating from which direction current is blocked. You can't go 'in' through the 'out' door. LOLMake sure the diode banks are dry - they might start working again once there's not enough moisture around them to short them.
 

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If you are sure the squealing noise is not the belt loose on the pulley or your power steering idler pulley- replace or rebuild the alternator. Preludes are now very old cars and everything that has not been replaced recently is on borrowed time... they arent that expensive but it will save you a lot of hassle in the future... From memory there is a 90A upgrade you can do....
 
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Discussion Starter · #8 · (Edited)
So I cleaned out the alternator connector and the port that it plugs into with two passes of WD-40. These things were filthy! Check it out...




This is the result of the port after the WD-40...



Cleaning the connector and port didn't resolve the issue, so now I am pulling apart the alternator to degrease everything with WD-40 and repack the two bearings with bearing grease.

I have hit a problem dissembling the alternator because Denso wanted to be impractical and seal the case with a shitty design. I am hoping someone can help me with it.

There are four nuts and four of something else with threads that hold the case together. I have removed the nuts but I don't know how to remove the thread things. Check out the photo's to see what I mean...


Does anyone know how these thread things can be removed?


So far, this is what I have removed...



This is the brushes and slip rings. I don't think they are the problem but if anyone can see something that isn't right then please let me know...


 

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An Accord alternator or the none vtec H23 alternator would net you a 90amp replacement and just needs to use a bolt and nut since there is no threading on those alternators.

Plus you can take off the pulley and swap them over.
 

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Yeah, if you can find one of those Accord ones, they're a tad more powerful.
You went way further into this than I thought you were going to. LOL Rebuilding an alternator is going to be good experience, though. Teaches you not to be afraid to rip into something broken and see if you can fix it. After all, you've got nothing to lose, right? It's already broken and not working, you're not out anything but time to try it yourself.
I'm pretty sure those studs are pressed into the pulley side of the housing, but that the other half of the housing comes away. To save time in the future, you don't have to host your photos on a separate site - you can upload them directly to PP.com. It used to be that way, and I'm thankful it is no longer.
The Denso part number on the tag should tell you what model it is, which you can then look up "alternator rebuild kit" on ebay to find brushes, rectifiers, bearings, the whole schmear. This link should take you to exactly what you need:


Doesn't say anything about being compatible with a 'lude, but it says it's for a '90 Accord, which should be exactly the same thing. Price is good....I might order one of these and try it myself - I do happen to have an old alternator core or 2 laying around, and I'd much rather rebuild them than buy the cheap Chinese-made crappy ones I was talking about as replacements.

The brushes maybe could stand replacement with fresh new ones - you've got it all apart, so you might as well. The heat-sink looking thing in the 2nd and 3rd picture you put up attached to the connector terminal is the diode bank (rectifier/regulator). With the rebuild parts available, there's no real reason to mess with it any further. Only worry about taking those studs out if you have to in order to get at the bearing. Don't go at those pressed in studs with a hammer. It might take them out, however, it's just as likely it might break the cast aluminum housing, and then you'd be SOL, and there's the distinct possibility that the threads could be damaged or the end mushroomed, also landing you SOL. The rebuild parts come with a new connector terminal, making your cleaning redundant....but the wiring harness side on the car will thank you to shoot some electrical contact cleaner in there and grease both side with dielectric grease after. WD-40 will displace water (it's what the WD in the name stands for, after all), but it's not particularly good for electronics - tends to soak into PCBs and so on. Also, it doesn't dry very clean.

Keep us updated with your findings! I'm super interested to see someone document an alternator rebuild!
 

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Discussion Starter · #11 · (Edited)
I'm pretty sure those studs are pressed into the pulley side of the housing, but that the other half of the housing comes away.
Thanks! Yeah, your right. I had a look at a couple of videos on YouTube of other people taking apart their alternators and saw that the bolts are not threaded in the centre but the casing is stuck together like you said. You need to beat the casing to vibrate it apart. I have a rubber mallet for this.


WD-40 will displace water (it's what the WD in the name stands for, after all), but it's not particularly good for electronics - tends to soak into PCBs and so on. Also, it doesn't dry very clean.
That is interesting about the name.

Yeah I find 40 doesn't dry clean on things either and I usually have to clean surrounding surfaces after with a cloth.


As much as I would like to rebuild my alternator from that kit just I don't have time to wait. I think the problem is just the rear bearing has ran out of grease. If degreasing the alternator and repacking the bearing with grease doesn't fix it then I'm just going to get a Chinese one to keep me going because the car has done 383xxx kilometres and I will be getting rid of it at 394000 as it will be due for a major service and I want to get another car. I have had the Prelude for almost eight years.

I can't get to one of the 8mm nuts on the case as I no longer have a socket set so I will need to borrow a ratchet and socket from my neighbour tomorrow. I'll keep the forum posted.

Thanks!
 

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The copper slip rings will not l3et you take the case apart. You need to remove the pulley nut and pulley from the other end. If you don't have an impact wrench this can be a chore. If you find that you are not able to do this, run the alternator down to a shop and they will zip it off probably for free.
 

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Discussion Starter · #14 · (Edited)
Are you sure about that? I am trying to access the rear bearing. Section 16-72 (Alternator Overhaul) in the shop manual states:

NOTE: It is only necessary to separate the pulley, drive end housing and rotor when the front bearing needs replacement.

Check it out...


Perhaps the shop manual is wrong. This wouldn't be the first time.
 

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I read the same manual but remember not being able take the alternator apart without first removing the pulley. Last year I had problems with replacing my alternator with a working rebuilt. I was finally able to swap around parts from 3 alternators to finally come up with a working one. My problem was finding a working voltage regulator. I can tell you that those 4 long through bolts are not just straight bolts.
 

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Discussion Starter · #17 ·
I think that's the way it is and Honda got it wrong in the shop manual.

I damaged the alternator while banging it with a hammer and it's become too much of a hassle to get the parts for a repair. Given I am planning on getting rid of the car in 11000 kilometres, I am just going to get a second hand alternator or an OEM unit to keep me going, what ever's cheaper.

This one looks good...


Thanks for helping out, it is so appreciated!
 

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You are welcome.. Yes...get a new one. I have bad luck with rebuilt alternators. I don't believe rebuilders actually test very well. With a multi meter you can test the stator, rotor, diode packs and you can visually check the brushes. What you can't test is the voltage regulator and it seems, neither can they. Good luck
 

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I too have not had good luck with pre-packaged reman alternators - they usually last about a season or two, then they're due for replacement again already. Rebuilt by a local shop to quality standards, that's usually as good as new, but the pre-packaged ones only come with like a 30 day warranty, and there's a reason for that. Anyway, it sucks it got damaged, that's too bad. But, the cheap replacements are better than nothing....and it's not like those can't be rebuilt by your own hands with the same kit if they fail.

And yeah, not kidding about the WD-40! WD-40 literally got its name from what it is. Water Displacer, desired results achieved on the 40th try, meaning formula number 40 - 1 thru 39 didn't work the way they hoped, so they let them go LOL! That really is the history behind that. Thank you, How it's Made! XD
 
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