yay electrical gremlins!

[91blazins10]

Alright I just drove the typhoon to work today after only about 10 miles on the new engine(yes I am that brave) plus it was really nice day and I couldnt leave it parked any longer. Its about 20 miles each way to work and on the way home tonight I noticed that all my power drops off(lights dim ect.) whenever I give it some throttle, at idle it is fine the battery guage looks normal but when I give it some gas it just drops very low and the all my lights dim, interior and exterior.. very strange, alternator is brand new 140amp cs144. any ideas?

 

[SY2932]

Re: yay electrical gremlins!

Double check to make sure EVERYTHING is free of corrosion and making GOOD contact. The connection from the alternator to the battery, and the grounds especially since there are several.

 

[MadPSI]

Re: yay electrical gremlins!

Ok, ok, and ok...

But seriously...

Sounds like a loose ground somewhere. Every time you load the motor you're apparently stressing a connection. From previous experiences, I've found that loose grounds can wreak havoc on your electrical system. I'd first start with the ground connection at your battery. If that checks out, then I'd make sure all the grounds running to your frame and firewall are secure. Note especially if your motor rocks substantially when you give it gas (possible motor mount failure).

Check these things, and if the problem persists, we'll go from there...

 

[sly dvl]

Re: yay electrical gremlins!

You may have a bad rebuild too. I've seen it before; if the rotor is bent then the slip rings will "knock" the brushes back into their housing, breaking the connection and reducing your charging output. Low RPM is Ok but when the Alt. spools up (I just love using that term) the brushes can't follow the bent rotor.

Put a meter on your Alt. output at idle and then slowly increase the RPM. If the voltage drops off as the RPM increases then you have a bad rebuild.

 

[kentuc]

Re: yay electrical gremlins!

Check to see if your fan belt is slipping. The new pulley maybe way small and cause a slip at higher than idle revs.

 

[91blazins10]

Re: yay electrical gremlins!

Alright well since this is brand new engine I just put in, I know its not the motor mounts(solid mounts) that engine doesnt move at all, grounds all check out fine, I kinda figured that because before I started it up I triple checked everything. So heres what I did, I had a old alternator laying around that still worked just squeaks alot and decided to install it just to see if the problem went away, and guess what! IT DID! :tup: So I put the cs144 back in just to see if it would still happen and it does, did a test on the cs144, it puts out 14.7 volts at idle, then drops down to 11.5 when you rev the engine. Looks like this thing is getting returned and I hope they send me one that works this time... :squint:

 

[SY2932]

Re: yay electrical gremlins!

This SURE looks like the belt is slipping behavior. Try this test.

On a cool engine, check the pulley temparature with your hand. It should be cool(ambient) to the touch. Start it up. Rev it up and do the 'low voltage' thing for about 30 seconds. Stop the engine. Now, BE CAREFUL, but touch the alt pulley again. If it's hot-as-hell, the belt was slipping.

If the alternator can produce 14.7 volts at any speed, it's probably OK.

DITTO. You probably don't have a way to measure your pulley diameter but on my CS-144, the diameter is 2.050" My stocker measures 2.200" so, there is over an 1/8" difference in the pulley diameter... You would *think* that the tensioner would over come this difference but you know how that says goes about assuming

. You may have to step down to a shorter serpentine belt. If that turns out to not be the case, be sure to let everyone know how you get taken care of.

 

[91blazins10]

Re: yay electrical gremlins!

Ok a couple more things I have 2 belts and the one I have on there now is .5in shorter than the belt ive used before, because I had issues with the belt squealing alot with the old alternator. Now when I first put this belt on it was very hard to slide on, now it must of stretched out and it was easier to put on but its still tight. Only thing I can think of is my tensioner is not working correctly, I might go with setup that you have Mike that doesnt require a tensioner but that means ditching the stock fan, which I think I might have to do because now having the intercooler blocking the radiator it seems like my engine isnt running as cool as before. I just want to drive this damn thing :rant: I have it limited to 5psi and it feels faster than when I had old motor running at 15psi ...... Im gonna try a couple things tomorrow and we will go from there.

 

[SY2932]

Re: yay electrical gremlins!

Welp, if you decide to spend MORE money lemme know and I'll hook you up with a turnbuckle and I won't even charge you the shop rate @ $100 an hour for machine time

. At the rate that I'm going, I will probably be driving my truck the week before the MI meet. That is, if I even drive it at all this year...

 

[91blazins10]

Re: yay electrical gremlins!

I just did what Dave suggested and its not slipping, the pulley is warm if anything just beacuse the engine has heated up, im going to take the alternator to a local autoparts store have them test it to see whats up.

 

[kentuc]

Re: yay electrical gremlins!

If the alternater is bad it would have to be a bad rotor winding that is loose or bad contact in the brushes

 

[91blazins10]

Re: yay electrical gremlins!

Well got the alternator tested and it is bad, puts out 11.5volts just as I tested before when it was in the typhoon. I really dont feel like waiting to ship this thing back and wait for a new one, im gonna take it apart and see if theres anything on the inside that I could possiably fix.

 

[91blazins10]

Re: yay electrical gremlins!

If the alternater is bad it would have to be a bad rotor winding that is loose or bad contact in the brushes

Just got done taking it apart, brushes were making bad contact because of a couple of big scratches in the slip rings, not sure how they got there everything else looks fine,(I highly doubt now that these alternators are 100% brand new) im gonna sand the slip rings down and put it back together and see how it is from there.

 

[sly dvl]

Re: yay electrical gremlins!

Sand your slip rings as uniformally as possible. Any high or low spots will cause the brushes to "jump" off the rings creating a no charge condition, just like the scratches did.

 

[91blazins10]

Re: yay electrical gremlins!

well its still doing the same thing, the stator looks brand new, I dont see a problem with that. This is the rectifier http://store.alternatorparts.com/index.asp?PageAction=VIEWPROD&ProdID=1469 that is in there now and it looks brand new also. Everything in there looks new except the rotor, it looks a bit burned and used, and for whatever reason the slip rings on it were all messed up. Heres what im gonna do im gonna run to autozone and buy a cs144, swap the rotor out into mine and hope this corrects the problem, if not ill swap other components and go from there. :myclone:

 

[sly dvl]

Re: yay electrical gremlins!

Set your meter to AC volts an connect it to the alt. output terminal. If you have a bad diode then the AC volts reading will be above the acceptable 0.5 volts, AC.
An open diode will result in a low charge rate at all times and will not produce any output, AC or DC. A shorted diode will produce more AC voltage, and will also lower your voltage output at all RPM levels.
Since you have good output at idle and low RPM I doubt this is your problem. I'm sticking with my original diag., bad rotor/slip rings.

 

[sly dvl]

Re: yay electrical gremlins!

A bad rotor (more specifically the slip rings) can contribute to a loss of charge as RMP increases if the slip rings are damaged (gouged) or the rotor is out of balance.
Think of the brushes trying to follow the contour of the rotor like a lifter following the cam lobe. At low speed there's plenty of contact, but at high speed the brushes are forced off the slip rings and are only in contact for maybe 50% of the time, reducing the field current.

 

[sly dvl]

Re: yay electrical gremlins!

Perhaps I misread or missed a post, but was the original complaint not "at idle it is fine the battery guage looks normal but when I give it some gas it just drops very low and the all my lights dim, interior and exterior".
I saw the 11.4 V reading post and just assumed that he was doing the test with the lights on or some other form of load which would explain the low reading when the charging dropped off.
But yes, you're right. If there's no load other then the ign system it shouldn't be that low during a no charge condition.
I've replaced two alternators in my time in the trade for these exact reasons. Good at idle but poor at higher RPM. Admittedly, I didn't repair them. Just diagnosed & replaced.

 

[kentuc]

Re: yay electrical gremlins!

The rotor windings if loose will expand out on acceleration. This would cause an open condition or a short condition. An open condition would result in no load battery reading and a shorted winding will show a load condition. Hence the lower than battery at rest reading.The rotor is shorted.
Repairing alternators since 1964 I have seem this shorted condition only a few times.

 

[91blazins10]

Re: yay electrical gremlins!

Ok I just swapped parts from the working autozone cs144, I swapped out the rotor, and the regulator with the brushes, now the damn thing only puts out 11.5 volts at idle. Only thing I can think of is the regulator is for a cadillac cs144 so maybe its bit different im not sure? The part# on it is different than my other one, but the connector is the same(both have the P-L-F/I-S). Only parts left to swap out is the rectifier and the stator. I never realized how easy these are to work on, from now on im doing all my own alternator repairs.