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Discussion Starter · #1 ·
Hello:

I changed my alternator about two weeks ago(had tested and confirmed failing before replacing).

On the way home today, as I came to a stop light, the lights surged downward and my volt reading went to 10.2 It had been reading about 12.5-12.8
prior to coming to a stop. As I accelerated, the volts went back up to 12.+

Is my newest alternator failing as well. My Saab is a '94 9000CDE Turbo with 2.3l engine. The alternator in put in is 80 amp. Is this the correct rating for the 2.3l turbo engine? I understand there is a 115 amp alternator as well for this engine size.

Any recommendations would be greatly appreciated.

wherewolfe
 

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Both readings seem a bit low. When I had a car with these things on, the driving voltage was nearer 14v.

Could be a bad alternator, but electronic or winding faults are usually result in a complete failure.

I would try: loose belt

Poor connection / rusty earth strap

Stuck brushes

Before blaming the new unit.
 

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Discussion Starter · #4 ·
DaveS:

Good question! No it would not cause these readings. Once the engine is running, the battery pretty much sits idle and has no effect on voltage as the alternator and voltage regulator take over.

The battery has the easy job: just ignite the engine.

wherewolfe
 

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Discussion Starter · #5 ·
Originally posted by sgould:
[qb]Both readings seem a bit low.  When I had a car with these things on, the driving voltage was nearer 14v.

Could be a bad alternator, but electronic or winding faults are usually result in a complete failure.

I would try:  loose belt

Poor connection / rusty earth strap

Stuck brushes

Before blaming the new unit. [/qb][/b]
Sgould:

Thanks for the feedback. I checked the belt this a.m and is seems to have alot of play. I did check the grounds and they are solid. I'll tighten the belts this pm. and see if this corrects the issue.

Thanks again for the reply.

wherewolfe
 

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I dont know the bits on a 9000. If it has the flat belt with 5 or so small grooves against the pulley wheel it needs to be a lot tighter than the old V-belt drives. On my 9-5 it's difficult to find any play at all.

Also I had this type of belt fray badly on my previous car (non Saab). I thought it was just slack, but looking closely (by chance
) I found it was on the point of failing - edge had gone and a tear was starting across the belt. the frayed bits had caught in something and the belt had jumped one groove sideways.
 

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Assuming you've got the multigroove belt and manual tension adjuster, you should be able to press it down only half an inch along the upper stretch, about 2 inches from the power steering pulley.

As sgould says, it's a lot tighter than the old v-groove belts.

If you've got a later car with an automatic tensioner, though, that's another matter....
 

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Discussion Starter · #8 ·
Thanks for the replies, Gents:

My belt is a serpentine grooved belt. The car is a 94-9000CDE. How do I tighten with the belt tensioner? When I replaced the alternator, I popped the belt off by drawing down on the pulley with an 18mm socket and slid the belt back on.

Upon inspection of the belt, it looks almost new with deep grooves and no indication of cuts or frays.

Can you explain how to tighten?
 

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I'm assuming that the system is the same or similar to the 9-5 for which I have details. The 9000 boys will be back from the Saab Owners Club weekend later


You said earlier that you felt the belt was a bit loose.

The only thing I can find in the "Remove belt" section is a note that says "Exercise the utmost care to ensure that the belt tensioner does not break at its end position"


Is there anything on BillJ's www.saab9000.com ?
 

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The belt will be self tightening,and if the belt was slack you would get a good charge at tick over and then lose the charge when revved as this is when the belt slips,so this is the opposite way to your problem.

What loads did you have switched on at the time? eg:heated screen,lights etc etc.
 

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Discussion Starter · #11 ·
Saabman: I had a/c , headlights and radio. The slack I see has about 1"-2"
play when pressing down on the center of the belt.
Prior to changing the alternator, the belt would flex about 1/2 that amount.

It seems surging occurs when I switch on the a/c

Any additional help is appreciated
 

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The slack should be about half an inch.
The tensioner can't be going to the end of its travel.

Unless....
Does the tensioner wheel move when you press down on the belt to get the 2 inch slack? You shouldn't be strong enough to get that much movement by hand.
 

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I have just re-read the whole post a faulty battery could cause it,if the plates have deposited sludge when braking these deposits can short out the plates out and cause the surge you describe,but I doubt this is happening? does it just happen upon braking?

I would check the charging system with a multimeter (the inside gauge is not over accurate),check the voltage under load (ie: lights/heated rear and heater fan swithced on) at 2,500 - 3000 rpm you should get around 13.4v at both the battery and alternator terminals,also check the continuity of all the earths and check the alternator for a good earth check for resistance between the body of the alternator and the earth terminal of the battery plus the main power lead between the alternator and possitive post of the battery.

If all the above checks out OK,the think about the battery?

If it only does it when slowing down do the revs drop to a very low level? ie:just above stalling? as this would cause the alternator to stop charging and a huge load to be put onto the battery alone.So also consider that it may be nothing to do with the charging system at all.
 

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Fair enough.... but he's still got 2 inches of slack in the belt, which is way too much....

This may be a silly question, but you have put it back along the right route? Looking at the drawing it seems possible to do it the wrong way, especially around the water pump.
 

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Discussion Starter · #17 ·
Gentlemen:

Sorry to take so long getting back to you, but emergency room visit early today.

I checked the belt at top dead center. It flexes
1/2-3/4"(actual measurement taken). I also tested the battery and it is 75% on each cell.

I did go back and check the earth grounds on the alternator and to the battery. All all secure and clean. Checked battery ground and is secure and clean.

I drove around later today with all electrical on(lights, radio, a/c, blower full blast) It seems that when I turn the air on, that is when I get a downward surge(dash lights flicker and dull momentarily) Volts ranged from 14.0 down to 11.2, but go back to average about 12.0 while cruising.

What do I need to look for next, or do you believe the alternator is not sufficient amperage to pull a continuous full load?

Two weeks ago, I did have a vacuum leak where the rpms dropped to making the car nearly die in traffic at a stop. I immediately found the leak and replaced the hose and my idle has been strong and steady since. As you noted above in your post, I did probably kick the alternator off and sucked some juice from the battery.

Any direction you can give me is greatly appreciated.

wherewolfe
 

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Discussion Starter · #18 ·
Originally posted by wherewolfe:
[qb]Gentlemen:

Sorry to take so long getting back to you, but emergency room visit early today.

I checked the belt at top dead center.  It flexes
1/2-3/4"(actual measurement taken).  I also tested the battery and it is 75% on each cell.

I did go back and check the earth grounds on the alternator and to the battery.  All all secure and clean.  Checked battery ground and is secure and clean.

I drove around later today with all electrical on(lights, radio, a/c, blower full blast)  It seems that when I turn the air on, that is when I get a downward surge(dash lights flicker and dull momentarily) Volts ranged from 14.0 down to 11.2, but go back to average about 12.0 while cruising.

What do I need to look for next, or do you believe the alternator is not sufficient amperage to pull a continuous full load?

Two weeks ago, I did have a vacuum leak where the rpms dropped to making the car nearly die in traffic at a stop.  I immediately found the leak and replaced the hose and my idle has been strong and steady since.  As you noted above in your post, I did probably kick the alternator off and sucked some juice from the battery.

Any direction you can give me is greatly appreciated.

wherewolfe [/qb][/b]
Gentlemen:

Can you say the word "intermittent ground". I was in the garage last night and took a flashlight to the alternator connections. Noticed the ground was bend at a right angle.
Straightened it out and put some ET around it to keep it straight up and down. Drove car today and absolutely no surges?????

Think I might be on the right track here??

Opinions,please
 

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Hmmm....This is why I told you to check the resistance on all the ground connections
Yes a ground connection that is not making a true connection will break down under a high load but will work fine when not under a high load,This might explain the surges as the ground connection would be put under a lot of load when slowing down ie the brake lights (plus the other high loads) and low revs causing it to fail.

Hope it stays sorted for you
 

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Discussion Starter · #20 ·
Originally posted by Saabman:
[qb]Hmmm....This is why I told you to check the resistance on all the ground connections    :rolleyes:         Yes a ground connection that is not making a true connection will break down under a high load but will work fine when not under a high load,This might explain the surges as the ground connection would be put under a lot of load when slowing down ie the brake lights (plus the other high loads) and low revs causing it to fail.



Hope it stays sorted for you      [/qb][/b]
Saabman

I appreciate your support and help.. next time I will listen more closely!

wherewolfe
 
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