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Old 17th March 2010, 14:04   #1
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Default Does a Bad Alternator lead to power loss of the Engine

Does a bad alternator lead to power drain from the engine.

Explanation: My car (M-800) at 3rd gear is doing easy 40-50, but sometimes I need to shift to 2nd because I can feel the Revs dropping. This is mostly in the case for the 3rd and 4th Gear. I suspect it to be the clutch, but can a bad alternator have an effect like this?

Please advise.

Last edited by krazydriver84 : 17th March 2010 at 14:11. Reason: forgot to mention the vehicle
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Old 17th March 2010, 14:18   #2
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Only if in case the alternator bearings are gone and if so you should hear a grinding sound from under the bonnet.
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Old 17th March 2010, 14:25   #3
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Quote:
Originally Posted by Psycho View Post
Only if in case the alternator bearings are gone and if so you should hear a grinding sound from under the bonnet.
There are no grinding sounds from under the hood. So am guessing the bearings are ok. However, while driving, sometimes the lights, Display lights go suddenly bright and then come back to normal.

So am wondering if the power loss is due to the alternator or not?
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Old 17th March 2010, 14:50   #4
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Quote:
Originally Posted by krazydriver84 View Post
There are no grinding sounds from under the hood. So am guessing the bearings are ok. However, while driving, sometimes the lights, Display lights go suddenly bright and then come back to normal.

So am wondering if the power loss is due to the alternator or not?
It would be a good idea for you to get the rectifier checked on the alternator for the sudden brightness issue.

Else it should not be the alternator.

PS: You didn't mention if the problem was when you were going uphill, overtaking or normal driving, also how many km has the car done?
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Old 17th March 2010, 15:01   #5
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Will get the rectifier checked this weekend.

The problem is during overtaking. The main problem seems to be that am losing revs. Usually the car bolts till 60-70 in 3rd, but recently it just seems to be losing the revs.
Car has done 1.06L Kms.
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Old 17th March 2010, 15:27   #6
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Revs don't drop because of a bad clutch - they rise when the clutch slips (without a corresponding increase in the speed of the vehicle).

Your's is the carb model right? I would suspect the fuel pump.
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Old 17th March 2010, 15:36   #7
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Its a 2003 MPFI model.
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Old 17th March 2010, 16:14   #8
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I am assuming that you mean lack of power when you say loosing revs. If so please do take it to your mech and have the compression tested for ring wear.
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Old 17th March 2010, 16:19   #9
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Bad alternator means poor charging of the battery and hence your batteries are drained out if you use electricals like headlights,music system.A batterywala can help identify this.

Get your plugs checked in addition to what the experts have said.

Any competent workshop should help
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Old 17th March 2010, 16:20   #10
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Does M800 has a dedicated RPM meter ? How do you check the dropping revs ?
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Old 17th March 2010, 16:30   #11
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hey Amit, 800 does not have a dedicate RPM meter. well I can feel them,
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Old 17th March 2010, 17:58   #12
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The first sign of a bad alternator is the glowing of the battery sign on the dashboard. If your battery sign is not glowing after starting, your alternator is fine. If you feel your car is loosing revvs, get your brakes checked. It might be that your brakes are jammed and is not letting the power translated totally on the wheels.
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Old 17th March 2010, 21:51   #13
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Quote:
Originally Posted by krazydriver84 View Post
Does a bad alternator lead to power drain from the engine.
...
Hi,
Yes, it does.

Used to be a not uncommon problem with alternators of a particular manufacturer, but have not heard of it of late.

The voltage regulator used to either fail totally, or become intermittent in its action, allowing the output voltage to rise unchecked. Would lead to boiling the battery dry, fused/blackened bulbs, and a significant drop in fuel economy. And in the 800 cc you could make out the drop in power. A larger engine would mask it.

Old MASS hands should be very aware of this.

Most people don't think of the alternator as a suspect. Why did you?

Regards
Sutripta

PS. Strange. Just after this post, saw the post on bubbling battery!

Last edited by Sutripta : 17th March 2010 at 21:59. Reason: Added postscript
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Old 18th March 2010, 00:24   #14
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Quote:
Originally Posted by Sutripta View Post
Hi,
Yes, it does.

Used to be a not uncommon problem with alternators of a particular manufacturer, but have not heard of it of late.

The voltage regulator used to either fail totally, or become intermittent in its action, allowing the output voltage to rise unchecked. Would lead to boiling the battery dry, fused/blackened bulbs, and a significant drop in fuel economy. And in the 800 cc you could make out the drop in power. A larger engine would mask it.

Old MASS hands should be very aware of this.

Most people don't think of the alternator as a suspect. Why did you?

Regards
Sutripta

PS. Strange. Just after this post, saw the post on bubbling battery!
Hi Sutripta,

Thanks for confirming my suspicions.
The reason I had this suspicion, was times when the lights used to go bright, I used to feel a slight drop in power of the car, and when the lights used to return to normal, I would feel the car surge a bit. Although these lasted a few seconds, I could still feel them under me.

However, taking everybody's advice, am gonna get the following work done this weekend:

- get the brakes checked for any jammin. (Precautionary check)
- Get the voltage regulator of the alternator checked and replaced if necessary. (top most priority)
- also get the compression of the rings checked (I highly doubt this)
- Get the clutch checked (Top most priority)

Any more advice.

Last edited by krazydriver84 : 18th March 2010 at 00:26.
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Old 19th March 2010, 13:18   #15
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krazydriver: I would also suggest get the electrical wiring inspected (potential rat bites) :-) as well. What you have mentioned about a potential electrical issue can happen due to rats - please note
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