Can a bad alternator cause loss of engine power & misfire?

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AdrianC
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by AdrianC »

DevonMark wrote:If it was the belt, surely the guys at SW Splitz would have noticed this? Perhaps I'll double check that they've checked it

I've no experience of or knowledge of that garage, but can't picture how they wouldn't have noticed... <grin>

I was just including that bit as an explanation of how the charge warning light can't be ignore with an expectation of getting you home without a check on why the light's on.
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by DevonMark »

AdrianC wrote:
DevonMark wrote:If it was the belt, surely the guys at SW Splitz would have noticed this? Perhaps I'll double check that they've checked it

I've no experience of or knowledge of that garage, but can't picture how they wouldn't have noticed... <grin>

I was just including that bit as an explanation of how the charge warning light can't be ignore with an expectation of getting you home without a check on why the light's on.

Yeh, thanks. I'll ask to make sure that they've checked the belt. Appreciate the help!

I just hate having a problem that's not definitely diagnosed.
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DevonMark
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by DevonMark »

AdrianC wrote:
DevonMark wrote:
AdrianC wrote:
The fact that the charge warning light didn't come on makes me sceptical about the nice easy "lack of charge" diagnosis, though. I've nursed cars, not charging, back and had the real fun'n'games of trying to avoid braking because the brake lights mean there's not enough sparks left to keep the engine running. Or misfiring in time to the indicators... But it's taken a LONG while after the charge light's come on for it to get to that stage.

Forgive me here, Mark, but I'm assuming you're not the kind of driver who'll fail to notice/respond to a bright red light for tens of miles...?

I would have noticed it if it had been on for miles, just might have missed it if it came on just as I was steering to safety through serious loss of power!

How fair in advance of a full breakdown would you expect the charge warning light to come on for the 'lack of charge' diagnosis to be feasible?

If we're talking about an alternator/wiring fault causing lack of charge only, then assuming a decent battery, and not sitting in urban traffic, then - even with lights/wipers etc - at least ten-twenty miles, possibly more. Less, if you've got a stonkingly large stereo and amp on or umpteen big fat driving lights.

If it's the belt that's gone, then not very long at all - but it'd be a cooked engine that stops you, rather than lack of charge. The temp gauge wouldn't warn you, either, since water won't be being circulated from hot bits of engine to the gauge's sender.

Right, I know this is a really stupid question (even by my standards), but are you referring to the fan belt or alternator belt?
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by ermie571 »

hey! i think I know the answer to this...my 1.9dg has only the one belt....does the alternator and water pump!

No fan that I can think of in the engine bay...that is Aircooled and is driven by the engine!!

Em
xx

oh - should add that some vehicles have a double belt....but think thats for aircon or power assisted steering or some new fangled modern technology!
Last edited by ermie571 on 07 Feb 2013, 20:05, edited 1 time in total.
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DevonMark
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by DevonMark »

Thanks Em! Thought so, just didn't realise the alternator belt had anything to do with the water pump before today.
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by ermie571 »

No worries....

tip to check....approach van and move to the REAR of the bus. Using key, unlock hatch
next, empty BOOT area of all crap onto driveway or pavement, or chuck over rear seat into main area of vehicle.
lift and remove carpet if one is present
Woohoo - engine lid is revealed!

turn the little turny things about 90 degrees, lift lid slightly and pull forwards....revealing...the engine!
(if you are bored at lunchtime, and have the necessary showbiz character, you can do this like a magic show in the office car park)
You should see the belt right in front of you, going from the water pump on the left, round the main engine pulley, then off to the alternator on the right.



Em
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by ghost123uk »

DevonMark wrote:
ghost123uk wrote:
DevonMark wrote: The van's been up with South West Splitz.... They have replaced alternator...

I bet the clue is there
Summat to do with a little blue wire (on the back of the alternator, it triggers the charging led by the way Mark, if it's not connected the charge warning led won't come on, ever).

Ah sorry, I geddit now - so you're saying that the charge warning light may not have come on because the wire that powers the LED wasn't working?! The plot thickens! Can I test this by turning the van on and seeing if the charge light comes on for a few seconds?

Yes you can test the LED trigger wire from the alternator by doing just that. Turn the ignition on, do NOT start the engine, the LED should stay brightly lit for as long as the ignition is on and the engine is NOT running (not just for a few seconds )

Let us know.
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by Mocki »

If your battery was totally flat, it would cause the engine to stop, I ran back from a weekend away a few years back knowing the alternator was u/s and nearing the end of the trip the engine just stopped when the brake lights and indicating had used up all the battery......
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by Ian Hulley »

Mocki wrote:If your battery was totally flat, it would cause the engine to stop, I ran back from a weekend away a few years back knowing the alternator was u/s and nearing the end of the trip the engine just stopped when the brake lights and indicating had used up all the battery......

Aye, done that ... hole in the electric tank
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Re: Can a bad alternator cause loss of engine power & misfire?

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Re: Can a bad alternator cause loss of engine power & misfire?

Post by DevonMark »

Back from garage again today with repaired alternator. Was running fine, has now decided to start stalling every time I stop revving.

Has this problem about 4 months ago.

Feeling peed right off - just want my van to work! Grrr.
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by Mocki »

DevonMark wrote:Back from garage again today with repaired alternator. Was running fine, has now decided to start stalling every time I stop revving.

Has this problem about 4 months ago.

Feeling peed right off - just want my van to work! Grrr.


Just check all the vac pipes, it's quite common for one of the advance retard pipes to get pulled off during alternator removal and refitting.....
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by DevonMark »

Mocki wrote:
DevonMark wrote:Back from garage again today with repaired alternator. Was running fine, has now decided to start stalling every time I stop revving.

Has this problem about 4 months ago.

Feeling peed right off - just want my van to work! Grrr.


Just check all the vac pipes, it's quite common for one of the advance retard pipes to get pulled off during alternator removal and refitting.....

OK, will do. Thanks.

[img]http://img.tapatalk.com/d/13/02/10/pyqa9e2a.jpg[/img]

I guess this is any pipes connected to the distributor vacuum unit (no 20 above)?
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by Mocki »

Picture nt showing here!

However, check mostly the vac pipes onto the air filter box as well as to the dissy
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Re: Can a bad alternator cause loss of engine power & misfire?

Post by DevonMark »

Just checked pipes and all are connected, but some look a little worse for wear. This one is connected to (what I'm pretty sure is) the distributor vacuum unit and the insulated part at the end looks a little frayed, at but no obvious leaks:

Image

Image

Also, the coolant level warning light has started flashing, but my coolant level is fine. Can't be because the engine's overheating because the needle hasn't moved!
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