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Blinking Oil Pressure light before start?!

 
Old 11-20-2007, 06:22 PM
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Tom928
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Default Blinking Oil Pressure light before start?!

Last night I went to start the 84 up and as soon as I turned on the key, the oil pressure and "!" indicators started blinking. I turned the key off (without engaging the starter) and then back on - both indicators begin blinking again. I went ahead and engaged the starter, started the engine and the blinking indicators stop. Oil pressure goes to 5 bar.
I tried this a couple more times and no more blinking indicators.

My gut feel is that something could be on the verge of failure.
Should I be concerned or am I just being paranoid?

Many thanks,
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Old 11-20-2007, 07:32 PM
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mark kibort
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yes, sounds like alternator !

mk
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Old 11-20-2007, 08:20 PM
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Bill51sdr
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Have you checked the oil level?
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Old 11-20-2007, 08:55 PM
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84totheFloor
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Originally Posted by mark kibort View Post
yes, sounds like alternator !

mk
Indeed. This has been happening to me consistently as I've been figuring out an electrical issue surrounding the alternator. It might be unrelated to the oil pressure entirely.

However, it's worth getting underneath and taking a look at the oil pressure wires, which stem off of the alternator wiring.
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Old 11-20-2007, 11:20 PM
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Alan
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Since it happened before start-up (and not afterwards) it clearly is an invalid warning. The dash should stay in bulb test mode untill you start the car. That you see warnings before starting indicates a problem with the alternator. The charging circuit is turning off the bulb test early - this should only happen after the car is started and is running. The central warning system thinks the car is running but has no oil pressure... hence the warning.

Since the car isn't running you know why you get the warning...

The problem is in the charging system. Likely your alternator is not charging either (though it could be...) have it tested.

Alan
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Old 11-21-2007, 12:01 AM
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pull the alternator and remove the brush holder, my guess is a worn down brush.........2 options replace the the brush set , new brushes are about 7.00 at the parts store. best option is to replace the regulator/brushes
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Old 11-21-2007, 12:47 AM
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I sincerely apologize if Tom's car caught this from mine....

With Alan and Merlin on the case, you're in for some big-time help!
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Old 11-21-2007, 02:36 AM
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my alternator ingested a few pebbles that took out a winding and the warning lights did what yours did. i guess brushes could do this, as breaking the circuit is the issue. if the circuit is not complete, those lights do all those things. I do remember it even did something with the oil pressure gauge.

anyway, thats probably what it is. couldnt hurt to change the brushes and see.

mk

Originally Posted by Mrmerlin View Post
pull the alternator and remove the brush holder, my guess is a worn down brush.........2 options replace the the brush set , new brushes are about 7.00 at the parts store. best option is to replace the regulator/brushes
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Old 11-26-2007, 02:53 PM
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Thanks for all the good feedback and my apologies for not responding sooner. The Thanksgiving holiday started early and was very busy for us this year.

Anyway, oil level was checked. Wires to the sensor are tight and not exposed or frayed. It is very interesting that the alternator could cause this issue. The car had been sitting for about 2 weeks without being started. The battery was weak as it took a few tries to get it to fire up. Since then, I have made sure the car has been started everyday and the problem has not occured again.

I would venture to say that when the battery is low (from no charge or just sitting) it causes the CWS micro controller to operate on a low supply voltage. This could cause the controller to generate erroneous signals until the supply voltage is increased. I am not sure how this would explain the open brush circuit causing a blinking display.

I let you know what I find.
Thanks again.
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Old 11-26-2007, 03:07 PM
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84totheFloor
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Tom:

Based on having had a similar experience, here's what I think might be a possibility.
When you turn the key to the just-beofre-ignition position, the car does a bulb check. When you get the blinky oil pressure light, I'll wager the voltmeter gauge light does not come on during this bulb check. This may be due to a grounding problem...

The alternator is kicked into action by an exciter wire that runs from the ignition switch to the jump post connection and then on to the alternator. If there is a voltage/ground issue with this wire, the voltmeter gauge light will not light during bulb check. The exciter wire thinks that the alternator is already charging, so it doesn't fire. Correspondingly, the oil pressure system thinks that the car is therefore already running and why is there no oil pressure?.

Point is, this could be due to a misleading electrical snafu, not a true oil pressure issue.

PM me if you want further suggestions on diagnosing.

Best of luck,
Tim
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Old 11-26-2007, 03:32 PM
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check the brushes.
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