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Discussion Starter #1
A friend of mine has a '97 STS with 125 K miles. He had the oil changed at the local dealer on Aug 13th. About a week or so later when he stoped at a light he got the "ding ding" chime and "low oil press" light warning, as soon as he added a few RPM the light went out. It was getting worse as time went on., If he put the shifter in nuetral the light would go out. I asked if he checked the quanity and he said no as the oil had just been changed. ( I'm going to see him tomorrow and get on him about that) He took the car into the dealer today and they told him the problem was the harmonic balancer. Neither of us is that well versed on the North star but what could the balancer have to do with low oil press. does the oil pump drive off of it or something. My thought was low oil quanity or a bad press transmitter I know some of you know quite a bit about these engines, any comments or ideas? All will be appreciated, thanks.
 

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There are several possibilities here; and maybe two 'dealers' involved(?) compounds the situation.

If dealer A did the oil change with the current specified oil (5W-30), dealer A gets an error. The specified oil for a '97 model is 10W-30. Some dealers will not make the effort to wharehouse all the different oils; you get what they have.

OR, the oil pressure sending unit could be failed/failing, and your friend is experiencing a combination of unfortunate events.

Yes; oil pump function is dependent on harmonic balancer torque. But unless the engine has been opened up recently, there would no reason to suspect oil pump operation. Dealer B gets an F grade for not asking more questions.

And of course, oil level is a consideration but less so with the Northstar because of the 7.5 quart capacity.
 

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2006 STS V8 AWD, '95 Ford Ranger
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The oil pump drive depends on squeeze from the harmonic balancer retaining bolt. If the retaining bolt is loose the oil pump drive slips.
 

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Discussion Starter #4
I thought I knew everything but once again. Strange designs on the Northstar but I sure like it. Dealer A&B are one in the same. He wasn't having the problem until he took it in for service in Aug,coincidence I guess. They are charging him $325 for the repair, I'll get the skinny when I see him tomorrow. Thanks for the info, Im going to do a little reading up on the oil system.
 

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White Diamond '03 DHS (with DTS floor shift)
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Oil quantity is not the problem. The CHECK OIL LEVEL message will come on at 2 qts. low, long before it will affects pressure. As mentioned the harmonic balancer does drive the pump, but unless it was removed and not torqued properly, I think that was a very poor diagnosis. The pressure switch is a much more common cause, though they make a lot less money replacing one. Personally, I'd insist that they replace the switch first.
 

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Discussion Starter #6
Too late, they said the balancer was loose/wobbling whitch didn't solve the problem so they changed the switch. They said they did a test and oil press was normal, also changed the oil back to 10W30. He had the chime and "stop eng, low oil press" when he went up a slight incline with the eng, idling. We drove it about 75 total miles and had the warning about 4 times once when he let off the gas pedal and the rest of the times at idle in gear. It didn't do it the last 40 miles or so. Wrong switch maybe or loose connection? Have to wait until Mon. to take it back to the dealer. Thanks for the info and if anyone can think of any thing else it could be we would appreciate hearing from you. Take care.
 
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