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low voltage, low oil pressure and flat spot 


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 Post subject: low voltage, low oil pressure and flat spot
Posted: Thu Mar 31, 2011 8:08 pm 
Stock as a Rock

Age: 30

Posts: 122

Joined: 21st May 2010

Ride: 1997 EL Ford Fairmont Ghia

Location: Brisbane
QLD, Australia

I have an EL fairmont ghia 6 cyl and it is developing a few problems.

When driving in traffic the car gets quite hot. I think there is a problem with the thermo fans as i have to turn the aircon on full boar to get the fans to kick into high or it will jsut get hotter and hotter and hotter. When the car gets to this temp, the oil pressure drops off substantially at standstill. In addition to this, my voltage has begun to drop substantially at standstill as well at all times.

It has also developed a flat spot in power between 1000 and 2000 rpm, which is more noticable when the aircon is on (feels like a turbo to drive). I changed the plugs about a month ago which fixed this for a couple of weeks, but the problem is back.

My questions are:
Is the oil getting so hot that it is getting more viscous causing oil pressure to drop?
Is it the battery or alternator that is dying causing low voltage?
Would either of these problems be causing a flat spot in acceleration?

PS: Last oil change i used castrol 20-40. When i undid the filler cap after driving to repco and back allowing the car to get quite hot, the oil was smoking. is this meant to happen?


 Post subject: Re: low voltage, low oil pressure and flat spot
Posted: Sat Apr 02, 2011 3:22 pm 
Stock as a Rock

Age: 32

Posts: 132

Joined: 18th Oct 2009

Gallery: 5 images

Ride: EF xr6 AU3 220kw xr8

Location: frankston
VIC, Australia

Very possible the alternator is on its way out, put a voltmeter on the battery when its running and check the charge rate, Be sure to keep an eye on the volts and rev the engine and see if the voltage changes, if it does fluctuate the regulator could be on its way out or the belt is slipping on the alternator which can be fixed with dry lube. I would say that the low voltage shouldnt affect the performance as you describe as the computer is designed to work at low voltages <5 v i believe.
The oil pressure switches can be dodgy at times, which i would say get it checked with a manual gauge. Is it burning oil? Are you losing water. Maybe headgasket leaking water into oil and evaporating in the crankcase causing the smokey look.
Also the relays for the thermos have a tendency of giving up the ghost for no apparent reason. I just had to replace mine as i had no fans at all when hot but i could get them to kick in when i disconnected the Coolant temp sensor, or done the diagnostic Key on, Engine off test which is the haynes manual. I Since replaced them and can only get the low speed to work but i believe its linked in with my air-con being out of gas which wont kick the compressor on so i cant get full speed fans. Maybe Check the with leads with a voltmeter for their resistance value and see if they are all within spec with regards to the power issue.





 Post subject: Re: low voltage, low oil pressure and flat spot
Posted: Sat Apr 02, 2011 3:47 pm 
Getting Side Ways

Age: 29

Posts: 4182

Joined: 30th May 2005

Ride: 1993 EB XR8

Location: BrisVegas
QLD, Australia

Low pressure on the guage and low voltage go hand in hand. Pull all the earths off, clean them and the mounting points then replace. Sit in shock and awe as you problems are solved.



ILL60 - EF XR8, Sunroof, Ticky Kit, 19x8.5/19x11 TE37's, 347, AFr185's, TFS BoxRcustom converter, Hurst Quarterstick, huge billet cam.

51TER - DL LTD. Stock.

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