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High temp, high oil press, low voltage???

  • Thread starter Thread starter junkstang95
  • Start date Start date Nov 13, 2005

junkstang95

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Nov 2, 2002
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Tampa
Nov 13, 2005
#1
  • Nov 13, 2005
  • #1
I have been having overheating probs recently. I replaced my t-stat w/a 180 pulled it again to verify it was in right (ya never know). I had my rad pressure flushed, replaced my belt, checked the elec fan....when the temp starts gong up Inotice the voltage gauge drops to about 8v and the oil pres gauge buries past H. What the hell? Any ideas?
 

Moffa

New Member
Apr 5, 2005
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Nov 13, 2005
#2
  • Nov 13, 2005
  • #2
Maybe the gauges are not reading the correct temp/oil pressure. It could be an electrical problem. I'd say check your oil pressure with a mechanical gauge to see if it really is high.
 

aleborjas

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Sep 11, 2005
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Nov 14, 2005
#3
  • Nov 14, 2005
  • #3
chack all the grounds thats inportant in those cars!
 

junkstang95

New Member
Nov 2, 2002
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Nov 15, 2005
#4
  • Nov 15, 2005
  • #4
I'll give that a shot...I hope its that simple
 

junkstang95

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Nov 15, 2005
#5
  • Nov 15, 2005
  • #5
aleborjas said:
chack all the grounds thats inportant in those cars!
Click to expand...


I'm a bit electrically ignorant, what ground points should I check?
 

aleborjas

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Sep 11, 2005
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Nov 15, 2005
#6
  • Nov 15, 2005
  • #6
next to the batery under starter selenoid, firewall to engine, battery to body, battery to engine!
 

Moffa

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Nov 16, 2005
#7
  • Nov 16, 2005
  • #7
Possibly a few places depending on what is tied into that circuit :x... If you have any resources try to get a wiring diagram
 

jrichker

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Nov 16, 2005
#8
  • Nov 16, 2005
  • #8
Grounds are important to any electrical system, and especially to computers.

1.) The main power ground is from engine block to battery: it is the power ground for the starter & alternator.

2.) The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

3.) The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.

4.) All the sensors have a common separate ground. This includes the TPS, ACT, EGE, BAP, & VSS

5.) The O2 sensor heaters have their own ground (HEGO ground) coming from the computer. This is different and separate from the O2 sensor ground. It is in the fuel injector wiring harness and comes out under the throttle body. It gets connected to a manifold or head bolt.

6.) The TFI module has 2 grounds: one for the foil shield around the wires and another for the module itself.

7.) The computer takes the shield ground for the TFI module and runs it from pin 20 to the chassis near the computer.

8.) The computer's main power ground (the one that comes from the battery ground wire) uses pins 40 & 60 for all the things it controls internally.

See http://www.fluke.com/application_notes/automotive/circuit.asp?AGID=1&SID=103#volt for help troubleshooting voltage drops across grounds
 

junkstang95

New Member
Nov 2, 2002
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0
Tampa
Nov 16, 2005
#9
  • Nov 16, 2005
  • #9
thanks for the awesome detailed response jr...I'll try everything and let ya'll know...
 

Black Sun 5.0

Founding Member
Mar 23, 2002
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L.I., N.Y.
Nov 16, 2005
#10
  • Nov 16, 2005
  • #10
Great list, I'll have to see if I can find these grounds on my car. I've historically had ground problems on my car. Always good days and bad days with this one.
 
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