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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Compression?

  • Thread starter Thread starter MUSTANGJOE
  • Start date Start date May 9, 2005

MUSTANGJOE

Silver Stanger
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Apr 9, 2002
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May 9, 2005
#1
  • May 9, 2005
  • #1
My compression is a little low guys...around 1.25, whats it supposed to be at and what can cause this?..Thxs
 
M

mr.b

Founding Member
Aug 30, 2002
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May 9, 2005
#2
  • May 9, 2005
  • #2
your compression is how much? i don't think it is 1.25!
 

MUSTANGJOE

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Founding Member
Apr 9, 2002
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May 9, 2005
#3
  • May 9, 2005
  • #3
mr.b said:
your compression is how much? i don't think it is 1.25!
Click to expand...


they told me 125...don;t know exactly were the decimal should go!..lol
 
S

Sicarius428

Active Member
Jan 6, 2004
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May 9, 2005
#4
  • May 9, 2005
  • #4
They probably mean 125 psi. Your rings are probably going on the engine. How many miles do you have? Are you burning any oil? You can try a heavier weight oil which should tighten it up a tad.
Kevin
 
T

TheUser

Active Member
Jul 25, 2003
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Springfield, MO
May 9, 2005
#5
  • May 9, 2005
  • #5
generally it's said that as long as all cyclinders are within 10-15% of each other, you're fine...so if all of your cyclinders are around 120-140, I wouldn't worry too much about it. My LX 5.0 has around 140-150 in all cyclinders on a stock motor.

Like said, thicker oil can sometimes seal the rings a little better.

and yes, 125psi
 

MUSTANGJOE

Silver Stanger
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#6
  • May 9, 2005
  • #6
The lowest is 115psi and the highest is 125. I just bought mobil 1 (15w50)performance oil. Does low compression mean I don't have the power I should have?..I have 80 000 miles, I'm not burning any oil or anything for that matter! Thanks
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
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May 9, 2005
#7
  • May 9, 2005
  • #7
here is my take (and i agree with James' thoughts). the relative comparison is what matters (just like he said). did the shop do a dry and then wet compression test? the comparison of those two tests really is more useful than dry alone.

see, there are many variations on how to do a compression test (some folks pull all plugs first, some dont have the motor warm, some dont prop the TB butterfly to WOT, etc). that can all account for a large range of results, on the SAME motor (variations of the test can give the same motor different results).

a leakdown test is much more revealing. I would not sweat those numbers myself, based on the info given.

good luck with that and the gears.
 
S

Sicarius428

Active Member
Jan 6, 2004
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May 10, 2005
#8
  • May 10, 2005
  • #8
As long as you aren't burning any oil or getting any gas in the oil you are fine. Take a sniff at your dipstick sometime just to make sure. If you do smell gas try changing the PVC valve first. Either way, as long as its running well and strong... drive it. The only other alternative would be to get a rebuild so drive it like its meant to be driven till then.
Kevin
 

MUSTANGJOE

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May 11, 2005
#9
  • May 11, 2005
  • #9
:d
 
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