1993 Ford Aerostar finding compression leaks

Tiny
AEROSTAR4
  • MEMBER
  • 1993 FORD AEROSTAR
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 309,000 MILES
My repair manual does not say the what compression should be on a good motor but that the minimum is 101. It shows the chart that references a 75 percent maximum difference between the lowest and highest compressions whereas a high 200 and a lowest 150 would be pushing the limits. The chart starts at 101 as the lowest and max 250 is 250 what the car had when it was new?
my manual tells how to do a compression check the proper way but where it says if there is a significant difference between the wet and dry compression results
would indicate the rings are definitely worn, what is a significant amount to expect
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Friday, February 27th, 2009 AT 2:03 PM

2 Replies

Tiny
OBXAUTOMEDIC
  • EXPERT
Hello,

Compare cylinders compression reading, typical compression readings are between 125 p.S.I. And 160 p.S.I. All cylinder readings should be within about 5% of each other

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Friday, February 27th, 2009 AT 2:11 PM
Tiny
MERLIN2021
  • EXPERT
If you have NO difference in wet and dry tests, you are doing good, if you see an improvement of 20 lbs or more, rings are worn. Uniformity is the key when Ford only give the high and low, uniform compression mean an engine that is close to in balance. 309,000, I would say you got your money's worth out of these rings!
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Friday, February 27th, 2009 AT 2:15 PM

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