1988 Other GMC Models sudden pressure cold

1988 GMC
130,000 MILES • V8 • 2WD • AUTOMATIC
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CHUCK MAY
  • MEMBER
  • 1 POST
i was checking my unit for coolant leak.it was cold
had not been started . i pump up pressure with
cooling system pressure tester to 16 psi.
looked over cooling system for leaks .
started unit observed pressure guage climbing to
25 psi. shut off unit released pressure to zero.
started unit again pressure did not go out of range
16 psi. possible head gaskets ?
Dec 6, 2009 at 10:27 PM
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MICKEY-D
  • ✓Experienced Mechanic
  • 304 POSTS
When an engine is cold. it can build up pressure until the thermostat opens. don't pump the tester, let it build normally, and see what happens. You should also pressure test the cap.
Jan 8, 2010 at 8:12 AM
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