Car Problem Reports

GMC Sonoma Heater Core Under Right Side of Dashboard May Leak Engine Coolant

GMC Sonoma Problem
17 Reports
Me Too

Model Years Affected: 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2001

Average Mileage: 130,009 mi (78,000 mi - 160,000 mi)


The heater core under the right side of the dashboard may leak engine coolant which can puddle on the passenger front floor. The loss of coolant may cause an engine overheating condition. Our technicians tell us that removal of the dash board is necessary to replace the heater on these vehicles.

  •  Rookie

    Replaced heater core - 5 hours and 100000 screws later the heater core is replaced and my fingers are bleeding engine coolant.

    Flag This
  • Visitor, , 148,000 mi

    heater wasn't working so disconnected it for a while. after reconnected, leaked massive amounts of fluid (about 1/2" on passenger floor) so disconnected it again. need to pull dash and fix as it's winter and no heat is no fun.

    Flag This
  • Visitor, , 160,000 mi

    Fluid leaking from under dash
    Pulled the dash half out

    Flag This
  • Visitor, , 78,000 mi

    heater core leak in duct work spaying on windshield when blower engaged, leaking heater core replaced.

    Flag This
  • Visitor,

    coolant leaked onto passenger side floorboard.. estimate was $350-400. had to take apart dashboard

    Flag This
  • Visitor, , 155,000 mi

    I have to check coolant daily. The windshield has a permanent foggy, moist appearance. I am waiting for the weekend to fix it. It's Wednesday today.

    Flag This
Ask a Question