Heater core obstruction

Old 01-09-02, 04:55 AM
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Question Heater core obstruction

1998 GMC Jimmy

Very little heat, to no heat, from heater. In hose to core is hot return hose is cool. Dealer claims core has an obstruction. Claims the Dex-Cool coolant can crystalize and cause a blockage. They want to replace the heater core. Technician claims its not worth trying to flush it. Instead they quoted me $750.00 to replace the core. My question is ------ Is there a solution which will disolve the crystal build up ? Can the core be reversed flushed ?

By the way, some days I get heat, other days absolutly no heat.
Thermostat has been replaced.
Pressure cap replaced.
Engine temperature a constant 195 F.
No leaks.
Old 01-09-02, 06:09 AM
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Does sound like the core.

Try disconnecting the heater hoses and sticking a garden hose (might have to cut off the end and clamp the rubber part to the heater core ) on one end and using water pressure to try to "reverse flush it". Sometimes works, sometimes not.

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