Jest spent a few hours trying to figure out why the heater on the Bonneville won't heat. Heater hoses were hot, heater core cold. Backflushed the core, water flowed, no junk out, new core installed last winter. Water temp 200*, but seemed to surge big time when the thermostat opened, then stopped flowing. Tonight I decided to check coolant flow through the heater, nothing. So I pulled the hose off the engine and started the engine. Still no flow. Hooked it all back up, drove to warm up engine again, and with thermostat open no coolant flow through upper radiator hose. What gets me is the engine doesn't run hot, but it's only a 15 minute drive for the kid to get to school.
In all my years of turning wrenches, I've never had a water pump fail to pump, it's always been the bearings failing first. Only thing I can figure is the impeller has broken, lost it's vanes, or something. I want to be sure before I tear it apart, it's not an easy job, the pump flange is behind the engine mount, which must be removed. I put a rebuilt pump in it two years ago, I'll be checking on a GM part tomorrow.
Anything else I should check before go any farther?
