The day before Christmas my water pump seized while I was driving and I had to have the truck towed. Due to the timing I had the shop replace the water pump and belt. Afterwards I realized that my heat wasn't hot like normal. I figured that there was just some air in the system that needed to be worked out but after 2 weeks now nothing has changed. I topped off the coolant a few times in the first couple of days but the level has been fine last couple times I checked.

What could have happened during the water pump replacement that would cause this problem? The shop wants me to drop off the truck for a coolant flush.

 

is the engine warming up?

 

yeah it's getting up to temp fine. After doing some reading of other threads I think there may still be a bubble in the cooling system. I'm gonna try to burp the system again and go from there.

 

check both heater hoses at normal operating temperature. they should both be too hot to hold, at around 195*.

next step would be a heater hose/heater core backflush in both directions to see if any rust or sludge or or mineral deposits will come out under water hose pressure. depending on how you want to handle it - your shop should do this under the warranty of the water pump work. just point out nicely - the heater used to work before the wp, now it doesn't, how about checking it out under warranty.

don't get pressured into paying a lot of extra money for a coolant flush unless you just want to, as the price of a wp job was not supposed to include a heater failure.

you likely already have all new, or almost all new antifreeze from the wp job, so a coolant flush is unlikely to accomplish much unless they use a chemical to remove rust and scale. you most likely just need a water hose flush of the core (both ways, maybe/maybe not with chemicals).

 

id flush the heater core

 

yeah it may be time for a flush. I drove the pass side onto a ramp and tried to get rid of any bubbles in the system. After allowing the engine to heat up I cranked the heat on high. I couldn't get any additional fluid into the system.