No Heat

[Corellian Corvette]

You need to replace your thermostat.

I literally just had this issue last week on my 09 4.8i. The only reason I knew THAT was because I had an old 540i with the m62 which ALSO had the same problem.

No heat. Bled the system, nothing. Replaced the heater valve (which is a good idea at this age anyway) - no heat and no codes.

One thing I noticed both times is that when I tried to bleed the car with my trusty bleeder funnel, the car would eventually boil over which was *strange*. However, in neither case did the car ever get hot when driving, or show any symptoms of overheating.

The only other reason I suspected the thermostat was that while the upper rad hose would get hot, the lower hose was never more that "engine compartment" warm - which can be mistaken for working I would imagine.

And yet, changed the thermostat and bingo - heater started working. So my guess is you have the same problem of a faulty or failing thermostat.

[LightlyToasted]

Apologies for the lengthy gap in posting. I had set this aside for a while, but it's getting cold again in the great white north so I cannot procrastinate any longer.

Heat was very weak in the cabin. Auxiliary water pump would not run in rest mode. Took out the pump and it bench tested dead. Have ordered a new one. I'll post the results later this week when I get it installed.

[LightlyToasted]

Replaced the auxiliary water pump today and filled and bled the coolant. While filling and bleeding I activated the auxiliary pump by turning the heat up full and fan to low with ignition on (just ignition, not engine on). The pump is clearly audible when running.

I have heat in the cabin now, and the rest mode works now. Just in time for Canadian winter! Now to get my winter tires on...