Heater stopped working--What to check
- Thread starter z3forfun
- Start date
Check water level? Make sure there's no air lock.
I just replaced the radiator. I filled it per on-line guide: Put heat to high, fan to low, key in "on" position (not running) and then add coolant with bleeder screw loose. I did that and when the level seemed correct (half way up the expansion tank) started and ran at idle for a bit. Added a bit of coolant after that and while driving the engine temp was mid-gauge, seemed to run fine but no heat, just air. Do I need to do a bleed? Thanks for the reply...
- Joined
- Nov 25, 2012
- Points
- 178
- Location
- Newport, South Wales,UK
- Model of Z
- Z3 M43 1.8 (1999) and Z4 E85 2.5 (2003)
Yes you have air locked in the heater core stopping the flow through it. Best is get the front of the car as high as you can get it maybe up on a pair of drive on ramps or securley jacked up at the front. This is needed to ensure the filler hole and bleed screw is at the highest point.
Run the engine up to temp and have the bleed screw open, once the thermostat opens you should start getting a flow, keep an eye on the bleed screw for escaping air. Heater in car should be set to Hot and fan on low when you bleed the car. Temp guage should be at 12 o'clock position at all times when you have a correctly bled system. As soon as you see no more air escaping tighten the bleed screw, check inside the car for heat from the heater, if its still cold then repeat till you get ythe trapped air out.
Run the engine up to temp and have the bleed screw open, once the thermostat opens you should start getting a flow, keep an eye on the bleed screw for escaping air. Heater in car should be set to Hot and fan on low when you bleed the car. Temp guage should be at 12 o'clock position at all times when you have a correctly bled system. As soon as you see no more air escaping tighten the bleed screw, check inside the car for heat from the heater, if its still cold then repeat till you get ythe trapped air out.
I will do this sequence as soon as I replace the cam positioning sensor (I got a code at the auto parts store). When I initially filled the radiator after replacing it the car was actually raised up at the front on jack stands as I was also cleaning the engine underside. It seems hard to see if any air is escaping from the bleed screw--I will loosen it more this time than last time. I hope this works--the previous owner insists that the heater worked when I bought the car a few weeks ago. Thanks again for your input...
You might not see the air but you'll certainly see the water squirt out when all the air is out. Before that though you'll usually start seeing bubbles spluttering. Then give it a few minutes and repeat.
I did as you suggested--raised the front end, heater fan on low, temp setting at highest, loosened the bleed screw and let it run for at least 10 minutes. I could see steam and water vapor coming from the bleed screw but the air temp did not change to warm. I felt the hoses around the heater valve at the firewall in the engine compartment and at first they felt cool/cold. I stopped the process, waited a few minutes and started the car again. The hoses started getting warm but still no warm air. I then tightened the bleed screw and suddenly I had coolant leaking from the heater hose that connects to the radiator just below the cap--looks the end of the hose has cracks. This could be a major headache since I can't see or reach the end of the hose (it goes under the upper manifold. I'm hoping I can trim off the end and have enough left to reconnect it. Any thoughts? I really appreciate your input to date.
- Joined
- Nov 25, 2012
- Points
- 178
- Location
- Newport, South Wales,UK
- Model of Z
- Z3 M43 1.8 (1999) and Z4 E85 2.5 (2003)
You are bleeding it OK but continue until the car gets up to running temp with front of car raised so filler is the highest point. Try trimming the split end hose but replacement is reccomended. The thermostat needs to be opened to achieve full coolant flow through the system.
Check that the hot water solenoid valve which feeds the heater it working properly - are both its pipes hot?
Also check for free play in the temperature control knob cable
Also check for free play in the temperature control knob cable
Thanks for the quick reply. Fingers crossed I can get this up and working properly...
Thanks for your response. I will be working on it again today...
I finally got the coolant system bled and the heater working. I added more coolant than last time--filled the expansion tank almost to the top and had the bleeder screw almost completely removed. I put a small towel around it to catch the coolant when it spits out of the bleeder screw. Ran it with heater fan on low, heat on high for a few minutes then checked and added more coolant (I was starting this process empty). The heat began properly, no rad leaks so it is done. And I sold the car a few days ago.