E46 not blowing heat when stationary but getting heat when driving

Does anyone have any ideas why my E46 does not blow heat when its stationary but I do get heat when the car is moving, the blower fans are working fine and the car is not overheating when stationary or when being driven

you have a code. You may not know it yet, but you have a 0128 code which means your thermostat is stuck open.

Originally Posted by jgold47

you have a code. You may not know it yet, but you have a 0128 code which means your thermostat is stuck open.

this....your thermostat is stuck open

If the thermostat is stuck open is the solution a replacement thermostat? and how easy is it to replace?.

Would this affect my air conditioning as well?

Clarify please.. There is no heat coming out of ANY vents while standing still. Or are you referring to having the lower vents on, and no flow-through air coming out of the dash vents?

Not being a "Dick" just wanting information as I get no air from dash vents unless I am moving when the floor vents are the only ones on..

Change your water pump and thermostat.

I would say you have air in the heater core, probably as a result of a slow coolant leak. A through inspection of cooling system, should reveal the problem, but it's most likely a crack down the expansion tank.

Do you mean you have no heat when the car is stationary and warming up, but you so when driving and warming up.. Or do you simply not have heat when stationary but you do when moving?

The first problem I have come to see as pretty common for e46s and just BMW's in general. If the second problem however, you should check and replace your cooling system. If you don't know when it was last replaced, replace it. A good rule of thumb for BMW cooling systems.

First thing you should do is check coolant levels daily and see if it is low/you have a leak somewhere. Also, open the OBC menu function 17 and monitor coolant temps to see if the thermostat is indeed on its way out.

I don't know how an open thermostat would cause this problem. I can see it if the problem was the reverse: heat while idling, no heat while driving. For this situation an open thermostat doesn't fit.

Neotate, does your coolant temperature stay dead center when you are driving on the interstate? I mean DEAD center, not 2 degrees off.

Originally Posted by WDE46

I don't know how an open thermostat would cause this problem. I can see it if the problem was the reverse: heat while idling, no heat while driving. For this situation an open thermostat doesn't fit.

I completely agree with this, and it sounds more like you have air in the system, or a system leak which would create low coolant flow to the peripheral systems, like heat. When you are spinning the motor at higher RPMs, you are generating more coolant pressure in the system, which will then flow coolant through your heater core. I'd check for leaks in the ET and radiator first before replacing random parts, then if no leaks are detected, properly bleed the system, and add coolant as necessary.

To Clarify I have air blowing when the car is stationary. the air flow is constant so i am getting air coming out of the vents, but its the air seems to get colder when I stand still, when I drive the air seems to get hotter. The temperature needle hangs around the centre of the guage as I'm driving down the motorway

Originally Posted by WDE46

I don't know how an open thermostat would cause this problem. I can see it if the problem was the reverse: heat while idling, no heat while driving. For this situation an open thermostat doesn't fit.

Neotate, does your coolant temperature stay dead center when you are driving on the interstate? I mean DEAD center, not 2 degrees off.

The temp gauge is a bad indication of actual coolant temp. We know that the gauge is buffered from 75-105 (or is it 115, regardless) degrees celcius. The only true indication of coolant temp should be done using the OBC menu. Especially when diagnosing a potential problem with the car.

Originally Posted by aikmanson

The temp gauge is a bad indication of actual coolant temp. We know that the gauge is buffered from 75-105 (or is it 115, regardless) degrees celcius. The only true indication of coolant temp should be done using the OBC menu. Especially when diagnosing a potential problem with the car.

This is correct to an extent. My needle will move slightly left (I mean very slightly) at 75-80. After 74 it moves to almost the first white mark. My Tstat is definitely stuck open as my temperature varies heavily with speed.

I agree with tonyguns. Bleed the system. Neotate, I also must ask, does the heat start working if you are not moving but increase the engine RPM? Say you increase it to 3000 RPM while standing still. Does the heat start working?

After I rev the car a bit over 3000 revs i start to get warmer air

Originally Posted by Neotate

After I rev the car a bit over 3000 revs i start to get warmer air

Sounds like your car is having a problem keeping water flowing through the heater core. It could be a stuck heater core valve (part #2 in this image):



Part Number: 64118369805 (at least for my 2004 330Ci)

Try bleeding the system before you take this part out to examine it.

with the car running started bleeding the system through the bleed screw first it was coolant then a lot of air came out and it was just air for 5 minutes still going, I've tightened up the bleed screw now. Am I supposed to bleed all the air out until coolant comes out from the bleed screw?

Originally Posted by Neotate

with the car running started bleeding the system through the bleed screw first it was coolant then a lot of air came out and it was just air for 5 minutes still going, I've tightened up the bleed screw now. Am I supposed to bleed all the air out until coolant comes out from the bleed screw?

EDIT - the car should not be running.

Yes, keep adding coolant to tank while you bleed. Once coolant comes out, drain ET to normal level using a turkey Baster or equivalent.

Originally Posted by aikmanson

EDIT - the car should not be running.

Yes, keep adding coolant to tank while you bleed. Once coolant comes out, drain ET to normal level using a turkey Baster or equivalent.

Put your key in the 2nd position ("RUN"). Do not start the engine. Turn your AC fan on minimum and then turn the temperature to maximum. Undo your ET cap and bleed screw. Pour water in while watching bubbles come out of the screw. End when just coolant comes out.

Nevermind. Do this:

Originally Posted by BMW-North

Hi Doug

I've done two complete coolant overhauls in the past 4 weeks on a 330 and 325 using pretty much the same method my dad taught me on old cars.

With car off pour coolant slowly into completely dry coolant system via the ET cap hole until full. In both cases the system only took about 3L of it's 8.4L capacity at this point.

Set ignition to position 2 and adjust heater so the max heat is on and the fan is on lowest setting. Leave ET cap OFF. Start car. The minute you start the car the water pump basically scoops all the coolant and starts to push it through the system. With only half the coolant in the system it will get hot fast and thermostat will open. The waterpump doesn't push air so you have to start adding the rest of the coolant.

Continue to add coolant slowly - at this point you need to rev the engine about 4 times up to about 4000 RPMs so that the waterpump is spinning hard enough to push the water through the coolant system. As the system fills it will push water easier and you will see the coolant starting to cycle as it will begin spitting back into the ET tank at the bottle neck. At this point you'll have about 90% full. Since the coolant is now getting hot put the cap on the ET tank.

Rev the car once or twice more and then open up the bleeder screw at the ET tank - don't remove it just turn it back a couple of turns to let the remaining air escape. This takes about 2 mins.

Turn car off - let it cool then adjust the ET tank level to the recommended bobbing position for a cold tank. Might take another 1/2 liter at most.

Done.


The TIS I have says basically the same thing except they forgot the engine reving. I think what many folk on here might not do is leave the cap off long enough and rev the engine - for me both of these things are essential for a proper bleeding of air.


BMW TIS: RA Venting cooling system and checking for leaks (M54 / M56)

Adding coolant:
To ensure the cooling system is properly vented, it is absolutely
essential to follow the steps below:
1. Open cap (1) on coolant expansion tank.
2. Open vent screw (2).
3. Switch on ignition.
4. Set heater control to maximum temperature.
5. Set fan to lower speed (so that heater valves open).
6. Fill with coolant slowly.
7. Close vent screw (2) when bubble-free coolant emerges.
8. Pour coolant into coolant expansion tank up to max. cold fill
level. Marking (2) is then on a level with upper edge of
coolant expansion tank.
9. Close coolant expansion tank
10. Allow engine to warm up until thermostat opens

Thanks all

Ill give it a go in the morning

I had the same problem with a 330 at work, there is a valve that controls flow to the heater core located near the drivers side near the firewall, I forgettthe exact name of it but if I remember correctly theres 3 hoses that go to it, its kind of a pain to get but its there, if you follow the coolant hoses to the back of the drivers side of the engine bay you'll see it, that could very well be the problem