Heat/Heater Core issue

[AdamPlaysDrums]

After running my car without a blower fan for several months, I finally got around to replacing it with a used unit from a guy on here (Quadrajet). Before I replaced it, I could only run the fan on 1. I did get heat, just not much airflow.

Now, with the heat on, the air is barely warmer than outside at best, EXCEPT when I'm on the highway. An hour highway drive kept the car nice and toasty, but around town I've got basically nothing. Is this a heater core issue, hose routing issue, maybe the blend flap isn't working? I tried searching for this, but it seems the highway heat is an uncommon factor.

P.S. any advice on quieting a squeaky fan? it's intermittent and not horribly loud, but an easy fix would be great.

[bmwm42]

A squeaky fan is fan that's getting ready to quit........have you bleed your cooling system?

[AdamPlaysDrums]

A squeaky fan is fan that's getting ready to quit........have you bleed your cooling system?

Balls. Well, anything I can do to silence it until it kicks the bucket?

And as far as the cooling system, yes I did. I had to re-seal the expansion tank, so i drained/bled/refilled with just the radiator instead of the whole block, which I was under the impression I could do. Is this not the case?

[bmwman91]

Not quite following what you meant here, "so i drained/bled/refilled with just the radiator instead of the whole block"

If you mean that you drained it from the plastic screw in the radiator and then refilled it / bled it from the rad bleed screw then you should be fine.

Your highway heat issue sounds like a blower that isn't really working well. Driving at highway speeds usually forces enough air into the inlets to push out quite a lot through the vent system.

[AdamPlaysDrums]

Not quite following what you meant here, "so i drained/bled/refilled with just the radiator instead of the whole block"

If you mean that you drained it from the plastic screw in the radiator and then refilled it / bled it from the rad bleed screw then you should be fine.

Sorry, yes that's exactly what I meant. I know there's a screw in the block to drain that as well, but I didn't bother with that and didn't know if that could cause a bad overall bleed.

The fan itself generates a lot of airflow, it's just not nice hot air.

[roguetoaster]

If it's not just an air bubble in the system causing the core to not fill I would look then to your mix flap or heater valve as culprits. Try bleeding the car on several different slopes, if you need to add more water than bleeds out you have probably solved your issue.

[AdamPlaysDrums]

Okay, I'll try another bleed tomorrow and see if I can't sort it out. What is the general optimal angle for a bleed? My guess would be front end up, which is quite easy in my angled driveway/garage.

[roguetoaster]

I think the optimal angle will be debated as long as M42s exist, but a couple of different tries can't hurt. Frankly, I always try to bleed mine on near to level ground.

[bmwman91]

I have never had trouble bleeding the M42 on level ground or at a slight angle on a driveway. The real key thing is that the bypass groove in the thermostat housing is clear. 90% of the air will come out within 30 seconds of your first start after refilling the system if that groove is unobstructed.