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Task Mastering: Heater Core & Wiper Assembly


jackm

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One of the first projects I knew I had to tackled when I got this 1971 seven months ago was getting the heater box out, to replace or renovate it. While I knew I would have to live without cooling in the summer, it was clear that the heater would have to work to make the car drivable in three other seasons.

 

The fan didn't operate, and I figured the motor was probably seized or broken, but I was a bit intimidated as a first-time restorer to deal with anything under the dash. But with most of the lights, blinkers and gauges working, the non-operational heater/blower felt like a glaring functional defect. The wipers and washer pump were also kaput, so these systems seemed like something I wanted to address once I got the car running and driving, however marginally.

 

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The washer pump was easy to remove -- and once I find a new motor -- should be a straightforward fix. And I was able to get the wiper motor and assembly apart with only a little more effort, though I couldn't completely get the wiper arm out until I rescued the heater box from the dash. I'm still a little wary about getting it all back in since the wiper assembly is a bit awkward to reach.

 

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I will also need a new wiper motor, since the existing one seems to have failed. The wiper armature was fairly frozen on one side, which may have killed the motor, so I welcome any advice on getting the whole apparatus back in, together and working right.

 

Getting the heaterbox out was a bit tougher than expected, in part because the tutorial applies to '72-'76 models that enable the two control faces attached to the cables to be popped out. I learned the hard way that for these earlier models the cables have to be detached behind the dash. There was also a circlip on the main cable that runs to the heater valve that flew off to who knows where as I contorted myself in the floorboards to reach it. But I felt a small jolt of satisfaction in finally getting this component out.

 

Once I did, I decided to fire up the car, just since I hadn't run it in a week or two. The starter turned well -- I had previously wondered if it was starting to fail -- but the engine immediately sounded like it wasn't getting any spark. I quelled my immediate fear and trepidation of a sudden no-start condition and jump into diagnostic mode. I started by taking a close look at the coil and distributor, and in just a minute or two noticed that in wrestling off the heater hoses, I must have dislodged the wire spade attached to the dizzy. With it attached back on, the engine fired right back up. 

 

That quick sleuthing and fix really buoyed my spirits. There's nothing quite like an old vehicle that had been running suddenly not firing to rattle a neophyte wrencher's confidence. Figuring things out in short order was a boost in the right direction.  

 

Meanwhile, I'm equally glad move ahead with a heaterbox fix or replacement unit. I will also try to see if I can rebuild the heater valve per one of the tutorials. In originally freeing the stuck valve I managed to break the cable off, so will need to consider how to rejuvenate or replace the cable.

 

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In terms of restoring the heaterbox itself, I guess the first place to start is to determine if the fan is still operational or salvageable. From there I will try to follow the how-to on taking the rest of the assembly apart to check the fan, get the heater core serviced, etc.

 

I'm all ears for advice and guidance, including whether I should just look for a replacement rather than attempt the rebuild.

 

I took this picture of the three wires attached, plus the orange-ish spade wire attached next to them. Which is these should I use to test the fan, and what does the orange wire do?

 

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Edited by jackm

14 Comments


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Re-doing the heater box yourself is a pretty involved project. You'll be in it for probably $500 at least since you will need new bowden cables and foam, which AutoDynamik sells as a reasonably-priced kit. The biggest $$$ will be re-coring the old heater core, which will absolutely need to be done.

 

There are some great articles on the subject and AutoDynamik has two very comprehensive documents on how to go about the rebuild. 

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Thanks for the tip. Does the heater core need to be in decent condition to be worth restoring, or is this something I should try to source as a replacement?

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You should be able to take it to any radiator shop, they will replace the channels and fins. 
 

You really don’t want to get everything riveted back together and have coolant all over your feet from a leaky heater core :)

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Your 71 has the early small valve design, so the valve, core, hoses AND the (2) grommets are different than the later design.  The only replacable part for the heater valve is the o ring.  Not sure, but I believe BMW does not offer them, so you’ll have to find one at your local hardware store.

 

Before you decide to replace the fan, try lubricating the bearings and spin it by hand. If you get it to spin, connect it to a battery for testing.

 

Some early heater fan motors use (2) different styles of mounting clips. There are round ones and flat ones. I went thru all of this when rebuilding the heater box in my 69.  See my long thread in the blog archives (2002ti wannabe project).

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Regarding the wiper mechanism, if you can afford it, buy ALL new pivots and arms. It will be like new. I sourced my parts from Walloth Nesch. Keep looking at their website, as some parts will be available now and then.

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I just did this job on my 1970.  Some of my experience may help you with your restoration.

 

Mark92131

 

 

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10 hours ago, Eric Metcalf said:

Does anyone know where to find the fan spring clips?

Post a WTB for them in the classified section.  

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Update: cleaned some thick grimy buildup around the edges, freed up the the two pairs of  vent door with a little WD40. Fan blades spun easily but when I put 12V on it, I got nothing. Did I bit more cleaning and lubrication around the motor and suddenly it’s whirring like a champ! I even reconnected to the car and had all three speeds on the knob functioning.

 

I suppose I still need to get the core out and serviced, and need a new cable for the heater valve, but with the blower operational does that change how I should go about restoring the whole shebang? What else should I do to keep the blower healthy now that I’ve got a wiring motor?

Edited by jackm
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On 7/2/2022 at 4:07 PM, jackm said:

how I should go about restoring the whole shebang?

 

You could buy the AutoDynamik kit, or you can buy some grommets and neoprene for the flaps, test the core and buy a new cable for the heater valve.  You saved a lot of cash and hassle getting your fan motor to work, lube it frequently to keep it spinning.

 

Mark92131

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On 7/14/2022 at 10:20 PM, Mark92131 said:

 

You could buy the AutoDynamik kit, or you can buy some grommets and neoprene for the flaps, test the core and buy a new cable for the heater valve.  You saved a lot of cash and hassle getting your fan motor to work, lube it frequently to keep it spinning.

 

Mark92131

Link ? hard to find

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10 hours ago, NMDerek said:

Link ? hard to find

 

PR Designsf is an affiliate company of Auto Dynamik, Inc. (autodynamiksf.com) in the San Francisco area, who have been servicing San Franciscans and the neighborhood since 1987.

 

PRDESIGNSF.COM

Specializing in BMW 2002 Heater Boxes

 

 

Mark92131

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