924Board.org

[Porver9two4]

The heater fan in my European-spec 1980 924na has died spectacularly.... the winter is coming.
What options do I have for replacement? Will the entire heater box out of a later squirrel cage equipped car fit and work in an early car?
I remember reading somewhere that a Fiat X1/9 fan motor could be used - anyone with experience?
I could pony up and buy a new replacement motor.... but given the cost of a new one and the likelihood of a new one eventually going the same way as the old one, I am trying to think more laterally.
So what options do I have?

[MikeJinCO]

I think I've got one that actually runs around here, but not guarantees. If I can find it, price is $20 but shipping always a problem from the US. I grafted a VW rabbit squirrel cage in and did a how to,it works well but got really ugly to get in there. One bug problem was the need to glue the box back together and I couldn't find an adhesive for that plastic. There are a couple of articles on how to get an early 944 fan and box under the dash also.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[morghen]

Driving my 1980 931 to work sometimes in the (now colder) mornings...and the fan is lacking performance. It takes half the way to work to clear the windscreen and half the side windows.

I've seen Noah add some more longer fins to the fan and he says it makes a difference...but i'm not sure i want to go that way.
Another option would be to upgrade to the later post 1981 blower...that would be much better.

But i wonder...is there any modern motor that we could drop into the old casing and spin faster on the same voltage and amp draw?
I' do a minimal change...keep everything the way it is..except the blower motor.
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Supercharger and EFI kits
https://www.the924.com

[Porver9two4]

[morghen]

No way a PC fan will blow enough air.
You need to gut a modern blower that works on the same voltage and control and draws the same or less amps as the original one....and you have to transplant the modern motor into the old casing.

I'd like to do that one day to my 931.
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Supercharger and EFI kits
https://www.the924.com

[Kenodog]

This is the best one I could find that is both good quality and powerful enough to do the job. The diameter is the same as the factory fan but obviously you would need to do a little cut-and-paste to fit it in :

https://www.amazon.com/Spal-30100403-Straight-Blade-Profile/dp/B003PB451G




Me
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1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

[Porver9two4]

Great find. Was just thinking along similar lines.

Something like THIS or THIS ONE from Australia..... Just need to measure for the right size, have a rummage in the depths of the barn for anything suitable or hit eBay.

[brian19600]

What I did:

http://www.924board.org/viewtopic.php?t=39299&postdays=0&postorder=asc&start=0
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78 924

[Porver9two4]

Great job Brian! That looks a neat install.

As it happens lady luck has smiled upon me For the first time in years I had to go to the breakers yard / wreckers at the weekend to try and find a part for one of my other cars..... which they didn't have. BUT what they did have was three 924s (all in really terrible condition) - two early, one late. The heater fans in the early cars were both seized... no surprise... but I pulled out the one that looked the best and put it to a battery at the yard. It didn't spin but did arc the leads (showing the windings were ok ) - because it didn't work the yard let me have it for $2! Well worth taking a punt on it for pocket change as even if the motor was toasted I had the frame as the basis for mounting another motor before transplant....


After a happy hour in the workshop I am pleased to report that the junkyard motor has been restored to full health and has very little wear. Technically the motors aren't designed to come apart, but they aren't complicated and if dismantled carefully it is perfectly possible to strip them, clean them and reassemble..... here are some pics....


The motor removed from its housing and fan blades removed.



These are the fixing tabs you need to unpick to get the motor to bits - a tongue fits into a slot, which is then pinched by a cold chisel punch mark folding in the edges of the slots - careful work with a small punch and fine screwdriver can prize these apart and leave enough material to be able to reuse them....



The offending bearing.... this was frozen tight to the shaft with crud and corrosion. You can see that it has sprung out the spring-steel retaining clip when removed, together with a felt washer probably designed to retain lubricant. Once freed from the motor shaft and checked, the bearing was reinstalled in the end of the motor cage surrounded by the felt washer and held in place with the spring steel clip. The bearing is self-centring so no need to worry about alignment.



The components of the motor ready for reassembly. I opted to take the brush end off the motor body, but either end can be removed the same way. The brush end has a spherical bearing retained in the same fashion as the fan end - I didn't need to take it out so left it in situ. I have cleaned it all up here, cleaned and polished the shafts and bearings and cleaned up the commutator.



This is a close up of the brush set - you can see their clever curved shape that accounts for the wear. The brush and holder are spring tensioned with a very simple hinge at the body end. You can also make out the spheircal bearing in the end cap, as above, held in by the spring steel clip.



.... and here it is all back together and tested. The motor with the fan fitted spins at 2700rpm at 12V and shifts a reasonable amount of air. I tested a small radiator fan motor which I was going to substitute if this one hadn't been restorable but, interestingly, the other motor only span at 2400rpm, so the original Bosch motor is preferable with this fan.




All I have to do now is fit it..... now do I do the job properly and take the dash out or go in through the top... hmmmm... decisions, decisions..

[brian19600]

Nice! And you saved yourself $235 for a new one!

The good thing about taking the dash out is:
You can get at and clean the 'ground crown'.
You can properly seal the heater box up and refoam the flapper. The heater box leaks precious air.
You can relube the cables.
You can have the heater core cleaned, or replace it.
You can get a good look at the rest of the wiring and instruments. Do the odometer repair? Replace all the bulbs.
Easier access to the fuse block and all the harness connectors.

Yeah it's a pain....but if you plan on keeping the car longterm, then it really is the way to go in preventative maintenance.
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78 924