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1984 633CSi Rises again!

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masonjones
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Location: Austin, Texas

Re: 1984 633CSi Rises again!

Post by masonjones » Thu May 31, 2018 2:24 pm

Song, did you replace your heater fan motor? After replacing these transistors multiple times I suspect that the real culprit is the old fan motors which either stick or are slow to start up and pull too much current. I replaced the heater and AC fan transistors and they both failed within a year. I even added a larger heatsink. I then replaced the AC fan motor and have not had a problem going on 2 years.

You can also use this higher power transistor which may help too: 2n5302. It's rated at 30A and 200W. But seeing how many people on the forums have the replacement transistors go out again so quickly makes me think there's more to it. The motor was about $65 and well worth it.
1985 635CSi

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hornhospital
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Re: 1984 633CSi Rises again!

Post by hornhospital » Thu May 31, 2018 5:01 pm

I was going to suggest an additional heatsink, too. This one works at the original mounting position with a little modification.

Good to see you posting again, Song. I'd thought you were gone for good.
Attachments
heat sink.jpg
heat sink.jpg (20.85 KiB) Viewed 210 times
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"

songzunhuang
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Re: 1984 633CSi Rises again!

Post by songzunhuang » Thu May 31, 2018 5:28 pm

masonjones wrote:
Thu May 31, 2018 2:24 pm
Song, did you replace your heater fan motor? After replacing these transistors multiple times I suspect that the real culprit is the old fan motors which either stick or are slow to start up and pull too much current. I replaced the heater and AC fan transistors and they both failed within a year. I even added a larger heatsink. I then replaced the AC fan motor and have not had a problem going on 2 years.

You can also use this higher power transistor which may help too: 2n5302. It's rated at 30A and 200W. But seeing how many people on the forums have the replacement transistors go out again so quickly makes me think there's more to it. The motor was about $65 and well worth it.
I only replaced the transistor. I had thought about the motor. Each time I do this, I check my motor to make sure it spins freely and sometimes I grease it up a bit. Given the cost, I can't see the harm in changing this out. I also like the idea of an upgraded transistor as well. Thanks for the specs as I just didn't know what to choose.
-----
Song Huang
1984 633CSi
Last 7 of VIN: 6997383

songzunhuang
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Re: 1984 633CSi Rises again!

Post by songzunhuang » Thu May 31, 2018 5:36 pm

hornhospital wrote:
Thu May 31, 2018 5:01 pm
I was going to suggest an additional heatsink, too. This one works at the original mounting position with a little modification.

Good to see you posting again, Song. I'd thought you were gone for good.
I'm still here! I've been super busy at work and then jetted off for 2 weeks on a 25th anniversary trip in Europe. I just got back last week. So slowly, I am getting back into action.
-----
Song Huang
1984 633CSi
Last 7 of VIN: 6997383

masonjones
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Location: Austin, Texas

Re: 1984 633CSi Rises again!

Post by masonjones » Thu May 31, 2018 6:11 pm

25 year anniversary trumps working on the car, congrats! :D

I bought the higher powered transistor but never had to put it in after I replaced the motor. I still have I believe an original spec 2N3055 on the AC fan and have run it a lot over the last 2 years without problem. I guess you could say the transistor is functioning as a fuse in a way and if it keeps frying there's something else wrong! :-k

$65 was just for the motor so if you decide to do that you'll need to reuse the old plastic fins. This was much easier on the heater fan as the plastic fins were much sturdier than on the AC fan. You can basically grab one end in each hand and twist them (carefully) until one side comes off. Then grip that shaft with vice grips and twist (carefully) the other plastic cage off.

I marked where they were on the old shaft and tried to line them up as closely as possible on the new motor shafts but it still took quite a bit of adjustment to get them to not rub on the surround. There's not much extra space in there!
1985 635CSi

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sansouci
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Re: 1984 633CSi Rises again!

Post by sansouci » Thu May 31, 2018 9:48 pm

hornhospital wrote:
Thu May 31, 2018 5:01 pm
I was going to suggest an additional heatsink, too. This one works at the original mounting position with a little modification.
Hey Ken,
What is the source and stock number of this heat sink?

Thanks!
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 535i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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hornhospital
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Re: 1984 633CSi Rises again!

Post by hornhospital » Thu May 31, 2018 11:35 pm

Grabbed the picture from eBay. Here's the listing:

https://rover.ebay.com/rover/0/0/0?mpre ... 3703037461

You have to saw a corner off to get it to fit the OEM heatsink/mount, but it definitely helps. I've always thought the original mount was a pretty poor heatsink.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"

songzunhuang
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Wheel swap and other fun

Post by songzunhuang » Sun Jun 10, 2018 12:35 am

My front tires wear on the outside and my rear tires wear on the inside. So I decided to swap the front and rear tires today to even out the wear.
Wheelswap.png
Tire swapping day.
Wheelswap.png (986.42 KiB) Viewed 120 times
In the process, I also noticed that my front outer tie rod on the passenger side has about 1/16" of play. Perhaps this was a result of my incident with the rockslide that took out my wheel? It was the front passenger side affected. I have a new wheel on there now. Anyhow this will be a nice opportunity to see if FCP's lifetime warranty applies.

OK, my car just topped 170K miles! I bought this car as. no-op with 142K on the odometer. It's getting near 3 years now and it has served me well as a daily driver. I still enjoy tinkering and learning on this car with the help of the folks on the forum. This car will be on the road for a whole lot longer.
170K.png
I've put 30K miles on this old car/
170K.png (1 MiB) Viewed 120 times
Later in July, I'll be finally getting my front spoiler (if Ralph makes the trip north) and then I'll upgrade the front sway bar (or at least put in poly bushings) and then think about paint. The roof is a mess and the front spoiler will need a coat. Anyhow, much fun. My convertible is getting lonely just sitting in the garage.
-----
Song Huang
1984 633CSi
Last 7 of VIN: 6997383

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sansouci
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Re: 1984 633CSi Rises again!

Post by sansouci » Sun Jun 10, 2018 4:12 pm

Song,
I haven't done the poly bushings, but you might want to inquire about the effect on ride quality. Here in the Northeast, we don't have smooth roads.
--Ken
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 535i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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