engine and drivetrain Some electric fan upgrade/install questions

[andrewro]

Guys, I am about to do the electric fan upgrade and I have a few questions I either missed or didn't find in the archives.

1. I have a 12" Hayden fan. Apparently the blade does not come off. Do I reverse the polarity to go from pull to push? Seems like this should work.

2. Do I need to remove the radiator completely in order to squirrel the fan down into the opening behind the grill, or can I remove the bolts and pull it back a little? It looks to me like it needs to come out, especially for devising a bracket for the fan.

3. For those of you with the rear-mount battery, where are you hooking into for your power?

Other considerations:

4. Later in the week I'll post a pic of my radiator drain plug and see if anyone knows whether I can get a temp switch that fits. I have not pulled it yet. I am running both the engine fan and a manual-switched electric fan at first, to make sure everything works. I'll kick it on if the temps get around 2/3 up the dial.

5. It's probably not going to drop below freezing here again until Fall, so I am thinking about running more water and less anti-freeze. Am I right that this is will be more effective for cooling?

I'll probably have more questions later; I've never really messed with radiators before.

Thanks,

Andrew

[Lars]

1. I have a 12" Hayden fan. Apparently the blade does not come off. Do I reverse the polarity to go from pull to push? Seems like this should work.

I have a 10 or 12" Imperial, which was made by Mr Gasket which actually made by Hayden. On mine the blade did come off via a small nut. I tried reversing the wiring hoping that would do it but it didn't.

2. Do I need to remove the radiator completely in order to squirrel the fan down into the opening behind the grill, or can I remove the bolts and pull it back a little? It looks to me like it needs to come out, especially for devising a bracket for the fan.

I didn't have to fit my fan down in there, but I didn't do any custom bracket either, I just used the accompaning peices and attached it to the radiator.

3. For those of you with the rear-mount battery, where are you hooking into for your power?

I used a spot on the fuse block that it a line that is only on when the ignition is on. It is basically an open fuse. But I can't remember which one it was.

Other considerations:

4. Later in the week I'll post a pic of my radiator drain plug and see if anyone knows whether I can get a temp switch that fits. I have not pulled it yet. I am running both the engine fan and a manual-switched electric fan at first, to make sure everything works. I'll kick it on if the temps get around 2/3 up the dial.

I just used an external temp sensor, that according to Keith K. you can have it hang next to the radiator rather than go through it (like I did). I have only run the electric and with the adjustable external one I have it so that the temp get to half and then the fan kicks on. It hasn't gone over yet.

5. It's probably not going to drop below freezing here again until Fall, so I am thinking about running more water and less anti-freeze. Am I right that this is will be more effective for cooling?

No idea, but remember to change it when before it gets cold.[/i]

[jgerry2002]

1. I have a 12" Hayden fan. Apparently the blade does not come off. Do I reverse the polarity to go from pull to push? Seems like this should work.

Most reversible fans you can swap the blade and reverse the wires.

2. Do I need to remove the radiator completely in order to squirrel the fan down into the opening behind the grill, or can I remove the bolts and pull it back a little? It looks to me like it needs to come out, especially for devising a bracket for the fan.

Yea to mount it properly it needs to come out. My '76 is custom, the 74 tii has a 320i fan in it. 320i fan is much easier to mount.

3. For those of you with the rear-mount battery, where are you hooking into for your power?

Power distribution block, E30 or otherwise.

4. Later in the week I'll post a pic of my radiator drain plug and see if anyone knows whether I can get a temp switch that fits. I have not pulled it yet. I am running both the engine fan and a manual-switched electric fan at first, to make sure everything works. I'll kick it on if the temps get around 2/3 up the dial.

There was a recent thread on this .. search. You can go custom or adapt using the drain plug.

5. It's probably not going to drop below freezing here again until Fall, so I am thinking about running more water and less anti-freeze. Am I right that this is will be more effective for cooling?

Probably not necessary unless you are racing. 50/50 with BMW blue coolant (don't bother with anything else) and distilled water. I see no reason to do anything different. Look at a new radiator if you are over-running it. Beyond a few years old they seem to lose efficiency. BMW coolant goes a LONG way to prevent this. My M3 after BMW coolant was spotless inside after 5 years and about 70k worth of bi-annual regular coolant changes.

[Guest Anonymous]

For the battery question, CD posted the drawing with part numbers some time back. Check the archives

[andrewro]

I'll go thru the archives again. I remember reading some discussions about the temp sensors, and I even posted in one of those threads. I'm just not sure which drain plug my car has until I pull it out.

My fan has a little nut which I removed but the fan itself seems stuck on the motor shaft. I'll try to gently prise it off tonight.

I'll also search the archives for the external temp sensor - I'll need more specific info but I'd like to try this. If it works, it sounds really easy to implement.

I was lower on oil than I thought, and topping it off seems to have made a small difference. Usually I run anywhere between 1/2 and 2/3 up the white range of the temp gauge when fully warmed up, but it gets pretty hot in GA and I want to head off any problems in the coming months.

Thanks folks!

[Lars]

I believe there is another thing holding it on there. I think it is some kind of washer.

[andrewro]

Mine has some kind of washer in the shape of a round-cornered rectangle, with four little tabs that fit into the plastic propeller body. It popped right out but the prop still wouldn't come off. I'll give it some gentle persuasion this evening. Thanks!

[Beaner7102]

Here is a good wiring diagram for you. With the switch, when you take your rad out - you need to to remove the old fan. take it to a local rad shop and have a plug welded in to fit your temp switch problem solved. Beaner7102

[jgerry2002]

Nice diagram...

We should FAQ this. Along with the driveshaft Visio I did recently.

[Beaner7102]

We should FAQ this.

I have sent it to Steve K already, it will be a FAQ item soon. Beaner7102

[TMK-001]

Hey Shaun, nice diagram... You have done a thermo on the agave?

Todd

[andrewro]

OK guys, the electric fan is IN. The engine fan is still in too. I have the cockpit switch but no thermo switch yet. I switched the polarity on the fan and it pushes air thru the radiator. The drain plug on my rad is a small bolt with a 13mm head - I'm guessing this is the 7mm thread? Who can tell me more about the external thermo switch? I did find that diagram a few days ago while searching the archives, and I used it to hook everything up. It's a great diagram and very helpful. I took a 30 minute test drive tonight but it's too cool outside to try the fan.

Thanks everyone!

Andrew