Author Topic: Electric fan conversion feedback/results... (Read 13626 times)

velomech · « **on:** February 05, 2008, 03:59:52 PM »

I decided to do the switch to the electric fan.

I priced some aftermarkets which were around $75, for just the fan, decided to go the route I chose with my 66 fairlane. I went to the pullapart, grabbed a low profile fan from a early 90's Taurus. This fan has some crazy CFM.

So, I found one, went home and started the project. While I was in it, I cleaned the front of the motor, and replaced the serpentine belt.

First, I am really happy about the room in there now.

I bought a thermostat switch and relay, and while I was checking hot spots for a hook up I grounded something by accident and in the results are posted in a thread form earlier today. So, I finished up and still am having secoond thoughts about the temp sensor/rod.

I tried to stick in on the pass side of the radiator above the return hose. The engine would get a little warm, 3/4 before it would turn on, and it's set on 185 degrees.

I moved the sensor to the side of the radiator where the coolant enters it. Now it comes on early and stays on too long. SO, I will work that out in time.

As for the HP savings, I didnt notice any. I did, however, notice that in between shifts the motor stays revved. It also stays steady while down shifting and rev matching the motor. So, Im impressed with that.

I think I notice a little bit of rev climbing around 3700-4200 rpm, it seems that there is a little difference there or it may be my mind playing tricks on me.

Seat of the pants dyno tells me, hardly noticable. Still, Im thinking it will at least get me some more mileage out of a gallon of gas seeing as how it's less mass eating up energy.

Just thought I would share this info, I dont know how many people have done this on a 92 318I. But I only have $30 in it, and aside from frying my fuseable link at the battery and wasting 6 hours of my time fixing it, Im happy with the results.

Also, Does anyone else have an AC auxilory fan that blows out through the grill when turned on? I reversed my leads so it blows with the flow of the radiator fan, "In through the radiator towards the engine".

I dont know if the PO wired it wrong or what, but Im ASSUMING that flow is supposed to into the engine compartment and not have two fans fighting each other...

Cheers and beers
Hodge

tjts1 · « **Reply #1 on:** February 05, 2008, 04:52:47 PM »

Get the colder E36 2 speed temp switch that replaces the existing temp in side of the radiator. Its the best solution. Those temp switches that you stick between the fins of the radiator (i think thats what you're using) are garbage and impossible to tune because they were never designed for this application.
It sounds the like your aux fan is wired backwards. Once you have a puller fan functioning properly behind the radiator, the aux fan becomes dead weight. Not only that but running both fans at the same time will overload your alternator. Theres no point to it.
Good luck
Justin

velomech · « **Reply #2 on:** February 05, 2008, 05:55:26 PM »

Good stuff bro, thanks.

Can you explain what a two speed switch is?

I saw mention of it in an earlier post but it lost me. I thought the radiator temp sensor was non linear, it thats the correct way to describe it. LIke it changes output as it gets hotter. I thought In order for the fan to actuate t would need a on/off type switch.

The thing you stick in the radiator IS total garbage, I would love another option. Is there a part number that you know of for the switch?

Cheer and beers
Hodge

tjts1 · « **Reply #3 on:** February 06, 2008, 10:24:57 AM »

The switch in the passenger side of the radiator is an ON/OFF switch with 2 temperatures. It activates low speed at a specific temp and activated high speed at a higher temp.
http://www.understeer.com/images/tech/fanclutchmod08.jpg
The one found in the E30 M42 has its temperatures set too high. I replaced it with a colder switch from the E36.
http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search.cgi?command=show_part_page&please_wait=N&make=POR&model=BE36§ion=ELgage&page=4&bookmark=24&part_number=61-31-8-361-787-M85
PN: 61-31-8-361-787-M85
This switch is normally used to activate the AUX fan in front of the radiator. I swapped the temp switch and cut the wires to the AUX fan and connected them to the new puller fan behind the radiator. This circuit is already has fuses and relays so its set and ready to go. If your new fan only has one speed, just connect it to the low speed side of the circuit.
Good luck
justin

velomech · « **Reply #4 on:** February 06, 2008, 01:10:53 PM »

I have a 92 318 E36...so I have one already?? right?

Cheers
Hodge

bmwman91 · « **Reply #5 on:** February 06, 2008, 01:57:09 PM »

Excellent thread! It has just the information I was after to get rolling on this. Thanks guys!

bmwman91 · « **Reply #6 on:** February 06, 2008, 02:02:52 PM »

Quote from: tjts1;42295

The switch in the passenger side of the radiator is an ON/OFF switch with 2 temperatures. It activates low speed at a specific temp and activated high speed at a higher temp.
http://www.understeer.com/images/tech/fanclutchmod08.jpg
The one found in the E30 M42 has its temperatures set too high. I replaced it with a colder switch from the E36.
http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search.cgi?command=show_part_page&please_wait=N&make=POR&model=BE36§ion=ELgage&page=4&bookmark=24&part_number=61-31-8-361-787-M85
PN: 61-31-8-361-787-M85
This switch is normally used to activate the AUX fan in front of the radiator. I swapped the temp switch and cut the wires to the AUX fan and connected them to the new puller fan behind the radiator. This circuit is already has fuses and relays so its set and ready to go. If your new fan only has one speed, just connect it to the low speed side of the circuit.
Good luck
justin

Question...did you run with a lower temperature thermostat as well (as per the Understeer article)? Also, why did you use an aftermarket electric fan? Does the auxiliary fan just not move enough air?

BrandC · « **Reply #7 on:** February 06, 2008, 02:12:54 PM »

Can anyone recommend an electric fan that fits easily onto the M42 radiator? Genius idea, using the AUX fan circuit.

haledj · « **Reply #8 on:** February 06, 2008, 02:22:07 PM »

All the electric fan conversion info I have found here says to use an aftermarket/volvo/ford/whatever fan as a puller. However on some other forums it seams that the m20 guys tend to just use the stock AUX fan. I know there are stock mounting brackets from non-ac cars that would mount the stock fan against the radiator if you have the AC condenser removed. I would imagine if the fan moves enough air for an m20, it will give us enough cooling.

tjts1 · « **Reply #9 on:** February 06, 2008, 02:31:58 PM »

Quote from: bmwman91;42313

Question...did you run with a lower temperature thermostat as well (as per the Understeer article)? Also, why did you use an aftermarket electric fan? Does the auxiliary fan just not move enough air?

I haven't read the under steer article. Just copied the hot link from another thread here. I don't recall which thermostat I used. I think it was just a direct replacement for this model and year. I used a JY fan from a Volvo 940/960. Another member here is using a very similar volvo 850 fan. I chose this fan over the just using the existing AUX fan for a couple of reasons. First of all its too small. Its designed work in conjunction with the clutch fan. Without an AC condenser I suspect it would be enough. The aux fan resistor pack tends to fail which kills low speed function. Also puller fans are generally much more efficient at moving air through the radiator than pusher fan. The volvo fan has both low and high speed built directly into the motor and its very reliable. The Volvo fan is also a lot quieter. http://www.m42club.com/forums/showpost.php?p=27468&postcount=84
Justin

haledj · « **Reply #10 on:** February 06, 2008, 02:45:26 PM »

Thats another thing I forgot, aftermarket fans tend to have flat blades rater than curved blades like most OEM fans and will be much louder.

D. Clay · « **Reply #11 on:** February 06, 2008, 07:08:55 PM »

Any 16" will fit and the hot tip is the curved blades as mentioned above. The A/C only activates the low side of the 2 speed fan in front of the condensor. If the resistor goes the fan doesn't come on at all with the A/C and the compressor builds up too much pressure at idle in traffic and starts to blow warm air. I'm running the pusher in front at high speed only and a single speed aftermarket puller behind the radiator. They come on at max from the A/C, low temp switch, and high temp switch. I might disconnect one in the winter but it really blows cold A/C in the summer.

sumyungguy · « **Reply #12 on:** February 07, 2008, 02:03:56 AM »

I just wired up the aux fan to run on low all the time, threw some water wetter in for extra cooling and haven't had a single issue. During the summer I ran it on high, I could run a switch inside to control high/low but haven't had a need to.

bmwman91 · « **Reply #13 on:** February 07, 2008, 09:57:32 AM »

Quote from: D. Clay;42344

Any 16" will fit and the hot tip is the curved blades as mentioned above. The A/C only activates the low side of the 2 speed fan in front of the condensor. If the resistor goes the fan doesn't come on at all with the A/C and the compressor builds up too much pressure at idle in traffic and starts to blow warm air. I'm running the pusher in front at high speed only and a single speed aftermarket puller behind the radiator. They come on at max from the A/C, low temp switch, and high temp switch. I might disconnect one in the winter but it really blows cold A/C in the summer.

Well, good thing I no longer have AC installed lol. I will see about yanking the fan off of the condenser and installing it directly in front of the radiator. With the E36 temperature switch, we'll see how it all goes. I would imagine that the aux fan is a bit more effective when it is not trying to push air through the condenser AND radiator.

gearheadE30 · « **Reply #14 on:** February 07, 2008, 08:48:04 PM »

For one reason or another, my car has the aux fan from an E36, which flws a lot more air than the e30 one. I didn't realize this at the time, so I ended up buying a volvo 850 Turbo puller fan and wiring it into the aux fan circuit. The low speed fuse will need to be uprated to 15 amp. The aux fan is still in there, as is all of the stock wiring, but it will come out when I paint the valence this summer. So far, the fan is really quiet and has only had to come on once, and that was in traffic. I am running the lower temp switch and the lower temp t-stat. I'd say that my AC works better now than it did when I had the aux fan and the engine fan going, but I did seal up the shroud pretty well. There isn't any place for large amounts of air to get in except through the radiator.