No radiator fan, good idea? - PeachParts Mercedes-Benz Forum

123mike · #1 01-15-2016, 06:27 PM

changed water pump and did not install rad fan. Since it's winter, not a problem, I'm thinking of using the ac fan with a switch in the summer. How great an idea is this? The ac rad is pulled. The plus seems like the engine is smoother with out it. Mike

bsmuwk · #2 01-15-2016, 06:37 PM

The AC fan isn't strong enough to quickly cool the engine - what happens if you forget to flip it on?

Get yourself a 10" SPAL and run it via a temperature sensing relay set up. All the benefit of not having the airplane fan/clutch with all the benefit of automatic and efficient cooling. Or just put the fan back in, because it's been working for 25+ years......

sleepstar · #3 01-15-2016, 07:11 PM

very bad idea. very bad.

mannys9130 · #4 01-15-2016, 09:18 PM

You need something.

While at speed, no fan is needed.

I'm a proponent for electric fans. More efficient, better for these engines where power is a prized commodity, and more modern.

I have my 190D set up so a 100* switch engages the engine driven electromagnetic fan clutch, and a 110* switch engages the aux fan. On BOTH fans I have a manual override switch to turn either one on and leave it on. Unless it is the middle of 110* summer in Tucson, I only need the engine fan to come on in bursts (when I'm sitting a lot).

I say install an electric puller fan with its on shroud on the engine side of the rad, and hook it up so the 100* switch turns it on. The aux fan will come on in an emergency and with the A/C on low speed by design.

Engine fans are antiquated and sap power.

vstech · #5 01-15-2016, 10:50 PM

my 190D 2.5L NA has been without a belt fan since the THIRD radiator went out due to body flex contact with the belt fan.

I picked up a cheapo 12" fan and controller, stuck it in the radiator wired to the glow controller circuit, and let it run 24/7 it ran fine all summer, yes the fan runs a while after shut down on and off. no biggie.

I have mine pushing, not pulling... no room for a decent fan in front of the water pump...

funola · #6 01-16-2016, 08:02 AM

My 85 has a good running engine, radiator and AC condenser fins are clean, temp gauge runs at 82 C normally. I removed the fan and fan clutch April of last year and has been running that way since ( love all that extra room created). I added a snap switch on the thermostat housing to control the ac aux fan automatically as well as a manual switch to turn the aux fan on whenever I want.

In my experience, as long as ambient is below 90 F, the aux fan keeps the temperature steady at around 82 C even sitting in traffic. Above 95 F ambient, the aux fan cannot keep up in traffic and the temperature would creep up to 100 C and beyond. In those situations, I pull over, shut the engine off, pop hood, let the aux fan run to cool engine down. I will probably add a small electric puller fan before next summer.

dieselbenz1 · #7 01-16-2016, 08:17 AM

I was chasing several leaks and removed the fan in my 124 several months ago like I had done in the past. I also never experienced any cooling issues maintains 80 degree water temp max. I really enjoy the added room and by design the fans come on automatically I just reduced the set point where the fans come on from 90 to 80 degrees. Only under heavy load do I hear the fans come on at ambient temperatures between -20 to +15 degrees C. so I have no concerns.

Chris W. · #8 01-16-2016, 09:01 AM

My 124 experience was different. I ran with no fan for several days in the summer while waiting for a new fan and clutch. Fine on the highway. Not fine in stopped traffic. Temp started to climb almost immediately when crawling in stop and go situations. Yes, electric fans did kick on eventually but I didn't like running that warm. And yes, I suppose I could have put a resistor in to change the set point, but I don't live in northern Canada. I live where hot conditions are common. New clutch and fan and my temps are rock steady in all conditions.

Rgds,
Chris W.
'95 E300D, 457K

Mxfrank · #9 01-16-2016, 09:14 AM

First of all, the electric fans aren't "A/C fans". If they are coming on whenever the A/C is on, the odds are your system is overcharged. They are intended to come on at low speed only when the A/C pressure is too high, or on high speed when the engine is close to overheating. They are very powerful cooling fans...the pair in my 190D pull 25 amps, and probably put out close to 3000cfm. More than enough to do the full job without the pump fan.

On the left side of your cylinder head, there is a row of four or five 22mm bungs in the water jacket. One of these is used for the temp gauge sender, one is used to tap water for the heater. There are at least two spares. Take out one of the unused plugs and replace it with a Porsche or VW fan switch...available in temperature ranges from 175F to 205. I use a 190F switch to control the electric fans. Although the pump fan is still in place, the electrics deploy first and do most of the work. My pump fan almost never engages. Temperature is consistently "on the thermostat", even in stop and go.

One point...on many cars, there is no separate fuse for the high speed fan circuit. Instead, there is a fuse internal to the relay. If you car has a black relay for this purpose, you should replace it with the superseding orange relay, which has a fuse in the top. If the fuse blows in the black relay, not only can't it be replaced, but it can start a fire.

The pump mounted fan consumes huge amounts of horsepower. This is probably why it's designed to come on so late, and why your temperature fluctuates in traffic. The later fans with thermostatic clutches are less wasteful than the ones with electric clutches, but either way it's a waste.

jabstick420 · #10 01-16-2016, 04:59 PM

Quote:

Originally Posted by Mxfrank

First of all, the electric fans aren't "A/C fans". If they are coming on whenever the A/C is on, the odds are your system is overcharged. They are intended to come on at low speed only when the A/C pressure is too high, or on high speed when the engine is close to overheating. They are very powerful cooling fans...the pair in my 190D pull 25 amps, and probably put out close to 3000cfm. More than enough to do the full job without the pump fan.

On the left side of your cylinder head, there is a row of four or five 22mm bungs in the water jacket. One of these is used for the temp gauge sender, one is used to tap water for the heater. There are at least two spares. Take out one of the unused plugs and replace it with a Porsche or VW fan switch...available in temperature ranges from 175F to 205. I use a 190F switch to control the electric fans. Although the pump fan is still in place, the electrics deploy first and do most of the work. My pump fan almost never engages. Temperature is consistently "on the thermostat", even in stop and go.

One point...on many cars, there is no separate fuse for the high speed fan circuit. Instead, there is a fuse internal to the relay. If you car has a black relay for this purpose, you should replace it with the superseding orange relay, which has a fuse in the top. If the fuse blows in the black relay, not only can't it be replaced, but it can start a fire.

The pump mounted fan consumes huge amounts of horsepower. This is probably why it's designed to come on so late, and why your temperature fluctuates in traffic. The later fans with thermostatic clutches are less wasteful than the ones with electric clutches, but either way it's a waste.

Mxfrank,

can you elaborate on this? I've got AC and the fan switch is in the dryer. Can this switch be rerouted to the block?
or is this a bad idea if the car is equipped with AC? wondering if it can run on both switches. one from coolant temp and one from AC dryer.
thanks,

vstech · #11 01-16-2016, 05:50 PM

He means the ac dryer switch is only to bring on 50% speed on the aux fan... and it shouldn't be engaging unless the condenser is clogged or the system is overcharged.

mannys9130 · #12 01-16-2016, 06:21 PM

In the extreme Tucson summer, my aux fan runs with the AC after a few minutes of driving. I force it to run high speed in summer because these AC systems can't handle that heat, even with R12. If you live in a moderate climate, the aux fan probably won't come on with the AC.

thatguy · #13 01-16-2016, 06:41 PM

Quote:

Originally Posted by mannys9130

In the extreme Tucson summer, my aux fan runs with the AC after a few minutes of driving. I force it to run high speed in summer because these AC systems can't handle that heat, even with R12. If you live in a moderate climate, the aux fan probably won't come on with the AC.

I have never actually had my AC fan come on high speed under normal circumstances unless I was deliberately trying to get it to run to test everything out (hot day, AC running, slow speed pulling hills in my neighborhood with a blanket over the grille), but the low speed mode will come on rather quickly in hot weather in summer.

I suppose it doesn't come on high speed because my car never exceeds the second line on the dash, 100*C, ever since I cleaned the radiator of debris and replaced the fan clutch in 2012. Oddly enough, though, my 95 diesel will get to about 95*c pulling hills at low speeds even in "winter" with temps around 55 degrees, but that seems to be about as high as it ever goes even at over 100*f.

Mxfrank · #14 01-16-2016, 07:09 PM

Quote:

Originally Posted by jabstick420

Mxfrank,

can you elaborate on this? I've got AC and the fan switch is in the dryer. Can this switch be rerouted to the block?
or is this a bad idea if the car is equipped with AC? wondering if it can run on both switches. one from coolant temp and one from AC dryer.
thanks,

The switch in your dryer comes on when the a/c system pressure is over 300psi (may be different on some models). Normal pressures are well below this, but you can sometimes reach this high on hot humid days.

if you want to do the mod I described, get a fan switch from an 80's Jetta or Porsche, they probably have them here on Pelican. If you have trouble finding one in the temperature range you need, just ask and I can help. These have 22mm bodies, and can screw directly into any of the unused ports on the side of your head (see photo), by just removing the bung with an allen wrench. The electrical connections can be wired parallel with the switch in the receiver dryer if you want low speed (this is how mine is set up), or parallel with the switch in the engine outlet if you want high speed. Everything will still work as before, except that the fan will also come on when the jacket temperature triggers the new switch.

http://www.ebay.com/itm/New-Beck-Arnley-Engine-Cooling-Fan-Switch-Blade-201-0809-/391353926560?fits=Make%3AVolkswagen&hash=item5b1e8303a0:g:61UAAOSwKtlWhRvR&vxp=mtr

vstech · #15 01-16-2016, 10:11 PM

Quote:

Originally Posted by Mxfrank

The switch in your dryer comes on when the a/c system pressure is over 300psi (may be different on some models). Normal pressures are well below this, but you can sometimes reach this high on hot humid days.

if you want to do the mod I described, get a fan switch from an 80's Jetta or Porsche, they probably have them here on Pelican. If you have trouble finding one in the temperature range you need, just ask and I can help. These have 22mm bodies, and can screw directly into any of the unused ports on the side of your head (see photo), by just removing the bung with an allen wrench. The electrical connections can be wired parallel with the switch in the receiver dryer if you want low speed (this is how mine is set up), or parallel with the switch in the engine outlet if you want high speed. Everything will still work as before, except that the fan will also come on when the jacket temperature triggers the new switch.

New Beck Arnley Engine Cooling Fan Switch Blade 201 0809 | eBay

the a/c fan control switch is a temperature switch, not a pressure switch.