dual aux fans from Gen2 W126 - PeachParts Mercedes-Benz Forum

cfh · #1 08-28-2015, 03:39 PM

I'm hoping to improve the cooling on a 1983 W126. I followed RollGuy's suggestion of wiring in a relay that runs the aux fan whenever the a/c is on. Also I pulled a larger aux fan from a Gen1 560 and it bolted right on and probably helps some; however I still notice the temps climbing if I'm stuck in traffic with the a/c on.

The Gen2 W126 cars come with a dual fan setup, at least on the gasser V-8 cars. Will that fit my 1983 SD?

mannys9130 · #2 08-28-2015, 05:36 PM

The better thing to do would be to put an electric radiator fan behind the radiator in place of the engine driven fan. You'd have your big single aux fan running with AC like Rollguy, and then you'd have a large electric rad fan pulling air across the rad at high speed even at a standstill. The engine driven fan sucks at idle. An electric fan is better from control and power sapping points of view.

leathermang · #3 08-28-2015, 05:51 PM

And if you have electric problems ... with NO engine fan...... you are SOL.
not good to take away all the redundant or backup designs in the system .

uberwasser · #4 08-28-2015, 06:36 PM

I wouldn't personally be too worried about that.

In a pinch you could run a wire from the battery to the fan.

And in a bigger pinch you could drive without the fan, so long as you keep moving and it's not scorching hot outside.

leathermang · #5 08-28-2015, 06:42 PM

It is called ' not putting all your eggs in one basket ' .... some people are old enough to understand where that old saying came from....others...not so much...

Mxfrank · #6 08-28-2015, 07:05 PM

Is the primary fan clutch engaging? If you have both primary and aux fans working well, then airflow isn't your problem: you should be looking at replacing the radiator.

compu_85 · #7 08-28-2015, 09:50 PM

IMO I'l stick with the one large fan. The dual fan setup doesn't cover much of the lower part of the radiator and is a PITA to install.

My car has the dual fans and I'm probably going to need to back convert it since one motor is going bad and I don't want to spend hundreds of dollars on a new one.

-J

mannys9130 · #8 08-29-2015, 02:03 AM

All front wheel drive cars have electric fans for everything. A quality electric fan set up will not give you any more problems than the aux fan currently in front and the electromagnetic engine fan on some MBs of the era.

I'll be removing my electro engine fan soon to replace it with a large electric fan. The benefits drastically outweigh the risk of losing power to the fan. tjts1 has converted several of his cars to electric fans and hasn't reported any issues. I've only dealt with 1 car in the shop at work where the electric rad fan wasn't engaging. It was a 90s Ford Escort and I fixed it by replacing a relay.

leathermang · #9 08-29-2015, 09:09 AM

Quote:

Originally Posted by mannys9130

All front wheel drive cars have electric fans for everything.

Is HIS car front wheel drive ?

They have to do that due to the engine being sideways....That to their detriment.

that is different from deciding to take away your basic mechanical reliability which came with the car.
There are stories in the archives of people having electrical problems on a trip.... and making it back to home across multiple STATES .. some by letting the engine idle overnight and only driving during daylight hours... not having any lights or any electrical stuff working....

GregMN · #10 08-29-2015, 09:32 AM

Quote:

Originally Posted by cfh

I still notice the temps climbing if I'm stuck in traffic with the a/c on.

Yes, they will climb.
Does it go into the red on the gauge ?
Does it boil over ?
Has it blown out a hose ?

If your stock cooling system is operating properly, it should handle just about anything you can throw at it in normal driving.

Clean debris off the radiator fins.
Is the fan clutch working properly ?
Is it time for a new radiator or a good cleaning ?

SD Blue · #11 08-29-2015, 12:17 PM

Ditto, the temps will climb a little.

Instead of re-engineering, especially on an over-engineered car, it might be better to ensure everything is operating as it should or you may be masking a problem that is only going to get worse.

You didn't mention coolant system flush, thermostat verification or cleaning of the condensor and radiator.

otto huber · #12 08-29-2015, 01:00 PM

There are some aftermarket options for a dual aux fan set up. The installation might be tricky, but definitely cheaper than OEM fans.

mannys9130 · #13 08-29-2015, 02:43 PM

Having an electric rad fan for someone like me with an 84 190D with electromagnetic clutch is literally no different reliability wise. The only difference is that the fan can turn at full speed even at idle, and that's a really good thing. If I have an electrical issue I wouldn't have any fan.

Now that these cars are old enough that the viscous fan clutches are failing, there's no better time than now to do an electric conversion. If one fan is disabled, you still have the other. Instead of spending cash for a new clutch, just put a high CFM electric on and ditch the shroud. You get more working room too.

VW is another prominent German manufacturer who over engineered their vehicles. Electric fans didn't plague them. Even newer RWD vehicles use electric fans, like American trucks.

cfh · #14 08-29-2015, 06:45 PM

Thanks for all the responses guys!

I'm definitely going to stay with the stock belt-driven puller fan - had a catastrophic failure years ago with a Lotus 907 when the fan sensor didn't trigger properly - granted that's a different situation with the motor, in the back, and not nearly as robust as our cast iron lumps right up front - but I don't want to go there again.

My fan clutch is good and I'm running a 25 to 30 % mix - mostly distilled waer; some Zerex and a dose of Water - Wetter. The car has about 170k miles and as far as I know has never been flushed. Not quite sure how to do that - I understand there are plugs in the block that should be removed - guess I'll look into that. I'll also pull the radiator and do a garden - hose flow test.

Problem has only come up on these hot Texas days - and it did boil over a few times, before I upgraded the aux fan. Since then there have been no boil-overs but the temp gauge going up does not inspire confidence. Putting the heater on brings temps back down.

I like the idea of the dual pusher auxillary fans if they work and will hook up - and not so worried about oem vs aftermarket prices - the junk yards around here have plenty of parts.

mannys9130 · #15 08-29-2015, 09:39 PM

If you're boiling over, you have a bad radiator cap and you're running too lean a coolant mixture. Put a new cap on it and flush the cooling system. 50/50 Zerex and distilled water. I don't use cooling system additives like water wetter, but be aware the Royal Purple product that is similar will turn your Zerex into Vaseline like gel. It happened to a guy over on Benzworld. Royal Purple had no response and blamed him for it. He couldn't flush it out after 20 flushes. It's almost as bad as mixing VAG G-12 with traditional antifreeze.