Hello evryone,
Has anyone done a fan upgrade to get alittle more power and mpg, replace the stock fan thats on the fan clutch and installed an electric fan that only needs to come on when you really only need it. I was pondering this idea since the stock fan is always turning and using some hp I figure little something might help in the long run. Any thoughts.


Peter
1984 300d 285k

Peter, several members have done this mod with a Spal fan. The cost is fairly steep to get all the components required. The main disadvantage is the lack of sufficient power to run the electric fan...........thereby necessitating a larger alternator.

Sure, you'd gain some efficiency, but, at what installation cost?

Brian,
Do you know of anyone who has retrofitted the dual fan stup from the 91 on 300se to a 300sdl? I came across a great deal on the dual fan assembly and the shroud from a 91 300se and was thinking of installing it on my 86 300sdl.
I was thinking that it might make my A/C a little more efficient.
It looks like it is a bolt in affair, and I only would have to move my horns and horn bar to the way they did it on the later cars.
I have no high coolant temp problems, I just want a little more air blowing across my A/C condenser this summer.

John

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John
1986 300sdl
1985 380se

So is the stock alternator just barely big enough to supply all the stock electrical needs? Sounds like you're saying it doesn't even have enough excess capacity to drive a fan?

Peter, I installed a 16" Spall electric fan inplace of the belt driven fan on my 85 300D. I bought the fan at a Good-Guys hot rod show from one of the vendors. along with the fan buy the rubber gasket that goes around the edge of the fan to protect the radiator fins. I think the mounting kit comes with the fan.

It makes it easier if you have the fan out and laying on your work bench. Install the mounts into the edge of the fan. I attached mine with Pop Rivits into the metal edge of the radiator. will need some spacers between the radiator and the mount arms when you pop them on. I used washers same size of the pop rivits.

For the wiring, I used a MB ice cube relay so it looked factory. I cut one off a PNP car so I had the plug and enough of a pig tail to solder my wires to.
good thing about MB plugs is you can take them apart and move the pins around to have what ever color or size you need in the proper hole.

I mounted the relay under the black box on the left fender next to the AC relay.

Power comes from the battery, or connect into the little black connection box on the R/fender by the battery with the 3 screws under the cover.
Power goes to #30, also had to hook power to #86.

Power goes from #87 to fan.

#85 goes to a switch in the car as a back up incase temp switch on engine doesn`t work. got this idea from some of our large trucks at work.

On top of the Thermostat we installed a temp switch to kick on the fan. got this from my indie. turns on at 212deg. or 100c and off around 80c what ever that is?

Temp switch is connected to #85 also or the same wire to the back up switch.

Your grounds will be the fan, the Temp switch on the engine, and the back up switch.

I had a plug that went to another temp sender on the thermostat housing. traced it down to a plug under the GP relay, then the a switch over valve behind the Brake Booster. went to something no longer in use, so used this wire.
I used 4ft long pieces of heat shring tubing to slip over the different colored wires, it hides them and it looks more professional.

I changed my sunroof over to manual, so will use that switch position for the back up switch. have to replace with a snap on/off switch, another PNP part.

Hope this helps?

also as far as an alternator, there are some writeups on the AL 129 X Bosch 115 amp. I picked up one at PNP on a 87 Saab for $14.35.
Had it checked out at Kragans. B+ voltage low 13.50 actual 14.66 high 15.20. looked like it was just put on as clean as it was.

I haven`t installed it yet, it`s in line behind some other projects.

I almost forgot, you will need a fuse for your power source for the fan. glad I reread this, reminds me I didn`t install mine.



Charlie ☺

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

You could add a relay to act like a J-K flip-flop and use the sunroof switch as-is, if it is easier.

I would add an indicator lamp.

What`s a J-K Flip Flop? where would I get one? Iam open to any new ideas.

Charlie ☺

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

In this case, it's using the switch to activate a self-holding relay. Press the top to turn the circuit on, and the bottom to turn it off. You will require a DPDT switch for that, but I believe that your sunroof switch qualifies.

Ok, thank you for the reply.

most of the time the fan never turns on. even driving around town in traffic. we will see how this plays out as summer comes on.

Charlie ☺

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

I did a 2 fan conversion on my jeep and loved it, manual switches, upgraded to 105 amp alternator. Its very high on my 'to do' mod list for my TD. Faster warmups, extended cooling possibilities after engine shut-down. 2 (or 3 if you includer the OE electric pusher fan) fans for redundancy. Absolutely worth it IMHO.

If I was going to install an automatic thermostat for the fan(s), I'd set it high... the oil cooler thermostat doesn't even open till 90+ degrees... no reason the fan should be spinning if the oil cooler isn't in effect.

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Cheers,
Robert

The stock alternator is either 55 amp or 65 amp depending on vehicle. That's quite marginal if you want to run all the lights, the blower, the wipers, the a/c and the current fan. Adding another 20 amps or so for a Spal fan would put you behind the power curve at night under high demand.

Don't know offhand if anyone has tried this............but, usually somebody has tried everything.

Personally, I don't think you'll get enough of a benefit with the dual fans to make the effort worthwhile. The single fan moves quite a bit of air when its running. The smaller dual setup will probably move more, but, it's got to be a small benefit.

I notice that some cars, the 190 for example, use the large fan for the smaller engines, for the turbo or 6cyl, the dual fans. I don't know what the CFM difference is, nor the amp-draw difference, but it appears that M-B did go to dual fans for more cooling.

On the 124 it is the opposite, with the6cyl 603t you get one large fan, with the 5cyl 602t you get dual fans, like M-B decided the larger cooling needs of the 603 required the single fan?

I'd say that the better way to save hp/fuel would be to put an electric fan-clutch on it like an early 190, very little drag with it disengaged yet gobs of cooling when it is engaged.

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Gone to the dark side

- Jeff

MB went from single to dual aux fans across the 124 and 126 lines in the late 80s. I don't think it had anything to do with reduced airflow requirements of the 602 vs the 603 in the 124.

Sixto
87 300D

On top of the thermostat? Where on top of the thermostat?

Isn't 80*C turn off too low? My temp gauge shows over 80*C even when cruising down a steep grade with 50*F ambient temperature. Definitely no need for the fan to be engaged yet your set-up might have the fan energized. I'd have the fan turn off at 85 or 87*C. Of course this is in a 124/603. IIRC 617s tend to show cooler temps on the gauge.

Sixto
87 300D