Electric Fan - PeachParts Mercedes-Benz Forum

1960mog · #1 06-06-2011, 04:09 PM

Hi
I would like to replace the engine fan with a electric fan in a 81 300SD.
Has anyone done this conversion in a 126?
What fan did you use?
How good dose it work?

Thanks
Tom

Gilly · #2 06-06-2011, 04:39 PM

126's in general had an aux cooling fan, I would have thought even an early one like an 81 would have it. Did someone possibly remove it? At any rate you should be able to come up with a 126 fan, you could maybe get all the associated brackets and stuff from a wrecking yard? The engine as well should be all set up to operate the fan, the wiring should all be there for it to operate by either the AC high pressure switch (for low speed fan)or the engine temp sensor (for high speed fan, there is a resistor for low and high).
Alternatively, if you don't care about originality, you could get an aftermarket fan, these would both fit in front of the radiator.
PS the engine fan should stay in place, the electric fan is a supplement to the engine fan, should have both.

compu_85 · #3 06-06-2011, 04:53 PM

I think he is talking about replacing the belt driven fan and clutch with an electric fan. IMHO I'd keep the clutch.

-J

Gilly · #4 06-06-2011, 04:58 PM

OK, or assuming it does have the aux fans, he could maybe wire up a constant switch for them, I know there is also an aftermarket kit to have them run constant except when the vehicle speed gets to a certain point and they are no longer needed. I assume this would also not interfere with the original operating parameters.
I agree that ideally the engine fan should be kept.

tjts1 · #5 06-06-2011, 06:17 PM

Turn it ON/OFF with a thermostatic switch in the cyl head or radiator. Its been done many times over.

1960mog · #6 06-06-2011, 07:07 PM

Thanks for you reply guys.
I was thinking to replace the belt driven fan with an electric one.
The auxiliary fan is wired to always run when the AC is on.
The engine gets hot when driving uphill and in city traffic.
It's actually a 88 560SEL with a 617A motor.
The engine is almost new and the radiator and oil cooler cam out of a
81 300 SD.
I use a 75 dec.C thermostat and the fan clutch seems to work ok.

What about the special coolant that promise to keep your engine running
10 dec. cooler.
dose that stuff work?

Thanks
Tom

Gilly · #7 06-06-2011, 11:20 PM

What do you consider "hot"? If it is the normal operating range I wouldn't sweat it, if it is approaching the red mark, then there is a problem.

The aux fan only runs when either the high pressure switch in the AC calls for it (NOT whenever the AC is on), OR if the engine temp switch calls for it (if the coolant temp is hot enough). If the AC calls for the fan it is low speed, if the engine calls for it it is high speed.

One thing to look at if the engine runs hot pretty much constantly, is if the outside of the AC condensor or the radiator itself is plugged up with dirt, dust, leaves, bugs, etc. Can be cleaned up with high pressure water, just not so high that the fins on the radiator could get bent.

I think the additives are a waste of money. If the coolant seems dirty I'd recommend changing the fluid. I'd recommend either the coolant MB sells or Zerez G05, the local parts store should carry the Xerex.

1960mog · #8 06-07-2011, 12:16 AM

Hi Gilly
It approaches the red.
Right now the aux. fan is wired to the ac compressor.
It will always run with the compressor but never without it.
I will change that and see what happens.
The radiators are clean (at least on the outside ).
If I drive the car on the open road without grades the temp is fine.
Maybe the engine/cooling system is not designed to handle the heavier
SEL body.

Gilly · #9 06-07-2011, 07:54 AM

I don't think there would be a difference between the SD and SDL radiator. I would still encourage you to try hosing out the outside of the radiator.
Might seem counterintuitive, but I would also go back to the stock thermostat. If you go low, the possiblity is that the coolant might not be staying in the radiator long enough. I think the stock one is 80C. How's the coolant look? Also have you checked the pressure cap?

tjts1 · #10 06-09-2011, 02:05 AM

Quote:

Originally Posted by 1960mog

If I drive the car on the open road without grades the temp is fine.
Maybe the engine/cooling system is not designed to handle the heavier
SEL body.

Maybe the cooling system wasn't designed to cope with Las Vegas heat day in and day out. The big advantage with an electric fan is that it can run at its maximum speed when the car is at zero MPH. I ditched the stock clutch fan and aux fans for a large puller electric fan. My 2.3 hasn't seen the high side of 100c since even in 110f heat with the AC running. But thats a completely different body and engine. Good luck

Hit Man X · #11 06-09-2011, 07:59 AM

SDL radiator is larger as the oil cooler is mounted in a different spot. The SDL vs SD weight difference is only a few hundred pounds, so any theory of the radiator cooling being insufficient is just silly at best.

My SD and SDL deal with excess heat fine, nearly as hot as LV and I do not have problems. Why? I have newer radiators (less than 10 years), correct coolant, clean condensers, working fan clutches.

The PO said the problem 'radiator came from the SD'... it is probably 20 years old or OLDER. Just buy a new radiator and get on with life.

1960mog · #12 06-09-2011, 03:33 PM

Good to hear the electric fan works in a 201. What size is your fan?
How many cfm?

I may just try the larger radiator from a 560 or 300SDL and mount the oil cooler somewhere else.
Thanks for the tip.

1960mog · #13 08-15-2011, 12:56 PM

I think i fixed my overheating problem.
After installing a new Behr 560 radiator, the engine temp doesn't go over 90 degree any more.
I replaced the original oil cooler with two 19 row "Racing oil coolers" from Ebay that I mounted in the front bumper.
Wonder that a new 300SD radiator would have made the same difference.