Pictorial on the electric fan install - PeachParts Mercedes-Benz Forum

Diesel Giant · #1 09-06-2007, 08:48 PM

I just finished up the install of the retrofit electric fan on the '81 300d in the shop.

I cant tell you how pleased I am with how it went.

Check out the pictorial:

http://dieselgiant.com/mercedeselectricfaninstall.htm

#2 09-06-2007, 09:25 PM

The engine fan really does not take up much power and is more reliable than an electric fan. After all, the clutch on that 81 lasted over 20 years of constant use.

For the turbo engines, I'd upgrade to the smaller diameter waterpump pulley and 9-blade plastic fan. This combo was introduced in the 1984 W123 and W126 updates. I've even seen a few people upgrade to the clutch and fan from one of the V8 W126 models.

TheDon · #3 09-06-2007, 09:37 PM

I don't think the Mercedes engineers would mount the fan directly onto the radiator...

Shawn D. · #4 09-06-2007, 11:27 PM

I'm going the same route and just received my SPAL 16" fan and pulse-width-modulated controller this evening. I decided to go with an electric fan because:

1) I've been running without a fan since I got the car in November and almost never "need" the fan. On the highway, the car stays at 82C and in stop and go traffic it almost never gets over 90C, and the highest temp I've seen was about 105C after getting stuck at a light for four cycles and only moving 1/4 of a mile in eight minutes (and this was during Atlanta's 105F temps last week).

2) When I put the fan clutch on, it seemed to work OK despite the loss of the juice, but the wobbling meant it was toast. The cheapest I could find a clutch was an off-brand for $140 plus shipping (it's $240 here at FastLane), so my cost of installing the electric fan will be on a par with replacing the clutch.

3) An 87-hp engine needs all the help it can get, and since I can set the PWM module to the temp setpoints I want, the fan will rarely be drawing any power.

4) I don't do "hack jobs" on wiring, so it'll be clean and reversible.

Quote:

Originally Posted by ForcedInduction

The engine fan really does not take up much power and is more reliable than an electric fan.

Yeah, but on an 87-hp engine, "(not) much power" is relatively more. Also, the clutch fan would not be moving as much air at idle in traffic when compared to an electric fan that can be running at 100% in traffic (assuming the electrical system is up to snuff).

Quote:

Originally Posted by ForcedInduction

After all, the clutch on that 81 lasted over 20 years of constant use.

Assuming it was the original and functional until the end.

renman · #5 09-06-2007, 11:33 PM

My 1984 3ooD came with an electric fan installed. It's on a relay hooked to the AC.

Shawn D. · #6 09-06-2007, 11:40 PM

Quote:

Originally Posted by renman

My 1984 3ooD came with an electric fan installed. It's on a relay hooked to the AC.

That's the auxiliary fan for the AC -- it's not the primary cooling fan and isn't triggered by temperature (on the W123 at least). The discussion here is about replacing the belt-driven primary fan with an electric one.

Jeremy5848 · #7 09-06-2007, 11:45 PM

How loud are these retrofit primary fans? The secondary fans on both my 123 and 124 cars can't be heard inside the car (with the windows closed and the a/c running) but are loud when standing in front of the car.

Based on a hasty web search, I notice that these fans draw a lot of current -- 13.9 Amps for the 15 inch models. Given the small alternator on the 617 motors, that's a lot, especially in slow traffic on a hot day, when the alternator output will be reduced. Both primary and secondary electric fans will be operating, along with the climate control system and its compressor. If it's a hot evening, add headlights. Clearly, it's a tradeoff.

Jeremy

Johnhef · #8 09-06-2007, 11:50 PM

Quote:

Originally Posted by TheDon

I don't think the Mercedes engineers would mount the fan directly onto the radiator...

actually, they used a similar design on the radiators in the 163 ML's

kerry · #9 09-06-2007, 11:58 PM

My 409d (617na) had an electric fan on it when I first purchased it. It could not keep up with the heat load climbing a steep hill on a warm day. I converted it to a direct drive fan. No problem handling the heat.

pj67coll · #10 09-07-2007, 12:06 AM

Quote:

Originally Posted by Shawn D.

That's the auxiliary fan for the AC -- it's not the primary cooling fan and isn't triggered by temperature (on the W123 at least).

You sure of that? My 240D's A/C compressor is seized and I can't even turn the AC on. But my aux fan comes on at temp's above 110F without fail every time.

As to the electric fan replacement. I guess there are pro's and con's on both sides. For myself, I'm not a fan of electric fans. I live in Phoenix and want my fan turning permanently without the possiblity of an electrical gremlin getting in the way. I've just had to spend 380 bucks on my POS Kia Rio to replace a defective electric fan after only 75K miles. Maybe I'm an old codger but I'll stick with Mercedes original engineering in this respect at least.

- Peter.

Jeremy5848 · #11 09-07-2007, 12:31 AM

Quote:

Originally Posted by pj67coll

You sure of that? My 240D's A/C compressor is seized and I can't even turn the AC on. But my aux fan comes on at temp's above 110F without fail every time.- Peter.

The aux fan is triggered by (a) coolant temps greater than about 105C and (b) refrigerant pressure above (don't remember) psi. Either or both. Yours is being triggered by the coolant temp (you mean 110C, of course

).

Jeremy

pj67coll · #12 09-07-2007, 03:29 AM

Quote:

Originally Posted by Jeremy5848

The aux fan is triggered by (a) coolant temps greater than about 105C and (b) refrigerant pressure above (don't remember) psi. Either or both. Yours is being triggered by the coolant temp (you mean 110C, of course

).

Jeremy

Nope. I mean ambient temp above 110F. My coolant never gets above 95C.

- Peter.

Shawn D. · #13 09-07-2007, 08:01 AM

Quote:

Originally Posted by Jeremy5848

The aux fan is triggered by (a) coolant temps greater than about 105C...

Well, it isn't on my 300td. There is nothing that could trigger it. The only two temperature sensing devices are the sender for the gauge and the sender for the HVAC (which tells it not to blow air in heat mode until the coolant is warm enough). There is no temperature switch at all.

In any case, the front mounted fan is still an auxiliary fan, not a primary cooling fan.

Mister Byrnzoil · #14 09-07-2007, 08:09 AM

I think electric fans are great, I have already converted my jeep, and the 300cd is next...

But I would not use those plastic mounts, I don't trust them. I would fabricate a bracket that mounts to the body and/or the original fan shround mounts.

Also as someone previously mentioned I would either upgrade the alternator or add another battery.

additionally I would wire a manual override, so that I could turn on the fans at my discretion.

Finally, I prefer 2 smaller fans as opposed to one large one, this gives more cooling options and also allows coverage of the oil cooler as well as the radiator.

ConnClark · #15 09-07-2007, 12:07 PM

Dieselgiant,

You should write shop manuals!!

I would have some concern over mounting the fan to the radiator in the manner shown, however for lack of knowing of a better way of doing it I'm not going to condemn it. This may deter some customers so you might continue to look for another way to mount it.

.