I have been working on a noise at 60 to 70 mph in my 500SEL. It seems that it started when the temperature got into the 80's and higher. I finally traced it to the cooling fan. I replaced the fan clutch first part of May with a BEHR because the old one never engaged. I didn't notice the noise until last week.
Should the fan be engaged with the engine at 190 deg, outside temp of 80 deg, rpm at 2500 and speed at 70mph?
I thought the fan clutch would disengage at higher speeds and only engage at higher temperatures.
When the outside temps were say 70 deg or lower I don't have the problem.
If it sounds like I am confused, you are correct.
Is there a break in period for a fan clutch? It has about 1000 miles on it now.

Please help

PaulM

__________________
84 500 SEL (307,xxx miles)

The gospel according to Mother Benz tells us that the engage/disengage temp is 100C (+-5C) coolant, i.e., exit temp of the air from the radiator.

The calibration of any given fan clutch could be off from the design temp; 190F(88C) is coming up on the cusp of the critical temp.

Above 3450 RPM the clutch releases at any temp.

Thanks Frank,
So with 80 deg outside and engine at 190 and then add the A/C heat explains it
What do you recommend I do? Get the engine temp down? 3450rpm is out of the question in this country. My quick calculation looks like 90 mph. The car would be happy but the police may not be.

PaulM

__________________
84 500 SEL (307,xxx miles)

Ja!

You can replace the 100C thermal switch to a lower one. It's not really a fix but a band-aid approach.

You can also wire in a thermostatically controlled relay to activate the existing electric fan at a preset temperature.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

The BEHR clutch you installed will have this silly behaviour if its a similar part as used in the W124 E300D

It acts like a switch rather than a clutch, it will kick in at about gauge temperature of 95 and then only shut off at gauge temperature of 80. The US made horton brand works just right and smoothly engages in and out at the 90-95 temperature mark.

The horton one also blows some air at idle speed regardless of temperature (good for AC)

I remember seeing a shroud for the fan clutch of a 500 SEL, its a piece with round holes in it - supposedly to prevent extra fan engagement.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

It sounds like the Horton fan clutch (They make air clutches for semi-truck cooling fans.) would be a nice upgrade, but you don't really have a problem at the moment. The fan makes noise when it works. I'm sure the fan on my 300D makes noise while working, but I can't hear it over the open exhaust. Same goes for my bike with a (loud-ish) Scorpion pipe. I can only ever hear the fan when it spools down after I turn the engine off. I can tell you that on the bigger military trucks I've worked on and driven that you KNOW with certainty when the fan is on and when it isn't.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Zulfigar, thanks for the reply.
This Behr fan clutch is acting like you described. I don't know the exact temperatures but I do know that when it comes on, it won't go back off until the car is stopped long enough for the engine to cool back down. The only thermostat I can find is an 84 deg C. On a warm day (80 F) the engine will run at 90c. It has been this way for the last 14 years. The radiator is about 6 years old and has been cleaned and flushed every 2 years. I really don't think the engine is running to hot.

Where did you find the Horton fan clutch? The only ones I can find looking on the Internet are for trucks and heavy equipment.

The old fan clutch I just took off did not have the plastic piece you mentioned. I just went out and looked at a 560 engine and it does have the plastic piece but the fan clutch is bad (it just spins freely). I will see if the plastic piece will work on the Behr and if it will I will give that a try.

Thanks for the information

PaulM

__________________
84 500 SEL (307,xxx miles)

You can try injecting some silicone oil into the 560 clutch, find a hobby store that caters to RC trucks, they would have the silicone oil, you want the 7000 wt oil. Add 5cc and test.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Just an update.
First, the 560 fan clutch I found with the cover is bad. It has some play in the bearing. Not much, but I can't trust it. The cover won't fit on the Behr fan clutch so that is out.
I can't find a lower temperature thermostat that is made like the generation 1 126 V8's.
I found a 160 deg Stant thermostat that they say will work. I found one, installed it and the car ran hot. Took it out, put in a pan of water on the stove and it started opening at about 175 deg. I also put the old 183 deg thermostat in the water. It started opening at about 183. I let the temperature go up to 200 deg and the original thermostat was open about 2 times more than the Stant 160. That explained to me why the engine overheated with the stant. By the way, the Stant was made in China. That explains it even more.
I have watched the temperature of the engine closely and it runs between 190 and 196 (I have a digital temperature gage add on) when the outside temperature is between 70 and 85, A/c on or off, idling at a light, 70 mph on the interstate, up hill, down hill, etc. At 70 mph on the interstate sometimes the fan clutch will be on and other times it will be off. There doesn't seem to be a pattern. At anything less than 60 mph I can't tell if it is on or off as it doesn't make the roaring noise.
My only option now is to wait until I can locate a used fan clutch that works or can be fixed. Buying new from the dealer is not an option at this time.
Does anyone have any other ideas?
Thanks for letting me vent.

Paul

__________________
84 500 SEL (307,xxx miles)

I don't get what your problem is....your fan clutch is engaged? As long as it's not always engaged and your car isn't overheating leave it alone. I'm sure you have bigger fish to fry, if not then just enjoy the car. I have a small oil leak, it's annoying, but is not worth tearing into the lower engine to replace the gasket. If the fan isn't causing you any detriment while driving the car then you should leave it be. Now if it starts overheating, that is a different story, but because your car is operating as it should with normal temps, save for the fan noise, I'd say you're ok.

__________________

1990 190E 3.0L

Well, you have a good point. I should leave well enough alone. However, after working on large mainframe computers for many years and cars for many years (yes, I am old) I learned that if there is a known problem (fan engaged when it shouldn't be), it needs to be fixed before it causes other problems. Remember this is a old car that likes gas and doesn't need the added stress of a big fan in the front of the car adding an additional load on the engine when it is not needed.
This is our traveling car. We are willing to put the gas in it to have a comfortable quiet car to ride in. So with the fan staying engaged when not needed, we use more gas in a noisy car.
We are wanting to go on another road trip out west, maybe in September, if we can get some things worked out. Last trip out we drove a little over 7000 miles but had to cut our trip short. We had planed on about 10,000 miles.
Why do we drive? So we can do and see what we want to do and see, not what some tour company wants us to do and see.
So I am not working on a "well enough" problem.
What bothers me most is the thermostat (BEHR) and the fan clutch (BEHR) are both made in China now. I can't seem to find anything make in this country or Germany.
The Pull-a-Parts don't have anything anymore (generation 1 126 cars) in my part of the country.
I checked with the local dealer and the fan clutch has to be ordered, $665.00, and they couldn't, or didn't want to tell me where it was made or the manufacturer. BEHR is an OE company, but have started using China.

Does this explain why "well enough" is not "good enough".

PaulM

__________________
84 500 SEL (307,xxx miles)

Went out today, just looking. I found out that the aux fan was intermittent on low speed. Sometimes it would work, sometimes it would not work. Traced the problem to the aux fan resistor down below the master cylinder. WorldPac had one in stock. Got it and now the aux fan works correctly. I don't know how this could cause my problem but it needed fixing anyway. I'll see how it does.

PaulM

__________________
84 500 SEL (307,xxx miles)