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2003 Mercedes ML350
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Discussion Starter #1
Hello! asking for help. Was driving my 2003 ML350 Mercedes and randomly the car when rev'd up, it sounds so like like the FAN is going extra fast and loud... It was not like that before and i know it is not normal.. It is super loud.
Was told if could be the thermostat or temp sensor going bad but the car isn't overheating..
Well, today going down hill (1 week after the issue), I noticed the coolant dash light came on and it went off after driving, butt i topped off coolant in the reservoir to the line and it is still making the loud fan noise when i gas the car and as it revs up, it gets louder..

What could be the issue?
 

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87 190d 2.5TD, 98 ML320, 09 CLS550
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113 Posts
Park it and do not drive it until you replace the fan-clutch. That may likely be over-paranoid, but read on...

This is a cheap $30-$40 part that bolts to a pulley driven by the belt. Your fan is - in turn - bolted to this clutch.

As these age, they can begin to freeze up - not providing the correct "slippage" as-needed. The end-result is: your fan spins at engine speed constantly (faster than normal), which can have dire consequences on the blades of the fan itself.

Now, it is completely normal for the fan to sound a tad loud when you first start the car and perhaps even the first 30-90 seconds you drive it w/ a cold engine. But if the loud "woosh" of the fan is constant even after a minute or so.. that clutch needs to be replaced.

I saw many European cars come into my shop with "outward" dents on the hood and a completely destroyed radiator and/or other parts because the fan could not withstand the stress of over-spinning and basically flies apart (shreds itself).

Most times, this does not happen. But you do NOT want to be that one-in-100 that has the fan failure.

And on a side note.. if you have not done it, just service the entire cooling system. Chances are likely that if the clutch is failing, the pump is just as old. An entire cooling system service kit is actually more cost-effective (pump/tstat/clutch) and piece of mind than just replacing the clutch. Consider the cooling system on your benz (or any European car) a "every 100K miles" service item.
 

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87 190d 2.5TD, 98 ML320, 09 CLS550
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Also please note: I cannot recall if the 2003 ML V6 had mechanical or electrical fan. I know for a fact my 1998 ML320 has a traditional mechanical clutch.

Based on what you tell me (revving engine increases fan noise), I am inclined to assume it is mechanical.

IF IT IS electrical, you probably need to have the vehicle properly scanned to see if the fan control is working properly or if something else is forcing it on (ac pressure sensor, engine temp sensor, etc). Without diagnosing w/ a proper tool, we are all just guessing.

Also note: those little "HyperTough" ODBC (bluetooth) connectors for android that WallyWorld sells are made by Autel. And for $35, they are damn good diagnostic tools. Includes one "Brand" (additional brands/makes are like $15, a "Brand/Make" is BMW/Audi/Volvo/etc) The software/app is the actual Autel MaxiAP. Even on my 2009 CLS550, that little bugger will dig into virtually every module on the car (engine,das,airmatic,trans,etc). Should be more than sufficient to scan a 2003 ML.
 

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2003 Mercedes ML350
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Discussion Starter #4
Also please note: I cannot recall if the 2003 ML V6 had mechanical or electrical fan. I know for a fact my 1998 ML320 does. But based on what you tell me (revving engine increases fan noise), I am inclined to assume it is mechanical.

IF IT IS electrical, you probably need to have the vehicle properly scanned to see if the fan control is working properly or if something else is forcing it on (ac pressure sensor, engine temp sensor, etc).
Hello, the car has a clutch fan in the back of the radiator (facing engine) and two electrical fans in front of the radiator (facing outside).

Ahhh. so the actual Fan is okay? Do you have a part number or something or where can i find that part?
What's a good way to test if it is broken?

Yes, it starts being loud from startt up and does not calm down.. it gets louder as you gas the car.

What is this pump you are talking about that is old?

By pump you mean water pump?.
Damn, i just bought this car.. :( where can i find a kit like tthat?
I am kind of on a budget.. you think it's okay if i just replace the fan clutch?

Like this? More Information for SKP SK46012
rock auto
 

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87 190d 2.5TD, 98 ML320, 09 CLS550
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113 Posts
At least replace the clutch.


AutohausAZ, PartsGeek, and FCP Euro are all good sources as well. No part number handy, but if someone here wants to chime who has access to StarTek parts catalog - feel free. I can tell you: if you order through FCP, their "Select your vehicle" tool has ALWAYS pulled up the exact part needed for me at least.

It is not particularly hard to replace, but you DO need a fan clutch tool (to break loose/remove the large nut). I cannot recall if the ML uses a 36 or 38 off hand... but that and some 6MM allen bolts are all that hold that on. In fact, you do not even need to remove the belt.

I only say "service the cooling system" because.. well... one thing most Euro cars have in common: cooling system issues. Mainly w/ age. Every 100K or so, cooling system parts start failing, getting brittle, etc. Not needed - but recommended if you can spare the $$ in the near future.
 

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2003 Mercedes ML350
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Discussion Starter #8
That looks correct at least. Rock Auto usually cross references the right part... most the time at least.
just ordered...you know what size are the 3 bolts on the clutch fan so i have everything ready? or what kind of bolts to remove?
 

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2003 Mercedes ML350
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Discussion Starter #9
You have one of those $40 fan clutches installed. Chinesium junk.

While keeping your engine cool, your next question will be how long is water pump bolt 7a.
ahh... what you mean water pump bolt 7a
 

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87 190d 2.5TD, 98 ML320, 09 CLS550
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The 3 bolts on your clutch should be a 6mm hex (Allen) if I recall correctly. May want double check.

I think the large but that attaches the clutch to the pulley is 36mm. You are supposed to have the counter/hold tool, but they are rarely used in the shop. We typically just give the 36mm wrench a stern whack with a hammer and it comes off (or my favorite: the impact fan clutch adapter). Of coarse, if you rent a fan clutch tool from the parts house, it should have the holder for you.
 
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