87 300TD...where's the roar? - PeachParts Mercedes-Benz Forum

zu! · #1 04-02-2016, 08:13 PM

I had my mechanic change out the fan clutch for me since he was changing the water pump anyway. I noticed though, that the fan still spun quite a revolutions times after the engine was stopped. And there was no roar at startup.

So I complained to my parts guy. He said no problem, ill give you a new one, just return the old one when you've replaced it.

I just did. Well, same thing. Brand new part. What gives? Here's the new part.

And here's the "old" one before I changed it out.

There's a directional arrow too, and if I follow it, then it turns clockwise with the direction of the fan (when one is standing in front of the car). This is how I installed it.

Is it possible to have two duds in a row? I remember when I first installed it, it was all nice and stiff. But after a short run, it can be turned quite easily.

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vstech · #2 04-02-2016, 11:08 PM

Did you get the clutch for the metal fan? Most use the cheaper clutch designed for the plastic fan. Then change to the 98E300D plastic fan. Better cooling and less money.

DONT GET THE 90-93 300D FAN!!! IT WILL TAKE OUT YOUR RADIATOR! !!

zu! · #3 04-03-2016, 12:10 AM

Thanks for the reply vstech. The fan is what came with the car. I remember being told to get the fan clutch for the 606 engine because it was cheaper. However when I went to my parts guy, he found it was actually more expensive!

So, I got the actual fan clutch meant for my actual model. And...there's no roar. So are you saying that the clutch for the metal fan will not work with the plastic fan?

Btw, I don't understand why everyone needed any of the special short hex wrenches etc. I used a regular 8 mm and didn't have too much trouble ... Maybe I've got small hands.

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vstech · #4 04-03-2016, 05:19 PM

The problem is with the clutch designed for the plastic fan being used on a metal fan. It'll fail. As long as the clutch is designed for the metal fan you should be good.
What brand did you get?

zu! · #5 04-03-2016, 07:55 PM

Quote:

Originally Posted by vstech

The problem is with the clutch designed for the plastic fan being used on a metal fan. It'll fail. As long as the clutch is designed for the metal fan you should be good.
What brand did you get?

It said Mahler on one place and Behr in another. Made in Germany. I was researching more into it and came up with one of GSXRS posts and he said that his never roared too. But in many other posts, they say theirs roars at startup. This tells you it works right?

Mine is stiff when cold, easy to turn when hot. Odd eh?

How do I tell if it's for plastic fan or metal fan?

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renaissanceman · #6 04-04-2016, 01:41 AM

Mine moves a lot of air at startup...I swapped in the plastic fan and a new clutch from eBay for a total cost of about $70 or so. I have about 4k miles on it and so far so good...the clutch looked to be quite high quality for the $50 I paid.

babymog · #7 04-04-2016, 07:01 AM

Should be engaged at startup, but quickly disengage.

For reasons I don't know, the FSM is very specific about storing this part upright, not laid flat. Possibly if it has been stored laying flat it will take a while for all of the viscous fluid to properly re-distribute? I don't know, just grasping for straws.

zu! · #8 04-04-2016, 10:52 AM

Well, that's odd...about storing it flat, that is. In both the ones I got, they were stored flat and in fact the box itself says to store it flat with a specific "this side up" sticker.

No, they both don't roar at startup. It's quite the pain to remove and install. Just to be clear, the copper strip installs facing the front right? Here are more pictures.

this is the original one.

the replacement that didn't roar.

The new one also did not roar and looks exactly like the replacement.

heres the box for part numbers and such.

I'm at a loss. Does it or doesn't it work? Twice now. Both exactly the same. Any thoughts?

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Zulfiqar · #9 04-04-2016, 11:43 AM

Theres your problem,

its a BEHR fan clutch which is trash. They came original in the W124 body E300D and are completely hopeless, the fan catches at 90C coolant temperature and cuts out below 90, the E300D has a 95C thermostat, so the fan is always locked.

As vstech said, the 98 model with the 11 blade fan wheel is a far better upgrade.

Before you do anything to change the fan clutch, take an air compressor and blow out the radiator and condenser fins. The clutch needs a lot of hot air to work, clogged fins will not allow air to pass.

btw - is your old clutch wobbly or scratchy to turn?

zu! · #10 04-04-2016, 11:52 AM

Thanks zul. My old clutch was working perfectly fine except that I thought it free wheeled too much when the engine stopped. It also did not roar at startup.

No Wobblies of any kind. It's a different brand though. Sachs.

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babymog · #11 04-04-2016, 12:18 PM

I'm not sure what you're looking for in this "roar". Mine start cold with no drama, but if I rev the engine immediately after starting I can hear the fan running and then drop out (1-3seconds?). Is this your roar? I don't really notice much in the cooler weather, maybe because the windows are closed. It also shouldn't freewheel when cold, if you grab the fan (engine off) and give it a spin and it makes around a revolution or less, it has fluid in it. A really bad clutch has play and /or will freewheel when spun by hand.

The FSM test is to idle the car until the gauge reaches a specified temp (I don't remember, 100C?), then the fan should engage and you will hear it when you rev the engine.

It also can not be locked, the clutch has an RPM-limiting function to keep the fan in one piece.

I suppose this original design could be improved on, many members here have had them fail after 25years and maybe 200k-300k miles, ... I buff the fan when off, spray it with a teflon coating and install it. If it's not damaged or out-of-balance, it should be good until 2041.

zu! · #12 04-04-2016, 01:03 PM

Well, I've heard it before in other Mercs and many others attest to it too, as an indication of whether ones viscous clutch is working correctly. The "roar" is heard when the car is first started, and dies down within s few seconds.

I have not ever heard my fan roar before, either with the old clutch or both of these new ones. Heck as I was taking pictures yesterday, I heard the correct roar when my Neighbour across the street started his old Toyota pickup. That's what I was looking for when I changed my clutch.

When stopped. It spins for quite s few revs too. That too is apparently not correct.

I guess I'm being a little OCD about this, but only cos summer is just around the corner and I'm always afraid of that with the 124 heads.

I'll blow out the rad with compressed air when I get home today. See if that helps.

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renaissanceman · #13 04-04-2016, 01:59 PM

The roar should not be affected by whether the radiator is clear...I'll check out my clutch later today to see how difficult it is to turn cold and see if I can get a video of the roaring for you.

I have the upgraded plastic fan and clutch, though, so sort of apples to oranges...but really, I recommend upgrading.

babymog · #14 04-04-2016, 02:07 PM

PM your email address to me or a cell # and I will send a quick video of spinning my fan by hand for comparison (has around 250k on it, but still fine).
I happen to have a bad one on the 140 next to a good one on the 124. The 124 spins about 90* when I give it a flick of the wrist, the 140 goes a couple of revs.

Zulfiqar · #15 04-04-2016, 03:55 PM

Do not expect the toyota roar from your fan as there are a few parameters missing, chiefly they are the toyota spins to 2000 rpm as it starts from dead cold and secondly the fan is quite overdriven in a toyota.

Add to the fact that it has more heavy duty truck like fan blades and holds close to 50cc of silicone oil. Thats a lot of oil.

Our little slim fan clutch does not hold that much and has a very narrow profile fan and our engines dont rev as we start them. So whatever little amount of oil is pooled at the bottom will distribute out quite quick. But this BEHR fan clutch is junk as it will never act like a clutch but more behave like a switch - I have been down that road.

Your original fan clutch can be resurrected with a shot (5 or 8cc) of 7000 wt silicone oil from an RC hobby shop or ebay etc.

if you slide off the bimetal spring you will see a small brass pin sticking out of a hole, that pin is a passage into the working chambers of the clutch - you need an irrigation needle to push that oil in there - heating up the clutch to 180F in an oven will help lots as cooling action will suck the oil in. Dont overfill it as it will never decouple. That is why I only wrote 5cc.