tweaked fan clutch 3.5 liter - PeachParts Mercedes-Benz Forum

werminghausen · #1 01-23-2013, 04:49 AM

I have filled up my old fan with silicone oil (1 1/4 tubes of 10000 Toyota oil) clutch and now the fan really makes some noise! with engine cold and not running the clutch 'slips' in a way as it did before the tweak.
With engine running and engine cold....I can rev the engine and the fan is really pulling air (which didn't happen before...great?) but on the other hand when I am driving 80 now...I can hear the fan...what didn't happen before either. But I fear that the clutch is now engaging too much.
So who can help me giving advise how to trouble shoot the thing. As I still don't know exactly how the clutch is working internally (what makes the clutch engage and disengage hydraulically?) I have no rule how much oil is correct in the clutch.
Tomguy I think mentioned that the fan might just explode if clutch doesn't engage at higher revs. I don't like that idea.

Questions:
1) Could there be too much oil in the clutch? How would I find out?
2) What are the symptoms if the clutch doesn't disengage enough?
3) I mean how should the clutch behave if in correct working order?
4)How much oil is correct? Or what is the rule...
5) why does Mercedes state that the fan clutch should be upright and not in any other position?

It is relatively easy for me to drain some oil ...but again...what oil level is good?

Martin

WANT '71 280SEL · #2 01-23-2013, 08:59 AM

1. Too much oil in the clutch will keep it engaged. Unfortunately I don't know how much to add. I'm pretty sure mine is dead as well but I plan to just replace it as I have a tendency to makes things worse when trying to repair unrepairable items. My recent p/s high pressure hose breaking causing an engine fire cemented this belief.

3. In working order, your clutch should only "engage" when at operating temp. Then, when the engine exceeds a certain rpm, it should disengage or slip.

5. It should be upright so the clutch fluid doesn't leak out. If you lay it on its slide, there's a decent chance some fluid will escape rendering it useless.

Best Regards,

David

werminghausen · #3 01-23-2013, 11:44 AM

Quote:

Originally Posted by WANT '71 280SEL

1. Too much oil in the clutch will keep it engaged. Unfortunately I don't know how much to add. I'm pretty sure mine is dead as well but I plan to just replace it as I have a tendency to makes things worse when trying to repair unrepairable items. My recent p/s high pressure hose breaking causing an engine fire cemented this belief.

3. In working order, your clutch should only "engage" when at operating temp. Then, when the engine exceeds a certain rpm, it should disengage or slip.

5. It should be upright so the clutch fluid doesn't leak out. If you lay it on its slide, there's a decent chance some fluid will escape rendering it useless.

Best Regards,

David

Thanks David

I am aware of the things you mention... the problem is a bit that we can repair the unit if we know how much oil there needs to go in.
The knowledge the forum has so far is too vague..it is more guessing. Some have success with filling the clutch with oil...some put too much (like I) some too little into the inner.
As this is try and error. I'll drain some oil and see if I am lucky the second time. I just can't stand the sound of a turboprop...this is what it sounds when I am driving on the highway with 80 mph.....It sounds if I'd drive faster the car will take off.
It pulls a lot of air through at idle....I have to say....no overheating any more but...

thorsen · #4 01-23-2013, 12:59 PM

I have to ask - why don't you just buy a new fan clutch?

Palolo · #5 01-23-2013, 12:59 PM

Quote:

Originally Posted by thorsen

I have to ask - why don't you just buy a new fan clutch?

Oh man... he is in Oman. Hard to get 108/109 parts there apparently.

-----

With regard to the lack of info on how much oil to refill it with, since there is no data for it provided by the manufacturer, "no one really knows" and since you're the one doing the R&D, by default, you are the current expert...

I must say, it isn't a commonly DIY'd part so the base of info isn't as wide or deep as with other things. I tend to DIY and tinker with stuff, but the return on tinkering with a fan clutch isn't as high here (vs "in Oman", say) so most folks just pick up another one.

(A well-shrouded electric fan is probably the best option for hot climates, and will bypass the viscous coupling guesswork. It will run as needed and isn't coupled to engine rpm. There must be modern vehicles around from which to poach a suitable one.)

Seems like you have a bit of "leak/refill" experimentation ahead, but it also seems daunting as how much has leaked (or removed) and how much remains inside is hard to determine after a while.

Good luck with it. It has been interesting to follow along, but I'm no closer to understanding them. Hopefully a lightbulb moment will occur soon.

werminghausen · #6 01-23-2013, 02:24 PM

Quote:

Originally Posted by Palolo

Oh man... he is in Oman. Hard to get 108/109 parts there apparently.

-----

With regard to the lack of info on how much oil to refill it with, since there is no data for it provided by the manufacturer, "no one really knows" and since you're the one doing the R&D, by default, you are the current expert...

I must say, it isn't a commonly DIY'd part so the base of info isn't as wide or deep as with other things. I tend to DIY and tinker with stuff, but the return on tinkering with a fan clutch isn't as high here (vs "in Oman", say) so most folks just pick up another one.

(A well-shrouded electric fan is probably the best option for hot climates, and will bypass the viscous coupling guesswork. It will run as needed and isn't coupled to engine rpm. There must be modern vehicles around from which to poach a suitable one.)

Seems like you have a bit of "leak/refill" experimentation ahead, but it also seems daunting as how much has leaked (or removed) and how much remains inside is hard to determine after a while.

Good luck with it. It has been interesting to follow along, but I'm no closer to understanding them. Hopefully a lightbulb moment will occur soon.

Thanks Palolo

I have the clutch open and drain a bit... to be a bit scientific: first cut at 45 degree angle, see picture
It is a try and error thing but my only chance right now.
You see the center pin hole and the lower one which I cut in and plug it later on with a set screw.

werminghausen · #7 01-24-2013, 06:49 AM

update: I 'rotated' the clutch to 50 degrees (steeper than 45degees) in order to drain more oil.
This way the oil level now is at 15.5mm below center point of the middle pin hole (was 14.7mm below center point with 45 degrees) . With the degrees it is easy to control the 'oil level'.

Unsure how much silicone oil I drained now...maybe 1/4 - 1/2 of on Toyota bottle (18ml).
I tested rotation the shaft with the clutch in the vice. after a few forth and back turns the clutch 'opens' now...meaning in the beginning there is a lot of resistance...then after some forth and back rotation the resistance goes down to maybe half...well I gave no data [Nm] ...but by feel.

I'll install and test the turbo prop effect...need to get my distributor to work before though.

Martin

werminghausen · #8 01-27-2013, 02:34 AM

update 2: I didn't drive yet but decided to drain some more of the silicone oil... 55 degrees (steeper) for the time being. This will drop the oil level to below 16mm measured from center point. Then I'll drive (I have renovated distributor now and I am waiting for new distributor rotor). I'll provide a sketch of the measurement of oil level for following generations of pioneers.

werminghausen · #9 01-28-2013, 02:42 AM

I tried to drain some more oil today (55 degrees steep) but no oil was showing up...why? I have no clue.
I'll test the clutch as is and will report back.

werminghausen · #10 01-30-2013, 01:51 PM

clutch was testing much better this time...no turboprop...any more. thank god.
I'll have an eye on this fan and see how it behaves.
Right now I am stuck with a bad running engine and try to get this thing going ...desperately.

werminghausen · #11 02-16-2013, 02:27 PM

I was wrong....still lots of fan noise. clutch is binding!!

I was draining still more silicone because of the humming noise I experience at higher speeds (at 80 mph). So if someone is brave doing the same as I did- be very careful not to put more oil is an needed. But it is impossible to tell how much is enough.
The noise is concerning me and I fear that the fan is exploding at some point.

I drained another good portion of the oil with the drain hole at 6 o'clock position, the used compressed air to drain even more.
After draining the oil I tested manually (hub in the vice and spinning the fan by hand) and the clutch spins more freely, after the first turns with more resistance. After the first resistance I can spin the clutch easily by hand as soon as the thing frees up after 1/2 turns.
I'll reinstall and test again and will report back

werminghausen · #12 02-17-2013, 06:23 AM

I tested my good old drained fan clutch in situ.
As I mentioned before I drained as much as would come out of the clutch. I cannot get more silicone out.
Fan has much less binding now.
After engine start I can get the fan to stop with thick leather gloves for protection. As soon as fan stops(while engine at idle) I can hold the fan with one finger...almost no resistance. Is this how it should be?
No one knows ...I know.

Driving with the fan clutch: no loud sound at high speeds. This means the
fan is not binding any more. The question is now... does the clutch engage at the higher temps when Pin is pushed inward? I need to wait until temps are high enough, like 212F? Then clutch should bind and stop at once when engine is shut off- correct?

Tomguy · #13 02-17-2013, 08:53 AM

Martin, you've basically got it... I think the fan should engage @160-175 though, not 212. It's correct, on a cold engine, to be able to stop the fan easily and keep it stopped; however, on a hot engine, that should not be an easy feat if possible at all.

WANT '71 280SEL · #14 02-17-2013, 10:01 AM

You're also correct in that the fan should stop (when hot) when the engine stops.

Best Regards,

David

werminghausen · #15 02-17-2013, 01:45 PM

Quote:

Originally Posted by Tomguy

Martin, you've basically got it... I think the fan should engage @160-175 though, not 212. It's correct, on a cold engine, to be able to stop the fan easily and keep it stopped; however, on a hot engine, that should not be an easy feat if possible at all.

My temp gauge stays typically a bit higher than 175 (maybe 195) with radiator clean and new thermostat and fluid...lucky me.
So you are saying under normal operating temps the fan clutch is/should be binding?