W202 Viscous Fan Coupling

Spinal

MB Enthusiast
Joined
Sep 14, 2004
Messages
4,792
Location
Uxbridge
Car
G350, Duster, S320, 900ss and a few more
It's that time in her life I'm afraid...

yes, the time where she gets all moody, overheats for no apparent cause and when you shove a carrot (or fennel when you're low on carrots) she just stops spinning.

Oh wait, I'm getting carried away...

Did a carrot test the other day, and my viscous fan is beyond dead; I could have stopped it with a piece of paper, and the engine was at almost 100C.

A few questions:
- I saw some aftermarket couplings on eBay for £35. Has anyone used these? Are they reasonably reliable?

- Or would you recomend getting an old original MB one from a breaker? (new from MB is too much money for a part that I need to work for another 6 months)

- How hard is it to fit? I'm assuming the fan comes off with the coupling with a simple spanner? Any advice?

TIA,
M.
 

Mercedes cozy

Active Member
Joined
Aug 6, 2006
Messages
885
Location
LONDON (Near Heathrow Airport)
Car
Mercedes ML 320 CDI W164 KEYLESS GO / (NOW WITH STAR)
mate, I have secondhand one if you want. If your in uxbridge and then i'm down the road. Very easy fit. The Thread on them is anti clockwise to open.
I use a lond strong flat screw driver and give it a whack on the edge of the nut and its pen.
 

grober

MB Master
Joined
Jun 22, 2003
Messages
30,687
Location
Perth, Scotland
Car
W204 ESTATE
They must be stored vertically-- period. If not they often go faulty -even from new. I would buy a new one from an agent who knows this. What price an overheated engine blown CHG??? They are made by Sachs and not too expensive
p.s. you could initially take the unit off and try cleaning the area with the bimetal strip in the centre. This strip reacts to the temperature of the air passing thro the radiator and by bending opens a tiny pin valve to operate the viscous coupling. This delicate mechanism can stop working due to being clagged up with road dirt. Sometimes all they need is a good [IN A VERTICAL POSITION ;)] careful!!! clean with WD 40+ cotton buds or similar to start operating again.
 

iscaboy

Active Member
Joined
May 12, 2010
Messages
604
Location
Devon
Car
W124 E300 D (1991)
as/if/when the viscous fan coupling in my w124 dies it will be binned, and replaced with some electric fans.
 
OP
OP
Spinal

Spinal

MB Enthusiast
Joined
Sep 14, 2004
Messages
4,792
Location
Uxbridge
Car
G350, Duster, S320, 900ss and a few more
mate, I have secondhand one if you want. If your in uxbridge and then i'm down the road. Very easy fit. The Thread on them is anti clockwise to open.
I use a lond strong flat screw driver and give it a whack on the edge of the nut and its pen.
Thanks - I am in Uxbridge. How much do you want for it?

They must be stored vertically-- period. If not they often go faulty -even from new. I would buy a new one from an agent who knows this. What price an overheated engine blown CHG??? They are made by Sachs and not too expensive
p.s. you could initially take the unit off and try cleaning the area with the bimetal strip in the centre. This strip reacts to the temperature of the air passing thro the radiator and by bending opens a tiny pin valve to operate the viscous coupling. This delicate mechanism can stop working due to being clagged up with road dirt. Sometimes all they need is a good [IN A VERTICAL POSITION ;)] careful!!! clean with WD 40+ cotton buds or similar to start operating again.
I've heard this a lot. Question is, how does one control what the courier does, or the transport company, etc... (not saying you're wrong, I'm just curious. Is there a plug in new new ones that needs to be removed? A plug that stops the silicone from seeping into the bearings?)

Cleaning the metal bar wont work... I did that a while back, and it did come back to life... but now it's truly died :(

as/if/when the viscous fan coupling in my w124 dies it will be binned, and replaced with some electric fans.
I'm fitting the electric fans to the front of the radiator, and hooking them into a switch inside. That way I can control when the electric ones come on, and hopefully the viscous will do it's job...

The car will be going through some pretty rough/hot weather... so backups are good!

M.
 

iscaboy

Active Member
Joined
May 12, 2010
Messages
604
Location
Devon
Car
W124 E300 D (1991)
The car will be going through some pretty rough/hot weather... so backups are good!

M.

Then just put a non viscous fan on. BTW if this is africa the default trick used to be to pull the thermostat.
 

grober

MB Master
Joined
Jun 22, 2003
Messages
30,687
Location
Perth, Scotland
Car
W204 ESTATE
Thanks - I am in Uxbridge. How much do you want for it?


I've heard this a lot. Question is, how does one control what the courier does, or the transport company, etc... (not saying you're wrong, I'm just curious. Is there a plug in new new ones that needs to be removed? A plug that stops the silicone from seeping into the bearings?)

Cleaning the metal bar wont work... I did that a while back, and it did come back to life... but now it's truly died :(


I'm fitting the electric fans to the front of the radiator, and hooking them into a switch inside. That way I can control when the electric ones come on, and hopefully the viscous will do it's job...

The car will be going through some pretty rough/hot weather... so backups are good!

M.


Your only way [not guaranteed of course] of increasing your chances that its been stored correctly is to buy over the counter from an agent who is aware of the "vertical storage" issue. I dare say that a 24 hours horizonal/moving about won't probably do any harm-its when its lying horizontal "on the shelf " for 2-3 months in motor factors, a breaker's yard, or some one's garage that its liable to expire . There is no transit plug that I am aware of otherwise the issue would not arise I guess.:(
 
OP
OP
Spinal

Spinal

MB Enthusiast
Joined
Sep 14, 2004
Messages
4,792
Location
Uxbridge
Car
G350, Duster, S320, 900ss and a few more
Then just put a non viscous fan on. BTW if this is africa the default trick used to be to pull the thermostat.

Thermostat? What thermostat? :p Being truthful, the thermo is still in there, but it's a brand new one. I was tempted to leave it out, but given that last year I had no issues with the stock build, I'm hoping it's the same thing year. Luckily, removing the thermostat is easy should the need arise...

I was also trying to decide what to put in the radiator too... I'm undecided between the normal 60/40 Water/coolant or trying some "Triumph Redline Water Wetter" which seems highly recomended on the track....

M.
 

iscaboy

Active Member
Joined
May 12, 2010
Messages
604
Location
Devon
Car
W124 E300 D (1991)
I was also trying to decide what to put in the radiator too... I'm undecided between the normal 60/40 Water/coolant or trying some "Triumph Redline Water Wetter" which seems highly recomended on the track....

M.

If your system is 100% leak free, and you are going to do something that will seriously stress it thermally, you could consider this
 
OP
OP
Spinal

Spinal

MB Enthusiast
Joined
Sep 14, 2004
Messages
4,792
Location
Uxbridge
Car
G350, Duster, S320, 900ss and a few more
If your system is 100% leak free, and you are going to do something that will seriously stress it thermally, you could consider this

I was considering a waterless coolant mixture, but I haven't found one which has better conductivity than water based.

ResizedImage600412-thermal-conductivity-graph.jpg


The advantage of the Evans one is that if it does "overheat", it doesn't turn to vapour causing you to stop... I would rather something that conducts heat better during the engine running... particularly as we will be pushing the car hard and fast....

M.
 

iscaboy

Active Member
Joined
May 12, 2010
Messages
604
Location
Devon
Car
W124 E300 D (1991)
If you are serious about pushing the car hard and fast then you need to consider some surgery, swap out the existing rad for a far larger one, and / or add additional smaller rads in circuit and also increase the total mass (eg # of pints) of the coolant in circuit.

We used to run stuff in seriously extreme environments, it really isn't rocket science, you just end up devoting a greater %age of engine output than stock to cooling, by running a heavier duty than stock cooling system.

If you are running down through africa, paint the car white.
 
OP
OP
Spinal

Spinal

MB Enthusiast
Joined
Sep 14, 2004
Messages
4,792
Location
Uxbridge
Car
G350, Duster, S320, 900ss and a few more
If you are serious about pushing the car hard and fast then you need to consider some surgery, swap out the existing rad for a far larger one, and / or add additional smaller rads in circuit and also increase the total mass (eg # of pints) of the coolant in circuit.

We used to run stuff in seriously extreme environments, it really isn't rocket science, you just end up devoting a greater %age of engine output than stock to cooling, by running a heavier duty than stock cooling system.

If you are running down through africa, paint the car white.

Unfortunately, our budget wont allow serious modification... I'm just trying to make sure we get there without (another) radiator exploding....

I've noticed Evans have a new NGK-R; which is less viscous and as such puts less strain on the pump... I'm tempted to try that!

Still need to get the viscous coupling sorted tho :p

M.
 

iscaboy

Active Member
Joined
May 12, 2010
Messages
604
Location
Devon
Car
W124 E300 D (1991)
Still need to get the viscous coupling sorted tho :p

M.


no question, if this is the timbuktu thing in your sig, lose the viscous coupling and put a solid coupling fan in there.
 

Users who are viewing this thread

Top Bottom