W124 overheating / cooling fans?

[yosshimura]

Its nice not to have to post often in the tech area , which means no problems .....

Anyway, I have seen my temp gage max out 2-3 times recently when idling for a few minutes (ie drive through at fast food). I read through the archives and I think it might be the fans.

Here is the scenario:
- 95 W124 / new water pump & hoses about 9K miles -5 mths ago / 110K miles
- WHile driving you would not have a clue of the overheating, needle is pegged at midpoint.
- Today, I noticed , after one of these "high temp" episodes that only oneof the two fans up front was spinning. Is this right? Or are they both supposed to run at once? Makes a little sence, since when the car moves temp goes back to normal.

Once I figure out if these dual fans are supposed to run simmulanously (sp?) I can either discard that as being the problem or address it. What is the correct name for these fans?

Thanks

[Arthur Dalton]

Both fans are wired in parallel, so they both work together..
Spin the non working one to be sure it is not blocked by a stick/etc.. it is probably bad...

[sydney]

Have you already ruled out the fan clutch as it is the device that engages the radiator
cooling fan as the engine becomes hotter. I think the electric fans are related to the air
conditioning. The fan clutch is a commonly replaced item. You should be able to
hear a change in the amount of air blowing when it is engaged. It should be engaged when
the engine is cold and will release after running for a short time like 30 seconds or so and
it should also then engage when the engine is hot. This is not to say you may not have other issues , but the fan clutch is definately related to cooling when the temperature
rises.

[yosshimura]

Originally Posted by Arthur Dalton

Both fans are wired in parallel, so they both work together..
Spin the non working one to be sure it is not blocked by a stick/etc.. it is probably bad...

We have a problem b/c when I noticed the passenger side one wasn't spinning today, I moved it and it just spinned without any hesitation with the push of my hand, while the other one was going full force... so even though in parallel only one is working

While in these episodes the a/c stops cooling, which obviously is tied to eng temp...

[RAYMOND485]

1984 300d Turbo 135k
Engine Hot, Turn Off Engine, Move Fan By Hand If Loose Replace
Fan Clutch $160.00

[Arthur Dalton]

Originally Posted by yosshimura

We have a problem b/c when I noticed the passenger side one wasn't spinning today, I moved it and it just spinned without any hesitation with the push of my hand, while the other one was going full force... so even though in parallel only one is working

While in these episodes the a/c stops cooling, which obviously is tied to eng temp...

The fan motor itself is at fault [ probably brushes, as you have verified the bearings are not locked up by hand spinning ]...
The a/c has a high pressure switch that will cut the compressor in the event that the high side pressure has reached a danger zone caused by high thermal load conditions, which is exactly what a non operating aux. fan will create. These two fans are activated by high coolant temp for the high speed and a/c high side pressure for the low speed. Either activation requires both fans to run at the same time, regardless of which system is being called for.
Fan motor should be replaced.

[justino]

I had a similar problem on a 1991 300e 4matic in the UK, 205,000 miles

When I bought the car it would overheat quickly, and max out when stationary. A new thermostat (very cheap and quick to fit) cured that problem immediately.

During the diagnosis of this I noticed that neither of my 2 electric auxillary fans worked. I managed to get one slowly back into life by tapping the centre spindle lightly with a small hammer. Following this I drilled a small hole into the plastic cowl which covers the centre of the fan motor and filled this with WD40 spray lubricant using the straw that comes with it. Shorting out the temp sender I let the fan spin for 5 mins to free it self up. You may wish to silicone up the small hole once all is well.

However this method hasn't worked on both fans, but is worth a try as a temporary fix. I think the power lead may have become detatched from the other, and it's not easy to get access to.

In any event with the new thermostat the car doesn't get hot enough to turn the fans on (105 degrees I think) and my aircon is out of gas which is the other trigger for turning them on.

[Michael K]

When did the problem start, right after the new water pump or later?

[yosshimura]

Fan motor? So I don't have to replace the whol fan assembly?

Problem started? hmm, I guess recently.....few wks.

Some mentioned fan clutch, I can check that as well, but no qiuestion I have to fix the non operational fan first.

[Arthur Dalton]

just that side..

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1M30LAGSC1NJ00QFW3&year=1995&make=MB&model=E-320-001&category=G&part=Auxiliary+Fan+Assembly


..Used to be able to get just the motor , but looks like they have the fan assemb now...

[zafarhayatkhan]

I would avoid using the AC in stop/go traffic until the fan assembly has been replaced. High temperatures are not only bad for the engine but they are worse for electronics/wiring. As it is, the electronics in these cars are hanging in there by a thread

If one fan has gone bad, the other one is probably on the way out as well. You can tilt the radiator to get the fan assembly out. Should take maybe 30 mins.

The fans on my car were running slow and intermitently blowing out the fuse.

These fans have been refered to as "garbage cans" on these forums, as they were a bandage, to update the W124 without changing the architecture.

Above 25 mph, the W124 does not need any cooling fan under normal conditions.

[Arthur Dalton]

There is also a little resistor modification that some use to trigger these fans a little earlier than spec..Cost a buck and works well in Southern climates.
It only takes a few degrees difference for 104s to get to that point of high temp run-up at standstill/traffic.
I have always installed a cabin manual sw on any Benz I have owned over the years , just in case I get into a high heat/thermal load condition..hardly ever use it, but it is nice to have ..another simple mod. Simply put a sw across the high side pressure sw and mount it in the cabin, under the dash..
This is a good addition for those who tow a boat/trailor....

[dtf]

Remember that your Transmission fluid is also cooled through the radiator system so if the Trans. fluid stays hot it could damage trans over time.

[Arthur Dalton]

Originally Posted by dtf

Remember that your Transmission fluid is also cooled through the radiator system so if the Trans. fluid stays hot it could damage trans over time.

True... that is why I mentioned then benfit of a manual cabin fan sw for towing ...

[yosshimura]

Thanks for the info... baically I understand the radiator needs to be moved and not removed? How much disassembly required? I didn't look at the detail in how its mounted, but it seems right there in front of the radiator.

thanks