500E running hot?

[Uberwagon]

Hello all.

My 500E is running warm at lower speeds, I know the left hand fan is not working at the minute but I can't trace the wiring very easily so as it never goes above 100 i've left that for the time being.

Before it always sat around 90°C unless I was travelling very slow but recently it has been running warmer.

The hoses are ok, I have no leaks, the expansion cap is fine and the radiator is clean and unblocked after a recent flush and coolant change, the coolant was a 40/60 mix of Antifreeze and water.

I was wondering the best way to test the Viscous fan as I want to look at this before delving deeper?

Dave!

 

[Mercedes cozy]

Dave

The Viscous can be a bit tricky to test. There are I think a couple of ways to check and this is the way I do it.

1) WIth the engine off try turning the fan by hand and if it turn very freely without any resistance then its gone.

2) The second way is a bit dangerous. I do it but would not recomend any only if they know what they are doing. With engine running at idel, you will need to get a wood stick (Use protect goggles) try and stop the fan from the edge. If you can't that meens the fan is ok. If you manage to stop it then its gone.

Good Luck

 

[Uberwagon]

Well it turns very freely with the engine off so i'm guessing it is shot, bugger. I wasn't sure if it was energised to work or energised to release.

I suppose this is a good thing in some ways as at least I can now fix it.

I know people have changed Viscous fans on Range rovers and Land Rovers etc but as the 500 is lubed up to fit in the engine bay I was wondering how good an idea this is?

Dave!

 

[Mercedes cozy]

How freely does it turn very or a little. Is there any resistance what so ever.

To be hundred percent sure. try the second test. For me this has always worked. May be not a safe way but its worked for me.

 

[Parrot of Doom]

I believe a carrot in the moving fan is a good test. Carrot survives = viscous coupling gone. Chopped carrot = coupling fine.

 

[Uberwagon]

I can spin it with my finger and it carries on turning half a turn afterwards.

I will have a bash at stopping the fan now, brb.

Dave!

 

[Mercedes cozy]

Thats your best bet as you don't wanna take that fan off for no reason.

 

[Will]

don't forget that most viscous fans on MBs have electro-clutches on them too, it should spin freely until this cuts in IIRC

Do you notice the fan cutting in when it gets hotter, if not the temperature sender maybe faulty?

Get a 2nd opinion before condemning it - carrot test would be good if it does manage to cut it

Will

 

[Uberwagon]

Well it acts like a very large Lathe so i'm guessing it's actually ok.

Just took a very quick run down the dual carrigeway and it rose to 100°C before sloping down when it normally only pops to 85°C.

Might change the thermostat then, very odd as it isn't doing it all the time.

Thanks for your help, i'll keep delving and see where it leads.

Dave!

 

[grober]

there is a known tweak to get your viscous fan to cut in early.see this site. http://pages.prodigy.net/jforgione/MB_vfc.html there is also a mod to get the aircon auxilliary fans to cut in at alower temp also. http://pages.prodigy.net/jforgione/MB_CTS.html

 

[Uberwagon]

Thanks for the heads up Grober, I like the idea of it kicking in early but I don't want it to be on all the time.

It has a resistor mod for the electrical fans to cut in early by the previous owner who I know did it properly, I may have a look though and see if all is the same, possibly this is why the secondary electric fan doesn't cut in at the minute?

I was in stop start traffic in Italy in June and it never raised above 90 for hours on end so something has gone amiss since then, as at high speed it runs at the right temperature i'm still inclined to think it is an electrical issue?

How constant to fellow 5.0L V8 drivers electric fans run? If they are on for much of the time then this could explain it, if they aren't then it must be something else?

Thanks for the replies guys, Mercs are new to me and I am yet to learn the foibles, if only it was my Peugeot

Dave!

 

[Vlad]

Reading your first post you mention that the car was running fine prior to the coolant change and now its running hot.....air-lock?

When the coolant was changed did you have the heater dials set to Max Heat....if not when you use the heater for the first time, you are likely to get an air-lock which in turn will give you the higher running temperature.

Only total cure is to drain the coolant again and re-fill.

 

[Bazzle]

Fan check.

Engine cold in mornig, start, fan comes on and will turn off as oil drains away. (open hood and you will hear it as you rev.
Engine real hot. Stop engine, open hood, fan will have a bit or resistance.

Fix that in operable electric fan...wire to 1st fan.

Air bubble sound feasible too.

Bazzle

 

[Uberwagon]

Thanks again for more ideas.

I'm just off to have a look at the second fan.

It ran fine just after the coolant change (Took ages to bleed properly mind you) but has started rising quite recently, not to a very high level at all but higher than before.

I'll follow a few more ideas from on here, thanks for the help guys!

Dave!

 

[Uberwagon]

I am now even more confused but not that worried any more

If I unplug the sensor that controls the fans it makes no difference at all.

I was under the impression that unplugging it should turn on both fans?

Right, about 30 seconds after turning the air con on with a warm engine the right hand air con fan kicks in and keeps the temp at a stable 100°C ish. If I turn off the Air Con then the same fan keeps the engine around the same temp, cutting in and out when needed. If I put the cabin heater on then even if the temp drops to 90°C the fan stays on so I presume it works on both a timer and temperature basis?

It all seems ok and I may be worrying about nothing, but I have no idea how the system is supposed to work, as unplugging the sensor has no affect on the fans operation.

Does anyone know of the fan operation and temps? Maybe the left hand fan doesn't cut in until very high temps are reached?

I am confused but slightly happier

Edited to add, just found the temp ratings and I am worrying over nothing, by the looks of it the resistor has died so is now back at the normal running temps!!!!!!

Dave!