W124 over heating

[london_keeps]

I recently bought a W124 E200 (1994) estate with a few minor problems (I hope!). One of them is that my mechanic can't isolate the reason for the engine to over heat.

The oil temperature starts to shoot up after sitting in a traffic jam for some minutes and it climbs as high as around 120C. Thankfully, I haven't seen it climb higher, and it maybe one of its symptoms that it doesn't get any hotter. The fan is working properly, the oil has been changed recently and my mechanic is planning to replace the radiator alltogether.
Ofcourse, the temperature drops below 100C as soon as the car starts moving.

I believe the engine is M111 with one big fan. The car has done just under 110k miles and just went through 108k maintenance service.

Any advice, experiences are much appreciated.
Thanks

london_keeps

 

[kid-jensen]

london_keeps,

You sure the fan is ok?

All your symptoms point to the fan viscous unit not stiffening-up.

Try the "carrot test"

 

[GaryC]

Hello,

If it keep staying in around 120 degree for long time, it might damage the gasket, beware!!

Yes, double check your viscous fan, if it work, it will sound like an aeroplane!!

Beside, are there any alr block inside your radiator? and is the thermostate (the one release water into the radiator) work?

Gary!

 

[Spike]

I agree that the "carrot test" should be your first point of call on this one.

Next, double check your thermostat & at around a fiver you may as well just replace it anyway.

Are you losing any coolant?

I would check that the system is holding pressure correctly. Is the expansion cap OK, check the whole system *very* carefully for leaks or seepage. It might be a very small leak (like mine) which was only visable when the engine was very hot and even then, the leak was so minimal that i virtually needed a magnifying glass to spot the 'fizzing' of coolant around the thermostat housing. On my 124, this was enough to send the temperature guage sky high without any appreciable loss of coolant, due to the fact that coolant will boil at 100 but only if its not under pressure - any leaks in the system and its gonna get hot.

 

[Leylandp76]

I give up.... what is "the Carrot Test"? :?

 

[jaymanek]

Hi,

May well be the radiator. If you take it to a specialist, they can check v easily for blockages, may even be able to repair.
If it does turn out to be rad, stick to MB, some non genuine ones dont last more than a year...


Jay

 

[Spike]

LOL

You could try using the search facility....but I did it for you below.

http://forums.mercedesclub.org.uk/viewtopic.php?t=2022&highlight=carrot

 

[Orlando 300E]

Carrot test -using a carrot to see if your fan coupling is working correctly. This will only work with a hydraulic coupling, not with straight electric fans. You use the carrot to see if the fan slows by pressing it against the blades (obviously being ****** careful with your didgets). As I understand the blades should be free to spin when cooling is not required -so the blade should stop spinning with a carrot! If like mine was, permanently locked -it just shreds the carrot at any temperature. Pass the vinaigrette!

To check your radiator, with the car up to temperature, run the back of your hand (not touching!) over the front of your rad (if you can get to it). If your rad is blocked, you will find cool areas -like mine was. You can get re-cores done, but don?t -the top plastic end tank came back with a split on mine :evil: . Used Euro Car Parts for my replacement, no problems over 15k miles in a year.

Hope that clears that up,
Orlando

 

[sunil sood]

[The oil temperature starts to shoot up after sitting in a traffic jam for some minutes and it climbs as high as around 120C. Thankfully, I haven't seen it climb higher, and it maybe one of its symptoms that it doesn't get any hotter. The fan is working properly, the oil has been changed recently and my mechanic is planning to replace the radiator alltogether.
Ofcourse, the temperature drops below 100C as soon as the car starts moving.

london_keeps[/quote]

my car had exactly the same heating problem at idle in traffic,but it is a 190e-1993-with 100k on the clock.

on my car,the clutch fan is electromagnetically controlled to come on and go off ,this is controlled by a cooling fan switch mounted on the top,front right hand side of the the cylinder head.

this switch tells the fan to cut in at the right temperature,mine was faulty-i replaced it for about a 10er from eurocarparts-problem sorted!

but if as you say your cars fan is working -is it viscous(as opposed to electromagnetic) operated as the the the posters state?then check your rad as stated above

 

[london_keeps]

thanks!

Thank you everybody! I will try the carrot test this weekend. Slight mistake with the temperature... the highest I've seen it go up to was 110C not 120C. Once I get my head round to determining whether my fan is electromagnetic or viscous, I'll do the tests you recomended too.

I'll post my findings (if I get there...).

london_keeps

 

[JonathanC]

Hi London_keeps

My '93 200TE does exactly the same, passes the carrot test and has no probs with the rad. The problem lies with the after market air con. If the air con is on and the car is at a standstill, the temp will rise toward the red. Turn it off and the temperature slowly drops again. This is because that air con requires and additional electric fan mounted on the radiator to provide extra cooling to offset the load driving the A/C puts on the engine. This fan is controlled by a thermo switch at the front of the engine, under the black plastic cover at the front of the head. On my car this is attached to a relay which switches the current to the electric fan. My problem was the relay wasn't seated properly and therefore didn't turn the fan on. Reseating the relay cured the problem.

Of course, this my have no relation to your problems but if you have A/C this is a quick check before you use too many carrots!

 

[JonathanC]

Hi London_keeps

My '93 200TE does exactly the same, passes the carrot test and has no probs with the rad. The problem lies with the after market air con. If the air con is on and the car is at a standstill, the temp will rise toward the red. Turn it off and the temperature slowly drops again. This is because that air con requires and additional electric fan mounted on the radiator to provide extra cooling to offset the load driving the A/C puts on the engine. This fan is controlled by a thermo switch at the front of the engine, under the black plastic cover at the front of the head. On my car this is attached to a relay which switches the current to the electric fan. My problem was the relay wasn't seated properly and therefore didn't turn the fan on. Reseating the relay cured the problem.

Of course, this my have no relation to your problems but if you have A/C this is a quick check before you use too many carrots!

 

[kid-jensen]

Just checked Europarts.

If it turns out to be the Viscous unit, it'll cost you £75 + VAT

 

[london_keeps]

just checked

I've just confirmed that my fan has electromagnetic clutch... so I can't actually have the pleasure of shredding those Carrots.
Having thought about it, it is actually likely that the radiator has a small hole somewhere, losing that pressure, as the car does have a lot of stone chip marks. I've been told it would cost me about £100 for the whole radiator and 1 hr labour.

And, no, my E200 didn't come with an air con. Thanks anyway.

london_keeps

 

[talbir]

I would reccomend first asking your tech what his mix of antifreeze with water was when he re-filled the coolant system ?

It should be a 50/50 mix, otherwise coolant can overheat.

Talbir

 

[sunil sood]

london

i would check the cooling fan switch as you confirm the car has an e/magnetic clutch fan-

you say your fan works ,it may be working but a tired ,faulty cooling fan switch can cause the fan to cut in late and cause overheating-i would check that the fan is working by pulling off the cooling fan switch connector and shorting the two connector wires -the fan electromagnetic clutch should click to indicate that the fan comes on -this test should be done with the ignition ON but engine OFF-for obvious reasons.

i would also check the fuse for the fan clutch circuit in the main fuse box-on my car this fuse also enable the tachometer to work-do not know if it is the same on your engine-it would be intersting to know!

also as talbir says the coolant mix of water/antifreeze is important-if there is a very strong antifreeze mixture-this will lose its cooling properties and lead to overheating.

THE carrot test does also apply to e/magnetic clutch fans as well as trhe principle is the same!!

good luck!

 

[Brian Duffy]

The problem that you describe is identical to what I've just cured on my W124. I'm not quite sure why you say that the carrot test doesn't apply because it does. Your fan isn't coupling......
The electro-magnetic fan is triggered by a 98-102 degree thermal switch with two round pins (part of the switch body is plastic and coloured red) easily accesible and takes about 10 minutes to change, located on the top r/h side of the engine, yours like mine isn't working.
Be careful, German and Swedish can offer you the switch for £8:50 with (bizarrely) the same part number as the MB item but it has a set point of 80-85 degrees which might be acceptable to you if you spend a huge amount of time in very heavy traffic jams but otherwise is very wasteful on fuel because your fan is engaged almost constantly.
I had to revert to the MB dealer for the more appropriate 100 degree switch for £17:50. The good news is that whichever switch you fit, it will control perfectly to their upper temps. Once the fan kicks in, the control is very good at either temp because of the design of the fan. The switches have their set points (in degrees) stamped into the brass body.
Let us know how you get on.
Regards
Brian

 

[Orlando 300E]

OK, my previous "sweeping statement" seems to have caused confusion. Hope this clears it up:

Hydraulic coupling fans spin all the time, but should only be driven when required to cool the engine -test with carrot to see if coupling is working correctly!

Electronically controlled coupling fans operate in the same manner as above with the drive being locked when cooling is required -test with carrot as above!

Electric fans (that is fan a attached to electric motor, not driven by a drive belt), should only spin when the thermostatic switch is triggered, the fan either is on or off -so a Carrot is useless!

Sorry for any confusion
O
p.s. Have you heard of the marrow test? :lol:

 

[nick mercedes]

> I've just confirmed that my fan has electromagnetic clutch...

If it's a E200 with a M111 engine it'll have a viscous fan, not a electromagnetic clutch, they're found only on the earlier 124 series with the M102 engine.

Nick

 

[london_keeps]

so...

Back to square one then. I am not at all sure what fan my car has.
To be honest, the car has gone through the 108k service recently at a respectable (I hope) MB Specialist and he's told me that the fan is Electromagnetic, and is working properly. To honor his views, I am going to suspect the radiator first, as I said previously, the car has a lot of chip-marks which suggest that the radiator could have taken a lot of beating too.

Does anybody know of a site where all these "which fan?" types of questions are answered? Being very lazy and not been bothered to check the car itself, I assumed the data at www.carfolio.com is correct, but it only goes as far as the engine model.