E320 CDI, 2005, W211 overheat

[jak gjini]

Hi all.
I've got an overheating problem with my Merc E320 Cdi 2005.
Bought the car a month ago, drove it a 100 mile trip when I bought it and no problem at all, then I didn't drive for 2 weeks when my next trip was about 50 motorway miles. After about 40 miles the car overheated so bad that smoke started coming out and smelled like an electrical wire burning.
Even all that the temperature gauge was sitting at 80. When I turn the AC ON the fan starts, when I turn the heating on the fan doesn't work, but the car still overheats even with the fan on.
The fan dos not start at all no matter how hot the engine is unless you turn on the AC.
What could it be? The cooling sensor? The coolant? The thermostat?
Please help.
I bought a new thermostat, a sensor and 5L of coolant.
But even though not sure.

Thanks for your replies and advices.

 

[coneybiller]

Does the engine temp gauge start from zero when cold? Or does it go straight to 80deg? Wondering if the coolant temp sensor is knackered AND possibly the thermostat stuck in the shut position causing overheating.
Did you say you have an electrical burning smell?

 

[coneybiller]

Didn't actually read all of your post (oops) The fan that runs when the A/C is on, is an electric fan. That is its soul purpose to cool the condenser. The main engine fan I believe is a viscous fan which should be temperature sensing. When you say smoke came "out". Where did it come from? Did u open the bonnet to find the coolant steaming away?

 

[jak gjini]

Hey coneybiller.
Thanks for fallowing.
The smoke came out from the top end of the engine close to the screen wipers.
I didn't see anything burnt or wires stuck together but I guess silicone type between the engine and the engine cover was probably causing the smoke as it looked shrunk as if it was slowly burned.
The temp gauge starts from 0 and it goes as it should to 80deg but then it sticks there.
I did open the lid of the water tank not long after the car was boiling hot but didn't have any pressure and pipes where quite soft as normal I would say.
Thanks mate.


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[coneybiller]

Hmm, doesn't sound like the engine was overheating then if the coolant wasn't boiling. The smoke you suggest sounds like something has come into contact with the exhaust manifold or exhaust down pipe, which has melted and caused the smoke. Normally if it was a wire and the sheathing had melted, it would throw and error of some kind or at least give you a tell tale that something was wrong, due to a wire grounding out! The other possibility is that you have an oil leak from somewhere that has begun to drip onto the exhaust causing the smoke!
Either way, I'd get it looked at by a garage. If's it's something rubbing on the exhaust it could cause a fire or damage something causing another issue/expense. Or if it's an oil leak, be it gearbox or engine then the leak needs to be fixed!
On a lighter note, it could be a piece of road debris that's somehow lodged in and stuck on the exhaust! Unlikely but not impossible!

Def get it on a ramp and get it looked at!

 

[coneybiller]

I really should read your threads more! (Tired, just finished a night shift lol) the viscous fan will not run until the coolant temp sensor reaches a certain temp. If the coolant temp is not reading properly, it won't switch on. However, I'm sure on a 211 it should throw an error to be on the fail safe side. But I could be wrong.
I would say you need to take it to a garage or use an OBD scanner and read the coolant temp! Can't remember how to do it, but there's a secret menu on the 211's multifunction display. By holding down 2 buttons on the steering wheel, you get a display up and a set of options. Batt voltage etc etc. Perhaps the actual coolant temp could be displayed there as apposed to the small bars for a gauge. Don't quote me on it though!

 

[BIG_G_1979]

Did the burning smell like diesel? Have you removed the engine cover and looked around the injectors? These engines are famous for the "black death" this is were the gases escape from under the injector washers and then the gases starts to melt the plastics in the surrounding area. Remove engine cover and look for melted plastic sort of looks like tar gunge if this is present then u need to replace the injector washers/seals

 

[streethawk]

Did the burning smell like diesel? Have you removed the engine cover and looked around the injectors? These engines are famous for the "black death" this is were the gases escape from under the injector washers and then the gases starts to melt the plastics in the surrounding area. Remove engine cover and look for melted plastic sort of looks like tar gunge if this is present then u need to replace the injector washers/seals

Straight 6 not v 6 iam lead to believe suffer.

 

[BIG_G_1979]

Yeah I6 suffers from black death, 2005 would have a I6? I thought w211 had v6 mid 2006

 

[coneybiller]

Don't think Black Death normally smokes, but then again that could be a very good explanation if I'm wrong! It also stinks!
It's a build up of carbon after the escaping fuel and gases solidify over time. If that is the case, it's a job most mechanics will shudder and shy away from! It's a ****ty job requiring a hammer and chisel and strong cleaning chemicals to remove!
And yes it'll be I6 from 05

 

[Gareth]

Yeah I6 suffers from black death, 2005 would have a I6? I thought w211 had v6 mid 2006

Mine is registered Dec 25th 2005 and is a V6.

 

[coneybiller]

Do u get the cheaper tax band then? Seeing as it's before 06?

 

[BIG_G_1979]

Mine is registered Dec 25th 2005 and is a V6.

Very interesting mines Aug 2006 which also has a 3.0v6 and it's a face-lift model I always thought that prefaclifts all had I6's? Maybe Merc didn't want to build anymore I6 as they could have started production runs of the v6 so use them instead? Sort of similar to dpf and sbc mine doesn't have either ( which I'm not complaining about)

 

[Gareth]

Do u get the cheaper tax band then? Seeing as it's before 06?

No idea, it was £270 when i renewed it for 12 months recently.

 

[coneybiller]

Could be the ML320cdi I was thinking of. Nearly £500 p/a to tax!!

 

[jak gjini]

Straight 6 not v 6 iam lead to believe suffer.

I have removed the engine cover. The engine and injectors look as new as it came out of the factory a year ago. No melted wires, no tar built around the injectors or anything.
The smell wasn't really like a diesel smell, more like a plastic.
I think I've got to take it to a specialist to do all the necessary checks.
Thanks guys


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