W211 - E320 CDI engine heating up very quickly

Page may contain affiliate links. Please see terms for details.

mbdaniel

New Member
Joined
Mar 14, 2019
Messages
11
Location
Cambridgeshire
Car
E320 CDI Sport
Hi all

I have a weird issue with a MY2007 E320 CDI (V6) with 105k miles that I'm hoping someone can help with ?

It is getting up to temp very quickly from cold (within a couple of miles of gentle driving) and the radiator fan is then coming on permanently. The temp gauge doesn't go above 'normal' but the exhaust gases seem really hot and it smells very hot even after short journeys.
A local indy has had a look and gone as far as removing the DPF and exhausts and having them checked (they were fine) and are now stumped.

There are no fault codes, coolant levels are fine, and the engine is running smoothly with no loss of power but it's not normal... the thermostat and coolant was changed at the last service earlier this year.

Where else to look ?
Injectors / breather hose leak / something else ?

Any help would be appreciated as the next step is the main dealer who will take my pants down for what is essentially a £3k car.
 
Well even though it was changed at the last service,the thermostat is the most likely culprit,there is no way a 320cdi gets hot until 7/8 miles has been covered at least.
 
If it was an MB specialist that looked at the car and couldn’t figure it , i wouldn’t hold out hope that MB would ?
 
Any faults shown on Star ?
 
On a 13 yr old car, you are wasting your £s taking it to MB

more than likely they will say “the computer says no problem”
 
Air lock in the coolant?
Could be


Well even though it was changed at the last service,the thermostat is the most likely culprit,there is no way a 320cdi gets hot until 7/8 miles has been covered at least.
That's what I thought... I guess there's no harm in replacing it again, and presumably that would resolve the airlock issue too (if done properly!)


Any faults shown on Star ?
Nope


On a 13 yr old car, you are wasting your £s taking it to MB

more than likely they will say “the computer says no problem”
Agreed - absolute last resort.
 
Well these thermostats come in a metal housing don't they? just take your one off and put it in a sause pan of water and heat it up and with some pliers lift it out when the water starts to boil and see if the stat has opened before you buy another one
 
Sounds to me like you're either low on coolant or have a blockage. I'd put a scanner on it and see what's going on. Try also to crank it when cold with the radiator cap off to make sure that there's not combustible gasses
 
Could be air in the system, have you tried bleeding it, turn on the heater to full, run the car and slowly release the filler cap to make sure there is pressure in the system, leave off the cap to help air escape. Not sure where your bleed valves are on this engine but find if you can and bleed those. Funny that your temp gauge says normal but the fan comes on ? Maybe faulty temp sensor if you really think it gets really hot, must be air or even water pump not circulating the coolant.
 
Are you sure it’s getting hot, just because the fan is coming in doesn’t always mean engine is overheating. Double check the engine temp with an thermometer. The fan could also run with ac pressure.
 
Are you sure it’s getting hot, just because the fan is coming in doesn’t always mean engine is overheating. Double check the engine temp with an thermometer. The fan could also run with ac pressure.

Yes, it's definitely getting hot. I'll try to bleed air through the expansion tank cap as detailed above.

Thanks all.
 
OEM thermostat installed? If not change it.
Otherwise remove the thermostat and test it.

Also check the temperature sensor, run the car with a diagnostic on it showing actual temperature and at the same time use an infrared thermometer to see if sensor is reporting correct (or near to).

Does it have a DPF, it's not stuck in a regen. loop by any chance?
 
I still would have thought an experienced Indy would have checked all the basic stuff ?
 
The DPF is the clue for me,
my guess is that you're in continual regen mode.

Hot exhaust, engine temp usual.
 
The DPF is the clue for me,
my guess is that you're in continual regen mode.

Hot exhaust, engine temp usual.
The DPF has been removed and checked by a local firm - confirmed OK.

How would I know if it was in continual regen ? Would there not be any codes if this were the case ?
 
Does a 2007 E320cdi actually do a regen in the dpf . I only ask because my same E320cdi doesn’t even have a dpf .
I thought the regen only started on the W212’s ?
 
The DPF has been removed and checked by a local firm - confirmed OK.

How would I know if it was in continual regen ? Would there not be any codes if this were the case ?
Was it an MB only specialist ? With Star
 
The DPF has been removed and checked by a local firm - confirmed OK.

How would I know if it was in continual regen ? Would there not be any codes if this were the case ?


Sorry for the late reply, I don't visit so often these days.

The DPF may be ok, and if it was in continual regen that it should be.

By monitoring the DPF temperature, and useful to compare that to the cat temperature, while in regen the DPF will hit temperatures as high as 800 C (depending on engine load.)
Normal running would see the DPF at 160 - 300ish. And that would be lower than the cat.
In regen the cat runs cooler than the DPF (as that is incinerating as the additional injected diesel hits it) that will then see temperatures of 300 - 450.
 

Users who are viewing this thread

Back
Top Bottom