270CDI ages to warm up

[pcraddoc]

I noticed ther other week that my CLK (W209) 270 CDI was not getting very warm (60 degrees approx - max). I had thrmostat replaced at local garage.
It seems a bit better now but it takes ages to warm up. Around 10 miles of commuter driving to reach around 70 degrees. It will eventually get to around 80 after a further 10 miles or so.

Is this normal? Also, I have noticed that the water in expansion bottle is nice and warm but there seems to be very little pressure in system when hot. You can easily remove the cap from the expansion bottle and get a little hiss at best!

Any ideas what it could be? Engine runs fine but I do get the diagnostic light coming on occasionaly. (throttle position sensor is the OBD code)

Any help or advice appreciated.

Thanks
Peter

 

[GH421]

it's the norm

i freeze my butt off every morning for about 25 minutes before anything warm comes through.

I think that's why they were fitted with the heater booster

 

[thedoc]

i wish i could start mine! never had the luxury of feeling any warm or cold air yet!

 

[pcraddoc]

"I think that's why they were fitted with the heater booster"

Do they all have these? I don't think mine has. Is this a pre-heater or something?

 

[EdmundIJones]

I reckon my heater booster is broken, not sure how to go about testing this out, I have the same problem as you, 10 miles to get some heat at all then more to get real heat.

It obviously takes longer on these very cold days.

 

[rpe2]

"I think that's why they were fitted with the heater booster"

Do they all have these? I don't think mine has. Is this a pre-heater or something?

In the dash settings under 'Heater', make sure it is set to 'on'

 

[Rory]

As others, make sure the heater booster is set to come on, and that you havn't got it selected to go off with the a/c button.

I mainly use mine for long trips, and it's 23 miles of reasonably flowing 40-50MPH A roads to get to the motorway. I reckon it takes all of those 23 miles to warm through.

 

[x332race]

My C270 engine takes ages to warm up to full temp but I have the "heater booster" activated and get warm(ish!) are coming through vents shortly after setting out...also heated seats help a lot!!

 

[walsi]

I reckon my heater booster is broken, not sure how to go about testing this out, I have the same problem as you, 10 miles to get some heat at all then more to get real heat.

It obviously takes longer on these very cold days.

Hi ya, it could be as simple as the glow plug packed up on the booster heater. You can get them anywhere just make sure you get the right one as they are slightly different to the engine ones. They are easy to change if you have a pit or acess to a ramp

Cheers Martin

 

[Bobby Dazzler]

I think the OP is making a slightly different point: not so much as taking a long time for the heater to blow warm air, but more about how long it takes for water temperature to increase.

I noticed much the same on our ML (same engine). From memory it used to be a touch below 80 deg C once up to 'normal' operating temperature, but in recent weeks it doesn't appear to go over 70 deg C. Maybe coinicidence but I've only noticed this during the recent cold snap.

I wondered if the thermostat might be iffy, but when it went in to the dealers last week for a service it was given a clean bill of health.

 

[walsi]

Hi ya, this is due to diesels running cooler than petrols, my vito wont even get up to 70 without the heater booster on in the cold weather (-3 and below)and if you are on the motorway going steady you can watch it cool down again once the booster is turned off. It is the way diesels are

 

[wemorgan]

I wonder if the engine would warm up faster if the cabin was set to recirculate mode? I think this will minimise the heat the cabin draws from the engine. Once the engine is up to temperature you can then return to fresh air setting. Just a thought.

 

[renault12ts]

W, I wouldn't think the heat drawn into the cabin for heat would have any significant impact on the time taken to warm the engine...it's a diesel thing...they run cool and even cooler in the current cold snap.

 

[proser]

I've blocked off part of the rad, the other day, and have noticed it warming up faster in this cold weather

 

[Rory]

Hi ya, it could be as simple as the glow plug packed up on the booster heater.

That's the auxiliary heater, and few UK cars have them.

The heater booster is an electric element in the water circuit - most, if not all, diesels have them.

 

[Danny DeVito]

Walsi what does your heater boost button look like ?? Ive a V220 7 seat but no book to tell me what the buttons are...does it have a symbol on it ?? and where do you think the element is located ?

 

[welland99]

The heater booster is an electric element in the water circuit - most, if not all, diesels have them.

I thought the heater booster was for heating air (like a fan heater) not for heating water. My W210 makes warm air very soon after starting up, and I presume this is because there is an air heating element somewhere. If it was heating water then it would not heat that fast.

I don't have a switch for the booster, it works automatically.

 

[welland99]

i freeze my butt off every morning for about 25 minutes before anything warm comes through.

I think that's why they were fitted with the heater booster

I think electric seats are better for warming freezing butts!:bannana:

 

[walsi]

Hi Ya, the heater booster is Diesel powered as is the auxilary heater on the vito, the booster heater heats the water and needs the engine to be running to work where as the auxlary heater will work on its own and can be set to work off the mini clock.
The symbol for the heater booster is three wavy lines and is the middle of the right hand dial on the heater controls.
Its the first time that i have heard of an electric water heater and didnt realise they fitted them on all diesel engined cars so you live and learn.
I will say that the heater booster will give warm air within 2/3mins even at -6 if stationary and will give hot air within 3/4mins when driving

Cheers Martin

Dannyboughtit, any other questions fire away as i have the handbook in front of me.

 

[Rory]

There seem to be all sorts of systems used by Mercedes without any proper explanation - the heater booster in my facelift W203 is set via the dash computer to either auto, off or controlled by the a/c button. Why the a/c button, unless it uses the a/c compressor as a heat pump, like Honda does on its diesels? No-one seems to know.

A & B Class diesels (and maybe other models too now) have PTC heaters and blow warm air out within seconds of start up.