how long for the engine to get hot? E320CDi

[maddog]

For Info I replaced my thermostat (e320 CDi 2000/X model) last week following the recent sub zero weather the engine temp was barely moving off the rest point until the ambient temperature went above +3c. In the summer it would get to around +60c on the gauge. Effectively tracking the abient temperature albeit not proportionally.

Over a period of 3 years the stat has gradually deterioted to the point where it was starting to open around 40c. It wasnt jammed open as the top hose would remain stone cold until the point when the stat opended.
Temp now runs at just over 80c on the gauge and doesnt vary regardless of traffic or motorway driving.

This is how it should be from the factory.
Warm up time to +40 is exactly the same but obviously it now continues up to +85c approx'.

On average morning trips comprising 3 miles urban crawl (reaches +50c) then onto motorway engine gauge reads +85c after approx' 4 miles on motorway.

The stat for my model year is 92c, early years were 87c.
Approx' £28 from dealer (wasnt is stock)
Fiddly to change due to restricted access but not technically difficult.
Allow 1 hour start to finish
No need to drain system (no easy drain points to access anyway.
Siphon with small bore tube in expansion tank
Disconnect the small bore hose that connects from the from stat housing to the expansion tank at the expansion tank end.
The hose is long enough to drape over the front of the engine bay into a bucket in front of the car.
With a cold engine start and allow to idle
The coolant pump will discharge coolant into the bucket until the level drops to the same level as the stat housing
Switch off and remove housing and stat assembly
Replace with new item which includes housing, stat, temp sensor and o ring gasket.
refill.
Job done.

It will still take for ever to heat up if left on idle but thats the same for most oil-burners

Mine is around 80 degrees this time of year just pottering around , goes up to 85 when the weather is warmer or in traffic not that i hold that much store in the gauge has done from new.

Hopefully people will understand that a 92 degree thermostat does not mean a running temperature of 92 degrees

Great thread

 

[DieselE]

We are not talking about walking pace, we are talking about a minimum wind speed of 70mph at 70mph on the motorway, plus a head wind increases this by a long margin. when the fan is running, it will hold a sheet of paper on the other side, it is the air passing through the rad that cools it, and not the air hitting a solid wall.



The fan does not draw air through at 70 mph as the noise would be unbearable at idle, so the air does pass through the rad, thats the way its made

I've been off line for a few days which is why there is a delay in my replying to your post.

The point I was trying to make is that when the car is moving through the air, most of the air it meets passes either over the bonnet or under the car (and I don't intend going into they aerodynamics of airflow under the car or the effect of air dams etc). The volume of air passing through the grille and subsequently the radiator is only a proportion of that striking the front of the car.

Air does pass through the radiator but because of the pipes and cooling fins it presents a resistance to the airflow and there is a pressure drop across it.

For both these reasons, the engine is protected from the full force of the wind.

The fan does not draw air through at 70 mph as the noise would be unbearable at idle, so the air does pass through the rad, thats the way its made

On any car with an electric fan, the fan will not be running when the car is travelling at speed. It will in fact be windmilling. Whilst the effect is marginal it does result in a further reduction in the airspeed in the area immediately behind it.

 

[glojo]

I see that all sorts of permutations are sneaking into this thread and it is drifting way off gtopic.

How long will it take for the engine to get hot? E320CDI

I fully accept that someone might live on the edge of a motorway or a de-restricted dual carriageway, but for the huge majority of owners the first 5 - 10 minutes of the morning journey will be at speeds of less than 30mph. We can waffle, or make various examples but on a modern E320CDI with a correctly installed and opearting thermostat until the thermostat opens we might just as well disconnect the radiator. It is not being used. The radiator is merely a barn door protecting the engine bay from the elements. the thermostat is shut. The thermostat will not open on a 320CDI until the temperature reaches the set figure, then and only then will the radiator start to work and cool water. it is NOT designed to heat water it is designed to cool it. It will not work until the thermostat opens so it must surely follow that having any type of cover over the radiator of a E320CDI is not going to be of any benefit whatsoever UNTIL hot water enters the radiator. I cannot imagine cionditions in Great Britain where the thermostat will not cope on a modern E320CDI which is what this thread is about.

I enjoy reading off topic remarks and was one of the first to mention the older type radiators with moveable vanes, but it is horses for courses and times move on. We are now in a situation where we see some super cars with six radiators. Imagine if we start blanking these off because we think they might need blinds.

If we want our cold CDI to warm up quicker, then what about using a lower gear to get the engine to rev higher? Would that not get the engine hotter, quicker?

John

John

 

[television]

Its very easy for people to take quotes from post and us them in not the same way as they were posted.

Just some basic facts.

Yes the rad is doing nothing until the thermostat opens.

After a Winter drive you will find that the top of the rad is much hotter than the bottom, and this is the case even when the fan has not come on, so why is that ?? could it just be that the forced air has cooled it, as the forced air does pass right through it, and not on it. If you dont believe that, take a look at the dirt and water that comes through the rad on a high mileage motor way used car that deposits itself onto the front of the engine and surrounding areas.

Now going back to the water cycle.

The water does not circulate until the thermostat opens, the water goes back into the engine from the bottom of the rad, if this water is icy cold then the thermostat will close again until it has warmed the last intake of cold water.

Now if we reduce the cooling area of the rad (bottom) the water that goes back into the engine will not be as cold, then the thermostat will stay open and the engine can get hotter.

Back in the 70's when there were not so many traffic jams, I used to take the fans off my cars, only to benefit from a quieter car and a few more BHP available, even in summer I got to most places without have to use the heater as a means of cooling. I have done this on Triumph P2500, Sprints and XJ6's and these cars stayed cool purely by the air passing through the rad.

It has been said here that not all of the frontal air hits the rad area, that maybe so, but you cant get away from the fact that if the engine fan can pull the air through at say 25 mph and you are doing 70 mph a lot of air is going to pass through the cooling fins on the rad and cool it.

The down fall of the Hillman Imp was that not enough air was available to cool it.

None of this is rocket science just plain simple facts

 

[television]

In Johns last reply we said what about using a lower gear, well this is built into the cars, thats why they hold onto the lower gears to warm up the engine faster, but this is only useful to a point, as an engine running light is not working very hard, and not working very hard means not get all that hot

 

[OzC36]

Bits of cardboard in Mercedes radiators? What next..?

Drip trays under Jaguar engines?

Wellington boots to walk around on unsealed paths?

 

[eurico]

What TV says makes a lot of sense. Even when the thermostat is closed there's a little water circulating through the system (besides the ammount that goes in to the heater) because the thermostat has either a "tell tale hole" or the housing has some sort of pressure equilibrium passage to maintain both zones at the same pressure. Otherwise, hot engine side water wouldn't allow the thermostat to open, working like a pressure cooker. As such, there's a little water flowing through the radiator when the thermostat is closed. In very cold weather, this makes a difference as very cold air is passing through the fins, wether the thermsotat is open or shut. Plus there's the fact that when the thermostat finally opens, the engine gulps a good load of freezing water as Malcolm said. When car manufacturers design the cooling system, it's meant for the worst case scenario: going up a sand dune in the Sahara in mid July with the A/C on. Otherwise, the engine copes with anything besides frozen water. I doesn't work properly but it doesn't sieze or stop because all the electronics are compensating for the poor combustion. One must admit that it's very difficult to design a system that has to maintain a constant temp when the heat sink can have a tem range of 50-(-20) ºC = 70 ºC. At some end there has to be a compromise. More modern cars are doing away with the thermostat and using variable flow electric pumps.
So, in my humble opinion, it does make sense to blank the radiator in cold weather to give things a little helping hand. Just don't forget to remove the cardboard bit before heading south in July!

 

[280gee]

This is quite useful:

< http://auto.howstuffworks.com/cooling-system2.htm >

if interested in how the cooling system works.

 

[OzC36]

This might also be useful:

 

[glojo]

This might also be useful:

I think this is a better diagram and clearly highlights how the thermostat stops any flow to the radiator, plus if you follow the flow of coolant you will see that turning the heater on full boost when the engine is cold will indeed prolong the length of time it would take to warm the engine? Coolant flows from the engine to the heater and then any wamth is passed into the heating system. Again I reiterate we aree talking about a modern 320CDI engine that is cold.

John

 

[television]

I think this is a better diagram and clearly highlights how the thermostat stops any flow to the radiator, plus if you follow the flow of coolant you will see that turning the heater on full boost when the engine is cold will indeed prolong the length of time it would take to warm the engine? Coolant flows from the engine to the heater and then any wamth is passed into the heating system. Again I reiterate we aree talking about a modern 320CDI engine that is cold.

John

The link though is for a 104 petrol engine from 1994,and fine for explaining the basic MB set up, so why do you reiterate that we are talking about a 320cdi that is cold.

You can push it around and ignore every point that I have made, but that will not change the basic facts about the heating and cooling of an engine.

No matter what goods we talk about, these days everything is marketed so that it will work in every country in the world, where as yesterday we sent things out specialized for that country, so that does leave room to make something work a little better if you have the brains and initiative to do it, like a nicely made little metal plate (not cardboard)that you could pop in under the air intake scoop to make things a little warmer when the time of the year dictates. Its all called basics, and no more or no less.

 

[Dieselman]

The link though is for a 104 petrol engine from 1994,and fine for explaining the basic MB set up, so why do you reiterate that we are talking about a 320cdi that is cold.

I think John was merely referring to the thread being about a 320CDI, which will suffer longer heating time as a result of better thermo efficiency of the engine compared to a petrol engine.

As the cabin heater requires the same amount of energy in either case, then the engine wasting less heat energy will take longer to warm up.

The original post says.
"I go to work - 3 miles, but takes about 15 minutes in the trattic.

my car is just about up to temp by then.

maybe the thermostat is stuck?

my wife's petrol CLK230 heats up in a fraction of the time."

 

[280gee]

Going back to basic thermosyphon systems; The whole system comprised engine (block) coolant passages, hoses to radiator and radiator. Blanking off a portion of radiator meant that both warm-up and subsequently the running temperature were influenced. This was very commonly seen on cars in the winter when I was a lad.

A more modern system as many willl know and can also be deduced from the diagrams is operating as almost two closed loops ( save for jiggle pins, bypass passages) when the engine is near cold.

This suggests to me (and discounting heater passages) that first the block coolant warms. When the block coolant is sufficiently warm the thermostat opens and then water begins to circulate in System 2 comprised of radiator etc.

Blanking part of the radiator therefore has little effect on System 1
during the initial warm-up phase, however it comes into it's own when System 2 is opened. This may be too simple though...

Were an example engine's coolant to remain in the region between thermostat opened and closed, i.e. where the thermostat is acting in it's role as a device having hysteresis then obviously radiator blanking will have an effect. In this case both affecting warm-up and running temperature.

 

[Dieselman]

Were an example engine's coolant to remain in the region between thermostat opened and closed, i.e. where the thermostat is acting in it's role as a device having hysteresis then obviously radiator blanking will have an effect.

Will it?
I think not, as the thermostat will simply restrict the flow to reduce the water flow.

 

[robert.saunders]

Soooooooooo, 'cos I is dim, is this why on my climate control (Mondeo or the C220 I had, both turbo diesel engines, both around 2200cc) set to AUTO the interior heater fan remains at very low speed when the engine /exterior temp is cold and then gradually speeds up as the engine gets warmer, until my desired temp (say 22c) is reached, when the fan then retards..?

I accept it doesn't blow cold around in the interior (at a time when I am cold too!) but is that the only reason or is it allowing the engine to heat as efficiently as possible?

As John would say, these are questions, as I'm not technologically minded

 

[television]

Soooooooooo, 'cos I is dim, is this why on my climate control (Mondeo or the C220 I had, both turbo diesel engines, both around 2200cc) set to AUTO the interior heater fan remains at very low speed when the engine /exterior temp is cold and then gradually speeds up as the engine gets warmer, until my desired temp (say 22c) is reached, when the fan then retards..?

I accept it doesn't blow cold around in the interior (at a time when I am cold too!) but is that the only reason or is it allowing the engine to heat as efficiently as possible?

As John would say, these are questions, as I'm not technologically minded

Many cars have air con systems where the fan remains on minimum until the water in the system is hot enough to be of use in warming the car and bringing the temperature up to the set temperature.

 

[Dieselman]

I accept it doesn't blow cold around in the interior (at a time when I am cold too!) but is that the only reason or is it allowing the engine to heat as efficiently as possible?

It just works on the water temperature entering the heater matrix, it isn't working for the benefit of the engine temperature, just to stop you freezing your watsits off..

 

[robert.saunders]

Fanks chaps, I can sleep well tonight now

 

[280gee]

Will it?
I think not, as the thermostat will simply restrict the flow to reduce the water flow.

Yes I think it will.
The system is dynamic and the thermostat has been chosen for it's special properties as I indicated. It will as you say restrict the flow of coolant, but not as you say, simply.

Anyway, the cooling system is always a good one for a stimulating discussion.

 

[television]

Yes I think it will.
The system is dynamic and the thermostat has been chosen for it's special properties as I indicated. It will as you say restrict the flow of coolant, but not as you say, simply.

Anyway, the cooling system is always a good one for a stimulating discussion.

Dont you mean heated discussion