Does The Cold Really Affect Diesels That Much?

[freestyle]

I bought my t180 as the cold spell was creeping in and over the winter i found it to be a little sluggish on cold starts, needing a little more throttle persuasion if i wanted to pull off quickly etc, and only just reaching normal temperature by the time i complete my short journey to work.

Today on a lovely sunny day i had the chance to be at the other office with the rav parked in the outside carpark basking in the suns glorious rays. When i left work i thought i had taken the wrong car! I knew it shifted but it was like a whole different animal, pulling like a rocket with a lot less throttle!

I know diesels need the engine to be hot to aid combustion but surely i shouldn't notice this kind of difference in performance?

[bothwell_buyer]

I've found it does make a difference how cold it is.... but then the generator really only runs at 1500 rpm. If its -15C or below, then it just doesn't start.

[Lupidog]

It will warm at a speed very dependant on the ambient temp. They perform best at the correct running temp. So the simple answer to your question is "Yes".

Your taking alot longer to warm up in very cold weather because:

The engine block is that much colder.

The Air being drawn in for combustion is that much colder.

The air-flow across that radiator is that much colder.

The Diesel is that much colder.

All of the above give the symptoms you describe.

[*srjp*]

Up here, -15 is not uncommon on winter mornings. If a diesel is left with less than a third of a tank it tends to find it very hard to start, and invariably stalls within a few minutes.

[Manxrav]

I,ve found that your "winter" mpg is always a lot less than your "summer" mpg. What Lupidog says in his post is bob on. It really does affect a diesel engine.

Regards Clare

[Jamesbelfast]

It will warm at a speed very dependant on the ambient temp. They perform best at the correct running temp. So the simple answer to your question is "Yes".

Your taking alot longer to warm up in very cold weather because:

The engine block is that much colder.

The Air being drawn in for combustion is that much colder.

The air-flow across that radiator is that much colder.

The Diesel is that much colder.

All of the above give the symptoms you describe.

The above reasons equally apply to a petrol engine. In fact colder air contains more oxygen and improves combustion.

So lets get back to basics. The internal combustion engine is a heat exchange engine which means energy from the effects of generating heat are transferred into motion.

Diesel engine are much more efficient in this process so more heat is converted into energy - thus less heat is wasted or lost into the engine unit itself.

Futhermore diesel compression ignition runs at much lower temperatures than that of a petrol or gas engine.

So to sum it up - diesel engines take longer to reach their optimum operating temperature because they are more efficient and run cooler and due to the stresses involved the engine components such as pistons, cylinder head and block will have a larger mass which again takes much longer to heat. As with all internal combustion engines be they petrol or diesel they will take longer to warm up in colder temperatures but with diesels the effect is just more noticeable.

[pgp001]

I ran an Audi A6 1.9 Tdi prior to me getting the petrol RAV 4.2 in January.

The Audi was barely starting to emit any warmth from the heater until I was arriving at work six miles away.

Th RAV is nice and cosy after about 2 miles, it is very noticeable how much quicker it warms up compared to the diesel Audi.

By the way after fitting the Ultragauge and driving a bit more sensibly, my fuel consumption has gone up from 25 to 33mpg.

That is measuring from brim to brim at each fill up.

Phil

[Mike JD]

Possible extra factors that might exert an influence: Colder tyres ergo lower tyre pressure ergo higher rolling resistance and longer till things get up to temperature. I have also wondered about the transmission. We 4x4 folk have a lot more transmissioning stuff slung underneath than lesser folk and all of that has fairly porridgy oil in it. Cold transmission fluids (sounds faintly rude) must mean more resistance and longer to thin and get to temperature. Discuss?

Mike D

It will warm at a speed very dependant on the ambient temp. They perform best at the correct running temp. So the simple answer to your question is "Yes".

Your taking alot longer to warm up in very cold weather because:

The engine block is that much colder.

The Air being drawn in for combustion is that much colder.

The air-flow across that radiator is that much colder.

The Diesel is that much colder.

All of the above give the symptoms you describe.

The above reasons equally apply to a petrol engine. In fact colder air contains more oxygen and improves combustion.

So lets get back to basics. The internal combustion engine is a heat exchange engine which means energy from the effects of generating heat are transferred into motion.

Diesel engine are much more efficient in this process so more heat is converted into energy - thus less heat is wasted or lost into the engine unit itself.

Futhermore diesel compression ignition runs at much lower temperatures than that of a petrol or gas engine.

So to sum it up - diesel engines take longer to reach their optimum operating temperature because they are more efficient and run cooler and due to the stresses involved the engine components such as pistons, cylinder head and block will have a larger mass which again takes much longer to heat. As with all internal combustion engines be they petrol or diesel they will take longer to warm up in colder temperatures but with diesels the effect is just more noticeable.

[Mistermena]

It will warm at a speed very dependant on the ambient temp. They perform best at the correct running temp. So the simple answer to your question is "Yes".

Your taking alot longer to warm up in very cold weather because:

The engine block is that much colder.

The Air being drawn in for combustion is that much colder.

The air-flow across that radiator is that much colder.

The Diesel is that much colder.

All of the above give the symptoms you describe.

The above reasons equally apply to a petrol engine. In fact colder air contains more oxygen and improves combustion.

So lets get back to basics. The internal combustion engine is a heat exchange engine which means energy from the effects of generating heat are transferred into motion.

Diesel engine are much more efficient in this process so more heat is converted into energy - thus less heat is wasted or lost into the engine unit itself.

Futhermore diesel compression ignition runs at much lower temperatures than that of a petrol or gas engine.

So to sum it up - diesel engines take longer to reach their optimum operating temperature because they are more efficient and run cooler and due to the stresses involved the engine components such as pistons, cylinder head and block will have a larger mass which again takes much longer to heat. As with all internal combustion engines be they petrol or diesel they will take longer to warm up in colder temperatures but with diesels the effect is just more noticeable.

I couldn't have said it better myself. Bob on

[Dorlyn]

Too many nuclear physists in this thread !!!

It would appear that the cold "Does indeed have a negative effect on the performance of your engine "

Must admit the thread made good reading though.

B)

[Jamesbelfast]

Possible extra factors that might exert an influence: Colder tyres ergo lower tyre pressure ergo higher rolling resistance and longer till things get up to temperature. I have also wondered about the transmission. We 4x4 folk have a lot more transmissioning stuff slung underneath than lesser folk and all of that has fairly porridgy oil in it. Cold transmission fluids (sounds faintly rude) must mean more resistance and longer to thin and get to temperature. Discuss?

Mike D

It will warm at a speed very dependant on the ambient temp. They perform best at the correct running temp. So the simple answer to your question is "Yes".

Your taking alot longer to warm up in very cold weather because:

The engine block is that much colder.

The Air being drawn in for combustion is that much colder.

The air-flow across that radiator is that much colder.

The Diesel is that much colder.

All of the above give the symptoms you describe.

The above reasons equally apply to a petrol engine. In fact colder air contains more oxygen and improves combustion.

So lets get back to basics. The internal combustion engine is a heat exchange engine which means energy from the effects of generating heat are transferred into motion.

Diesel engine are much more efficient in this process so more heat is converted into energy - thus less heat is wasted or lost into the engine unit itself.

Futhermore diesel compression ignition runs at much lower temperatures than that of a petrol or gas engine.

So to sum it up - diesel engines take longer to reach their optimum operating temperature because they are more efficient and run cooler and due to the stresses involved the engine components such as pistons, cylinder head and block will have a larger mass which again takes much longer to heat. As with all internal combustion engines be they petrol or diesel they will take longer to warm up in colder temperatures but with diesels the effect is just more noticeable.

The affects of thick oil in the transmisionn will be minimal but if there is any effect at all it will cause the engine to warm quicker as the porridgy oil as you call it will apply more load to the engine and as we all know the heavier the load the quicker the engine will gain heat.:)

[Mike JD]

Too many nuclear physists in this thread !!!

It would appear that the cold "Does indeed have a negative effect on the performance of your engine "

It makes a brass monkey's eyes water too

Mike D

[freestyle]

Cheers for all the responses guys!

[local hero]

Cheers for all the responses guys!

Just to add my 2penneth, and i aint no fizzisist, once you reach normal running temp should your cars performance not improve in cold weather, because all engine tuning for performance is about getting your engine to breathe better, larger valves, more valves, less restrictive air filters, tuned exhausts, etc etc, Well colder air entering your engine is denser (or is it me thats dense) which is why we have Intercoolers, super cool nitro kits etc. Stew

[Jamesbelfast]

Cheers for all the responses guys!

Just to add my 2penneth, and i aint no fizzisist, once you reach normal running temp should your cars performance not improve in cold weather, because all engine tuning for performance is about getting your engine to breathe better, larger valves, more valves, less restrictive air filters, tuned exhausts, etc etc, Well colder air entering your engine is denser (or is it me thats dense) which is why we have Intercoolers, super cool nitro kits etc. Stew

Your idea of cooler air works to a certain extent - well in theory anyway. The problem being most modern engines have oxygen sensors in the exhaust so if they detect oxygen levels outside the specified paramaters the ECU automatically compensates. So in essence fitting a cold air supply without a remap of the ECU settings is pretty pointless. Fuel burning inside any engine has optimum ignition characteristics so there is no point in throwing in more oxygen without fuel to match and vice versa.:)