My real car's engine temp

[Big G]

I drive a mk4 golf TDI and in the normal UK weather the engine temp sits just below the 90 degree mark on the gauge. The Mrs has exactly the same car, but her's has AC and mine doesn't and her's sits bang on the 90 mark.

Now the snow has arrived it's dropped to probably the 80 degree mark, but when I use the heats on level 3 the temp drops to probably 60 degrees. If I use the heaters on level 2 the temp goes back to around 80.

Is this normal or is my antifreeze a bit off? It's never frozen solid, but I haven't ever changed my coolant since owning the car lol. I've had it for almost 3 years now. I'll get it checked anyway and replace it needed.

[smokes]

diesel always run cooler than petrol any hotter than 80 degrees will eventually cause the head to warp or lead to gasket failures. You could always put some cardboard in front of the radiuator like london taxi cab drivers do in the winter. not reccomended though. If you didn't have any anti freeze you would have siezed the water pump or cracked the block.

If the temperature is dropping it is probably cause there is snow between the bonnet and the windscreen. Which is where the air intake is for fresh air to the interior. but you should top up the coolant once a year as the gylcol(anti freeze) will evaporate off over time.

[Nightshade]

Although it's best to change anti freeze every once in a while, in practise most people don't. Modern stuff will go a very long time without loosing it's ability to stay unfrozen, so I wouldn't worry about it.
Besides a frozen cooling system wouldn't be affected by the level your fans on.
But remember that the more hot air you ask the car for, the more heat you're displacing from the engine into the cab. A cool engine is a happy engine (with the exception of when you're trying to start a diesel). So don't panic unless it starts getting too hot.

I don't mean to burn you smokes but, please for god's sake don't put cardboard in front of the radiator!
The original idea was to block the cooling effect of the radiator and stop it reducing engine temperature before the engine had a chance to get warm - a secondary effect was to stop the coolant freezing if the wind chill factor exceeded the antifreezes freezing point. A principle that was completely obsolete by 1930 with the invention of the thermostat and the advances in antifreeze technology by about 1940. So unless you've got 1940's antifreeze in a 1930's car, it's pointless and more likely to make the engine run hot!
I see people doing it and I want to shake them!

[mark christopher]

Originally Posted by smokes

diesel always run cooler than petrol any hotter than 80 degrees will eventually cause the head to warp or lead to gasket failures. You could always put some cardboard in front of the radiuator like london taxi cab drivers do in the winter. not reccomended though. If you didn't have any anti freeze you would have siezed the water pump or cracked the block.

If the temperature is dropping it is probably cause there is snow between the bonnet and the windscreen. Which is where the air intake is for fresh air to the interior. but you should top up the coolant once a year as the gylcol(anti freeze) will evaporate off over time.

lol fell off my chair laughing at that..... friggin arm chair mechanics!

engines will safley run above 100 deg C without damage or boiling, as your an expert ill let you figure out how they dont boil over when the coolant temp is over 100deg c

[mark christopher]

Originally Posted by Big G

I drive a mk4 golf TDI and in the normal UK weather the engine temp sits just below the 90 degree mark on the gauge. The Mrs has exactly the same car, but her's has AC and mine doesn't and her's sits bang on the 90 mark.

Now the snow has arrived it's dropped to probably the 80 degree mark, but when I use the heats on level 3 the temp drops to probably 60 degrees. If I use the heaters on level 2 the temp goes back to around 80.

Is this normal or is my antifreeze a bit off? It's never frozen solid, but I haven't ever changed my coolant since owning the car lol. I've had it for almost 3 years now. I'll get it checked anyway and replace it needed.

i would look at getting a new thermostat fitted, mates passat with same engine suffered the same as yours, the stats get weak and open early or stick open preventing the engine from getting to norm temp, when you call on more heat from the heater the engine is cooled and carnt build up temp.

[Big G]

yeah I think I might since they're cheap and easy to replace.

Coolant doesn't boil at 100 because it's boiling point is higher than water? plus it's in a airtight system? also not sure how my antifreeze can evaporate when locked into an airtight system, but hey. I don't have all the answers since I'm asking for advice

[smokes]

I was trying to keep it simples......

I Design much more complex pressurised systems than car engines. Yes I know you can run them to a 100 degrees c but I wouldn't recommend it.

[mark christopher]

Originally Posted by smokes

I was trying to keep it simples......

I Design much more complex pressurised systems than car engines. Yes I know you can run them to a 100 degrees c but I wouldn't recommend it.

you may do but (but do you understand em?) i work on "basic" car cooling systems and have done for 25 plus years
you best tell ford and many other manufactures they have got it wrong as cooling fans dont come on till around 100deg and your claiming no more than 80!! (on what grounds??) its total bolox that the head will warp or the gaskets will fail at 100. most thermostats open at 80 to 92 deg c, tad more than you recomend!

simple is often danjerous as running engines too cold causes wear and uses more fuel!

[mark christopher]

Originally Posted by Big G

yeah I think I might since they're cheap and easy to replace.

Coolant doesn't boil at 100 because it's boiling point is higher than water? plus it's in a airtight system? also not sure how my antifreeze can evaporate when locked into an airtight system, but hey. I don't have all the answers since I'm asking for advice

yup mate did his and was easy job, coolant does not actually stop boiling its an antifreeze and lubricant/rust inhibitor.
the presure lowers the boiling point of the coolant, same as a pressure cooker thats why if u have a hot engine and you take the cap off it boils out

[Aaran]

most thermo's open at 70-85c (i have the qh thermo book which lists them all , average is around 72/3c )

and yes its a common as muck vw golf mk4 fault with the thermos opening to early, they jsut go sloppy and dont shut fully, shove a new one in and all is done. also the coolant temp sensor can start to fail which can cause the needle to read low (will either be a 2 pin green or 3 pin blue plug on the top rad hose) jsut change them both when the system is empty of antifreeze

had your windows fallen out yet? got to love that fault to! (most reliable car i have ever owned in my life, not lol)

[Big G]

it's falling out in this car yes, but it was before I owned it lol

The window in the skoda at work just fell out lol. the Mrs pushed down on hers when it was frozen and it stayed up and the mech went down lol

[SlowOne]

I work with gas turbines. Parts of the engine work in a gas whose temperature exceeds the melting point of the metal it passes over. However, that does not make me an expert on the likelihood of pistons melting at the compression temperature because of the cooling systems in play in a reciprocating engines. Not wishing to flame you either Smokes, but sometimes it is better to be though a fool than get on your keyboard and remove all doubt!

If Mark says it's the thermostat, it's the thermostat, and if he says they work around 90 deg, they work around 90 deg - all his advice to me has been spot on. It isn't what you know, it's what you have done to apply your knowledge in context that counts. Mark has done that, we haven't - listen and learn.

MkV Golf is it? You have my deepest sympathy!! Check out the pages on Honest John (.co.uk) about the Golf MkV, and then look at the same age Focus. A mile of faults for the MkV and a few for the Focus. Just where does this fabled VW reliability come from? We have three VW cars in the pool at work, and each of them has failed on a journey in the last twelve months - two of them are '10' plates!!

Change the thermostat Big G, and I'm sure you'll have a cure.

[mark christopher]

Originally Posted by Aaran

most thermo's open at 70-85c (i have the qh thermo book which lists them all , average is around 72/3c )

and yes its a common as muck vw golf mk4 fault with the thermos opening to early, they jsut go sloppy and dont shut fully, shove a new one in and all is done. also the coolant temp sensor can start to fail which can cause the needle to read low (will either be a 2 pin green or 3 pin blue plug on the top rad hose) jsut change them both when the system is empty of antifreeze

had your windows fallen out yet? got to love that fault to! (most reliable car i have ever owned in my life, not lol)

id buy a new book then, they aint been that low for years, all modern cars run hotter to help emmisions, take a look below not one below 80 deg

http://auto.howstuffworks.com/question248.htm

http://autos.yahoo.com/maintain/repa...ques018_2.html

http://www.ehow.com/how-does_4895412...tats-work.html

http://www.ehow.com/how_2189728_test...hermostat.html

http://www.helium.com/items/1766866-...rmostat?page=2

this is more relevent to the car
http://www.eurocarparts.com/ecp/c/Vo...bada3a48c&TSTA

oooo look 87deg




Thermostat
The thermostat is simply a valve that measures the temperature of the coolant and, if it is hot enough, opens to allow the coolant to flow through the radiator. If the coolant is not hot enough, the flow to the radiator is blocked and fluid is directed to a bypass system that allows the coolant to return directly back to the engine. The bypass system allows the coolant to keep moving through the engine to balance the temperature and avoid hot spots. Because flow to the radiator is blocked, the engine will reach operating temperature sooner and, on a cold day, will allow the heater to begin supplying hot air to the interior more quickly.
Since the 1970s, thermostats have been calibrated to keep the temperature of the coolant above 192 to 195 degrees. Prior to that, 180 degree thermostats were the norm. It was found that if the engine is allowed to run at these hotter temperatures, emissions are reduced, moisture condensation inside the engine is quickly burned off extending engine life, and combustion is more complete which improves fuel economy.
The heart of a thermostat is a sealed copper cup that contains wax and a metal pellet. As the thermostat heats up, the hot wax expands, pushing a piston against spring pressure to open the valve and allow coolant to circulate.
The thermostat is usually located in the front, top part of the engine in a water outlet housing that also serves as the connection point for the upper radiator hose. The thermostat housing attaches to the engine, usually with two bolts and a gasket to seal it against leaks. The gasket is usually made of a heavy paper or a rubber O ring is used. In some applications, there is no gasket or rubber seal. Instead, a thin bead of special silicone sealer is squeezed from a tube to form a seal.
There is a mistaken belief by some people that if they remove the thermostat, they will be able to solve hard to find overheating problems. This couldn't be further from the truth. Removing the thermostat will allow uncontrolled circulation of the coolant throughout the system. It is possible for the coolant to move so fast, that it will not be properly cooled as it races through the radiator, so the engine can run even hotter than before under certain conditions. Other times, the engine will never reach its operating temperature. On computer controlled vehicles, the computer monitors engine temperatures and regulates fuel usage based on that temperature. If the engine never reaches operating temperatures, fuel economy and performance will suffer considerably.

[phil c]

Hi sounds like mark is correct in his diagnosis of your problem , the thermostat is located in the block on your car just to the right of the alternator , it's located in a plastic housing held on by two ten mm bolts or two five mm allen key bolts , do not undo the housing on the side of the head above the gearbox like most techs do because it's empty, and also only use the red antifreeze in your car as mixing the two types causes problems , hope this helps

[mark christopher]

cheers phil.

now i have a merc vito i may be calling on you if im stuck! northy has one too

[showtime]

Originally Posted by mark christopher

yup mate did his and was easy job, coolant does not actually stop boiling its an antifreeze and lubricant/rust inhibitor.
the presure lowers the boiling point of the coolant, same as a pressure cooker thats why if u have a hot engine and you take the cap off it boils out

i'm sure you meant that the pressure in the cooling system raises the boiling point of the coolant

just pointing it out

[mark christopher]

Originally Posted by showtime

i'm sure you meant that the pressure in the cooling system raises the boiling point of the coolant

just pointing it out

yup well spotted been a long day......

[passat130]

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[phil c]

No prob Mark , any time you need any info give me a shout

[smokes]

Err don't flame me but Even though you have mechanical seals on the pump you will get some leakage, it to do with fluid shear between the seal and the shaft. basically your seals rely on the fluid to stop the seal melting and keep it lubricated. Now what happens is the friction the seal creates heat the fuild so you get some evaporation of the fluid. on car engines it might be 6ml a year. I have some customers who are happy with a leak rate of 60ml an hour ! But that is with bigger pumps and much nastier chemicals.
Anti freeze is like oil in engine will chemically breakdown due to heat exposure. Reason to change to oil is it changes chemically from an alkali to an acid due to heat and particulates absorbsion.

So no system is air tight if you have pump in it!

I didn't assume that the thermostat as I assumed the engine was warmed up and at operating temp. As my experiance with vags is because the all have the same demister that doesn't work. By the time your wind screen is demisted the engine will be at operating temp. or you will be tryiung to drive the car through to very small apartures. thank god for quick clear screens made by Ford. Ford holds the patient and refuses to license it to anyone else!

I also worked at vag in engineering, we all know about the windows lifter but because so many cars share this part its a pita to do an engineering change on it.

Yes I have rebuilt the head on a car after it they got it to 110 degrees C I had to get the head re skimed. Angry driver and a loose cooling hose.

Also the 100 degree cut in wouldn't necessarly mean that the coolant going to head / block is 100 degrees c. the fan temp sensor is usually linked close to the radiator inlet as is how they are supplied to OEMS with radiator. there also temp sensor in the engine block cooling which is what you see on the dash guage. ( whiuch not technically true) As there is a guage damping algorythm written into ECU on how it output sensor reading to the dash. Which why fuel tank guage can give false readings.
Which something they found out on a car that I was working on basically it drained the tank faster that the guage could keep up with.

For the gas turbines I know jet engines pump the Jet fuel into the blade to cool them and heat the fuel up before being passed to the fuel injectors, or what I call a very large tap... Which they use silly putty and diamond shards/dust to polish. Also the blades are single crystal but this so they can cope with creep. Theres a bunch of other aerodynamic tricks they also use for cooling but i don't have the knowledge on that.

As say I am not a mechanic. I was just guessing based on what was stated, and what i assumed was a warmed up engine.

my keyboard is fecked missius spilt water on it so i= iu every time a press it.