Mk4 thermostate Azj engine 2.0 L NA

[H Daniel]

032121110F WAO vs 050121113C
Hello every one ..
it is AZJ engine 2.0 L NA. It's original thermo is opening on 87° 050121113C ...
about the other thermo that's opening on 83° 032121110F...both are original.
Can i install the 83° thermo instead of 87° one ?? Because, it is very hot here, dubai??
Waiting for your opinions.. Thank you .

 

[Genesis]

A lower opening temperature does not increase the cooling system's capacity. It only changes the operating range; well before you reach the overheat point the thermostat is fully open, and at that point it is simply a function of the capacity of the radiator via coolant flow and/or fans to reject said heat into the atmosphere.

The lower-temperature one, in other words, will result in lower operating temperatures within the cooling system's capacity but does not improve the ultimate capacity of the system to remain within limits.

 

[H Daniel]

A lower opening temperature does not increase the cooling system's capacity. It only changes the operating range; well before you reach the overheat point the thermostat is fully open, and at that point it is simply a function of the capacity of the radiator via coolant flow and/or fans to reject said heat into the atmosphere.

The lower-temperature one, in other words, will result in lower operating temperatures within the cooling system's capacity but does not improve the ultimate capacity of the system to remain within limits.

So is it ok to change without being bad to the engine or not??

 

[bn_]

I fully agree with Genesis, you would just see more oscillating temps, but you would not really improve your situation...

If you really have issues with heat, then i would exchange the water cooler for the R32/VR6 1J0121253S (look out for soldered fins!) Maybe yours is just clogged and/or the fins are long gone due to oxidation

 

[H Daniel]

I fully agree with Genesis, you would just see more oscillating temps, but you would not really improve your situation...

If you really have issues with heat, then i would exchange the water cooler for the R32/VR6 1J0121253S (look out for soldered fins!) Maybe yours is just clogged and/or the fins are long gone due to oxidation

oscillating temps,?? How this ?? And why??

 

[H Daniel]

A lower opening temperature does not increase the cooling system's capacity. It only changes the operating range; well before you reach the overheat point the thermostat is fully open, and at that point it is simply a function of the capacity of the radiator via coolant flow and/or fans to reject said heat into the atmosphere.

The lower-temperature one, in other words, will result in lower operating temperatures within the cooling system's capacity but does not improve the ultimate capacity of the system to remain within limits.

lower opening temperature does not increase the cooling system's capacity. ????.

I dont wanna increase the cooling capacity but just to improve operating temperatures???

 

[H Daniel]

I fully agree with Genesis, you would just see more oscillating temps, but you would not really improve your situation...

If you really have issues with heat, then i would exchange the water cooler for the R32/VR6 1J0121253S (look out for soldered fins!) Maybe yours is just clogged and/or the fins are long gone due to oxidation

Maybe yours is just clogged and or the fins are long gone due to oxidation??

No everything are good

 

[bn_]

How do you determine that your temps are too high? Is your temp gauge raising? If not, you dont have an issue.
If yes, then lowering the opening temperature of the thermostat will not fix it. Your temperature will still reach the red area in load situations, just a few seconds later as it can heat up the ~5 liters of water by an additional 4 Kelvin. On the other hand you are running your engine at a lower temp than specified in low load scenarios, also slightly bad.

What you want is to get the heat away and this is done at the radiator.

 

[H Daniel]

But the difference are not big, it's only 4 degrees (87°- 83°) to harm the engine in low load scenarios ...actually it is not raising but in the 3dmfd display gives coolant degree 101°c , the engine oil is 106°c and automatic transmission oil is 105°c or 110°c

 

[bn_]

engine oil at 106°C is perfectly fine...

 

[H Daniel]

engine oil at 106°C is perfectly fine...

Engine oil Range from 105° to 110c°...what about coolant and transmission oil temp?

 

[Genesis]

lower opening temperature does not increase the cooling system's capacity. ????.

I dont wanna increase the cooling capacity but just to improve operating temperatures???

Why?

Engines are designed for a specific range of operating temperatures; that's why they have a thermostat and that is its job -- to regulate the temperature within the operating range.

Dropping the lower end doesn't improve operation and might result in less-complete combustion (bad; it will impair fuel economy) -- it will not improve the system's ability to reject heat (e.g. prevent overheating.)

Once the thermostat is completely open and the fans are running on high continually the system is out of capacity to remove heat. You will go from that state to overheating very rapidly and using a lower-temperature thermostat will not change this.

If there is a compromise in the heat-removal capacity (e.g. fans not operating properly, especially if one or both are dead, clogged radiator, sludge in the engine impairing heat transfer, usually due to someone mixing coolant types inappropriately at some time in the past, bad water pump where the impeller is not coupled 100% to the shaft, etc.) then a lower temperature thermostat will not improve the situation. If that is the case you need to find the cause and fix it.

101C is normal under load in warm/hot weather and your oil temperature is fine as well.

The high speed fans come on at 102C for the coolant and I HAVE had them cycle on and off (entirely normal) in hot temperatures, with A/C on, in stalled traffic. When moving at a reasonable speed they shouldn't even in very hot weather as the airflow through the radiator is sufficient.

 

[H Daniel]

Why?

Engines are designed for a specific range of operating temperatures; that's why they have a thermostat and that is its job -- to regulate the temperature within the operating range.

Dropping the lower end doesn't improve operation and might result in less-complete combustion (bad; it will impair fuel economy) -- it will not improve the system's ability to reject heat (e.g. prevent overheating.)

Once the thermostat is completely open and the fans are running on high continually the system is out of capacity to remove heat. You will go from that state to overheating very rapidly and using a lower-temperature thermostat will not change this.

If there is a compromise in the heat-removal capacity (e.g. fans not operating properly, especially if one or both are dead, clogged radiator, sludge in the engine impairing heat transfer, usually due to someone mixing coolant types inappropriately at some time in the past, bad water pump where the impeller is not coupled 100% to the shaft, etc.) then a lower temperature thermostat will not improve the situation. If that is the case you need to find the cause and fix it.

101C is normal under load in warm/hot weather and your oil temperature is fine as well.

The high speed fans come on at 102C for the coolant and I HAVE had them cycle on and off (entirely normal) in hot temperatures, with A/C on, in stalled traffic. When moving at a reasonable speed they shouldn't even in very hot weather as the airflow through the radiator is sufficient.

Yes actually you absolutely right but are you sometimes the engine oil temp jump to 115 °C and the auto transmission to 117 °C and the coolant temp to 105° are these temp degrees are normal in a very hot outside atmosphere...waiting your reply ..thank you ..

 

[Genesis]

115C for engine oil is of no concern at all; that is WELL within normal limits for a full synthetic.

I do not like that ATX fluid temperature and this is a sore spot with basically ALL factory ATX setups except those with auxiliary coolers -- and typically only trucks with towing packages have those. They do matter in a big way. It keeps transmission shops in business, especially if you don't change the fluid at reasonably-frequent intervals.

But running a colder thermostat is not going to do much (if anything) to address that. I don't know if its practical to add a secondary transmission cooler or not but if it is then that's the answer to the ATX fluid temperature problem (and the only one that will make a difference.)

 

[H Daniel]

115C for engine oil is of no concern at all; that is WELL within normal limits for a full synthetic.

I do not like that ATX fluid temperature and this is a sore spot with basically ALL factory ATX setups except those with auxiliary coolers -- and typically only trucks with towing packages have those. They do matter in a big way. It keeps transmission shops in business, especially if you don't change the fluid at reasonably-frequent intervals.

But running a colder thermostat is not going to do much (if anything) to address that. I don't know if its practical to add a secondary transmission cooler or not but if it is then that's the answer to the ATX fluid temperature problem (and the only one that will make a difference.)

So from your words , the 117C° for my (09G 6 speeds ) auto transmission oil temp is not good although i always changed every 30000 km
(motul multi ATF ) or (liqui moly top tech 1200ATF) and i don't have auxiliary cooler just the standard cooler and i dont like to install any secondary cooler..so what can i do to keep it cooler ?

 

[bn_]

You need to understand that the engine oil is putting its heat into the coolant via a heat exchanger. Same applies for the automatic transmission oil. While driving their temp will never be below the coolant. And age of oil is not an factor for the temperature.

So if we look at this situation here:

...coolant degree 101°c , the engine oil is 106°c and automatic transmission oil is 105°c or 110°c

The engine itself, the engine oil and the transmission oil are all putting its heat into the coolant. At this point it does not matter if your thermostat opens at 87, 84 or -10°C. All of them are fully open in this situation. You need to loose the heat to the environment.

So lets look at what VW did:
If you had a bone stock MK4, they fitted radiator 1J0121253AT
If your car had a trailer hitch, 1.8T engine, AC, automatic transmission or was build for a hot weather country, they fitted 1J0121253AD
If you had a VR5, VR6 or R32 engine, then they always fitted 1J0121253S
If you had an ARL, then they always fitted 1J0121253AC

Now what is the difference?
Sizewise 1J0121253AT and 1J0121253AD are the same, i suspect that AD has better heat transfer and thus better cooling.
1J0121253S has the same width and height, but is thicker = more area to transfer heat to the air passing by.
1J0121253AC for ARL is more or less the same as 1J0121253S, but is mounted differently due to the additional FMIC.

Theres one more thing that was done for (i think) R32 with DSG. They fitted an additional water cooler 1J0121212A to make sure that the additional heat by the engine an the gearbox is lost.

Now you can either live with what you have, i dont think that there is an issue with the temps, especially if you change the ATF on a regular basis. Or you change the radiator for a good quality (mahle behr) 1J0121253S. Check if you have an additional 5mm or so space between the intercooler and the engine if you intend to do so.

The "issue" with the mk4 (non R32) platform is the small area where air flows towards the radiator...

 

[H Daniel]

You need to understand that the engine oil is putting its heat into the coolant via a heat exchanger. Same applies for the automatic transmission oil. While driving their temp will never be below the coolant. And age of oil is not an factor for the temperature.

So if we look at this situation here:


The engine itself, the engine oil and the transmission oil are all putting its heat into the coolant. At this point it does not matter if your thermostat opens at 87, 84 or -10°C. All of them are fully open in this situation. You need to loose the heat to the environment.

So lets look at what VW did:
If you had a bone stock MK4, they fitted radiator 1J0121253AT
If your car had a trailer hitch, 1.8T engine, AC, automatic transmission or was build for a hot weather country, they fitted 1J0121253AD
If you had a VR5, VR6 or R32 engine, then they always fitted 1J0121253S
If you had an ARL, then they always fitted 1J0121253AC

Now what is the difference?
Sizewise 1J0121253AT and 1J0121253AD are the same, i suspect that AD has better heat transfer and thus better cooling.
1J0121253S has the same width and height, but is thicker = more area to transfer heat to the air passing by.
1J0121253AC for ARL is more or less the same as 1J0121253S, but is mounted differently due to the additional FMIC.

Theres one more thing that was done for (i think) R32 with DSG. They fitted an additional water cooler 1J0121212A to make sure that the additional heat by the engine an the gearbox is lost.

Now you can either live with what you have, i dont think that there is an issue with the temps, especially if you change the ATF on a regular basis. Or you change the radiator for a good quality (mahle behr) 1J0121253S. Check if you have an additional 5mm or so space between the intercooler and the engine if you intend to do so.

The "issue" with the mk4 (non R32) platform is the small area where air flows towards the radiator...

So the solution here is to change the radiator to 1J0121253S but unfortunately the original one is not exist here so is there any
Alternatives for original radiator ???