fastalan
Veteran Member
Re: Coolant temp on the high side, car drives fine w/ VAGCOM log graph
I seem to have a problem with my coolant temperature reading on the high end however the car drives just fine.
Below is the graph generated by my VAGCOM log. note: If the pic is too big I will try to fix it afterward.
Here's the story
1) Went to Cypress Mountain to check out the snow last weekend and on my drive up to the mountain, 4th gear accelerating, the red coolant warning light along with the alarm came out with temp needle moving fast toward the red zone. Since I can't just stop right away on this stretch of road, I slowed down dramatically, shifted into third gear, pretty much crawling slowly. As soon as I slow down the temp started to drop back toward normal and by the time I've found a safe place to park, the needle was almost back to the normal range. Turned off the engine, opened up the hood to check around, the radiator, the hoses, the engine bay just did not feel like it has been overheated. Ambient temperature was about 0 degree Celsius. So I got back driving, again in third gear going uphill with a constant speed. Then as soon as I shifted into 4th gear and started accelerating with any kind of load, the needle started to move toward the right. I decided to turn around and on the way back I turned on the heater (the heat was pretty hot) and carefully drove home without drama.
2) Coolant reservoir is a bit lower than the min, about 0.5 cm lower. I noticed a slight drop in coolant early this year, and including topping up this time, I've put in about 300-400ml of coolant.
3) Tried to look around the car from the topside of the engine bay, including the belly pan near the timing belt cover, and hoses that I can physically see, I really can't spot any coolant leak.
4) The above graph is from today's drive to work. I log it and I can see that if the sensors were telling the truth, the temperature reading seemed really high! It seemed to me that once the car has warmed up, with temp at over 110C, the two radiator fans, as hard as they spin, can't seem to drop the temp down. However, turning the heater on max did reduced the temp reading quickly. You can see from the graph I had to park the car, let it idle in order to cool down because during one section, again, I accelerated under 4th gear and I can see the needle wanting to move to the right. I also let the car idle quite a bit at the end also trying to reduce the coolant temp, both time with heater on maximum. The coolant warning light did not come out today.
5) Coolant has been flushed once by the dealer back in Sept 2012, 60000 km. I now have over 150000 km.
6) Coolant color is real nice pink, no dirty stuff inside the coolant bottle. The two needles (the sensor pins) seem clean enough. I refilled with Canadian Tire OEM Coolant for Porsche/Audi/VW, meets VW TL 774F.
7) My car has the VW Canadian spec block heater, if I plug it in a few hours before I drive, the temp needle will register a few clicks higher from left, but once I started the engine with coolant flowing, the temp needle do drop down right away. So at least the coolant is still being pushed around this part of the system.
8) I change the engine oil a few weeks ago, it looked just like what used diesel oil should look and smell like.
What could be the problem causing the high temp while driving? A dying and weakening water pump? Bad sensor? Could some kind of partial blockage or area with bottleneck, like the far end of the cooling system, around low pressure EGR or engine oil cooler area, cause this problem.
What other VAGCOM parameters can I tick to log in order to provide more data to help the diagnosis?
If I drive gingerly, with the heater on, I can more or less keep the coolant temp in the 95c to 110c range, but this is not a normal behaviour and it definitely won't work in summer.
I seem to have a problem with my coolant temperature reading on the high end however the car drives just fine.
Below is the graph generated by my VAGCOM log. note: If the pic is too big I will try to fix it afterward.
Here's the story
1) Went to Cypress Mountain to check out the snow last weekend and on my drive up to the mountain, 4th gear accelerating, the red coolant warning light along with the alarm came out with temp needle moving fast toward the red zone. Since I can't just stop right away on this stretch of road, I slowed down dramatically, shifted into third gear, pretty much crawling slowly. As soon as I slow down the temp started to drop back toward normal and by the time I've found a safe place to park, the needle was almost back to the normal range. Turned off the engine, opened up the hood to check around, the radiator, the hoses, the engine bay just did not feel like it has been overheated. Ambient temperature was about 0 degree Celsius. So I got back driving, again in third gear going uphill with a constant speed. Then as soon as I shifted into 4th gear and started accelerating with any kind of load, the needle started to move toward the right. I decided to turn around and on the way back I turned on the heater (the heat was pretty hot) and carefully drove home without drama.
2) Coolant reservoir is a bit lower than the min, about 0.5 cm lower. I noticed a slight drop in coolant early this year, and including topping up this time, I've put in about 300-400ml of coolant.
3) Tried to look around the car from the topside of the engine bay, including the belly pan near the timing belt cover, and hoses that I can physically see, I really can't spot any coolant leak.
4) The above graph is from today's drive to work. I log it and I can see that if the sensors were telling the truth, the temperature reading seemed really high! It seemed to me that once the car has warmed up, with temp at over 110C, the two radiator fans, as hard as they spin, can't seem to drop the temp down. However, turning the heater on max did reduced the temp reading quickly. You can see from the graph I had to park the car, let it idle in order to cool down because during one section, again, I accelerated under 4th gear and I can see the needle wanting to move to the right. I also let the car idle quite a bit at the end also trying to reduce the coolant temp, both time with heater on maximum. The coolant warning light did not come out today.
5) Coolant has been flushed once by the dealer back in Sept 2012, 60000 km. I now have over 150000 km.
6) Coolant color is real nice pink, no dirty stuff inside the coolant bottle. The two needles (the sensor pins) seem clean enough. I refilled with Canadian Tire OEM Coolant for Porsche/Audi/VW, meets VW TL 774F.
7) My car has the VW Canadian spec block heater, if I plug it in a few hours before I drive, the temp needle will register a few clicks higher from left, but once I started the engine with coolant flowing, the temp needle do drop down right away. So at least the coolant is still being pushed around this part of the system.
8) I change the engine oil a few weeks ago, it looked just like what used diesel oil should look and smell like.
What could be the problem causing the high temp while driving? A dying and weakening water pump? Bad sensor? Could some kind of partial blockage or area with bottleneck, like the far end of the cooling system, around low pressure EGR or engine oil cooler area, cause this problem.
What other VAGCOM parameters can I tick to log in order to provide more data to help the diagnosis?
If I drive gingerly, with the heater on, I can more or less keep the coolant temp in the 95c to 110c range, but this is not a normal behaviour and it definitely won't work in summer.