Overheating while coasting @ 60mph??
11-28-2013, 09:08 AM
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Overheating while coasting @ 60mph??
Hello all, this is my first post on this forum since I'm normally a Jeep guy :-P.
HISTORY: My wife has a 2002 TT 180 w/ 48k miles on it. It has had odd overheating issues for a long time. Before we met, she had a shop do $4,000 worth of cooling system work to fix whatever was going on. They replaced the fans and other stuff but she doesn't know exactly what they did. Pretty sure they took advantage of a pretty girl that knows nothing about cars...
SYMPTOMS:
It will get one (sometimes 2) notches hotter than straight up and down while idling, coasting downhill at 60mph and even while climbing on the interstate. While idling, the fans will come on and off but never seem to stay on long enough to keep the engine at normal temp.
I have repeated the downhill coasting experiment several times and it will not get hot consistently. It only seems to get hot after being driven slightly hard (hard accelerations coming onto the interstate, etc).
FIXES:
I have done a coolant flush.
50/50 G12 coolant is at correct level
Replaced Coolant Temp Sensor (replaced green w/ green)
Replaced Fan Relay (big box under battery)
HYPOTHESIS:
The only thing I can think of, is that maybe the crappy garage she went to didn't replace the stock water pump. They're known for their plastic impellers failing so maybe only enough of it has failed for it to get hot sometimes. Maybe sometimes the impeller comes on and off the shaft. Seems far fetched but made sense w/ the coasting downhill symptom (since in N it wouldn't have enough engine speed to circulate coolant) until it started getting hot while in gear.
PLEASE HELP.
HISTORY: My wife has a 2002 TT 180 w/ 48k miles on it. It has had odd overheating issues for a long time. Before we met, she had a shop do $4,000 worth of cooling system work to fix whatever was going on. They replaced the fans and other stuff but she doesn't know exactly what they did. Pretty sure they took advantage of a pretty girl that knows nothing about cars...
SYMPTOMS:
It will get one (sometimes 2) notches hotter than straight up and down while idling, coasting downhill at 60mph and even while climbing on the interstate. While idling, the fans will come on and off but never seem to stay on long enough to keep the engine at normal temp.
I have repeated the downhill coasting experiment several times and it will not get hot consistently. It only seems to get hot after being driven slightly hard (hard accelerations coming onto the interstate, etc).
FIXES:
I have done a coolant flush.
50/50 G12 coolant is at correct level
Replaced Coolant Temp Sensor (replaced green w/ green)
Replaced Fan Relay (big box under battery)
HYPOTHESIS:
The only thing I can think of, is that maybe the crappy garage she went to didn't replace the stock water pump. They're known for their plastic impellers failing so maybe only enough of it has failed for it to get hot sometimes. Maybe sometimes the impeller comes on and off the shaft. Seems far fetched but made sense w/ the coasting downhill symptom (since in N it wouldn't have enough engine speed to circulate coolant) until it started getting hot while in gear.
PLEASE HELP.
11-28-2013, 10:38 AM
#2
Might seem like a silly question, but how is the heat out of the dash? Replacing the coolant pump might be a good idea regardless. Also, there should be a thermoswitch for the fans, I don't know if you replaced that..
11-28-2013, 12:16 PM
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The thermoswitch? Where is that? I called the Audi dealer trying to figure out where this 2nd sensor is and they had no clue...can't seem to find anything on any forums either.
11-28-2013, 04:04 PM
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Heat from dash is hot. No problems there. I'm trying to avoid replacing water pump/timing belt...last option :-P. Trying to get it to stop running hot so we can sell it.
The thermoswitch? Where is that? I called the Audi dealer trying to figure out where this 2nd sensor is and they had no clue...can't seem to find anything on any forums either.
The thermoswitch? Where is that? I called the Audi dealer trying to figure out where this 2nd sensor is and they had no clue...can't seem to find anything on any forums either.
Blocked radiator / thermostat or water pump I would say. On every Audi we have ever owned the temp gauge always reliably points to 12 o'clock.
If you have VAG.com you can check to see if the gauge is correct. The clusters are also a high failure item (there was a long expired recall) mostly the fuel and temp gauges.
11-29-2013, 06:11 AM
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Several possibilitles but one is most important
If she still has the original water pump she is driving a time bomb. Water pump, tensioner, and timing belt MUST be changed every 5 years regardless of mileage (or 60K is that comes first but not in your case). You are looking at a $5K+ top engine overhaul bill if it fails. However, I can't imaging how a shop charged $4K for work if that was not included (about $750 for just that at an independent shop. DieselGeek makes the best replacement kit. Tow the car to the garage and get it done.
If it is the original water pump, broken plastic blades is the most likely explanation of your problem. Most replacement pumps are metal.
Other possibilities include the thermostat and fan temp sensors. Many folks, myself included, have had the engine running hot after replacing the thermostat with a non-Audi model. Even though I bough a thermostat of the same manufacturer that Audi uses (Wahler) it did not open/close the same as the version they make for Audi. Once warm, the temp sensor should be steady in the middle of the dial irrespective of outside temps and driving style. I've had mine on freeways at 115 degree climbing a steep hill and 0 degrees around ski resorts with the needle riding dead center.
If it is the original water pump, broken plastic blades is the most likely explanation of your problem. Most replacement pumps are metal.
Other possibilities include the thermostat and fan temp sensors. Many folks, myself included, have had the engine running hot after replacing the thermostat with a non-Audi model. Even though I bough a thermostat of the same manufacturer that Audi uses (Wahler) it did not open/close the same as the version they make for Audi. Once warm, the temp sensor should be steady in the middle of the dial irrespective of outside temps and driving style. I've had mine on freeways at 115 degree climbing a steep hill and 0 degrees around ski resorts with the needle riding dead center.
12-18-2013, 04:35 PM
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Conclusion
After changing thermostat, coolant temp sensor, flange, full flush, changing fan control module, and installing the Diesel Geek timing belt/water pump kit I had run out of ideas. Even the dealer was like, "well, you did everything WE would have done..." Great. So I brought it to a shop and they figured out what was wrong with it.
It will cost $1800.
It was not overheating.
There was nothing wrong with the cooling system and all my repairs were done correctly.
It was...the instrument cluster malfunctioning.
SOB!!!
So, if you're having a similar problem, don't throw parts at it...get it checked. Especially if your cluster is already a little gibbled up w/ lines streaking thru the LCD. We're not going to get it fixed unless we can somehow convince Audi to pull their thumbs out of their rears and fix it for us.
Really cool tidbit I found out while doing this. The TT has its own on board OBD2 readout. If you hold recirculate and then the UP arrow, release, and press recirculate again the display will show 01C. If you use the left dial and rotate it until you see 49C, you will now see your engine temp in real time. In Celsius.
Good luck! Thanks for all the help. :-)
It will cost $1800.
It was not overheating.
There was nothing wrong with the cooling system and all my repairs were done correctly.
It was...the instrument cluster malfunctioning.
SOB!!!
So, if you're having a similar problem, don't throw parts at it...get it checked. Especially if your cluster is already a little gibbled up w/ lines streaking thru the LCD. We're not going to get it fixed unless we can somehow convince Audi to pull their thumbs out of their rears and fix it for us.
Really cool tidbit I found out while doing this. The TT has its own on board OBD2 readout. If you hold recirculate and then the UP arrow, release, and press recirculate again the display will show 01C. If you use the left dial and rotate it until you see 49C, you will now see your engine temp in real time. In Celsius.
Good luck! Thanks for all the help. :-)
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12-19-2013, 06:42 AM
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12-21-2013, 07:30 AM
#9
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After changing thermostat, coolant temp sensor, flange, full flush, changing fan control module, and installing the Diesel Geek timing belt/water pump kit I had run out of ideas. Even the dealer was like, "well, you did everything WE would have done..." Great. So I brought it to a shop and they figured out what was wrong with it.
It will cost $1800.
It was not overheating.
There was nothing wrong with the cooling system and all my repairs were done correctly.
It was...the instrument cluster malfunctioning.
SOB!!!
So, if you're having a similar problem, don't throw parts at it...get it checked. Especially if your cluster is already a little gibbled up w/ lines streaking thru the LCD. We're not going to get it fixed unless we can somehow convince Audi to pull their thumbs out of their rears and fix it for us.
Really cool tidbit I found out while doing this. The TT has its own on board OBD2 readout. If you hold recirculate and then the UP arrow, release, and press recirculate again the display will show 01C. If you use the left dial and rotate it until you see 49C, you will now see your engine temp in real time. In Celsius.
Good luck! Thanks for all the help. :-)
It will cost $1800.
It was not overheating.
There was nothing wrong with the cooling system and all my repairs were done correctly.
It was...the instrument cluster malfunctioning.
SOB!!!
So, if you're having a similar problem, don't throw parts at it...get it checked. Especially if your cluster is already a little gibbled up w/ lines streaking thru the LCD. We're not going to get it fixed unless we can somehow convince Audi to pull their thumbs out of their rears and fix it for us.
Really cool tidbit I found out while doing this. The TT has its own on board OBD2 readout. If you hold recirculate and then the UP arrow, release, and press recirculate again the display will show 01C. If you use the left dial and rotate it until you see 49C, you will now see your engine temp in real time. In Celsius.
Good luck! Thanks for all the help. :-)
Module master could have fixed your cluster for about $350. All later Audis have that feature with the climate control.
12-23-2013, 12:32 AM
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Actually, used a VagCom on it several times. It never threw any sort of code indicating bad gauges. Never threw anything related to this at all. Only codes it had were related to the disintegrating vacuum lines that were promptly fixed.