12v overheating questions
Thread Starter
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1st Gear
Joined: Jan 2006
Posts: 9
12v overheating questions
I'm new when it comes to Audi's, consider myself a skilled DIY'er, and was hoping somebody could help pinpoint my overheating problem. My post is long winded, but I want to give as much info as possible.
Our '97 A4 Quattro (with the 2.8 12v) needed it's timing belt replaced. While I was replacing it, I also replaced the water pump and T'stat which was included in the kit I purchased from Blaufergnugen. I also replaced the cooling fan switch located in the radiator on the lower driver's side, and the coolant temp gauge located back near the firewall.
I've bled the system using the 2 bleed points I could find (firewall heater hose, and bleeder located on steel pipe that wraps around backside of engine). I've got a crummy Haynes manual that says there is a 3rd bleed point up front, but I can't find it. It seems to still be running hot. It used to sit perfectly at the 1/2 point on the temp gauge before the swap., but now it slowly but ccontinously rises to ~3/4 of the way up, before I shut it off. It climbs from ~1/2 to ~3/4 in the matter of 2 miles. The radiator heats up, which means the thermosat opens up and permits flow through it.
Here's my biggest problem.
It loses coolant through the expansion tank overflow. Almost like it's building excessive pressure. I replaced the cap, thinking it's faulty, but it's doing the same thing. The oil temp stays around 200, like it used to.
Questions:
Could having the cam timing off by 1 tooth generate that much excessive heat, that it runs too hot for the cooling system? I used the tools supplied from Blau, and belive I installed the timing belt right, but I'm not 100% sure.
Is there a 3rd air bleeding point on the 2.8 12v engines? If so, can somebody get me a pic?
Roughly when should the electric fan kick on? If I push the Snowflake button on my heater control, it comes on, but it doesn't turn on, even when it's reading ~3/4. Shouldn't it?
Any advice or help is greatly appreciated.
Our '97 A4 Quattro (with the 2.8 12v) needed it's timing belt replaced. While I was replacing it, I also replaced the water pump and T'stat which was included in the kit I purchased from Blaufergnugen. I also replaced the cooling fan switch located in the radiator on the lower driver's side, and the coolant temp gauge located back near the firewall.
I've bled the system using the 2 bleed points I could find (firewall heater hose, and bleeder located on steel pipe that wraps around backside of engine). I've got a crummy Haynes manual that says there is a 3rd bleed point up front, but I can't find it. It seems to still be running hot. It used to sit perfectly at the 1/2 point on the temp gauge before the swap., but now it slowly but ccontinously rises to ~3/4 of the way up, before I shut it off. It climbs from ~1/2 to ~3/4 in the matter of 2 miles. The radiator heats up, which means the thermosat opens up and permits flow through it.
Here's my biggest problem.
It loses coolant through the expansion tank overflow. Almost like it's building excessive pressure. I replaced the cap, thinking it's faulty, but it's doing the same thing. The oil temp stays around 200, like it used to.
Questions:
Could having the cam timing off by 1 tooth generate that much excessive heat, that it runs too hot for the cooling system? I used the tools supplied from Blau, and belive I installed the timing belt right, but I'm not 100% sure.
Is there a 3rd air bleeding point on the 2.8 12v engines? If so, can somebody get me a pic?
Roughly when should the electric fan kick on? If I push the Snowflake button on my heater control, it comes on, but it doesn't turn on, even when it's reading ~3/4. Shouldn't it?
Any advice or help is greatly appreciated.
5th Gear
Joined: Apr 2005
Posts: 6,508
From: South Bay
RE: 12v overheating questions
welcome to the forums! could be a water pump problem..an awesome resource for the 12v engine is the 12v development forum on audiworld. check it out:
http://www.audiworld.com/forum/12v.html
http://www.audiworld.com/forum/12v.html
Site Moderator
Joined: Sep 2005
Posts: 13,664
RE: 12v overheating questions
ORIGINAL: 1997a4
I'm new when it comes to Audi's, consider myself a skilled DIY'er, and was hoping somebody could help pinpoint my overheating problem. My post is long winded, but I want to give as much info as possible.
Our '97 A4 Quattro (with the 2.8 12v) needed it's timing belt replaced. While I was replacing it, I also replaced the water pump and T'stat which was included in the kit I purchased from Blaufergnugen. I also replaced the cooling fan switch located in the radiator on the lower driver's side, and the coolant temp gauge located back near the firewall.
I've bled the system using the 2 bleed points I could find (firewall heater hose, and bleeder located on steel pipe that wraps around backside of engine). I've got a crummy Haynes manual that says there is a 3rd bleed point up front, but I can't find it. It seems to still be running hot. It used to sit perfectly at the 1/2 point on the temp gauge before the swap., but now it slowly but ccontinously rises to ~3/4 of the way up, before I shut it off. It climbs from ~1/2 to ~3/4 in the matter of 2 miles. The radiator heats up, which means the thermosat opens up and permits flow through it.
Here's my biggest problem.
It loses coolant through the expansion tank overflow. Almost like it's building excessive pressure. I replaced the cap, thinking it's faulty, but it's doing the same thing. The oil temp stays around 200, like it used to.
Questions:
Could having the cam timing off by 1 tooth generate that much excessive heat, that it runs too hot for the cooling system? I used the tools supplied from Blau, and belive I installed the timing belt right, but I'm not 100% sure.
Is there a 3rd air bleeding point on the 2.8 12v engines? If so, can somebody get me a pic?
Roughly when should the electric fan kick on? If I push the Snowflake button on my heater control, it comes on, but it doesn't turn on, even when it's reading ~3/4. Shouldn't it?
Any advice or help is greatly appreciated.
I'm new when it comes to Audi's, consider myself a skilled DIY'er, and was hoping somebody could help pinpoint my overheating problem. My post is long winded, but I want to give as much info as possible.
Our '97 A4 Quattro (with the 2.8 12v) needed it's timing belt replaced. While I was replacing it, I also replaced the water pump and T'stat which was included in the kit I purchased from Blaufergnugen. I also replaced the cooling fan switch located in the radiator on the lower driver's side, and the coolant temp gauge located back near the firewall.
I've bled the system using the 2 bleed points I could find (firewall heater hose, and bleeder located on steel pipe that wraps around backside of engine). I've got a crummy Haynes manual that says there is a 3rd bleed point up front, but I can't find it. It seems to still be running hot. It used to sit perfectly at the 1/2 point on the temp gauge before the swap., but now it slowly but ccontinously rises to ~3/4 of the way up, before I shut it off. It climbs from ~1/2 to ~3/4 in the matter of 2 miles. The radiator heats up, which means the thermosat opens up and permits flow through it.
Here's my biggest problem.
It loses coolant through the expansion tank overflow. Almost like it's building excessive pressure. I replaced the cap, thinking it's faulty, but it's doing the same thing. The oil temp stays around 200, like it used to.
Questions:
Could having the cam timing off by 1 tooth generate that much excessive heat, that it runs too hot for the cooling system? I used the tools supplied from Blau, and belive I installed the timing belt right, but I'm not 100% sure.
Is there a 3rd air bleeding point on the 2.8 12v engines? If so, can somebody get me a pic?
Roughly when should the electric fan kick on? If I push the Snowflake button on my heater control, it comes on, but it doesn't turn on, even when it's reading ~3/4. Shouldn't it?
Any advice or help is greatly appreciated.
1st Gear
Joined: Dec 2005
Posts: 78
From:
RE: 12v overheating questions
Timing off by one tooth may generate heat but not to the extend of overheating if all your cooling parts are working properly. We need more info so here's the questions:
1. Does the car overheat idling or when it is moving or both?
2. Does the electric fan comes on when the needle is 3/4?
3. What temp rating is the radiator fan switch that you bought?
4. Stupid question but did we make sure the t'stat is pointing at the right direction with the arrow up?
5. Was upper radiator hose hot once the car warms up to normal operating temp? Was it tight when squeezed?
eCarToys
1. Does the car overheat idling or when it is moving or both?
2. Does the electric fan comes on when the needle is 3/4?
3. What temp rating is the radiator fan switch that you bought?
4. Stupid question but did we make sure the t'stat is pointing at the right direction with the arrow up?
5. Was upper radiator hose hot once the car warms up to normal operating temp? Was it tight when squeezed?
eCarToys
Thread Starter
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1st Gear
Joined: Jan 2006
Posts: 9
RE: 12v overheating questions
Wow, that was fast!
Bent frame:
The Water Pump is driven off of the timing belt I believe. So I'm thinking, it's either working, or it's not. It's not leaking anywhere on the engine except out of the expansion tank overflow.
Thanks for the tip on Audiworld.
Onepoint8tee:
Each time I return to my garage, I remove the cap. There's no fluid in the resevoir, and I can hear a gurgling sound. At first I thought it was burping the system, so I'd refill and repeat. I'm starting to wonder if it's more serious, because I've repeated that process 5 times now, and it still runs hot.
Thanks.
Bent frame:
The Water Pump is driven off of the timing belt I believe. So I'm thinking, it's either working, or it's not. It's not leaking anywhere on the engine except out of the expansion tank overflow.
Thanks for the tip on Audiworld.
Onepoint8tee:
Each time I return to my garage, I remove the cap. There's no fluid in the resevoir, and I can hear a gurgling sound. At first I thought it was burping the system, so I'd refill and repeat. I'm starting to wonder if it's more serious, because I've repeated that process 5 times now, and it still runs hot.
Thanks.
Thread Starter
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1st Gear
Joined: Jan 2006
Posts: 9
RE: 12v overheating questions
Ecartoys:
1. It overheats when driving. Within 2 miles of normal city driving (2-3K) it's went from 1/2 to 3/4.
2. No the electric fan doesn't come on when the needle is at 3/4. I should mention that I took the car into Miramar Audi after the timing belt swap, and asked them to pressure check the system, and find out why the fan wasn't kicking on. They said it was a faulty sensor, which I replaced.
3. I bought it over the counter at an Audi dealer, so I'm guessing it's the same. They didn't ask me which range I'd prefer.
4. The T'stat has a "jiggle" valve which gets placed in the vertical position. Yes, it was.
5. Yes, it was hot (as was the radiator) but it didn't appear tight.
Good input. Keep it coming.
1. It overheats when driving. Within 2 miles of normal city driving (2-3K) it's went from 1/2 to 3/4.
2. No the electric fan doesn't come on when the needle is at 3/4. I should mention that I took the car into Miramar Audi after the timing belt swap, and asked them to pressure check the system, and find out why the fan wasn't kicking on. They said it was a faulty sensor, which I replaced.
3. I bought it over the counter at an Audi dealer, so I'm guessing it's the same. They didn't ask me which range I'd prefer.
4. The T'stat has a "jiggle" valve which gets placed in the vertical position. Yes, it was.
5. Yes, it was hot (as was the radiator) but it didn't appear tight.
Good input. Keep it coming.
1st Gear
Joined: Dec 2005
Posts: 78
From:
RE: 12v overheating questions
With what you are saying so far here's my input, electric fan should kick on when the needle goes to 3/4. Not coming on could be two things - bad sensor or bad wiring. You can test it by jumping the wires at the sensor. There are low speed and high speed setting on the switch/sensor. If it comes on for both low and high then the sensor is bad(or your radiator fan control unit is bad). Since your car was not overheating before that rules out the latter expensive part being bad.
Purging coolant is due to water pump overcavitation, generating air bubbles and high pressure. Your upper radiator hose should be hot and tight when the car reaches operating temp with the engine off. You might want to check and see if the water pump still have all it's blades.
A defective fan clutch can also cause overheating if the electric fan is defective but usually the temp will go down when you are driving/coasting.
eCarToys
Purging coolant is due to water pump overcavitation, generating air bubbles and high pressure. Your upper radiator hose should be hot and tight when the car reaches operating temp with the engine off. You might want to check and see if the water pump still have all it's blades.
A defective fan clutch can also cause overheating if the electric fan is defective but usually the temp will go down when you are driving/coasting.
eCarToys
1st Gear
Joined: Jul 2004
Posts: 24
From:
RE: 12v overheating questions
This is gonna sound strange but, turn the air conditioning on. That would make the fan run at low speed all the time. Since you know that the fan is now running all the time, if the car still gets hot you know it is not a fan problem. I have never really looked in to how my Audi works, but I bet that with the air conditioning OFF the fan only runs when the RADIATOR reached a certain temp. It just happens to be when the ENGINE temp gauge reached 3/4. So when you car over heats the fan still shouldn't be running because the RADIATOR is still less than the temp required to start the fan. Even though the engine is hot. I am betting on some dumb air bubble. Good luck
On the darkerside, I used have a boat that over heated. There were 2 versions of the water pump. One was left hand turning and one was right. The impeler blades were the only difference. Check the part number of the water pump. The boat did just what your car is doing, because the pump was in effect turning backwards
On the darkerside, I used have a boat that over heated. There were 2 versions of the water pump. One was left hand turning and one was right. The impeler blades were the only difference. Check the part number of the water pump. The boat did just what your car is doing, because the pump was in effect turning backwards
Thread Starter
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1st Gear
Joined: Jan 2006
Posts: 9
RE: 12v overheating questions
GeneBopp,
I'll keep you posted. I appreciate everyone's help. It looks like I'm going to rip the front of the car off, and re-inspect everything again. I'll be sure to pay special attention to the water pump and thermostat since I've got a cooling problem.
One other thought I had is that the timing belt tensioner may have lost some of it's tension, which would take the tension off the water pump pulley, allowing it to slip and not move an adequate amount of coolant. Just a thought.
Keep your fingers crossed!
I'll keep you posted. I appreciate everyone's help. It looks like I'm going to rip the front of the car off, and re-inspect everything again. I'll be sure to pay special attention to the water pump and thermostat since I've got a cooling problem.
One other thought I had is that the timing belt tensioner may have lost some of it's tension, which would take the tension off the water pump pulley, allowing it to slip and not move an adequate amount of coolant. Just a thought.
Keep your fingers crossed!