Audi A4 B6 1.8t Intermittent Coolant Leak (only happened once)
#1
02-24-2018, 04:01 AM
Audi A4 B6 1.8t Intermittent Coolant Leak (only happened once)
Hi All,
First post on Audi Forums !! I have an interesting problem with the cooling system on my 2004 A4 1.8t... here's a little how it goes...
Last week my wife took the car to a job she had around 300km away from home, on the last day as she was driving to work from the hotel, a few kms away, she suddenly saw the temp rise to around 110 (always sticks back on 90 usually), she was just pulling into her place of work and when parked she saw that the coolant reservoir was empty..... at lunch time she went to the petrol station next door and bought somef Audi coolant and topped up the system to just below max. 4 hours later when she went back to the car, the level was the same... but as soon as she started the car, coolant came gushing out from beneath the car and it quickly overheated. She called roadside assistance and they took it to a local mechanic. They identified a broken hose underneath the car (??) and ordered a new one from Audi and fitted it. They then tested and stated the leak was fixed and took it for 10-15km test drive...... On the highway it again overheated, no loss of coolant though.
They called me and told me that the water pump was gone as no coolant was circulating and that they would replace it if I wanted..... I said no, and per my roadside assistance policy, asked them to re-repatriate my car to my home address, the idea being I would get the work done closer to home....
When the car arrived home, I thought I would have a look first before taking it in... so I let if idle and tried to see what was going on.... when I removed the bleed bolt (on the pipe that runs across the top of the block) I saw that indeed no fluid was present, even though the reservoir was on max.... I squeezed the pipes coming from the top the rad and low and behold a load of large bubbles went in to the reservoir, liquid could now be seen at the bleed bolt, and the level in the reservoir dropped to just below min. I topped up the reservoir and repeated the squeezing of the tubes, but no more bubbles were created, but I could clearly see the fluid bubbling away at the bleed port. I thought to myself, ok perhaps these guys didn't properly bleed the system and that's why it overheated...
I drove it around the block a few times, and the temp stayed at 90 on dot and the level of coolant stayed the same. I then parked up and ran vagcom and had no fault codes .... So then I proceeded to test by running the car at 2000RPM for 10 minutes.... again no change in fluid level and no change in temp.... I thought "voila" it was just an air bubble and it is cleared.....
As a final test, I increased the RPM to 2800 RPM for 5 mins...... minutes 1-4 all good..... minute 5 .... all of a sudden coolant was pouring out from somewhere underneath onto the road (I can't easily see from where with the engine pan tray in place), I dropped the RPM and the leak stopped......
I topped up the reservoir again (The cap on the reservoir was pressurized, I had to loosen it slowly and carefully), confirmed there was still fluid at the bleed port and repeated all the tests..... (10 mins at idle , 10 mins at 2000 RPM and then 10mins at 3000) and no leak this time.....
I am kind of scratching my head, although on the surface, after the last tests it all looks fine.... but I can't explain to myself why on the previous test on minute 5 at 3000 did I suddenly loose a lot of coolant....... So I am not sure if the car is road worthy or not ? It seems the system is pressurized, and it is not a constant leak...
Can anyone here explain this sudden quick leak ? All I can think of was there was another air pocket and some valve opened temporarily with the pressure increase and now it is cleared ???
Many thanks in advance.....
Adam
First post on Audi Forums !! I have an interesting problem with the cooling system on my 2004 A4 1.8t... here's a little how it goes...
Last week my wife took the car to a job she had around 300km away from home, on the last day as she was driving to work from the hotel, a few kms away, she suddenly saw the temp rise to around 110 (always sticks back on 90 usually), she was just pulling into her place of work and when parked she saw that the coolant reservoir was empty..... at lunch time she went to the petrol station next door and bought somef Audi coolant and topped up the system to just below max. 4 hours later when she went back to the car, the level was the same... but as soon as she started the car, coolant came gushing out from beneath the car and it quickly overheated. She called roadside assistance and they took it to a local mechanic. They identified a broken hose underneath the car (??) and ordered a new one from Audi and fitted it. They then tested and stated the leak was fixed and took it for 10-15km test drive...... On the highway it again overheated, no loss of coolant though.
They called me and told me that the water pump was gone as no coolant was circulating and that they would replace it if I wanted..... I said no, and per my roadside assistance policy, asked them to re-repatriate my car to my home address, the idea being I would get the work done closer to home....
When the car arrived home, I thought I would have a look first before taking it in... so I let if idle and tried to see what was going on.... when I removed the bleed bolt (on the pipe that runs across the top of the block) I saw that indeed no fluid was present, even though the reservoir was on max.... I squeezed the pipes coming from the top the rad and low and behold a load of large bubbles went in to the reservoir, liquid could now be seen at the bleed bolt, and the level in the reservoir dropped to just below min. I topped up the reservoir and repeated the squeezing of the tubes, but no more bubbles were created, but I could clearly see the fluid bubbling away at the bleed port. I thought to myself, ok perhaps these guys didn't properly bleed the system and that's why it overheated...
I drove it around the block a few times, and the temp stayed at 90 on dot and the level of coolant stayed the same. I then parked up and ran vagcom and had no fault codes .... So then I proceeded to test by running the car at 2000RPM for 10 minutes.... again no change in fluid level and no change in temp.... I thought "voila" it was just an air bubble and it is cleared.....
As a final test, I increased the RPM to 2800 RPM for 5 mins...... minutes 1-4 all good..... minute 5 .... all of a sudden coolant was pouring out from somewhere underneath onto the road (I can't easily see from where with the engine pan tray in place), I dropped the RPM and the leak stopped......
I topped up the reservoir again (The cap on the reservoir was pressurized, I had to loosen it slowly and carefully), confirmed there was still fluid at the bleed port and repeated all the tests..... (10 mins at idle , 10 mins at 2000 RPM and then 10mins at 3000) and no leak this time.....
I am kind of scratching my head, although on the surface, after the last tests it all looks fine.... but I can't explain to myself why on the previous test on minute 5 at 3000 did I suddenly loose a lot of coolant....... So I am not sure if the car is road worthy or not ? It seems the system is pressurized, and it is not a constant leak...
Can anyone here explain this sudden quick leak ? All I can think of was there was another air pocket and some valve opened temporarily with the pressure increase and now it is cleared ???
Many thanks in advance.....
Adam
#2
02-26-2018, 02:15 PM
HI All,
A quick update, Today I took the reservoir out to have a good look underneath, and there is no evidence of any leaks, neither on the reservoir itself, or anywhere in the engine bay below.... so I have ruled that one out.
Looking around, between the firewall and the engine block I could see a load of pink fluid on top of the gearbox... so I am now thinking that the coolant flange is leaking...... but I still cannot explain why I had such a fast leak at 3000 RPM just the once with the above testing...
any ideas ?
Thanks again !
Adam
A quick update, Today I took the reservoir out to have a good look underneath, and there is no evidence of any leaks, neither on the reservoir itself, or anywhere in the engine bay below.... so I have ruled that one out.
Looking around, between the firewall and the engine block I could see a load of pink fluid on top of the gearbox... so I am now thinking that the coolant flange is leaking...... but I still cannot explain why I had such a fast leak at 3000 RPM just the once with the above testing...
any ideas ?
Thanks again !
Adam
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