Coolant leak when engine is hot...
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2nd Gear
Joined: Feb 2008
Posts: 591
From: Winnetka, CA
Coolant leak when engine is hot...
I found that I have a really big coolant leak on the driver side of my 2005 3.0 V6, near the firewall.
That car sat on a lot for over 7 months, exposed to rain and sun and without being driven, so I suspect something dried up and became brittle causing the leak. The car has only 27k miles on it.
This only happens when the car reaches operating temperature and the thermostat is open, otherwise there is no leak when the car is cold.
And obviously there is no leak when the car is just sitting, with the engine off.
I was only able to kinda localize the leak when I crawled under the car, but I will have to work from above and remove a lot of stuff to get the root cause of my problem.
The catch is that I cannot warm up the car to check where the leak comes from as I started to remove the things that obstruct the view, plus the engine get way too hot to work on and I need to wait until things cool off to resume work.
Does anyone know which hose/component tends to leak? Specifically one that only leaks when the engine is warmed up?
I am open to thoughts and suggestions.
TIA.
That car sat on a lot for over 7 months, exposed to rain and sun and without being driven, so I suspect something dried up and became brittle causing the leak. The car has only 27k miles on it.
This only happens when the car reaches operating temperature and the thermostat is open, otherwise there is no leak when the car is cold.
And obviously there is no leak when the car is just sitting, with the engine off.
I was only able to kinda localize the leak when I crawled under the car, but I will have to work from above and remove a lot of stuff to get the root cause of my problem.
The catch is that I cannot warm up the car to check where the leak comes from as I started to remove the things that obstruct the view, plus the engine get way too hot to work on and I need to wait until things cool off to resume work.
Does anyone know which hose/component tends to leak? Specifically one that only leaks when the engine is warmed up?
I am open to thoughts and suggestions.
TIA.
Thread Starter
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2nd Gear
Joined: Feb 2008
Posts: 591
From: Winnetka, CA
Yes, this is my B6. I posted here because I got nothing on the A4 section, and I seem to get much better technical answers here. I thought the A6 also came with that V6 engine until mid-05 when the 3.2 was introduced along with the new grille.
3rd Gear
Joined: Dec 2008
Posts: 1,941
From: IL
Zippy,
with a disclaimer that I haven't the vaguest idea how the engine bay of an A4 looks like, I would say that no hose should especially be prone to leaking. We all know that.
Seven months of sitting though may have indeed caused some of them to dry.
Only with my engine bay in mind, I would say that you should check the hoses at the "connecting" points, around the clamps. That's typically where the weathering mostly occurs.
If it isn't a hose and it is near the firewall, then it could be the rear of the cylinder head where the main pipe attaches to the head. Maybe the o-ring gasket is worn out and doesn't provide for a tight fit anymore as the hot coolant expands it.
As some people said before, shouldn't the coolant leave a "crusty" trail as it dries out?
with a disclaimer that I haven't the vaguest idea how the engine bay of an A4 looks like, I would say that no hose should especially be prone to leaking. We all know that.
Seven months of sitting though may have indeed caused some of them to dry.
Only with my engine bay in mind, I would say that you should check the hoses at the "connecting" points, around the clamps. That's typically where the weathering mostly occurs.
If it isn't a hose and it is near the firewall, then it could be the rear of the cylinder head where the main pipe attaches to the head. Maybe the o-ring gasket is worn out and doesn't provide for a tight fit anymore as the hot coolant expands it.
As some people said before, shouldn't the coolant leave a "crusty" trail as it dries out?
Last edited by chefro; Jul 13, 2009 at 11:32 AM.
Thread Starter
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2nd Gear
Joined: Feb 2008
Posts: 591
From: Winnetka, CA
Unfortunately gettting to where I suspect the leak is located is a nightmare. Tons of hoses with plastic clips that no human being can reach to disconnect... 
Because the leak is fairly new and I have not driven that car there is no crusty deposit anywhere, but I thinbk you are right about the leak being located at a hose connection.
Because the leak is fairly new and I have not driven that car there is no crusty deposit anywhere, but I thinbk you are right about the leak being located at a hose connection.
3rd Gear
Joined: Dec 2008
Posts: 1,941
From: IL
I understand your frustration, Zippy.
Well, I doubt the back of the engine is much different that a 2.8 in terms of cooling parts.
Back by the firewall should only be two hoses that actually go through the firewall to the heater core.
One is connecting to the main rear pipe itself, while the second one to secondary pipe that runs under the manifold to the back of the water pump housing (again, I only have in mind the 2.8 12FV engine in mind). Maybe that's where your trouble comes from, one of those two at the connection point.
Those crimping-style clamps could be a nuissance.
I hope you find the problem.
Well, I doubt the back of the engine is much different that a 2.8 in terms of cooling parts.
Back by the firewall should only be two hoses that actually go through the firewall to the heater core.
One is connecting to the main rear pipe itself, while the second one to secondary pipe that runs under the manifold to the back of the water pump housing (again, I only have in mind the 2.8 12FV engine in mind). Maybe that's where your trouble comes from, one of those two at the connection point.
Those crimping-style clamps could be a nuissance.
I hope you find the problem.
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