Coolant leak at O-ring under intake manifold
 

Dear Forum,


Though having lurked for some time, I've never actually posted on this forum. Here goes. Vehicle is my son's 2002 Audi A6 Quattro Avant, Tiptronic auto tranny, 3.0 AVK engine, ~167k miles. While the car is in pretty decent shape for its age, it recently ate its water pump bearing and tensioner bearing (at only ~60K miles after replacement by a local german car specialist). Needless to say, many bent valves, including one broken exhaust valve which punched a hole in that piston and gouged the valve seat. Only good thing was that it was the frontmost piston that needed replacing. I was able to replace it without pulling the engine by removing the front sump and oil pump. After rectifying all this (piston, heads, timing belt system including water pump and thermostat) and putting everything back together, engine ran fine. Unfortunately, I have a coolant leak. The leak appears to be at the O-ring between the coolant pipe that runs down the driver's side of the valley below the intake manifold and the complicated coolant pipe across the back of the engine. In other words, the worst possible place! Incidentally, both of these pipes are metal, and not plastic (magnet sticks to them).


As I see it, I have these options:

a) simplest and cheapest, but least likely to succeed: add something like Bar's Leak additive to the cooling system to try to seal the offending O-ring joint.

b) remove the pipe across the back of the engine, which will require removing pretty much everything off the back of the engine. Needless to say, I don't have small hands and my back is not in the greatest of condition.

c) remove the pipe that runs down the valley, which of course will require removing pretty much everything off the driver's side front of the engine after putting the front end in service position. This of course undoes the timing belt alignment.


Oh, did I mention that this is happening in my driveway? Fortunately I live in Albuquerque, and the weather is pretty nice at the moment. Also, though this vehicle has been in my family for nearly 10 years, it's starting to get to the point where there are always things going wrong with, it, so we really just want to get it in driveable shape to sell (without having a really bad conscience afterwards). Anyone interested?


Suggestions? Or does anyone know a really trick way to fix that O-ring? Thanks in advance!


Regards,

Jerry from Albuquerque

Coolant leak at O-ring under intake manifold
 

I thought of another possibility that avoids major dissassembly of parts on either the front or back of the engine. If I carve a length of metal pipe out of the coolant pipe in the valley, and replace it with rubber hose, I should be able to R&R the O-ring. I think this would be a better approach than trying to seal the leak with chemical means. I also think some good quality rubber hose would be at least as durable as the plastic coolant pipe replacements that seem to be available these days.

Any thoughts? Thanks in advance,

Jerry from Albuquerque

I think you are on to a winner here. How would you connect the rubber hose, with jubilee clips?
Forget taking the pipe off!! Sounds like a nightmare of a job
Let me know how you do
All the best
Andy from UK