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Slight coolant leak - need some advice - now resolved. Lingering fears...
So - every now and then, I have found a small amount of coolant underneath the car. Couldn't figure out a pattern at first, until I realized that when driving with windows open (clima off) - no drip. With windows closed (clima on) - drip.
Very small amount of leakage, can't tell in the expansion tank.
Found the leak location (99%) today, at the rear of engine, passenger side, there is a small coolant connector with a "Phillips head" plug in it. Looks like a bleeder screw.
The location is a bit moist with coolant and I can see how it has dripped down a bit. Looks like the hose clamp is not tight enough and hence it slowly seeps out there.
First the location:
Where it's actually seeping:
Tried to find the part number for the hose and better understand what I'm up against here. "Easy" fix will be to try to access and replace Audi standard hose clamp with normal adjustable one and tighten it a bit. It is tight as hell back there and a major cable assembly goes right in front of it.
However, I fear the pipe may be plastic and hence overtigthen could be very dangerous. Better to replace this hose if I can. Or at least have the "bleeder part" ready to go if needed.
Any help or guidance appreciated!
Last edited by carl viking; 10-25-2015 at 03:42 AM.
Reason: Update with resolution
After spending a few hours adding another hose clamp and then cleaning the area well, running the car, I realized the leak is actually from the back side of the actual elbow. That is the - the plastic piece that the bleeder screw screws into.
Hmm, now I need to find the part number for it. I have looked in the HVAC and Cooling section on the online websites and I can't find it.
After spending a few hours adding another hose clamp and then cleaning the area well, running the car, I realized the leak is actually from the back side of the actual elbow. That is the - the plastic piece that the bleeder screw screws into.
Hmm, now I need to find the part number for it. I have looked in the HVAC and Cooling section on the online websites and I can't find it.
MP? Mishar?
The only way to get the piece is to buy the whole hose assembly that IIRC runs from the electric heater valve block to past the firewall in engine area. I went thru this when I needed a bleed screw replacement. In that case I just bought a D3 4.2 hose on eBay and stripped out what I needed. You might look at ads and pics there and just match up by appearance.
I also suspect to get in there you will end up pulling intake manifold. Way easier to pull W12 manifold than most motors--if you haven't done it already for things like spark plugs.
Found the parts slide from when I asked audiusaparts to try to track down the bleeder o ring. Again, if your leak is at the 90 degree elbow, I suspect you will find any D3 hose you can find on EBay will give you the elbow if you strip it out from the rest of the hose assembly--as in, the curved rubber hoses are where the motor specific deltas probably come in.
Found the parts slide from when I asked audiusaparts to try to track down the bleeder o ring. Again, if your leak is at the 90 degree elbow, I suspect you will find any D3 hose you can find on EBay will give you the elbow if you strip it out from the rest of the hose assembly--as in, the curved rubber hoses are where the motor specific deltas probably come in.
That diagram is very helpful. I was unable to find anything similar.
Hmm, eBay searching.
It's also interesting that the two pieces (from hoses 16 and 17) are identical but located on different sides of the firewall. That is, the one I have leaking (16) is on the engine side of the firewall, the one attached to hose 17 is located on the rear of the firewall.Same part, same grommet (21).
Not looking forward to this part search...
That diagram is very helpful. I was unable to find anything similar.
Hmm, eBay searching.
It's also interesting that the two pieces (from hoses 16 and 17) are identical but located on different sides of the firewall. That is, the one I have leaking (16) is on the engine side of the firewall, the one attached to hose 17 is located on the rear of the firewall.Same part, same grommet (21).
Not looking forward to this part search...
Yes, what you say is correct. If you are on the engine side of firewall for elbow, it may be an intake pull but not more if rear hose clamp is accessible. Check if that clamp is screwed on or a pre fit type you have to cut. I think the other hose could be worse--intake and pulling the heater valve, which then gets into pulling the ECUs. Also, are you sure it is cracked and not just a clamp or bleeder screw o ring issue? Mine was just the bleeder screw o ring in the end.
First - again a "Thank you" to MP for the diagram above. As you can see there are two of these L connectors (adapters). First tried new O-ring - actually made the problem worse. Which in hindsight makes sense - it further forced the crack open.
After sourcing a new L connector (with attached hose - not sold separately), I tried tackling this problem.
I was hoping to try to do this without removing the intake, which was doable, but tight. The biggest issue is the ECU electrical connector, that is right on top of this L connector.
Loosened the vacuum hoses and the rigid vacuum connector at back of intake to get some clearance. Loosened the hose from engine to the connector - while relaxing the hose clamp of course (sorry for the slight fuzziness):
Classic "oh ****" moment. The lower half of the connector was stuck in the hose!
Created a special tool for this - a dulled pick tool:
After a few nervous moments I got it out.
Removed the back connector (inside ECU tray and next to heater block):
Inserted new L connector and then tried getting the hose back on. It sucked. Clearly a time when skinny fingers 4 feet long would have been useful.... I do use fishing line on the hose clamp just in case I drop it down there.
Success!
Top off coolant (about 1 liter), test drive and no more leaks. Top off and it has held since. Nice!
Looking closely at the L connector, it was cracked at the back seam of the bleed screw neck (the original leak and problem), and the material is very weird, the plastic has clearly deteriorated. I also realized that I had gotten out the entire piece, no loose plastic pieces floating around in the cooling system. It was only two pieces originally - I broke it apart further to investigate.
Of course this raises the question - if this L connector is in this bad of a shape - what about the other? Which is impossible to get to without removing the ECU harness. The only good news here is that the one I replaced is the the supply line, the other is the return. Maybe, maybe, it will last longer due to slightly lower temperatures and less heat "shock" when high heat is called for in cold temperatures. I hope so!
FWIW, I haven't seen that kind of deterioration on the larger fittings like these. I have never had one of those elbows out, though have been near them in pulling heater valve block for inspection; it was all clean and in good shape. I know the plastic deterioration from my Mini, which has some real crap large plastic pieces like the thermostat housing that are well known to fail even in 5 years/50K miles.
Here it strikes me as more likely some prior stress crack to that elbow, which I can envision from the pics. As you found, it is tight to work there. Opens up better w/ an intake pull, which is surprisingly easy. I have also pulled ECU's to get at valve block, which is also not hard or particularly time consuming once you learn a trick or two about the chastity belt anti tampering fastening set up they use.
Anyway, could also be be a manufacturing issue, or got stressed in something like a prior valve cover gasket replace. The one place I had a piece of plastic in the cooling system that seemed to get eaten or turn to mush internally is up at the front of the motor where a smaller line T's toward the two heads just above the water pump. Access there is relatively easy.
FWIW, I haven't seen that kind of deterioration on the larger fittings like these. I have never had one of those elbows out, though have been near them in pulling heater valve block for inspection; it was all clean and in good shape. I know the plastic deterioration from my Mini, which has some real crap large plastic pieces like the thermostat housing that are well known to fail even in 5 years/50K miles.
Thank you!
The weird thing is that the plastic *looked* good from the outside, and especially on the heater block side...
Originally Posted by MP4.2+6.0
Here it strikes me as more likely some prior stress crack to that elbow, which I can envision from the pics. As you found, it is tight to work there. Opens up better w/ an intake pull, which is surprisingly easy. I have also pulled ECU's to get at valve block, which is also not hard or particularly time consuming once you learn a trick or two about the chastity belt anti tampering fastening set up they use.
I removed the intake for the thermostat and it was, as you say, easier than expected. Still nicer if you don;t have to...
Besides the ECU cables - I also wonder about the metal color stressbar on top on the connectors, that goes across the entire engine room - from strut to strut - it looks really hard to remove.
Originally Posted by MP4.2+6.0
Anyway, could also be be a manufacturing issue, or got stressed in something like a prior valve cover gasket replace. The one place I had a piece of plastic in the cooling system that seemed to get eaten or turn to mush internally is up at the front of the motor where a smaller line T's toward the two heads just above the water pump. Access there is relatively easy.
I check those religiously - as well as the thin hard plastic lines you have had problems with... The sad part is that it's really hard to tell if they are about to go, and it's a lot of work to replace in preventative maint purposes...
The weird thing is that the plastic *looked* good from the outside, and especially on the heater block side...
I removed the intake for the thermostat and it was, as you say, easier than expected. Still nicer if you don;t have to...
Besides the ECU cables - I also wonder about the metal color stressbar on top on the connectors, that goes across the entire engine room - from strut to strut - it looks really hard to remove.
I check those religiously - as well as the thin hard plastic lines you have had problems with... The sad part is that it's really hard to tell if they are about to go, and it's a lot of work to replace in preventative maint purposes...
I have never pulled the strut brace; never encountered anything where it seemed close to necessary.
The small coolant lines are not very hard actually. They are in two major sections--toward the back, and then up toward the front. Splice point between the two sections is a clamped hose at around the driver' fender area under hood. You may notice that T point in plain sight that looks like it would be very hard to deal with; it is just a molded in part of the rear section so you install as one assembly.
From putting in the new ones, they are somewhat pliable and flexible. My old ones were rock hard for years. My guess is you have the rock hard ones too. Hardest single connection is the one in the back near the center of the intake manifold. The rest of it comes out at the various clamp points. Without a lot of fuss actually, and you just thread new lengths in the same way. Only other thing I remember fully removing was that grey foam block on drivers side in plain sight where the line passes through or under it--it has a slit for either that or the hood cable.
I think the rear hose section is the most vulnerable to heat soak and where mine had various issues back to when dealer apparently cracked it and left a splice. After one of the other guys noted an issue with his front section, I did it preemptively too. Pricey for what you get, but I do a variety of preventative maintenance to avoid break downs and sudden big issues.
09-17-2015, 06:05 PM
Slight coolant leak - need some advice - now resolved. Lingering fears...
