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Signs of a milkshake

 
Old 01-19-2019, 07:23 PM
  #11  
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Originally Posted by MP4.2+6.0 View Post
FWIW, it is very difficult to tell from your spark plugs pictures where the oil is coming from. Stepping back, those plugs have a good amount of oil on them. Some of it is long term running through the engine and baked on, while other might be either fresh from combustion or running down the plugs as you remove them.

I would get the valve cover gaskets in order, if that is an issue contributing to this. I would also look at oil consumption rate, and maybe post that. One question I have is whether what you may have is some start up condensation running through the PCV system and then in to the engine. That creates sort of a sludgy mess combined w/ oil vapor that the engine has to burn off. It is a key contributor to valve fouling on later FSI (direct injection) gas motors. If you do a lot of short distance driven cold starts, you will have more of that condensation that doesn't burn off in a single engine cycle. If you combine it with some oil burning and probably related looser tolerances to piston rings, might explain both the general look of the plugs and some amount of water in the oil. You might also check the PCV valve, and also an obscure part often called in the vernacular the suck valve, aka the vacuum suction pump. Fancy lingo for a splitter in a vacuum line going to the brake booster--either T shaped like in my D3 W12 or Y shaped like my old C5 4.2. Search for more info.
I have new valve cover gaskets, I haven't done it yet because the coolant issue seemed more important. Should the valve cover gaskets be installed with additional gasket maker product?

I try not to start any vehicle unless I'll be able to let it reach operating temp for that very reason. I'll see if I can locate the vacuum suction pump and take a look, I'm familiar with the location of the pcv valve. I was thinking, in order to perform a leak down test I need to get the piston to TDC, is this done by rotating the alternator bolt? I hope I don't have to remove the nose just to rotate the engine by hand!
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Old 01-21-2019, 10:43 AM
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do a coolant leak down test first to see if you are losing pressure.
My loss of coolant turned out to be the two O rings on the back of the heads. Connect the cooling cores in the head via a crossover pipe.
Engine out job. New O rings on, havent had a drop of coolant missing in 6 months.
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Old 01-22-2019, 04:18 PM
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Originally Posted by Greg5OH View Post
do a coolant leak down test first to see if you are losing pressure.
My loss of coolant turned out to be the two O rings on the back of the heads. Connect the cooling cores in the head via a crossover pipe.
Engine out job. New O rings on, havent had a drop of coolant missing in 6 months.
Engine out, how much did that cost or did you tackle it yourself? I would love to keep the car but I don't think I'm that committed!

Did the leak down test make your leak apparent? I have everything ready to do a leak down, if I can figure out how to rotate the engine. Wondering if I can tilt the radiator forward with the top hose disconnected?
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Old 01-22-2019, 07:49 PM
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I did it myself. I have a 2 post lift and a rolling steel table to receive the power train.
Coolant leak down test no engine turning necessary. It was a verrry slow leak. 1 psi per hour drop. But visually it was not apparant.
Oil analysis confirmed 9% coolant contamination.
You cant really tilt the rad. You can put the entire front clip into service position and you will have all the room in the world to work on the front end of the engine.
Once you do it once, you will be putting it into service mode for any engine work. Takes 10-15 mins once you have done it once and know all the fastener locations.
Then turn the engine via the crank. or alternator. turning via crank requires special tool.

Whole youtube video series i made of the removal and teardown:

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Old 01-27-2019, 11:26 AM
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Originally Posted by Greg5OH View Post
I did it myself. I have a 2 post lift and a rolling steel table to receive the power train.
Coolant leak down test no engine turning necessary. It was a verrry slow leak. 1 psi per hour drop. But visually it was not apparant.
Oil analysis confirmed 9% coolant contamination.
You cant really tilt the rad. You can put the entire front clip into service position and you will have all the room in the world to work on the front end of the engine.
Once you do it once, you will be putting it into service mode for any engine work. Takes 10-15 mins once you have done it once and know all the fastener locations.
Then turn the engine via the crank. or alternator. turning via crank requires special tool.

Whole youtube video series i made of the removal and teardown:

https://www.youtube.com/watch?v=qC0CucnLdwY&t=541s
Wow, awesome vids. In one of the vids you pointed out coolant passages behind the timing covers, I would have never guest those were there. If coolant leaks there I can see why it wouldn't be apparent when pressure testing etc. You removed the engine to address oil leaks which was a good time to go over everything, but would you remove the engine if you only suspected coolant leaks behind the timing covers? Just curious.

I had the front off when I changed the oil cooler so I'm familiar with that process. However, I think I'll just start with a compression test. My oil analysis reported 2.38% coolant contamination.

Last edited by a_alyte; 01-28-2019 at 03:24 AM.
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Old 01-27-2019, 03:02 PM
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Part of the reason for the pull was the dissapearing coolant which was more of a co cern than the oil leaks. Coolant contamination will ruin an engine far quicker than old oil. But between the leaks and the relatively slow dissapearamce of coolant, i would add 2-3 quarts of oil in the time it would take for 1 quart of coolant to dissapear. Thankfully the engine bearings suffered no damage, oil analysis confirmed engine to be in great health.

your contamination is low, more frequent oil changes would suffice for the time being IMO if you dont want to pull.
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Old 02-11-2019, 06:21 PM
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So I'm loosing coolant at pretty rapid rate and the car has just been sitting. The level drops about 1/4" in the reservoir after about three days or so.

Thinking back to when I changed the oil cooler, I don't recall seeing the oil cooler tube which is prone to cracking. When I was changing the oil cooler I was unaware of the tube, but I just can't recall seeing a place for it. My oil cooler had two opening on the back where I installed new o-rings. Does the 2007 A8 indeed have this part? If it fails would it leak externally, I have no external leaks?

Since it's cold and I haven't had time to remove the front bumper to perform a leak down, I did a 'cold' compression test. I know the manual says to perform this test on a warm engine (approx. 86 deg), I was just looking to see if the numbers were beyond the manuals 'max difference of 43.5 psi.' Here's what I got:

Cyl 4 = 270 Cyl 8 = 275
Cyl 3 = 269 Cyl 7 = 260
Cyl 2 = 280 Cyl 6 = 280
Cyl 1 = 255 Cyl 5 = 262
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Old 02-11-2019, 06:43 PM
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If I recall, the FSI motor does not have this part, but I'm not entirely sure. Have you checked your oil for signs of contamination?
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Old 02-11-2019, 10:13 PM
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Originally Posted by a_alyte View Post
So I'm loosing coolant at pretty rapid rate and the car has just been sitting. The level drops about 1/4" in the reservoir after about three days or so.

Thinking back to when I changed the oil cooler, I don't recall seeing the oil cooler tube which is prone to cracking. When I was changing the oil cooler I was unaware of the tube, but I just can't recall seeing a place for it. My oil cooler had two opening on the back where I installed new o-rings. Does the 2007 A8 indeed have this part? If it fails would it leak externally, I have no external leaks?

Since it's cold and I haven't had time to remove the front bumper to perform a leak down, I did a 'cold' compression test. I know the manual says to perform this test on a warm engine (approx. 86 deg), I was just looking to see if the numbers were beyond the manuals 'max difference of 43.5 psi.' Here's what I got:

Cyl 4 = 270 Cyl 8 = 275
Cyl 3 = 269 Cyl 7 = 260
Cyl 2 = 280 Cyl 6 = 280
Cyl 1 = 255 Cyl 5 = 262
Don't know D3 spec, but back in my 8:1 compression late 70's era when Audis used to eat head gaskets I would have died and gone to heaven if I had those kind of numbers! I would get 150 psi on a good day, and 165 was like stellar or rebuilt as new motor. With a blown head gasket, I might see 100 or less. As in big percentage difference. Modern 4.2 is of course now a good amount higher compression, but my casual sense it those look good AND you have very little variance among them. Also, if it blew the gasket into the water jacket, besides the milkshake stuff it would typically bubble in the coolant overflow bottle shortly after start up with cap off way before engine reached operating temp, and sometimes if driven a ways it might even blow out the overflow bottle due to high pressures.

Have you confirmed there is no coolant on the ground ever? And, no coolant that might run out of a hiding place only while driving, like puddled on top of the belly pan, or in the bottom of the plenum under the covers where the heating valve set up is?

Last edited by MP4.2+6.0; 02-11-2019 at 10:19 PM.
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Old 02-12-2019, 04:48 AM
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Originally Posted by MP4.2+6.0 View Post
Don't know D3 spec, but back in my 8:1 compression late 70's era when Audis used to eat head gaskets I would have died and gone to heaven if I had those kind of numbers! I would get 150 psi on a good day, and 165 was like stellar or rebuilt as new motor. With a blown head gasket, I might see 100 or less. As in big percentage difference. Modern 4.2 is of course now a good amount higher compression, but my casual sense it those look good AND you have very little variance among them. Also, if it blew the gasket into the water jacket, besides the milkshake stuff it would typically bubble in the coolant overflow bottle shortly after start up with cap off way before engine reached operating temp, and sometimes if driven a ways it might even blow out the overflow bottle due to high pressures.

Have you confirmed there is no coolant on the ground ever? And, no coolant that might run out of a hiding place only while driving, like puddled on top of the belly pan, or in the bottom of the plenum under the covers where the heating valve set up is?
The compression specs in my manual say new = 145-203 psi, wear limit = 130 psi and max difference between cyl = 43.5. A few days ago I pressurized the cooling system to 1 bar and looked on top and under the car for about 20 min and I didn't see anything, cold engine of course. The belly pan showed no signs of coolant either. My coolant reservoir does not bubble and the fluid is still nice and pink. I thought maybe the system was purging air but the loss of coolant has been going on too long now in my opinion. The plenum area near the bleed valves is dry.

Originally Posted by Jack88 View Post
If I recall, the FSI motor does not have this part, but I'm not entirely sure. Have you checked your oil for signs of contamination?
Oil analysis confirmed small percentage of coolant in oil so I changed the oil cooler. Car has only been driven 700 miles since. Car has been sitting for months and I can see chocolate color under oil cap and in crankcase. I was hoping this was due to cold weather + sitting, but I don't know anymore.
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