Oil mixed with coolant?

2015 AUDI A7

18,745 MILES

ANDRIN ATEM

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393 POSTS
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WA1LGAFE8FD016685. My Audi q7 3.0T supercharged has an issue with oil mixing with coolant after I took out the intake manifold to replace a PCV water pipe which connects direct to the inlet where the thermostat is located. After replacing I started engine notice cylinder 4,5,6 had firing, took of the coil and plug on the cylinder 4 noticed coolant coming out from the plus hole, then later pull out the dip stick, noticed it's all milky. However, the car does not have over heating issues, it started when the car started complaining of check coolant level stop the car and check coolant level. Please can you help me with possible areas and cause of oil mixing with coolant of this particular model, also help me with the coolant system diagram, oil and air diagram so I can know how to engage a proper fix. Any further information will be of great help to me, I am in Cameroon, no Audi companies but I can do myself if I get guide and directives.

Mar 2, 2024 at 5:03 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi,

I'm not sure I understand what was done. Do you mean this started after the lower intake was removed and reinstalled?

Do me a favor. I attached a pic below of the coolant flow throughout the engine and engine compartment. Take a look at it and let me know what you had to replace.

Take care,

Joe

See pic below.

Image (Click to enlarge)

Mar 2, 2024 at 2:38 PM

ANDRIN ATEM

MEMBER
393 POSTS

Please advise on the colors, the red is hot water blue is coolant, brown and the other colors, could you help me with the color meaning, from that I can retrace my steps.

Mar 3, 2024 at 12:37 PM

ANDRIN ATEM

MEMBER
393 POSTS

From this diagram, does water go through the air intake manifold?

Mar 3, 2024 at 12:37 PM

ANDRIN ATEM

MEMBER
393 POSTS

These four points I marked with red, does water go through them or air? Because I manually filled them with water hoping to bleed air out of the system.

Image (Click to enlarge)

Mar 3, 2024 at 12:42 PM

ANDRIN ATEM

MEMBER
393 POSTS

From this diagram I can clearly see I am dealing with a blown head gasket. Because I noticed water leaking out from the spark plug holes on bank two after car idled for about 10 minutes, I shut off the engine and took out the plugs on cylinder 4,5 and realized coolant coming out. The diagram explains why and how coolant could come out. Please advise me if I am wrong. Also, oil mixes with water.

Mar 3, 2024 at 4:07 PM

ANDRIN ATEM

MEMBER
393 POSTS

Please also help me with the diagram on replacing a head gasket and tuque specifications on tying bolds trimming. At this point I am looking at head gasket replacement.

Mar 3, 2024 at 4:09 PM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi,

That isn't good news. Please note, this is a difficult procedure. It will require specialized tooling to retime the engine and camshafts.

Take your time and it is important to have the timing correct before turning the engine.

Take a look at the directions below. The directions are set up for removal of the cylinder heads and then install. The last two pics are the tightening sequence and torque specifications.

Let me know if this helps.

Take care,

Joe

See pics below.

Images (Click to enlarge)

Mar 3, 2024 at 9:04 PM

ANDRIN ATEM

MEMBER
393 POSTS

Thank you.

Mar 3, 2024 at 10:25 PM

ANDRIN ATEM

MEMBER
393 POSTS

Does this manual apply for a 2015 AudiQ7 supercharged? Thank you.

Mar 4, 2024 at 12:01 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi,

No. I looked at the heading where you indicated a 2017 A7. However, they will be similar. Sorry about that.

I attached the directions below based on the VIN. When you are putting things together, make sure to lubricate the coolant pipe o-rings with either coolant or a thin coating of oil. That will help prevent damage to them.

I hope this helps.

Joe

See pics below.

Images (Click to enlarge)

Mar 4, 2024 at 7:03 PM