TSI - how to bleed?

[vtraudt]

Older Audi/VW had a bleed hole in one of the 2 lines going to/from the core (at the firewall), exposed (bleeding) when pulling the hose back.

Do the 2.0T also have that?

What is the correct method of bleeding the heater core?

Changed water pump, and still have just cold air blowing from vents (engine at operating temp).

[Smac770]

What year and model is in question here?

[vtraudt]

What year and model is in question here?

Likely same for all TSI.
Transverse engine.
2012 Passat CC

[Smac770]

Well, a B8 A4, regardless of engine, would be the same as you already quoted, pull right side coolant hose back from firewall union, bleed hole is there. But a 2012 CC, no idea. I have no idea why the 2012 CC would do it any differently. You could hit up cardiagn.com and see if they have manuals for a 2012 CC to check.

[vtraudt]

[QUOTE=Smac770;14856285] pull right side coolant hose back from firewall union, bleed hole is there. /QUOTE]

Will check where the heater core hoses run on the transverse 2.0T and if they have a bleeder hole.
I saw a video suggesting to use the 'overflow' hose branching of the heater core line (back of engine, more towards driver side, leading to reservoir top corner), and syphon out (pull vaccuum until good fluid, long use ending down low for syphoning action.

[vtraudt]

[QUOTE=vtraudt;14856309]

pull right side coolant hose back from firewall union, bleed hole is there. /QUOTE]

Will check where the heater core hoses run on the transverse 2.0T and if they have a bleeder hole.
I saw a video suggesting to use the 'overflow' hose branching of the heater core line (back of engine, more towards driver side, leading to reservoir top corner), and syphon out (pull vaccuum until good fluid, long use ending down low for syphoning action.

Heater core hoses on the transverse engine (2012 Passat) are not 'readily' available and i therefore think they might NOT have the bleeder hole (to be exposed by pulling hose back and to let air out).

[Smac770]

As mentioned, should always just go to the correct workshop manual and look up the actual process. Document was on cardiagn. Seems to be nothing more than fill tank, close it, start engine, maintain 2k rpm for 3 minutes, top off.

[vtraudt]

As mentioned, should always just go to the correct workshop manual and look up the actual process. Document was on cardiagn. Seems to be nothing more than fill tank, close it, start engine, maintain 2k rpm for 3 minutes, top off.

Hmh. Then need to look for other cause for 'cold air from heater'.

[Smac770]

If the CC is like the Audis, there's a coolant flow shutoff valve that is kept closed until the coolant is up to temp, then it's opened allowing coolant to flow through the heater core. On the B8.0, it was vacuum actuated, with a solenoid in the vacuum line that was controlled by the car. On the B8.5, it was electrically actuated directly. But making sure coolant is actually flowing through there would be an important thing. Maybe the core is clogged.

[vtraudt]

If the CC is like the Audis, there's a coolant flow shutoff valve that is kept closed until the coolant is up to temp, then it's opened allowing coolant to flow through the heater core. On the B8.0, it was vacuum actuated, with a solenoid in the vacuum line that was controlled by the car. On the B8.5, it was electrically actuated directly. But making sure coolant is actually flowing through there would be an important thing. Maybe the core is clogged.

Will check if I can get to the heater core hoses. If so, I can check flow (and reverse flush core while at it).

[vtraudt]

If the CC is like the Audis, there's a coolant flow shutoff valve that is kept closed until the coolant is up to temp, then it's opened allowing coolant to flow through the heater core. On the B8.0, it was vacuum actuated, with a solenoid in the vacuum line that was controlled by the car. On the B8.5, it was electrically actuated directly.

Need to find a coolant system diagram for the transverse engine (Passat, CC, Golf, etc) to see if and where such a coolant flow shutoff valve exists.

Now that you mention it, I DID find that on a 2010 Q5 2.0T, near the firewall.

[vtraudt]

On the transverse engines, where is the 'heater control valve', 'coolant shut off valve' or 'N82' (?) located so I can check/test it?

Also: when should the auxiliary coolant pump be running (and/or how to test)?

[Smac770]

The V51 afterrun coolant pump circulates coolant through the turbo on engine off. It's not used otherwise, as it circulates coolant in the opposite flow direction of normal engine operation. There doesn't seem to be any coolant shutoff valve in that implementation. The CC manuals are on cardiagn.com, as pointed out previously. Beyond that, you should seek a VW CC forum to see what they can offer.

[vtraudt]

The V51 afterrun coolant pump circulates coolant through the turbo on engine off. It's not used otherwise, as it circulates coolant in the opposite flow direction of normal engine operation. There doesn't seem to be any coolant shutoff valve in that implementation. The CC manuals are on cardiagn.com, as pointed out previously. Beyond that, you should seek a VW CC forum to see what they can offer.

Maybe it is called different (not V51) in the Q5, but there it is simply a shut off valve to stop flow the heater core; in that application, the valve is located at the firewall (in the lines going to the heater core).

Edit: the V51 you are referring to is the afterrun coolant pump (as we called it on the 2.7T and TT225 etc). It is NOT the coolant shut off valve I found on the Q5 longitudianl 2.0T (and I did not yet find one on the transverse TFI engine).

[Smac770]

I know the V51 is not the N422. V is pump, N is valve/solenoid. As I mentioned, the coolant section of the engine manual for the CC refers to no devices except the V51. So where I would find reference to the N422 in an Audi manual, I find no such reference in the VW manual.