Fuel Pumps

[Classik]

Hello Shopp,

I'll try the radiator cleaning then, thanks. Regarding the oil temperature I'll try to log that more precisely tonight after work, but it seems to more or less match the coolant temp.

Good suggestion on the pressure in the expansion tank; of course I'll follow your procedure but everytime I tried, there was nothing more than a small pssschit, coolant is 'calm' in the tank. Also I can see some coolant coming from the return hose into the tank so there is still some flow going on, probably not enough if this is a clogged radiator issue.

More later tonight, many thanks again!

PS: spent the R8 coolant cap money on the air leak tester, but I definetely start saving again. Must have!

[Shoppinit]

So I got my car out and tried to do what I told you to do.

I opened the expansion tank to relieve pressure. Then I warmed it up to about 80 degrees and opened the expansion tank again. Slight release of pressure as you described.

Took it for a gentle drive. Couple of squirts of power. Temp on the AC went up to 98 fairly easily. Dropped a bit as I coasted.

Stopped the car and felt the rad - or what ridiculously small amount is exposed. Too hot to touch on the top left (facing the car), could keep my finger on the top right, so much cooler.

Took it for a more sustained blast. Logged the MAFs and temps with the Vagcom. Saw the temps go as high as 101 out of the corner of my eye. I’ll look at the logs later.

Took a long time to cool back down. On my 3km cooling down run, the temp went back down to 95 ish. Oil temp was showing about 90ish so I turned it off.

How does this compare to your experience?

[Classik]

Here we go:

1/ Sucking tests hose 32:

Sucking at cold or hot engine temperature on hose 32 is the same: it blocks fine and holds vaccum very well. However I can freely blow into the hose without resistance, is that expected?

2/ Sucking tests SAI valves 10:

Blocked both ways (pressure & vaccum), although positive pressure doesn't hold well. What I'm trying to say is that I'm able to push a very (very) little bit of air into the valves if I blow as much as I can into the hoses. Same behaviour both sides.

3/ Thermal camera: mostly for the fun as the radiator is almost entirely hidden by the condenser

Like you I can also see the left side is much hotter than the right side. I understand the i/o are on the left but shouldn't the temperature be more evenly distributed? Signs of a clogged radiator? Honestly can't tell. I suppose I'll know better when I'll get my hands on a radiator cleaning fluid, hopefully tomorrow as we are supposed to leave this weekend

And for the fun: engine on fire!

[Classik]

So I got my car out and tried to do what I told you to do.

I opened the expansion tank to relieve pressure. Then I warmed it up to about 80 degrees and opened the expansion tank again. Slight release of pressure as you described.

Many thanks for taking the time for those tests! So I followed your procedure step by step, and @75° or so I opened the tank: not even a small pschiit..

Took it for a gentle drive. Couple of squirts of power. Temp on the AC went up to 98 fairly easily. Dropped a bit as I coasted.

Stopped the car and felt the rad - or what ridiculously small amount is exposed. Too hot to touch on the top left (facing the car), could keep my finger on the top right, so much cooler.

Took it for a more sustained blast. Logged the MAFs and temps with the Vagcom. Saw the temps go as high as 101 out of the corner of my eye. I’ll look at the logs later.

Took a long time to cool back down. On my 3km cooling down run, the temp went back down to 95 ish. Oil temp was showing about 90ish so I turned it off.

How does this compare to your experience?

Sounds very much like my experience here, same kind of figures and behaviour, except -which is not insignificant- that when the engine is hot my Aircon cuts (above 100°C or so) and the car looses lots of HP (feels sluggish and unreactive compared to cold start). So either you also have the same issue as me (clogged radiator, or whatever that might be), or I just discovered a new problem with my aircon failing at high engine temp

If other RS6 owners have the time for a coolant temp log, that would be great!

[Shoppinit]

I was careful to check that the AC stayed on. As far as I can tell, it did. Certainly I’m convinced that my car’s temperature regulation is working fine.

It’s normal that the rad is hotter on the side the coolant flows in. As it flows across the radiator the heat transfers out.

Damn you, now I need a thermal camera.

[Shoppinit]

1/ Sucking tests hose 32:
Sucking at cold or hot engine temperature on hose 32 is the same: it blocks fine and holds vaccum very well. However I can freely blow into the hose without resistance, is that expected?

This is what I would expect. The flow should go towards the intakes.

2/ Sucking tests SAI valves 10:
Blocked both ways (pressure & vaccum), although positive pressure doesn't hold well. What I'm trying to say is that I'm able to push a very (very) little bit of air into the valves if I blow as much as I can into the hoses. Same behaviour both sides.

No air should go in. Are you sure it’s not leaking out the corner of your mouth rather than the valves? Either way, it’s vacuum that’s on these pipes so if it’s holding negative pressure then great.

3/ Thermal camera: mostly for the fun as the radiator is almost entirely hidden by the condenser
Like you I can also see the left side is much hotter than the right side. I understand the i/o are on the left but shouldn't the temperature be more evenly distributed? Signs of a clogged radiator? Honestly can't tell. I suppose I'll know better when I'll get my hands on a radiator cleaning fluid, hopefully tomorrow as we are supposed to leave this weekend

Exit from the rad is bottom right on my car IIRC. There are 2 different versions of the cooling circuits, and 2 different rads, so maybe it’s different on yours. Doubt it, though.

[Classik]

The one I use doesn't have an impressive resolution but is very small as it connects directly on your smartphone (careful: different hardware for iphone or Android platforms).

https://www.amazon.fr/Seek-Thermal-UW-E ... 3252&psc=1

May I ask if you have an idea for the Aircon?

[Shoppinit]

The AC is a weird one. I’ve experienced it going off in other cars when the engine temp goes too high. I have a vague memory of it happening in the RS6 when properly giving beans up the Pyrenees, but I’m not 100% sure of my memory. Certainly it was the only time I’ve seen the temp needle move from 90 degrees and I stopped for a while. I remember checking for fault codes and seeing none.

Today my oil temps stayed pretty low. When I’m playing around properly they go up to 120 easily.

The classic problem with the AC is a faulty high pressure switch. There must be a way of checking for AC deactivation through excessive temp or high pressure switch. I’ll have a look in the VCDS scripts, but since I can never connect to my hvac I might struggle to find the info.

Have you got a scan which includes your hvac?

[Classik]

The AC is a weird one. I’ve experienced it going off in other cars when the engine temp goes too high. I have a vague memory of it happening in the RS6 when properly giving beans up the Pyrenees, but I’m not 100% sure of my memory. Certainly it was the only time I’ve seen the temp needle move from 90 degrees and I stopped for a while. I remember checking for fault codes and seeing none.

Today my oil temps stayed pretty low. When I’m playing around properly they go up to 120 easily.

The classic problem with the AC is a faulty high pressure switch. There must be a way of checking for AC deactivation through excessive temp or high pressure switch. I’ll have a look in the VCDS scripts, but since I can never connect to my hvac I might struggle to find the info.

Have you got a scan which includes your hvac?

Good to know regarding oil temp, not to be that worried then. Yes my new scan can now log the hvac. Last time I checked there was an intermittent communication loss with engine ECU (from memory). Need to check again. Could the issue be as simple as a loss of hvac fluid that a simple refill would cure?

[Shoppinit]

So I found a scan that I did of Sid's car and that helped me find the info.

Measuring block 002 of the HVAC will tell you why the AC is being stopped. The first value is the current state, but the other 3 values are the last three reasons which is pretty interesting info. I need to find a way to get my Vagcom to talk to my hvac so I can see if there's anything interesting in there.

/ Can you connect to your HVAC and tell us what the 4 values are in block 002?

[Classik]

Sure, doing it straightaway.... Do I need to start the engine? If yes my neighboors will hate me (gutted straight pipes )

[Classik]

OK, engine not started I have the following in block 2 (shut-off criteria) :

5.0 / 0.0 / 0.0 / 0.0

[Shoppinit]

5 is engine not running. Which is normal if you read it with the engine off. No stored values for previous values so are you sure the AC was going off? What were the symptoms?

[Classik]

No stored values I'm afraid, the vag-com is almost new. Symptoms are AC suddenly stops and the ECON switch is lit. No more fresh air, loads of humidity, as if I turned the aircon off manually.

[Shoppinit]

The Vagcom may be new, but the info is stored in the hvac. Weird that no values are stored. Unless you cleared all the fault codes recently? That could reinitialise everything to zero.

I’ll try to check mine tomorrow.

Has it happened since you changed the thermostat and water pump?