Suspected Aux Rad Leak

[rugbybloke]

Noticed small amount of steam eminating from front drivers side whilst stationary in traffic. Going to get it checked out. Sod's law that this happens 8 weeks after the dealer warranty expired (purchased the car from an Indy in August). From reading on here though I don't think it's too expensive to replace the aux rad.
Have most people fitted a genuine Audi replacement rad or should I look elsewhere?

[Spaceman_RS4]

Gen Audi ones on eBay the now £135 a side. I'm doing mine in new year. With a bit of luck it was the exhaust from the car in front bud.

[watts6087]

Noticed small amount of steam eminating from front drivers side whilst stationary in traffic. Going to get it checked out. Sod's law that this happens 8 weeks after the dealer warranty expired (purchased the car from an Indy in August). From reading on here though I don't think it's too expensive to replace the aux rad.
Have most people fitted a genuine Audi replacement rad or should I look elsewhere?

I had the same thing on mine. Only had the steam once and it's not done it since and that was 6 months ago.

[MikeFish]

If you have a leaking aux rad it will only do it when your car gets vey hot and you have been siting in traffic otherwise the aux rads are not used and therefore it might appear that you no longer have a problem.

[MikeFish]

And if it is the drivers side that needs replacing, don't bother replacing it, it will only fail again. Take it to MRC and get a cold air feed fitted instead. By the time Audi charge you the labour for the removing bumper and fitting, plus the cost of a new rad it works out cheaper to get the CAF instead (although a remap will also be required).

[adsgreen]

Remap not required for caf.

[MikeFish]

Remap not required for caf.

It is required if you do the full cold air feed as carried out by MRC.

[adsgreen]

Remap not required for caf.

It is required if you do the full cold air feed as carried out by MRC.

Why?

Sorry - simply don't agree.
there is nothing involved with the CAF that requires the engine ECU to be updated.
Lets gets a few facts straight.
You will not see more airflow into the airbox. All you are effectively doing is extending the airbox power flap so that it doesn't pick up any ambient engine bay heat. The power flap is then removed and plugged to prevent a vaccum leak.
As such ALL that is happening is that the air charge remains closer to the external ambient air temperature and reduces by a small amount the increase in air that would normally happen via heatsoaking.

You are not suddenly getting vast amounts of unmetered air nor is it any colder than the air the engine first sees when you start the car. As such you just reduce the rate the intake air temperature rises as the engine gets hotter. No remap required at all for this mod.

FWIW - I also have and highly rate the MRC CAF. I'm just fully aware of what it does and does not do.

[rugbybloke]

I have noticed the coolant level dropping so a leak is likely. For those that have had the CAF mod does this present any over heating issues in hot weather in start stop traffic as you are effectively removing part of the cooling system? Will a CAF give any performance gains or is it simply a case of replacing the aux rad with a more reliable component?

[MB2]

I don't have the CAF but my guess is by removing one of the rads you are soaking up some of the safety margin Audi built into the car (allbeit whilst simultaneously removing a design faut/weak spot). Bearing in mind Audi need to sell the car & have it work all over the world I would say in the UK you would be quite safe with one or probably even no additional radiators - if you commuted in & out of Athens every day then maybe they would see more use (& I wonder if they would be more or less likely to fail)

[MikeFish]

From MRC website:
Cold Air Feed
Removal of RHS radiator, air box flap and addition of cold air feed with trumpet. This will give more consistant intake temperatures and with a high flow air filter is the best you can do for consistant low temperature and high flow intakes. Requires a stage 2 Remap with sec air removal.

Im not a gullible person but If Doug says it needs doing then I'll take his word for it. To be honest, I never questioned it as I had the pre cats gutted at the same time and wanted a remap anyway so it didn't make any difference I was having it remapped anyway. However, I assumed it was either something to do with the removal of the rad (possible stop monitoring it's temp) or maybe some to do with air box flap monitoring.

[adsgreen]

Ah the key here is the secondary air injection pump removal - this needs a remap in order to stop the car throwing a code.
If you keep the SAI pump fitting the caf then nothing else needed. No monitoring on the aux rad or airbox flap.

[MikeFish]

I have noticed the coolant level dropping so a leak is likely. For those that have had the CAF mod does this present any over heating issues in hot weather in start stop traffic as you are effectively removing part of the cooling system? Will a CAF give any performance gains or is it simply a case of replacing the aux rad with a more reliable component?

My coolant level was dropping due to a leak on my near side rad so I had that changed whilst the bumper was off for the CAF.
I haven't had mine through the summer yet but there are others that have and have had no issues. I've read that even highly modified cars and supercharged cars have been running without this rad.
You are not getting any extra power per se, just more consistent power. You know how on some cooler days the car feels like its flying? Well the idea is that it should be like that all the time, however it's not magic so whilst it helps with this it doesn't eliminate the lower power experience from higher air inlet temperatures. So rather than giving you more power it tries to stop you losing power.

[MikeFish]

I don't have the CAF but my guess is by removing one of the rads you are soaking up some of the safety margin Audi built into the car (allbeit whilst simultaneously removing a design faut/weak spot). Bearing in mind Audi need to sell the car & have it work all over the world I would say in the UK you would be quite safe with one or probably even no additional radiators - if you commuted in & out of Athens every day then maybe they would see more use (& I wonder if they would be more or less likely to fail)

Yes I've read that in the UK it is quite safe to run without it. Maybe not the same story in other places such as Saudi, Dubai etc.
I've also read that the temperature gauge is fixed so that it doesn't go over half way. Ive noticed that my car and the wife's old BMWs temperature gauges never moved once they got to normal operating temperature. Unlike my Alfa where you can clearly see the rise to the point when the fan comes on and then the temps drop back down again until the fan turns off.
I'd like my Audi to behave the same but I'm not sure if this is fixed via software or the gauge itself.

[Stairs]

I have this problem as well, I am the 'get in my car to drive it.... not fix it' kinda person, could someone tell me what an Aux Rad does? As my car has not blown up yet I havent lost any sleep over the steam at 100 degrees issue.... Should I be losing sleep or can the car run with this problem, as reading some of these posts it sounds like the Aux rad is an add on for safety.

Thanks in advance!