Covering Radiator for MPG Gain

MPG Lover

MPG Lover

Member
Not sure if this has been raised before, but has anyone ever partially covered the radiator to get the engine warmer (& quicker) for MPG gains?

I have had my A2 a number of weeks now and I am generally very happy with the car. However one of its quirks is how long the engine (the 1.4 TDI) takes to warm up - and this is during the summer! I previously had a similar quirk with Honda Insight 1 litre aluminium engines who sometimes in winter had difficulty heating themselves and could lose heat if you had the cabin heater on full blast. I note the A2 has an auxiliary cabin heater. The modders in the Insight community would drop a piece of cardboard or laminated sign material in front of the radiator during the winter months for a 5 MPG gain.

Is the A2 cooling system similarly over-engineered? Is a similar mod possible in the A2 or would it be unwise?
 
Hi MPG Lover
This is one of the effects of running a very efficient diesel engine. The heat that goes into the coolant is waste energy so the less there is, the better the fuel consumption.
As you say, the TDi has a 3kW auxiliary heater (a bit like a mini central heating boiler) which heats the engine, and the cabin, when the outside temp is below 5 degC. (Q. does anyone know if the Webasto diesel heater was replaced by an electric heater on later cars) It adds slightly to the fuel consumption but the car actually warms up quicker in winter and heater performance is fine.
The cooling system is well engineered - normally the gauge gets to 90C and never moves, regardless of the outside tempertaure. Airflow into the engine compartment is already minimal so I'm not sure if partially blanking the radiator core would be worthwhile. I don't see you could cause any damage providing you keep an eye on the temp gauge - just make sure airflow to the charge air cooler is not affected.

Cheers Spike
 
If your A2 isn't getting up to temp quick enough it may have an airlock in the cooling system. Have you tried bleeding it?, is the coolant level correct.

I'd never advocate blanking any part of the radiator, Audi probably spent quite a lot of money engineering the cooling system (And I know that it is engineered to handle all temperature extremes). Blocking part of the airflow through the rad vanes may help the engine warm up quicker, but should you get caught in traffic, the A2's bonnet isn't the quickest and easiest to pop in the middle of a traffic jam when the overheating starts. The last thing you need to do to an aluminium engine is overheat it, the bills would soon outstrip the mpg saving you might get!
 
Thanks for your replies. I still think a radiator block would help after seeing the 5MPG winter gain in the Insight, but as you say and I hadn't thought it through - the radiator / engine compartment is pretty much covered already!
 
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Interesting idea, however i don't think Audi spent millions on R&D to have someone stick a piece of tin foil over the Rad. If you want the diesel to get hot quickly turn the heater system off, it take less than a mile from cold. You will freeze in the winter but the car will be warm quickly:D

Emm
 
Emm said:
less than a mile from cold
Click to expand...

Less than a mile to get to 90 degrees?!? My A2 takes a full 5 minutes / 3 miles to reach 90 degrees (in summer!). Perhaps my cooling system does need burping afterall?
 
Well maybe thats a slight exaggeration, but it should take no time at all.

Rubbish with the Econ button on, much better with Air Con and better still without the heater on.

Emm
 
have a look at the 1.2 TDI front end - a lot of the intakes were covered up on this model to improve aerodynamics and might also affect cooling.
 
spike said:
(Q. does anyone know if the Webasto diesel heater was replaced by an electric heater on later cars)
Cheers Spike
Click to expand...

Yes sir, my 2005 has an electric heater, which you can shut off with the ECON button if you like. Unlike the Webasto, the electric heater directly heats the air that goes inside the car. It is quite effecient and quick. But during the winter I preheat the engine with an electric coolant heater combined with a heater inside the car. I then usually leave the climate contol OFF until the temp has reached 90 degrees.
 
:bump: When I went for a drive this evening, which was the first on a relatively chilly evening (about 9C) I had the heater on and during urban driving the engine took a full 30 minutes to get up to 90 degrees. It spent a large amount of the time at 60 or just above 60 degrees. I am now convinced that partially covering the radiator will help. I hope to arrange this in late October (after moving house) and will report back then.
 
Covering the radiator will not make any difference to how quickly the engine gets up to temperature.

There is a thermostat on the engine that stays closed until it reaches operating temperature to achieve just this. If your car is taking longer than others to warm up there may be a problem with the thermostat.
 
MPG Lover said:
Less than a mile to get to 90 degrees?!? My A2 takes a full 5 minutes / 3 miles to reach 90 degrees (in summer!). Perhaps my cooling system does need burping afterall?
Click to expand...

Don't bother. My 2003 TDi has done so ever since I got it. I even think 5 miles is fast, especially since I normally don't get to the highway until after a minute or 5.
On the highway, it heats up quite nicely. But compared to any petrol car I've owned, this diesel is running really cool indeed.

For the record, my 2003 model (August 2003) also only has an electric aux heater that only heats the interior (when outside temps are below 5 C or so).
I'm not sure about your 2002 model. But I'm quite sure that this info is somewhere on this forum. A search for 'webasto' or 'heater' should do the trick.
 
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