2 hours ago, snowathlete said:

 

Thanks for taking the time to explain that, it makes sense now that you've pointed it all out to me. So the DSG has it's own stat so that it gets up to temp as quick as possible, along with the engine. Then it opens up to the oil cooler to stop it getting too hot. Makes sense.

 

I like to know how these things work when I'm trying to figure out a problem with them. I've suddenly got a more serious than the MPG issue, but I suppose it could be related to it; I have a coolant leak, but this is recent. I started a new thread about that, but this will help me a little to figure out where the leak is, whether it's isolated to the cold circuit or the whole system.

 

Once that's sorted, this understanding of the system is useful because I want to fit a coolant pre-heater. Defa produce some but none validated for this engine on the Superb, they say that is because of the stat between 6 and 7 for the DSG. This doesn't make sense to me though because you could install a pre-heater in the system in the position like the Webasto shown in this diagram is and heat up the cold circuit part of the system (exchanger - not that it'll do much without the fans blowing, and back to engine and the DSG. Defa said the problem was the stat doesn't open until it reaches 75C and there heater only goes up to a peak of 70C. Okay, so the DSG stat won't open until the engine runs it a little hotter still, but surely 70 at engine, exchanger and DSG and cold elsewhere is better than cold everywhere... I don't see the problem, but if you do then please let me know! Appreciate your help so far and very interesting (does that make me sad? Perhaps I need to get out more).

Yes, I like to understand how systems work, makes fault finding 10 times easier.

 

I can't understand why any heater wouldn't work when installed in the position shown in the Golf diagram.

Coolant would circulate just as it does in a cold engine.

Would heat the heater matrix then start to warm the block/ head.

So you would get instant heat & better MPG from cold.

 

Best of luck finding your coolant leak.

Immediately above the pool on the floor is the obvious starting point & may save you climbing underneath.

But the under covers can divert the leak & mislead.

4 hours ago, AwaoffSki said:

Sorry, thought you knew on Sunday and now Wednesday. 

No hurry then, the sun will come up tomorrow. 

 

Knew coolant was low a few days back just topped up and hoped it would be ok. Only this afternoon that I checked again and noticed the coolant on the ground. Must have been some the day before as well but I didn't get round to moving the car to check. As you say, you be easy enough to find where it's coming from tomorrow. 

11 minutes ago, snowathlete said:

 

Knew coolant was low a few days back just topped up and hoped it would be ok. Only this afternoon that I checked again and noticed the coolant on the ground. Must have been some the day before as well but I didn't get round to moving the car to check. As you say, you be easy enough to find where it's coming from tomorrow. 

 

Check if it's leaking from the EGR cooler first - yours had the fix before you bought it which has been known to kill the EGR valve just after so it may hae been replaced. Only a thought - they are difficult to get at so leaks are not unkown.  To find stuff like this an inspection camera is uselful.

We went over to Wales this weekend in the Superb, 70mph (set on cruise which I have added to maxidot) is about 2130rpm so a bit lower than I thought.

 

The journey up at a 75mph cruise early Saturday saw 46mpg average. 

70mph cruise on the way back today saw 54mpg. 

Both on the computer, will calculate when I refill. 

 

Both were pretty clear runs, so I suspect the gearing is hampering the mpg significantly for 5mph to make such a big difference. 

It was pretty windy around here this weekend: could part of the big difference in mpg be due to you driving into a headwind on Saturday and benefitting from a tailwind today?