VW Mk4 Golf Estate 1.9SDI

[1.9SDI]

Interesting train of thought here. I had assumed that synthetic oil alleviated most of the 'cold oil' problems – is this not the case?

I was also looking into an alternator-free engine and thought of power generating shocks/springs supplemented with a small battery, but the cost outweighs the benefit at the moment.

Thanks for the tip Euromodder, I'll look into it. I also want to get rid of the roof bars as I don't use them and they just cause turbulence along my roofline. I've already fitted smaller, aerodynamic door mirrors to easy the airflow.

[1.9SDI]

It's also interesting that my thermostat may not get hot enough to activate. I'm wondering if the NA and turbo engines have different temperature settings as my temp gauge stays a pretty constant 74 degC?

[paulgato]

It's also interesting that my thermostat may not get hot enough to activate. I'm wondering if the NA and turbo engines have different temperature settings as my temp gauge stays a pretty constant 74 degC?

I can't think of any reason why the SDi should be designed to run at a different temperature from the TDi. All engines I have ever known, whether petrol or diesel, have had thermostats that open about 87 degrees, giving a regulated temperature of 90+ degrees.

(As I understand it, engines would be happier running even hotter, but the practical limit has always been the boiling point of the water used for cooling. Even under pressure, the coolant (mostly water) can't be much hotter than 100 degrees (well, 110 is probably fine) without local boiling happening in the hotter parts of the engine. Thus engines are designed to run at a little under the boiling point of water. Users of Evan's Waterless Coolant sometimes advocate slightly higher engine temperatures as that stuff boils at 180 degrees C (?) even without pressurisation.

As I said earlier, the thermostat I removed last year was operating - i.e. opening and closing - but it was beginning to open at 65 degrees rather than 87. My guess is that your thermostat is simply faulty and needs replacing. I would check that, and put a working thermostat in before doing any grille blocking. Very simple to check in case you haven't done that before. At the temperatures your engine is running at, the thermostat shouldn't open at all, ever, and virtually no heat should be going to the radiator. If the hoses to and from the radiator are hot or even decidedly warm when Scanguage reports a coolant temp of below 87 degrees (or whatever the opening temperature of your thermostat should be if it's different, but I'd be willing to bet it's the same as the TDi) then your thermostat is faulty.

[paulgato]

Interesting train of thought here. I had assumed that synthetic oil alleviated most of the 'cold oil' problems – is this not the case?

I was also looking into an alternator-free engine and thought of power generating shocks/springs supplemented with a small battery, but the cost outweighs the benefit at the moment.

Thanks for the tip Euromodder, I'll look into it. I also want to get rid of the roof bars as I don't use them and they just cause turbulence along my roofline. I've already fitted smaller, aerodynamic door mirrors to easy the airflow.

For me it's not really a cold (viscous) oil problem, but heating the oil sump gently (the lowest point in the engine) will warm the whole engine up, and that will reduce the amount of time the engine spends at fuel-guzzlingly low start-up temperatures. You can get electric coolant heaters too, which I'm sure work at least as well, if not better, but I don't like the idea of the noise they generate.

Power generating shocks sound like a great idea. Are they available commercially?

Roof bar delete, ...nice. I was thinking of doing that, and making them easily removeable and re-fittable by cutting round holes in the head liner to give ready access to the fixing bolts, and using sticky tape to cover the holes when the bars are not being used. PVC insulating tape is remarkably good at keeping the weather out of things and it comes in a wide range of colours.

The standard method of roof bar removal involves removing the entire head liner, and I'm not sure I can be bothered with that. Also, I might want to carry things on the roof at some point, although I haven't felt the need for a few years now.

[Xist]

Originally Posted by paulgato

Roof bar delete, ...nice. I was thinking of doing that, and making them easily removeable and re-fittable by cutting round holes in the head liner to give ready access to the fixing bolts, and using sticky tape to cover the holes when the bars are not being used. PVC insulating tape is remarkably good at keeping the weather out of things and it comes in a wide range of colours.

The standard method of roof bar removal involves removing the entire head liner, and I'm not sure I can be bothered with that. Also, I might want to carry things on the roof at some point, although I haven't felt the need for a few years now.

That is exactly how it is on my Subaru. I removed the cross-members easily enough, but I just do not think that it is worth removing the rest of it.

I have needed to put the cross-members back a few times now, though, and I have only had the car a little more than one year.

[euromodder]

Originally Posted by 1.9SDI

It's also interesting that my thermostat may not get hot enough to activate. I'm wondering if the NA and turbo engines have different temperature settings as my temp gauge stays a pretty constant 74 degC?

74°C is pretty low IMO.

Can you find out what thermostat should be in there, i.e what temp it should open ?

[euromodder]

Originally Posted by 1.9SDI

Interesting train of thought here. I had assumed that synthetic oil alleviated most of the 'cold oil' problems – is this not the case?

Apparently, you can still notice the difference when swapping the oil in winter.

Knowing I was going to switch grades, I had a few looks at what the car used @ a set speed (50 kph) on a particular stretch of road early on in my commute.
After swapping to 0W30, FC was lower.

Not very scientific I know but conditions (weather etc) were otherwise quite stable.

[Tootler]

Originally Posted by 1.9SDI

Hello all, I own a VW Golf Estate in the UK (would that be Rabbit Stationwagon or Golf Variant overseas?). As the first wave of Fuel Duty increases has taken effect today, VAT increase on the 4th Jan and a further Fuel Duty increase later in the year, I thought it would be time to see what I could do to save fuel money by making it go further.

I drive about 10k miles per year and already follow many of the fuel saving driving techniques. Documented fuel consumption is 44MPG on a mixed cycle but I can easily achieve 53MPG and can approach 67MPG on highways at 65MPH average. I never exceed 2000RPM except in 5th gear.

I've already ordered a suspension lowering kit (aluminium body coilovers) which not only increase aerodynamic efficiency but also save weight on the steel originals. I've been trying to find lightweight lower control arms (pressed steel) and hubs (cast iron?) but no luck so far, plus there's a huge potential saving in the rear suspension system. Continuing the weight saving theme, I've dumped the spare wheel and bought a couple cans of tyre weld and a 12V air compressor. I've also bought some cheap used alloy wheels from an Audi A3 and increased pressures to 45PSI.

Planned mods after fitting the suspension upgrade is to convert to 100% biodiesel, saving me at least 25% on fuel costs. Also to continue with a few aero mods and any more weight saving mods I can easily and cheaply do. One of those will be replacing the wing mirrors with smaller DTM Cup mirrors which are about half the area of the originals. And, by careful scanning of ebay, I'd like to find some even lighter alloy wheels and cover with smooth discs, and maybe reduce the width of the tyres from 195mm to 165mm. I'd really like to know how to ease the airflow over the wipers, if anyone knows?

Also, does anyone know if it's worth swapping the hydraulic power steering to electric? The pump robs nearly 8HP under load (and a coresponding amount of fuel) and even when not in use still uses power to pressurise the system. Obviously this will put more load on the alternator but is the trade-off worthwhile? Also, on an alternator related theme, I could change the rear lights for LED versions and the headlights to 35/35HID bulbs. How much of a saving on the alternator load (and fuel) would this be?

I have a few engine mods planned - most dramatically the bio conversion. But I also want to find out if the ECU can be mapped for economy, and find out if there are more efficient fuel delivery systems available (injection system)? This is my first diesel so I'm also keen to find out if there are more efficient inlet and outlet manifolds, if anyone knows?

So, to recap, I've broken down my mod categories as follows, in priority:
1. Engine efficiency
Biodiesel conversion
ECU remapping?
Fuel delivery/manifolds?
2. Aerodynamic efficiency
Lower suspension
Smooth wheel covers
Smaller mirrors
Wiper, vent, etc mods?
3. Weight savings
Remove spare wheel
Lighter, narrower road wheels
Replace heavy components?
4. Systems refinement
Electric power steering?
High efficiency lighting?
(the question marks are those mods that I'm not sure if they are worthwhile)
Are there any other mods that are proven to be cost effective?

I'm now off to read the forum stickys so I may well end up answering my questions, but feel free to chip in and add to my list.

Cheers, Steve.

Hi there, I've just bought a Golf SDI. Can I join your thread? I thought it might be useful to have another SDI owner posting up mpg data for comparison.

[paulgato]

Hi again,

I've had good success with running alternator-optional. In fact I've barely used the alternator since January. I plug the car into the mains every night on the driveway, have a 10A charger installed in the engine bay, and have a large AGM battery installed. For the vast majority of my daily driving this works fine and I don't need the alternator. I have cut one small wire close to the alternator, and fitted an inline plug/socket, so if I do need the alternator I just reconnect that wire. (I'll fit a switch on the dash at some point, but I use the alternator so rarely it hardly seems worth the trouble.)

I reckon I'm saving about 10% on fuel from ditching the alternator. Since I'm plugging the car in every night I also fitted a 2kw engine coolant preheater, which I switch on from indoors via a remote control fob thing an hour before driving off. I reckon that saves me another 5% overall. Obviously the shorter the journey the greater the benefit of pre-heating. According to the pumps, my overall mpg has jumped up from about 70mpg to about 80mpg since plugging in every night. That's a 15% improvement, and I'd say that's being conservative.

I've spent a lot of time working on this mod, and quite a lot of money too, mainly trying to extend the alternator-free driving range to the point where I would never need the alternator (second battery in the rear, DC/DC converter, etc...) but in fact the majority of the benefit can be had by simply fitting one really good battery in the engine bay and an appropriate battery charger. 10% off your fuel bill is a fair amount, so this is a mod that will pay for itself quite easily if you do any number of miles in a year.

Of course it only works if you have a driveway - somewhere you can plug in every night.