My egr valve had started weaping oil front the small hole on the offside (Pd130) I remember my passat did the same. What purpose does this hole serve? I'm guessing blocking it up is a no no?

The hole is a vent (there's another one on the opposite side) which serves to maintain atmospheric pressure on the lower side of the actuating diaphragm. This allows it to move unimpeded when vac is applied to the upper surface.

Don't block it up - wrap a small piece of rag around the valve and change the rag at each service. The leak is due to wear in the valve stem seal which allows oil from the charge air to leak out.

Yet another "standard" VAG design fault.

rotodiesel.

You could also buy a small metal plate from ebay and block the egr valve so that it becomes inactive. It doesn't do you any good anyways.

Here's a direct ebay link:

http://www.ebay.co.uk/itm/EGR-blanking-blank-block-off-plate-VW-T4T5-R5-R6-SEAT-SKODA-KIA-FORD-AUDI-VOLVO-/110844596337?_trksid=p4340.m185&_trkparms=algo%3DDLSL%252BSIC.NPJS%26its%3DI%26itu%3DUCI%252BUA%26otn%3D10%26pmod%3D120845824099%252B120845824099%26po%3D%26ps%3D63%26clkid%3D7604443558204264811#ht_940wt_1336

Here is why you should not block EGR valve

http://www.briskoda.net/forums/topic/224847-25-tdi-egr-valve-blanking/page__view__findpost__p__2647479

I've not seen any difference in economy on my car whatsoever in winter after disabling the EGR. Where in the summer, there's been a nice increase in mpg. It also has a lot better response, when you put the food down. I think the most significant and visible change was the smoke level, which decreased immensely. At least this is what i personally experienced.

In winter, the difference is not so much in economy but in engine and interior warmup time. For older 1.9TDI, good luck trying to warm the interior up while town driving with EGR disabled. Unless you have an electric heater, of course.

I don't have an electric heater and yes it takes a bit more time than usual; i'm guessing approximately 10km extra for it to warm up properly. I can live with it though and i'm always doing highway travel when using the car. I never do short runs in my diesel. In my opinion it's a waste of money. :-)