Petrol engines cylinder head leak
The rubber seals harden with age, then they don't seal, then the engine starts leaking coolant, then the heads leak more coolant, then the seals go properly and the AA man says 'blown head gasket', then you go to a garage and they don't like the look of it, then the head studs snap when they're taking the heads off, then they call you, then you cry, then you have to find a specialist to get the studs out, or find someone who can supply a recon engine.
Coolant leakage from those rubber gaskets is NOT a sign of head gasket trouble. AA man and non VW garages (also some VW garages without experience) don't understand these engines. The gaskets, as mentioned above, are affected by cold weather. You will know the difference when a head gasket is leaking. I have been running my 1.9DG for almost a year now, 8,000 miles, with a Wynnes sealant in the cooling system and it has cured the small leak from those gaskets. I also know of other owners who did the same. The Wynnes product is not the same as Radweld, BarsLeaks or the Halfords equivalent and works in a totally different way. I can only speak of my own experience and urge anyone who tries it to follow the product instructions carefully.
Ran ours for about 6 months with a fairly steady leak from nearside. Was much worse over frosty winter and seemed to be better if we ran the van every few days. (Although probably more to do with evaporating it all off than actually slowing it down!) Previous owner had used Holts RadWeld, but all that seemed to do was gunk up the entire cooling system, and make no difference to the leak!
Radweld and it's equivalents are totally unsuitable for these engines and many other engine types as well. It can cause a solid lump to form in the cooling system and cause complete failure. This though is occaisonally due to the way it is added to the system and not following instructions.
Frostbus, since you asked I will tell it as I have had it explained to me by guys who know much more than I do. Radweld and similar products work by producing solids when they make contact with air. Ideally they should only do this when they find a leak and and as the material meets air, through the leak, it forms a seal. Trouble is that it also forms solids when it meets the air at top of the radiator and in expansion tanks. These solids can be pumped around the engine and then cause blockages in narrow passages etc. According to the technical information, Wynnes Radiator Stop Leak works differently to traditional materials in that it consists of fine organic fibres that slowly close external holes but do not interrupt coolant flow. They recommend using it as a long term cooling system additive . This may sound like a load of bs but I was originally recommended it by a garage that frequently works on Porsche waterboxers. I also know of three other T3 owners that have been running their engines with it and two of those for over two years. I was a little wary of using it at first but contacted Wynnes Technical dept and they assured me that their experience with Transporters showed it to be quite safe to use. I would point out though that I have no reason to beleive it will repair a split hose, leaking cylinder-head gasket (not to be confused with water-jacket sealing rubbers on a T3), corroded radiator or cracked header and top-up tanks.
