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Jim Adney wrote: >If it was just idling the whole time that would surprise me, too, but maybe >there's something wrong with the cooling system, like a missing bellows or rust- >thru somewhere. A lot also depends on one's definition of "fairly chilly" and >one's perception of time can also get distorted when you're in the middle of >something. At least that's what my wife tells me.... ;-) > > > I guess it was about 35 degrees out, but indeed, the rubber joints between the fan housing and the heat exchanger elbows is badly cracked and do leak a modest amount of air. I bought some 2" no-hub plumbing joints for this spot- they're 2 1/4" internal diameter, which is just right. They're cheap enough that if they only last a few years, they're plentiful and easily replaced. >Either valve will be overcome if the pressure exceeds the limit of the valve. >The pressure limit of the regulator is it's set point (~30 psi) while that of >the pump is about 20 psi, so the usual route would be thru the pump valve. > > > One of my manuals states that the relief pressure of the pump valve is 64psi, so if both the relief valve and the regulator are in like new condition, the route for vapor out the main ring is out the regulator into the return, I would imagine, once the pressure in the line exceeded 30psi. >If both valves are working, holding 20 psi on the gas will raise it's boiling >point somewhat, but I don't know how much. If the rubber tip on the pump valve >is cracked then it's possible that it lets the gas depressurize, lowering the >boiling point. This is one possible explanation as to why this problem seems >worse on some cars. > > > I can buy this especially if the boiling point is as low as I think it is. It doesn't take a "hot" car to have this happen, just a modestly warm engine. Obviously a hot car would make it worse. >It's interesting to note that Mercedes had this problem in their D-Jet cars and >they put out a fix for it. The M-B fix was to remove the regulator and reach in >the side port with a drill and drill a 1mm hole in the central stem. This made >a permanent bypass in the system, but the pump has plenty of capacity to >provide the extra flow. > > > Looking at a cutaway of the pressure regulator, I see how this would work. >In the meantime, the fuel pump primer pushbutton is a lot easier to do. > > > Agreed. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~