Date:         Tue, 11 Jan 2000 19:31:56 EST
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Re: Eurospec conversion/ coolant pressure/valves/etc.
Comments: To: albell@uvic.ca
Content-Type: text/plain; charset="us-ascii"

I must agree that things aren't consistent with my experience here.

In my conversion, I went from I-4 diesel to I-4 gas, so these comments can't
directly address WB to I-4 problems, but:

1. I had to replace my heater valve. Why ... it was old, and VW parts person
said VW had changed the internal seals of this simple ball valve. I was told
that this valve was the same one used on the Golf/Passat/Jetta series. I had
the impression that one heater valve fits all, but not sure. My valve mounts
inside the passenger compartment near the glove box.

1.a. Replacing the radiator? The maximum pressure applied is still given by
the cap. 15 psi release cap (really 12 in my experience) is independent of
drive pump. Age, sure, pressure - doesn't make sense to me.

2. I monitor coolant pressure all the time. On deceleration, particularly on
a long grade or similar, I see a reduction in pressure. With hard
acceleration, pressure increases. If the main coolant tank drops from its
mount and falls below the inlet level to the pipe going to the radiator, the
pressure and temperature go up. In fact the gauge has been very useful. With
air in the tank or lines, the pressure buildup is slow and the max is quite
low (1 to 4 psi). No air, the pressure comes up quickly and goes to 12 psi.
Never see more than 12 psi gauge. Replaced the cap with another VW and a
Stanton. No diff. Also easy to see how well the system seals overnight. I
typically see 1 to 5 inch vacuum overnight.

To summarize, in my system, the coolant system pressure is directly
determined by power dissipated by the engine. Temperature goes up , pressure
goes up. Temperature (heat load) goes down, pressure goes down. Note that the
temperature measurement we follow is at the block. I intend to install a
temperature sensor at the radiator also, just to follow the real coolant
temperature. The thermostat is capable of rapidly modulating the coolant flow
at the block. I find the pressure variation to significantly faster than the
gauge temperature would indicate. Oh yes, rapid acceleration of the engine
(in neutral) will cause will cause a quick of 4 to 7 psi in the system
pressure which must be related to the head pressure developed by the pump.


My fractional centimes worth,

Frank Grunthaner