Date: Mon, 19 Apr 2010 13:07:11 -0500
Reply-To: John Rodgers <inua@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <inua@CHARTER.NET>
Subject: Re: Over-full overflow tank..cause for alarm?
In-Reply-To: <x2v6bc66ccf1004190918k7c3093cdgf9975743d9419dcf@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Don,
Varying road conditions will result in variations of the temp needle
position. I seem to have read somewhere that the pressure cap is set at
1 atmosphere - which is essentially 15 psi at sea level. Expect any
change in altitude to result in migration of coolant from the expansion
tank to the overflow tank. If the pressure cap is working properly and
there are no leaks or holes in the tubing between the expansion tank and
the overflow tank - then the coolant should be drawn back into the
expansion tank as the coolant loses heat. While the over flow tank does
have high level marks, if trouble shooting, it is better to check
absolute coolant level by first allowing the engine to cool. Coolant
should draw down to the bottom mark. If not, then there is a problem -
assuming the level was correct to begin with.
John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com
On 4/19/2010 11:18 AM, Don Hanson wrote:
> My first 'longer' trip in my 84 (with an inline 4 Golf Jetta motor) since
> around Xmas. I've been driving it, after letting it stand for a few months,
> for a month now on shorter trips. Everything seems fine, no poor running or
> power loss, no strange behavior at all...
>
> I may be 'gunshy' now or perhaps overly-concerned for no real reason but
> when I first got this van, I caused myself some extra work because I was
> unfamiliar with the WBX cooling system. I didn't get a proper air-bleed
> after flushing the coolant for new..This resulted in some odd temperature
> behavior issues that I didn't 'pick up' on until I had damaged my
> headgasket. I had to replace the headgasket on the I-4 motor, no big
> deal..about 3-4hrs only, but I could have done BIG harm if I'd ignored
> it...thanks to the list I caught it in time to avoid major damage..So now
> I've learned to pay close attention to how my WBX cooling system (the I-4
> plugs almost directly into the stock vanagon 'circulatory system') is
> behaving.
>
> Yesterday I did about 250 miles around Mt Hood going to and from a bike
> race and I noticed my temperature gauge was reading slightly lower than
> usual. I put a tank of premium fuel into the van and that is what I was
> burning on this trip, if that would make a difference.
>
> My temp gauge usually reads on or just slightly above the second of the
> bottom two marks...below that LED. Yesterday I was seeing the needle just
> above the bottom of those two lines, even when climbing to ~5000'...until I
> got back to low elevation when I noticed it back nearly to where it always
> has been...Some fluctuations in the reading...Not a fluttering of the
> needle, the gauge looks to be operating normally...but the needle would
> move, over a 10-20min period from quite cool to where it normally has run
> and maybe fall again...So my gauge is showing 'system running very slightly
> cooler than normal'
>
> When I got home I went back and opened the license plate to check my
> coolant overflow tank level. It was over-full and poured out about a cup of
> coolant when I removed the cap...So I opened her up to check the pressure
> tank...No air in there. The coolant looks normal, also..no combustion by
> products are evident. Water pump feels fine, though I didn't take off the
> drive belt and spin it...Next, I went to the air bleed screw in the rad. It
> took about a cup of coolant, added right into the bleed screw hole, as I've
> devised as 'my' method of getting the last air bubble out of my radiator.
>
> So what would cause my coolant to 'migrate' from the pressurized cooling
> system into that overflow tank? and should I be concerned? It's not
> running out of the Normal temp range, but pretty close to 'too cool'... any
> change in operating temp is alarming to me, since when my first problem
> happened, the symptoms were 'cold air from the heater' and the temp gauge
> behaving quite erratically...
>
> Don Hanson
>
>
>
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