Date:         Sun, 25 Apr 2010 21:33:29 -0700
Reply-To:     Robert Keezer <warmerwagen@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Keezer <warmerwagen@YAHOO.COM>
Subject:      Re: cooling system diagnostic help? Long,
              lots of info about whats been done so far.
In-Reply-To:  <m2z6bc66ccf1004251903n5002e208oe0172e8fc15fa875@mail.gmail.com>
Content-Type: text/plain; charset=iso-8859-1

Don, the firstr thing I think of is the rear heater core leak. The coolant in it circulates from the cylinder head. If coolant leaks out, air gets in and that can cause engine overheating.
Since you don't know the condition of the thermostat, I say it might not be  opening, hence the cool hoses up front. 
 
Robert 
1982 Westfalia 95 Golf engine
 
 
 
 
 
 
 
 
 


--- On Sun, 4/25/10, Don Hanson <dhanson928@GMAIL.COM> wrote:


From: Don Hanson <dhanson928@GMAIL.COM>
Subject: cooling system diagnostic help? Long, lots of info about whats been done so far.
To: vanagon@GERRY.VANAGON.COM
Date: Sunday, April 25, 2010, 7:03 PM


  Hi all, recently I've noticed my cooling system is being weird.  The
vehicle is an 84 vanagon with an inline four rabbit/jetta motor installed
using diesel parts.  It is hooked up to the unmolested Vanagon water
circulating system..All the sensors and senders are identical to a vanagon
and hook right into the vanagon dash.  This vehicle has been mine and
working satisfactorily for a couple of years and 40k miles, without any
recent changes.

  I noticed my operating temperature, as indicated by the dash guage has
been lower than normal...for about a week now. Under regular driving in
normal outside temps, it's moved to the lower end of the two marks on the
guage face, when it used to hover around the upper end of those marks.  With
extra load or a hot hot day, it might move up to near the LED until the fan
would start..So I am thinking the gauge and the fan are opreating without
fault.  I also noticed, once recently,  the overflow tank was over the fill
neck...I re-bled the radiator and topped it up at the bleed screw, then
ordered a new pressure tank cap and a thermostat, which have not arrived
yet.  Thinking that might be the cause of the overfull overflow tank..

  Today I came home from a 150 mile trip, where the gauge hovered around the
lower of those two lower marks the whole time, including some sustained
climb in 4th gear (manual 5sp tranny)..it did go up slightly as I was
climbing..I have a 3-gear hill to my house, then a gate I must get out to
open and drive through...then some more climbing to my shop/garage.  When I
got in, the coolant in the engine was boiling and it blew some out of the
rear heater...musta been the 'weak link' in the system..The gauge didn't
show "Hot"..it was reading between the upper of the two bottom range marks
and the LED in the center.  My LED is inop..btw.. The fan didn't come on.
The engine is running as always, no missing no loss of power, no smoke or
increased fuel or oil consumption, no odd starting behavior..Normal.

  Ok, so that is what caused me to start diagnosing this afternoon, the
boiling coolant and the steaming blown rear heater (which I have not looked
into yet, but from the coolant dripping out and the steam under the seat it
is obvious something let go..)
  I pulled the spark plugs, after inspecting the belt (no PS no AC) and
putting a listening device on the water pump.  The plugs look perfect...no
sign of coolant in any of the holes.  I turned the motor over without the
plugs and no coolant squirted out...The water pump sounds and feels fine and
both hoses going forward are hot to the touch as well as all the other hoses
in the engine compartment...Hot to the touch.
  Inside the pressure tank:  When I looked under the cap there was some
'sandy-looking' stuff and there seems to be some down in the pressure
tank..When I started the motor, I saw some gasses or bubbles coming in the
small top hose into the pressure tank..."Head gasket" is what I thought,
till I removed the plugs and they look so good.

  Ok now forward to the rad...The lower hose (passenger side) is barely warm
and the hoses where they are "Paired-up" next the shift linkage behind the
spare...again, barely warm, though the engine was again boiling
over...New-ish Bus Depot radiator, new-ish water pump.(~1yr old)
.Thermostat: Unknown.  New temp II sender and temp (instrument) sender.

  I put some NAPA coolant into the system last fall.  Said "Good for
protection of all metals, including aluminum"...It also says (now that I
read the small print..contains Phosphates and Silicates)  That crap in the
overflow tank looks suspiciously like silicate...sandy looking stuff.
Plugged radiator maybe?...

  So anyone care to make some suggestions what I should start with in the
morning?

  If you read all this, you may have something to guess from...

  Don Hanson