Date:         Tue, 15 Feb 2005 19:52:03 EST
Reply-To:     Trvlr2001@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         No Name Available <Trvlr2001@AOL.COM>
Subject:      Re: [subaruvanagon] temperature fluxuation, why?
Content-Type: text/plain; charset="US-ASCII"

In a message dated 2/15/2005 4:45:51 PM Pacific Standard Time,
westysubie@tactical-bus.info writes:
On 2/15/05 4:59 PM, "geofmoser" <geofmoser@hotmail.com> wrote:

>
>
> I am currently on a cross country trip with my recently converted 85
> vanasub.  This is my problem.  I figure that the temperture should
> stay at a constant temperature once the engine has warmed up.  Mine
> sometimes   gets up to 210 degrees max, but when I rev the engine
> speed to over 4000  rpms it goes down to a lower temp.  On the highway
> it goes down to around 125 degrees.  I have tried to bleed the system
> for hours on end, just had the system power flushed by a gaurage and
> it problem stayed the same.  I can't quite figure it out but I think
> it might be air bubbles still trapped but really unsure at the moment.
> If you have any insight let me know I would greatly apreciate it.
> Thanks Geof
>
This has been heavily covered with detailed notes that I posted.

When you go over about 3k you are pumping water through the radiator and
heater cores at an increased flow rate.  Add to that the cold air (the
external air temps very critical) hitting the radiator AND the front heater
core.  The front heater core gets continuous air flow from the outside, not
the inside.  You will drop temps in the heater ckt from the heater core
getting hit with max cold air and the thermostat is held partially open at
about 169 degrees.  However even in my coldest and worst case testing I
never dropped that low.  I never tested below about 0 degrees external with
any gauges on anything in the loop.  In theory though if I carried my test
figures down to about 17 or 20 below I would say that 125 degrees is
possible.

If found that at about 70mph I hit the biggest temperature drops.

Note that in a subaru the heater ckt normally does not get external air and
is a smaller heater core by about 30 percent surface/flow.  On the subaru
you are trying to heat a volume that is massively smaller than a vanagon so
interior temperature loading of the heater core is far less making for far
less heat exchange again.  Testing I did on my daughters jeep which has the
same ckt as subaru showed that all of this is critical to controling engine
temps.  Testing I did also showed that if you use a bypass you could be
making it better or worse.  I found that the size of a bypass as well as its
location was critical and extremely variable.

Another are I did some testing on recently was the air flow around the
engine.  What I found surprised me.  It was far more massive than I had
thought.  But then remember the original vanagons were air cooled and were
probably designed for that kind of air flow.  At higher speeds the cooling
effect could be very good.  Remember we are still a boxer engine with both
the oil source and the heads right in the air flow. Stock subaru air flow is
going through the radiator.


Fixes I have done to control the temp drops are
1.  blocked the majority of the air hitting my front heater core.
2.  using my rear heater core for main heat
3.  restricted about 20 percent of my radiator air flow

My temps now rarely drop below 150 degrees even on 15 degree below temps.
And then only for short periods on acceleration while the thermostat is
readjusting to the new temperatures.
Folks,
If you've got a Vanagon,
You've got an old Vehicle....
It probably Needs a New Radiator???
Made a big difference in mine.
JC...