Date: Thu, 11 Mar 2004 19:12:59 -0800
Reply-To: TinkerMan <tinkerman007@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: TinkerMan <tinkerman007@YAHOO.COM>
Subject: # Vanagon motor overheating alert device (was: Coolant hoses -
replace them! )
Content-Type: text/plain; charset=us-ascii
Hello Volks!
The amount of emails I got following my initial reply
to Warren's ("Warren.K.Lail-1" <wlail@OU.EDU>) posting
proved that engine loss due to overheating is a very
hurting problem for all Vanagon owners...(actually,
any car owners...).
Yes, it seems that many manufacturers "plant" a very
profitable design flaw into their products, whereas
the coolant temperature meter (which is supposed to
warn us of a nearing engine overheat condition) might
not do it's job properly, resulting in a very
expensive and painful engine replacement!
Why does this happen?
Many times, even if the meter is doing it's job
properly the driver doesn't notice it or even a
flashing lamp simply because he is distracted by other
things or has the sun shining in his eyes...
An other potential problem is the design of the
coolant temp warning system: in the Vanagon, the temp
sender is mounted into the thermostat housing, which
is made of plastic, and is where the coolant actually
passes through which makes it a theoretically good
sensing point, but if for some reason the coolant
drains out of the system (like when I had a leak in
the oil cooler union which caused much coolant to leak
overnight) then the sender just senses the temp of the
AIR in the thermostat that bares no relation to the
actual motor temperature...
In the Vanagon, there is another warning system design
to warn of missing coolant (those two prongs in the
expansion tank) but these fail too. And that's exactly
how I lost a motor...:-(
So after that happened to me, I understood what was
the design flaw that caused this catastrophic
situation: the temp sender isn't mounted to the motor
head, and also no audible warning in case you're not
watching the temp meter.
I set out to design my solution to this flaw, and came
with a nice solution of monitoring BOTH the standard
temp sender (of the meter, not the one the ECU
monitors) as well as the cylinder head temp, and
sounding a loud alert when one of them starts climbing
higher than normal, as well as showing which sender
triggered the alert.
The circuit isn't very complex and is fully
adjustable, which makes it easy to configure it to
both hot and cold climates, or winter/summer.
Basically, it's a pair of analog comparators that
compare the senders outputs (the one in the thermostat
and an additional one bolted to the cylinder head)to
the predefined setting, and sound a buzzer and flash a
LED lamp.
I don't have the circuit at hand right now, but since
several people contacted me directly requesting more
info and possibly posting pictures of my design, I
will try to dig it up (it's been 7 years...).
Anyway, I remember another list member came up with a
simpler solution of attaching a thermal switch
(similar in concept to the one used in the radiator to
start the cooling fan, but of a more convenient
mechanical design to aid in bolting it to the motor
head) which directly triggers a buzzer in the cab.
The problem of this design is that it isn't adjustable
to actual temps and you have to locate a unit of the
proper temp range. I couldn't find his postings in the
archives, but maybe he's still on the list or someone
might find his original post.
Also, if someone can find web space where I can post
the info if I find it, I might try to publish the
details for the benefit of fellow vanagonites...
Whew! What a long post, which shows how much I
understand the pain of other Van-a-gone owners...:-)
=====
Cheers, T-man.
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