Date: Sun, 23 Jul 2000 21:29:36 -0400
Reply-To: Matthew Bulley <gmbulley@bulley-hewlett.com>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Matthew Bulley <gmbulley@bulley-hewlett.com>
Subject: Re: Valve seat drop on 81 vanagon
Francois--
Air cooled VW motors have essentially two cooling systems for the two
separate areas that need cooling; although the two systems have a lot of
cross over duties. Both use air as the primary "dispersal" agent, and are
finely controlled by means of a thermostat and carefully controlled ducting
and seals.
One area, the heads and cylinders is cooled by means of deeply finned metal
surfaces that are immersed in a bath of rushing air produced by your
cooling fan. The faster your motor turns over, the faster your fan blows,
the more air is rushing by, thus the more heat is displaced. Good, simple.
Conversely, if you are in too high of a gear for the circumstances, the fan
may not be spinning fast enough to displace all of the heat in the
heads/cylinders. Bad.
The second area, the "bottom end" and crankcase, which has all the bearings
and mobile metal parts, is also cooled by an oil bath, which circulates
through an air-exchanger oil cooler. The cross over duty is mainly the
bottoms of the pistons, and the cylinder sleeves which also receive some
cooling from the oil splash, but not much. Same thing is true as with the
air: the faster the motor turns over, the faster the oil circulates through
the cooler and the more heat (theoretically) can be displaced. Hot oil was
not your problem. Hot heads were.
A dropped valve is symptomatic of overheating of the heads because of the
motor being out of tune, or because something is improper in the cooling
system (often the case), of because the operator is not using the proper
gear for the load and speed (lugging up a hill in fourth, rather than
downshifting to third).
You oil pressure light comes on when your oil pressure drops below a safety
limit due to catastrophic mechanical failure, loss of oil, or (in very slim
circumstances) overheating to the point of extremely low viscosity. An oil
temperature gauge will not keep you from dropping another valve, but will
indicate if your oil is hot. A head temperature gauge will help, but is
unnecessary if you have a fundamental understanding of how the engine
operates, and keep it in good tune.
If you need to add either type of gauge, I would highly recommend VDO
gauges, which are the OEM for VW of your Vanagon's vintage. Have a mechanic
install them, and instruct you on where the reading should fall under a
variety of circumstances.
Although you don't say so, I assume you are having the motor rebuilt prior
to the trip to Alberta. If not, you definitely run the risk of sucking in
another valve as the three other cylinders try to haul the load.
Best of luck,
G. Matthew Bulley
Bulley-Hewlett
Mount Olive, NC USA
877.658.1278 Tollfree
www.bulley-hewlett.com
My Agenda: Stop Suburban Sprawl.
My Methods: Revitalize older, highly-dense, urban towns. Champion
mass/rapid transit and fast Internet service to these towns. Demand
replacement of archaic, "separationist" zoning laws with neo-traditional
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The Result: All Americans obtain superior living opportunities; sprawl is
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inheritance.
Find out more at http://www.cnu.org
-----Original Message-----
From: Francois Vezina [SMTP:fvezina@sfu.ca]
Sent: Sunday, July 23, 2000 6:18 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Valve seat drop on 81 vanagon
Hi all
Last week I lost compression on one piston on my air cooled van
because of a valve seat that dropped. From what I've seen on the
type2 list, it is apparently common when the engine is overheating.
Well I thought those engines were not overheating that much... Some
fellows suggested that I have installed an oil temperature gauge. I
remember that some peoples were talking about oil temp gauge on the
vanagon list not so long ago SO this is my questions.
Does the oil light in the instrument panel indicate low oil or too
hot oil? (I know it is silly but I don't know)
If its the latter it did not work last week...
IF I should put an oil gauge is there a particular type to choose or
the one at say Canadian Tire is OK?
How long would it take to a mechanic to install it ($$$???) (I'm not
really good in mechanic).
I'm gonna go in Alberta with the family in two weeks (from Vancouver)
so I don't want to bust another valve because my van is loaded and
overheat in the rockies...
Any suggestions?? comments??? experiences??
Thank's it is appreciated
Francois
Francois Vezina M.Sc.
Department of Biological Sciences
Simon Fraser University
8888 University Drive
Burnaby BC.
V5A 1S6
Voice: (604) 291-5422
Fax: (604) 291-3496
