Date: Fri, 24 Aug 2001 13:33:16 -0700
Reply-To: Daniel Schmitz <djs@GENE.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Daniel Schmitz <djs@GENE.COM>
Organization: Genentech, Inc.
Subject: Re: Cracked head/temp sensor...
Content-Type: text/plain; charset=us-ascii
Ed,
If the cracked head you cite is only cracked externally i.e. where the
temp sensor screws into the head and not internally in the combustion
chamber, your problem may not be as serious as you think, at least not
to the extent that you need to pull the engine out and take it apart.
Your temp sensor (Temp Sensor II) screws into a hole (might be blind or
might be drilled through) in the finned area of the head, if memory
serves. For the crack to be the cause of your engine running poorly, it
would have to be such that the sensor cannot contact the cylinder head
sufficiently to raise its temperature. If the sensor can be screwed into
the head, it should work assuming the sensor itself is good. But these
go bad often, and are relatively inexpensive.
A compression test would confirm if the crack is actually into the
combustion area. If you have good compression, there may not be a need
to tear down your engine. You can try just replacing the sensor with a
new one. If you can't actually attach the sensor to the head any longer
because of the crack, you may find an identical sensor hole on the
opposite head (same position), especially if your heads are not original
(doubt it for a 1980). If you can screw in a known good sensor in the
opposite head, you can run a wire to the FI connector. This would at
least let you drive the van until you decide to pursue a more permanent
fix.
Re damage, running excessively rich is better than running very lean
(you won't burn up anything), but you will want to change your oil
because it can become diluted by gas over time. Not good for
lubrication. And the carbon build-up will eventually cause problems.
Re other work, the Type 4 engine is pretty robust in the lower end. The
heads are the weak point, with exhaust valve seats dropping after high
mileage/running hot. If you are removing the engine anyway, the least I
would do is fix the crack and have a quality valve job done on BOTH
heads. Some machine shops can install seats that will stay in place
longer than the stock seats.
Hope this helps!
Dan
Original post:
****
I've just (finally) entered the world of VW ownership with a 1980
Westfalia.
The interior's in top shape, some surface rust on the outside, but all
in all
not too bad. Engine-wise, however... the head is cracked at the point
the
temp. sensor for the FI screws in, thus giving an incorrect temp reading
and
therefor fuel mix. The result is that, once the engine is nice and hot,
I can
only do 80-90 km/h (50-55mph) flat out (that was with a tail wind) and
she's
guzzling gas like crazy. The fuel pump is delivering 100%, so it's not a
fuel
delivery problem. I can find my way around as long as I have a shop
manual in
front of me.
Q1: As long as I pull the engine to replace the cracked head, what else
SHOULD I do, bearing in mind I want a quick turnaround, not a complete
rebuild.
Q2: Since I limped home in this sorry state (300km/180miles) have I
possibly
damaged/burnt/fried anything?
Q3:This was the professional diagnosis from recommended Porsche/VW
mechanic,
but are there any other possible culprits lurking in there?
Thanks in advance
Ed
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