Date: Sun, 23 Jun 2002 15:39:28 -0500
Reply-To: wilden1@JUNO.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stan Wilder <wilden1@JUNO.COM>
Subject: Commentary on Air Cooled Cylinder Heads
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Commentary on cylinder heads
I've been working with the Type IV Air Cooled VW engines exclusively for
about seven years now and after restoring five 80-83 Westies for resale,
I've found two problems common to every dead vehicle I've encountered.
The first and most expensive repair problem is the cylinder heads.
Here are my findings:
Dropped Seats are the most common, second problem I find is seats that
have dropped back into the port.
If the dropped valve is in #3 cylinder it can normally be attributed to
overheating.
If the dropped valve is on any other cylinder I first suspect that the
heads were improperly rebuilt or there has been a long term condition of
lean burn from a faulty injector, poorly adjusted valves or a lifter that
fails at high Rpms.
Anytime you purchase a new head or rebuilt head you must remember that it
failed for a reason. Discovering the reason for failure is key in getting
the full life out of your new heads.
The 83 Westy that I drive is the only Type IV engine that I've ever found
both heads matching, they were both VW OEM and both had loose then
dropped valve seats. In every other engine I've encountered they have had
one each of the AMC and VW OEM heads. In addition many of the heads that
are readily identifiable as rebuilds have cracks in the welds from the
rebuild process.
There are always going to be arguments as to which head is better, the
OEM or the AMC.
Considering that most VW OEM heads are quite old and may have been
rebuilt several times I'm going to stick my neck out and say that they
are probably the better of the heads when they are new. The problem is
that there are no new VW OEM heads available.
As luck would have it I've only found one head per vehicle (except my 83)
that had to be replaced and it was always the OEM VW head.
One head re builder (my friend in the Aircraft Cylinder rebuilding
business) states that the only way to weld a head properly is to cut some
material from the fins and use it as the welding alloy. This procedure
was applied to a rebuilt head that he did for me and I nursed 140k out of
the head and I set it back under my work bench when I installed two
matching AMCs on my recent rebuild job. The head appeared to be in good
condition with no cracks or loose seats and was functioning normally when
I removed it. I've since traded it for other VW parts.
On the vehicles I've purchased to restore and put back on the road;
they've never been owned by an individual (to my knowledge) that had any
genuine mechanical skills or understood the frailties of the VW Air
Cooled Power Plant.
I'm guessing that the drivers pretty much kept up with the 70-75 mph
traffic flow for the first ninety days and then progressive lagged behind
as their engine began disintegrating under their heavy foot.
I've had several POs tell me that they'll run 80 mph all day long. This
makes me suspect that the engine is going to be a basket case and I buy
accordingly.
Even with the condition of bad cylinder heads the engines are serviceable
since they fail before the damage can reach the crankshaft bearings or
over-rev damaging other vital engine parts. I suppose that the heads are
a fail safe even if it was never intended that way.
Every failed engine or failed part has a story to tell.
A little detective work will pay off in the knowledge that you've found
the flaw and fixed it, hopefully enabling your replacement part to
function properly for a full life cycle.
Stan Wilder
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