Date: Wed, 1 May 1996 16:57:21 -0400 (EDT)
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: "H. Steven Dolan" <dworkin@mtolympus.ari.net>
Subject: Re: freshly rebuilt 1600DP running VERY HOT!
On Tue, 30 Apr 1996, bill (w.r.) crick wrote:
> My Question:
> There was a mention that all of the cooling tin was important.
> Well I have a 76 Type II which I believe has a Type IV engine.
> I know there are two peices missing on my van, and will try to
> describe them here hooping someone can tell me the importance
> of these pieces.
> The stainless pipes that come out of the cylinders, and joint them to the
> rest of the exhaust (on a watercooled car these would be the cast iron
> exhaust manifolds) cracked. I had a mechanic get them welded. When
> he was showing me what he had done, there were four crumpled tin things
> on the shop floor that looked like they went over these 'stainless
> manifolds' like some sort of little shroud. When I asked if they were to be
> replaced, he said no they are not needed. They were sort of half curved
> pipes, two of which would go around the 'manifolds'. What are they? What do
> they do? What happens if I don't have them?
They sound like the heat shields for the manifolds. As the exhaust gas
exits the heads into the exhaust manifold, it is as hot as it ever will
be. To keep it from radiating into the area around the cylinders the
manifolds have a sheet metal heat shield spaced off them ~1/4 in. If they
are not there, the pipes add their heat to the air that is cooling your
cylinders, which makes it less able to cool. Not great, but probably not
immediatley fatal. Steve sez get 'em back, put 'em on.
> Also anyone know why the 'manifolds' cracked? The mechanic said that he had
> never seen this before.
Ideally, the heat exchangers are hung from the engine block by metal
braces. Over time these have a tendency to come loose or break off,
after which the whole exhaust system is hanging from the manifold. Then
you back into a curb which flexes the exhaust system on the manifolds and
breaks them in half at worst or at least sets you up for new manifold
gaskets ('76-78).
Steve Dolan
Been there, Done that (Got the t-shirt)
|