it's not a matter of is proper backpressure needed,
but more that exhaust vales will burn after a while with an exhaust leak
near that exhaust port,

I don't see which engine Tom the question asker has ...
but I'll say that I find slightly burnt or rough exhaust valves on
waterboxer 2.1's all the time.
it's normal even ..
I go to do head gaskets, check the valves for leakage, and the exhaust ones
are usually a little leaky ..
like doing 80 % of the sealing they should be doing.

so given that, it's not that smart to run with significant exhaust system
cracks or leaks.
It  could even be a fire hazard.
in any engine.

Scott
www.turbovans.com

----- Original Message -----
From: "tom ring" <taring@TARING.ORG>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, May 10, 2010 8:04 PM
Subject: Re: Good local mechanic worked on my 85

> And a question.  I have had a very minor to major break in the exhaust for
> a
> few thousand miles.  The very minor was a lengthwise split about 2 inches
> from
> the head and extending for about an inch and a half.  That was around in
> somewhat patched to not patched for a couple cycles for about 5 thousand
> miles.
> The major was the driver side forward cylinder.  Broke at the flange.  Bad
> mojo.  20 miles home.
>
> Patched with the nasty white exhaust paste wrapped with the high temp buck
> a
> foot exhaust wrap and then with steel fence wire with about 1/16 to 1/8
> spacing.
>
> Lasted for 150 miles, almost all I needed last summer.
>
> So the question - is proper/even back pressure a critical thing on these
> engines?  Because this thing is more balanced cylinderwise and just in
> general
> than I remember.
>
> tom
> K0TAR
>
> On 10 May 2010 at 21:27, tom ring wrote:
>
>> Just had a local private mechanic install a new exhaust on an engine that
>> had
>> at least 1 broken stud.  He removed and welded a couple other support
>> bits
>> during the job.  Replaced the oxy sensor with new.  Installed all new
>> fuel
>> lines and covered them with the old outside protective plastic shrouds.
>>
>> I supplied the new exhaust kit and fuel line kit but nothing else.  He
>> picked
>> up the oxy sensor and replacement studs as well as a few other gaskets
>> and
>> bolts.
>>
>> Total bill - $330 including additional parts and shop.  I like Westside
>> VW, but
>> this was a lot cheaper for 10 hours of work.
>>
>> He is in the Minneapolis metro if anyone is interested.  Contact me at
>> the
>> shown email address.
>>
>> tom
>> K0TAR
>>
>>
>> __________ Information from ESET NOD32 Antivirus, version of virus
>> signature database 5103 (20100510) __________
>>
>> The message was checked by ESET NOD32 Antivirus.
>>
>> http://www.eset.com
>>
>>
>>