Date:         Sun, 16 Apr 2006 13:49:37 -0500
Reply-To:     Raceingcajun <raceingcajun47@BELLSOUTH.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Raceingcajun <raceingcajun47@BELLSOUTH.NET>
Subject:      Re: '80 Air Cooled Vanagon
Comments: To: Christopher <chris@MIRAIUSA.COM>
Content-Type: text/plain; charset="iso-8859-1"

Hi Chris,

    I don't think I would go to the expense of replacing the valves as a
maintenance item. Although it wouldn't be a bad idea to check the valve
guides for wear, in particular the exhaust valves.
    You see the tip of the rocker arms travel in an "ark". The friction on
the valve stem cause's the valve stem to try to follow this ark. This will
wear the guide over time, maybe 75,000 to 100,000 miles. It's simple to
check when doing a valve adjustment. If you have hydraulic lifters you can
do the same, just get the cylinder at TDC. Pull the valve covers and roll
the engine so you have clearance at the rocker/valve. ( where you would
normally adjust that cylinder ) Try to rock the valve stem/spring up and
down, not in and out. If you can move the valve stem more than .004 inch the
guide/valve stem is worn. The reason this is important is that as the valve
closes, following the ark of the rocker arm, the valve head hits it's seat
on one side first. This constant one side hitting will sometimes cause the
valve stem the break at the head of the valve. ( the term is "Dropping a
valve" ) In layman's terms it means "VERY BIG BUCKS".
    With 80K on the engine, I don't mean to say .004 inch clearance means
tear down immediately, but it's getting close. Better to prevent a fire than
to have to put one out!

Howard

Subject: '80 Air Cooled Vanagon

  I was thinking of yanking the heads and having
> the valves replaced as maintenance.  It was recommended to me by a local
> mechanic.
>
> Looking for your advice to keep this motor running well into the 150K
range.