Date: Fri, 18 Jun 2010 09:16:19 -0400
Reply-To: Ken Wilford <kenwilfy@COMCAST.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Ken Wilford <kenwilfy@COMCAST.NET>
Subject: Re: Last gasp: low compression exhaust valve can't pass smog
In-Reply-To: <AANLkTikoljmqjB7KPO2YJcMJngixhbJxJoH33y59Hsut@mail.gmail.com>
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Roland, it is great that you have the problem tracked down to one
particular cylinder and one specific valve. I was having a similar
issue with a customer's Vanagon just a little bit ago and here is what I
did. Check the valve adjustment on that cylinder and if you can, loosen
the adjustment on those valves to zero lash. That means the valve stem
is just touching the adjuster (zero turns after contact). Now recheck
your compression. Many times the valve adjustment is too tight and this
can make you have issues with the valve not closing all the way. If
your compression comes up then you know you have done something good.
If not, you haven't lost anything but a few minutes of your time. I did
this on my customer's van, adjusted the timing so that it was exactly
spec (7 degrees BTDC) and it passed with flying colors after failing
twice before. NJs emission testing is virtually the same as California
(same company does it).
Let us know what you find out.
Ken Wilford
John 3:16
www.vanagain.com
Roland wrote:
> Ok,
>
> So, again trudged to the smog station after various lower cost attempts
> (California).
> - High HC at idle, 270 PPM and more. The max allowed is 120.
> - HC at 2500 RPM is fine (because of course the compression happens at that
> speed).
>
> Apparent root cause: exhaust valve, cylinder #4
> - compression is in the 85 lb range, vs the others in the 130-145 lb range.
> - leakdown test said "84% out of exhaust".
> - I can see / feel/ hear an occasional miss at idle (I think).
> - So it seems pretty clear that lower compression / miss will cause high HC.
> - It runs fine, last weekend just did a 270 mile trip.
> - Root cause of bad valve? Don't really know, the engine has AMC heads,
> vehicle has over 200K miles, so obviously the heads were redone at some
> point. About 4 years ago I blew the water pump on the freeway, didn't turn
> it off right away, but also passed smog after that event. Maybe just more
> time caused the valve to go bad. But I believe I've also read that the
> valves in AMC head go bad faster than expected. Also, the upper bolt is
> missing from where the exhaust manifold / header attaches to #4, but I can't
> feel any air/exhaust flow -- maybe the lower bolt is holding the gasket.
>
> Potential paths:
> - get the left side head replaced, not sure I am willing to do it myself,
> tough to get at, seems like many peculiarities on this one, I may screw
> something up. ( I would if I still had my Austin Healey). The 2 shops I
> spoke with would use a new head, from their estimates it must be many hours
> of labor.
> - go to the California Carb appeals to the referee. I have the papework, I
> think I've spent enough $ that they may give me a 1 time waiver. (i.e.
> delay facing the problem, but I am planning some trips, I don't want this
> engine to go bad this summer.).
> - get both heads replaced while we are at it? (I don't have all the
> records, but the bottom end probably has 200K + miles on it.)
> - costs just go up from there.
>
> Anybody have any ideas at all high I could get past the smog test without
> replacing the head?
>
> Thanks!
> Roland
>
>
--
Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: 856-327-4936
Fax: 856-327-2242
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