Date: Fri, 18 Jun 2010 13:57:30 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Last gasp: low compression exhaust valve can't pass smog
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
their test for ' emissions at idle rpm' wouldn't make any sense if it was
not taken while the engine 'idling with spec rpm' .
Most smog check printouts I've seen have the idle rpm stated on them, that
the reading was taken at.
you can try ...
but I would expect that the would expect rpm to be something like 750 to 900
rpm, in that range.
The spec sticker on my 85 Adventurwagon Ca model says '850 + or minus 50
rpm, Idle Stabilizer Disconnected'
so I would think the smog person, or machine ,would check emissions at idle
in that range.
but you can try.
'the thing is though' ..smog check or not, it would be much better to just
fix it.
Usually things just get worse when you keep operating it with worn out
parts.
and checking the rocker arms/hyd lifters is well worth doing, for sure.
Scott
www.turbovans.com
----- Original Message -----
From: "Roland" <syncronicity1@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, June 18, 2010 10:07 AM
Subject: Re: Last gasp: low compression exhaust valve can't pass smog
> Hi Ken,
>
> Thanks for the suggestion. I think it is worth one my try at the valve
> adjustment. Like you said, a few minutes of time. Just checked, one of
> the
> shops I asked to try and get the van through smog shows the timing was set
> to 6 BTDC. But this is worth checking again also.
>
> The only other angle I can think of is to raise the idle speed for the
> test. As I mentioned it seems that this cylinder is firing fine at higher
> RPMs. For example one of the recent smog results shows the HC at 60 PPM
> at
> 2524 RPM, but then 304 PPM at 895 RPM. I wonder if the smog testing
> parameters have a maximum RPM for idle. What if I set the idle RPM at
> 1250,
> or 1500 and the HC actually went down then?
>
> Does anybody have a comment on setting the idle higher for the smog test
> and
> therefore reducing the number of low compression misses?
>
> Roland
>
> On Fri, Jun 18, 2010 at 6:16 AM, Ken Wilford <kenwilfy@comcast.net> wrote:
>
>> 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
>>
>>
| 
