Engines have crankcase ventilation systems that cycle gasses from the
crankcase through the air intake rather than venting them directly into the
atmosphere.

The amount of fuel contaminants in the oil will affect the air-fuel mixture
to some degree, and in a marginal engine can make the difference between an
acceptable level of HC emissions and a level too high. Clean oil will
contribute less HCs to the intake, so the exhaust will be a bit cleaner.

Worn piston rings contribute to the amount of unburnt gasses that
contaminate the oil, exacerbating (exhausterbating?) the situation.

I almost always change the oil before a smog test. It's a habit I picked up
in my air-cooled VW days.

Ron

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Mike
Sent: Friday, September 22, 2017 16:24
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Emissions Test Failure

I've also been told an oil change helps. Don't know how though.

Sent from my iPhone

> On Sep 22, 2017, at 3:47 PM, Steven Johnson <sjohnso2000@GMAIL.COM> wrote:
>
> You definitely want to get the engine good and warm so that the
> catalytic converter is well heated so that it is doing the best job it
> can for a smog test.  Driving just down the street will not warm it
> up enough.   You need to drive it for 15 minutes to 1/2 hour, especially
> with the cooler temps in
> your area.   If you have not done a tune-up in a while, I'd be sure to do
> that as well.
>
> Steven
> 91 Westy
>
>> On Fri, Sep 22, 2017 at 2:46 PM, David Boan <dboan@outlook.com> wrote:
>>
>> I recently moved to Idaho and had to get an emissions test for my '85
>> Westy, which I did today.  It failed one part of the test - the HC
>> (PPM) at idle were 350 (the standard is 220).
>>
>>
>> I spoke with my mechanic who said it was possible that the catalytic
>> converter was not warmed up enough (I had only driven the van down
>> the street a few miles before the test).  He suggested driving for
>> awhile and test again.
>>
>>
>> Has anyone run into this?  Does that advice sound right?
>>
>>
>> Thanks
>>
>> David
>>
>> Boise ID
>>

.