Date: Wed, 30 Apr 2008 15:23:45 -0700
Reply-To: Mark Drillock <drillock@EARTHLINK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mark Drillock <drillock@EARTHLINK.NET>
Subject: Re: Lifter adjustment VOODOO
In-Reply-To: <927419.84210.qm@web36401.mail.mud.yahoo.com>
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Exactly what I have seen a few times as well, both with 2.0 aircooled
and waterboxers. That points out that both Ken and Bob are right, just
under different conditions. Ken mostly works with old vans and things
are often far from factory specs and so a different adjustment procedure
is called for. Ken's method gets the vehicle running when the factory
way may not and I do it the same way at least to start with. Then I
crank the adjustment in a 1/2 turn per screw on one side at a time,
checking if it will still start and idle ok before moving on.
I always want to use a compression test as part of the adjustment when I
have had the head off or lifters out. Seldom has the engine shown good
compression on all cyls if the factory adjustment was followed. Setting
the valve to zero lash is a reasonable starting point IMHO.
As Dennis pointed out, there can be mechanical faults or rebuilds that
strayed too far from the ideal. I helped a friend with an 2.0 aircooled
last year. We installed a new cam and lifters into an engine with low
miles since it was 'rebuilt'. Going by the markings on it indicated it
was a GEX rebuild. It had 2 cam lobes worn so flat that they were nearly
round and the lifters were scored as well. After the new cam and lifters
went in we had to use zero lash or it would not run at all. Maybe that
was due to something like Dennis' theory of weak valve springs or
machining that was not compensated for with spring shimming.
Mark
Jake Beaulieu wrote:
> Yeah, this topic is giving me a headache. I have an 82 AC Westy. If I set the lifters to 0 clearance it runs "OK", but put it one or two turns in and it barely runs. A couple weeks ago I measured the compression at 0 clearance, then set the lifters to +1 turn and let it sit for TWO weeks. When the van first started after sitting for two weeks it ran great until the oil pressure came up (5-10 seconds), then it just barely chugged along. A compression test revealed that the compression had dropped from about 170 psi to 120 psi on all cylinders (I don't have the numbers in front of me). Backed the lifters out to 0 clearance again and compression jumped back up to 170 and it ran "ok".
>
> Since the van ran great at +1 turn until the oil pressure came up, I am wondering if the valve springs are weak. It is as if the oil pressure is high enough to fill the lifters, then continue to pump up the lifters to the point that they are compressing the valve springs and forcing the valves open. I don't know how one would go about measuring the strength of the valve springs?
>
> jake
>
> Mark Drillock <mdrillock@COX.NET> wrote:
> The problem is that lots of times the engine won't run right if at all
> when first set to either 1-1/2 or 2 turns. It can take time for full
> lifters to bleed down a little. Turning in the screw on a lifter that is
> fully expanded and filled with oil just opens the valve and then
> compression can be low or even zero. Wait some hours or days and the
> constant pressure from the valve spring will force some oil to escape
> from the lifter and eventually things will be ok. This problem is why
> over the years this topic has been so controversial here. A fully bled
> lifter is too long at first because it has too much oil in it. Put that
> lifter under tension from the adjuster screw and the oil won't compress
> but the valve spring will and the valve will open. Left that way for a
> while the constant pressure from the valve spring will eventually
> squeeze some oil out, which is what is needed. Then when the engine is
> started the lifters will pump back up but only to the right length.
>
> Mark
>
..........
>>>
>>>> At 10:27 AM 4/30/2008, Chris S wrote...
>>>>
>>>> Although I'm getting ZERO messages from Gerry again, I'm hoping
>>>>> knowledgeable folks will reply to me directly.
>>>>>
>>>>> I'm confused about proper lifter adjustment. According to Bob Boston
>>>>> I
>>>>> should do 1.5 turns past contact. According to Ken Wilfy I should
>>>>> just
>>>>> leave the lifters set at first contact.
>>>>>
>>>>> Sooo... what is it? And why?
>>>>>
>>>> 1 1/2 turns in from a fully expanded lifter. Because it allows the
>>>> lifter to adjust itself in either direction. If you set it at "first
>>>> contact," the lifter can't expand to adjust for a valvetrain which is
>>>> getting looser.
>>>>
>>>
>
>
>
> ---------------------------------
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