Date: Sun, 21 Jan 2007 22:03:47 -0500
Reply-To: Mike <mbucchino@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike <mbucchino@CHARTER.NET>
Subject: Re: Opinions Please
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It's the difference between the mindset of a person doing business (having
to make a buck), versus a private owner doing his own maintenance (trying to
save a buck). I've been both, so I understand it completely. Ben, needs
to remember that a little careful thought, some skilled troubleshooting, and
attempts at an easy fix first, before you jump into an unnecessary,
expensive and total teardown. The proper use of a cylinder leakdown tester
is not widely known, and poor results must be rechecked after attempts to
cure the leak on the affected cylinder(s). Experienced aircraft mechanics
(like myself) can explain the benefits of a proper test and interpretation
of the results. If one of the valves appeared to be the cause of the
excessive leakdown, I would 'stake the valve' by giving it a good rap with a
rubber mallet, to see if it improved the reading and solved the leak. Often
it would! If a small carbon particle or other debris is stuck in the valve,
it can't seat properly. If the cylinder was the source of the high
leakdown, you would squirt a few drops of oil into the sparkplug hole,
rotate it once around and test again. If this healed the leak, you knew it
was only temporarily cured, because that indicates that the rings are worn,
requiring top end overhaul. If the oil didn't cure it, you had leaking head
gaskets, or a cracked head or case, or broken rings/ scored cylinder walls,
etc. Aircraft parts are VERY expensive, so one has to be sure what's broke
before you go off trying to fix anything. It seems that foreign car parts
(particularly NLA ones!) are might costly nowadays, too. Anyone can R&R
parts until the problem is solved, but a true mechanic uses his brain and
all available resources, before spending the customer's money on possibly
unneeded parts or procedures. I'm not saying that Ben is not a good
mechanic, but the advice he's giving here seems to be a knee-jerk reaction
to a given situation, based on his personal policies,practices and
procedures. All good troubleshooters start at the simplest, easiest fix
first. Getting back to basics can be easily forgotten when you spend your
days dealing with much larger issues. KISS (Keep It Simple, Stupid) has
been quoted many times in similar situations. It's the only way to fly!
Mike B.
----- Original Message -----
From: "Rich Bennington" <rich.bennington@CHARTER.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, January 21, 2007 9:07 PM
Subject: Re: Opinions Please
> <
> Date: Sun, 21 Jan 2007 17:38:43 -0500
> From: Ben <huotb@VIDEOTRON.CA>
> Subject: Re: Opinions Please
>
> Denis, i understand but what is the point? you have a problem anyway! it
> need to be open, there is no way out, wile there, it's nothing to take a
> look at the pistons or/and head. The only thing good about a leak down it
> to
> tell the customer (or friend) the approximated price of parts, even then,
> if
> it show a leak on the pistons side it doesn't tell you that the heads are
> worned out or close to it! the thing that people don't understand is a
> leak
> down will tell you that your +- 400$ on a 3 to 5 k job. The time to go
> there
> and open everything is practically the same. I don't even do compression
> check anymore, i look at the engine, drive the van, touch the engine for
> vibration and i know. What i'm trying to say is that with a leak down,
> you
> can only tell that the price may be bit higher.... or lower!
>
> Cheers, Ben
>>
> Ben,
> I have FIXED a cylinder with poor compression by just adjusting a valve!
> This was an older vanagon with a lifter/valve combo that just didn't like
> 1.5 turns in - it had 90 PSI. At .5 turns in, the compression went from
> 90
> up to 150, within 5psi of other cylinders(these are high-altitude
> readings,
> so its even more referenced to sea level). Point is, valves totally
> closing
> should be examined before rebuilding - one may not have to even pull the
> head!
>
> Now, admittedly, one does not have to do a leak-down for this -- but it
> would have been faster and more accurate if I had done that vs. using a
> compression test.
>
> Rich
>
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