Date: Fri, 9 Aug 2002 01:08:40 -0500
Reply-To: Stan Wilder <wilden1@JUNO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stan Wilder <wilden1@JUNO.COM>
Subject: Re: Why this type IV engine caught fire,
spun the mains and ruined everything.
Content-Type: text/plain; charset=us-ascii
Frank: First, I personally think that a few more pictures (if you have
them) would be really instructive.
Stan Replies: I don't have a digital camera and after putting in an
honest eight hours removing, cleaning and disassembling this engine I
didn't feel much like putting another $8.00 into a dead horse. I'm on the
outside of being a professional engine rebuilder so I just measured,
investigated, and examined every individual part.
Since this engine had a fire along with the seizing it was fairly rusted
on the steel internal components. My immediate assumption was that almost
all of the parts were unusable but out of curiosity I stayed with the
examination and removed the rust, carbon and other contamination with the
hopes of some great discovery.
The #3 main bearing was physically welded to the crank shaft and did not
have lateral or rotational movement. This condition along with the
visible black coloration as seen through the oil holes tells me that this
was a friction failure exacerbated by oil starvation.
The #2 main showed primarily signs of oil starvation that ultimately
discolored the bearing and crankshaft from intense heat.
The number #1 (flywheel) bearing showed a general looser fit and scoring
of the crank shaft.
All of the rod bearings were simply worn out from lack of oil and exhibit
crank scoring.
There was minor scoring of the camshaft bearings, along with surface
rust.
Just as a by product of being hosed down by the fire department while the
engine was cracking from being seized and the magnesium fan shroud was
burning furiously the cylinders were distorted and the rings were firmly
set to the cylinder walls with rust.
Some things just didn't need checking: The case showed signs that there
was enough heat to start aluminum flow on one of the rear external oil
galleries. The lighter gauge metal in the oil cooler simply melted away.
I have no doubt that many professional engine builders or engineers might
find things that I could miss by lack of experience but what I found was
very scary and prompted me to junk the works and just get the whole
parcel out of any potential for reuse.
Its a little late to go dumpster diving and recover anything I tossed
there two nights ago for any farther investigations.
I've disassembled a lot of high mile engines but this engine was a real
learning tool to enforce the procedure of check it twice.
------------------
Frank Wrote: Second, in every case I saw of bearing deformation due to
over crush or pin or slot alignment, the journal seized in a few tens of
hours of operation.
Stan Replies: I concur with you on this issue but I must add my
speculation that the vehicle may have been used only for short runs that
never warmed the engine to full temperatures until the event of its final
demise.
I use the carbon build on the piston tops and cylinder heads to read that
this engine ran for many hours before it failed.
Thanks for your comments;
Stan Wilder
On Fri, 9 Aug 2002 00:54:56 EDT FrankGRUN@aol.com writes:
>
> In a message dated 8/8/02 7:19:57 PM, wilden1@JUNO.COM writes:
>
> << If you look at the bearing you'll see that the pin missed the
> bearing
> alignment hole.
> The pin applied undue pressure on the bearing that may have been a
> friction factor as well.
> The bearing became ever so lightly egg shaped as the case tightened,
> this
> condition may not have caused the crank to lock while the rods / etc
> were
> being installed but eventually it caused the engine to fail from
> oil
> starvation to almost all engine bearings.
> Every bearing shows signs of operating under extreme heat and are
> failed.
> I can visualize that the engine may have held 5/8 pounds of oil
> pressure
> and the idiot light might not have signaled the operator but as
> heat
> built up and the oil thinned it could have continued with enough
> pressure
> that the sender might not activate the oil indicator light.
> During installation the case may have originally dropped together
> properly but considering Murphy's law the bearing could have moved
> as the
> case was rotated, rolled over or handles in the bolting together
> process. >>
>
> Stan,
>
> Good observations as usual but I think my experiences may have been
> a bit
> more harsh than yours.
>
> First, I personally think that a few more pictures (if you have
> them) would
> be really instructive. In the air cooled cases I have cracked
> (almost all
> type 1 spinners) I often encountered strongly warped sealing
> surfaces and
> oval bearing recesses due to gorillas drawing down misaligned and
> contaminated case halves. I also often encountered the spun main or
> rod
> bearing because the journal to bearing surface had not been properly
> measured
> with plastigage.
>
> Second, in every case I saw of bearing deformation due to overcrush
> or pin or
> slot alignment, the journal seized in a few tens of hours of
> operation. As
> you well know, any metal to metal contact in the engine will destroy
> it. Its
> the thin oil film that staves off the ultimate disaster for millions
> of
> revolutions. If that gap is too thin, then metal to metal and gone.
> Of course
> a similar threat lies in waiting if the gap is too large. A too
> large bearing
> gap will make it impossible to define a standoff film with adequate
> shear
> strength.
>
> Third, a key lesson for the amateur engine rebuilder is cleanliness,
>
> cleanliness, cleanliness. Put that thing together wearing a clean
> white
> cotton glove and it will sing. Throw it together with an air gun to
> keep
> moving the dirt away from the area that you are wrenching and the
> extra parts
> inside that flying ball mill will come back to bite you.
>
> Just a comment.
>
> Frank Grunthaner
>
>
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