[Vwdiesel] [Audi-VW-Diesels] RE: Cheapo rebuild--Crankshaft

Fri Feb 11 22:23:22 PST 2011

Yes indeed. That said, if you’re going to build motors, you need to start measuring stuff.  Measure your crank and rod journals to be sure they are good,  as in within tolerance so that the bearing clearance comes out right, and also to be sure you have stock unground cranks in both, so the intended swap fits, and you can order the right bearings if need be.

I would avoid the block that had the catastrophic rod bolt torque forgettage/ failure.  Sometimes you get side loading that puts small cracks in the cylinder wall that aren’t immediately apparent, UNLESS you decide to check for cracks (dye penetrant, mag particle test, etc...)  

If you measure up the bores on the two other blocks, pick the one that is closest to leaving your piston collection with a couple thou clearance (.004 across the diameter if possible) Select your pistons to match the holes they go into, then weigh them, and match the weights by die grinding inside the piston.   To get all silly about it, then assemble your rods with bearings, measure the ID of the bearings and match them to the crank rod journals  you are using, shooting for min .0015 clearance with tolerance to .0025 preferably around .002 

Now this is not rocket science, don’t get scared off. You can accomplish all this with proper technique, and less than 50 bucks worth of tools.  You need a good quality vernier or digital calliper, and a set of spring loaded measuring sticks that spring out to measure  across the bore of a circle.   Good enough callipers are 30, good ones are a hundred ish.  The springy things are under 20.  Unless you measure, you really are assembling based on faith and hope and failure tends to follow close behind.

Ya know, I have NEVER managed to pull off a quick and dirty rebuild. 

-james

From: Audi-VW-Diesels at yahoogroups.com [mailto:Audi-VW-Diesels at yahoogroups.com] On Behalf Of Dave Cook
Sent: February-11-11 11:15 PM
To: Audi-VW-Diesels at yahoogroups.com; 'VW Diesel Group'
Subject: Re: [Audi-VW-Diesels] RE: [Vwdiesel] Cheapo rebuild--Crankshaft

I am reading this as, "you should probably use the Vanagon crankshaft, likely the bearings took the brunt of the abuse and it is the best bet."  Also, "you'd better use new bearings if you are going to move one crank to another block"

Correct?

Hmm, I suppose as much as I've torn the block down at this point, it doesn't matter much which crankcase I use, does it?  

So much for a quick 'n dirty rebuild...

Dave Cook

--- On Sat, 2/12/11, James Hansen <jhsg at sasktel.net> wrote:

From: James Hansen <jhsg at sasktel.net>
Subject: [Audi-VW-Diesels] RE: [Vwdiesel] Cheapo rebuild--Crankshaft
To: "'Dave Cook'" <davevw at yahoo.com>, "'Audi-VW-Diesels Group'" <Audi-VW-Diesels at yahoogroups.com>, "'VW Diesel Group'" <vwdiesel at vwfans.com>
Date: Saturday, February 12, 2011, 2:40 AM

-----Original Message-----
From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com] On
Behalf Of Dave Cook
Sent: February-11-11 7:26 PM
To: Audi-VW-Diesels Group; VW Diesel Group
Subject: [Vwdiesel] Cheapo rebuild--Crankshaft

At this point I am starting the doubt the feasability of my goal of getting
the engine together this weekend.

I have three engines in the garage:

1) Original in the car, threw the rod.

2) Mostly complete, planning to rebuild. Engine code is from a Rabbit

3) Longblock, engine code from a Vanagon

I got #2 mostly torn down preparing to clean up the block, paint it, and
hone the cylinders. This was slowed by an eye infection and a broken water
pump bolt but both those things are being taken care of/taken care of.

I pulled the sprocket off #2 to discover that the woodruff keyway has been
damaged both in the sprocket and in the crank.

So what to do?

__________
Don't use that unless you have to. JB weld is okay for that kind of thing,
but not preferred, especially if you have a donor sitting beside it.
_____

As you could see in the pics, the crank is damaged at least some in the
in-car motor. I was not planning to tear that apart until it was time to
transfer parts to the new motor, for ease of remembering where everything
goes. 
Pictures are worth a thousand words. Link?

I had basically nixed the Vanagon block (#3), thinking that this particular
engine had worked really hard pushing the Vanagon around until the valve
embedded itself into the head. 
___

Measure the cylinder bores to know for sure.

What I'm wondering about is if the Vanagon crank would have taken much of
the damage, or if it would have been in the bearings? 
____
should be fine.

I presume that it would be a bad idea to use the Vanagon crank in #2 with
#2's bearings. So if I was going to use the Vanagon crank I would want to
use new bearings to put them together. Right?
_____
correct, bad idea. Can't successfully use bearings foreign to a journal
they must be new. There's other stuff to a journal. For instance, the
bearing is a tad big, and the cast halves "crush" the bearing shells into
the bearing bore. Without the correct crush, they get loose in their home,
and the crush reduces the I.D a tiny bit, which is allowed for on a new
bearing. No crush, loose bearing eventually, so it turns away from the oil
journal hole, and gets worse.

I haven't gotten the crank all the way out of the block yet, but the main
bearings were looking ok overall so I was hoping to get away without having
to replace them.
____
Bearing shell can only be used in the block it was originally installed
into, just as a rod bearing can only ever be used on the rod in which it was
originally installed..
-james

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