Miata Mailing List: March 1996, Message #152
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   From: rsilveno@kootenay.awinc.com (Reijo Silvennoinen)
Subject: Re: DIY 60,000 miler?
   Date: Sun, 3 Mar 1996 17:57:52 -0500

You wrote:

>Baby's got 50k miles on her now, and I'm thinking about The Big Service.
>I would really like to do the work myself for both economic and personal
>reasons - I like working on her.  How feasible is it?  
>She's a 90, so there's that problem with the crankshaft.  I understand
>that's due to the woodruff key (I'll find out what that is when I get my
>manual) being replaced incorrectly.  If I am aware of this, is it easy
>enough to get right?  I'm paranoid a Mazda tech will screw it up and my
>crankshaft pulley will break off, just like poor Wendy.  If I did it and I
>know it's right, I'll be much happier.  If it's possible I'll be unsure that
>it's in correctly, I'll bring it to Mazda and make sure that it's mentioned
>on the work order.
>My mechanical background:  I'm good with machines and have worked as a bike
>technician in the past.  My hands are educated, you might say, but not in
>car stuff.  I'm not afraid of either getting dirty or following directions.
>I have a good collection of general tools, and will be expanding the
>Miata-specific collection for the job.  I currently do all the service on
>her, but changing oil is not exactly rocket science.
>Please, anyone who's done the job, share your experiences with me.  I've got
>a few months, but the end of the summer is the likely time for Baby's
>surgery.  I keep thinking how I'd rather spend that $300 on tools and toys
>than on labour of which I am not 100% confident.
>
>Keith and Baby, who got washed yesterday and snowed on today :(
>
>_____________________
>Page de Home:
>http://www.ottawa.net/~tanner
>Heavy Miata Content!
>Netscape 2.0 enhanced
>_____________________

Yes, you can do it provided you are mechanically inclined and have a few
tools and parts:

        10 mm, 12mm, 14mm sockets/rachet plus large one for crank pulley (I
used 13/16").
        Phillips screwdriver
        Torque wrench

        replace the front crankshaft and camshaft seals (didn't replace my
camshaft seals and one is seeping at 95,000 km)

        might as well replace your belts as a part of preventative
maintenance since they are coming off anyway - spares

Procedure:

This will be greatly simplified:  Basically what you have to remove are the
parts mounted on the front of the engine block.

This involves removing the valve cover, belts at the front of the engine,
and all the plastic covers on the front of the engine.  Oh yes, I think I
recall having to remove some engine antifreeze so that the thermostat
housing can be removed (the cam belt cannot be replaced) - just enough that
it won't drain out when taking the thermostat cover off.

Key steps include making sure that the engine is rotated to TDC (top dead
center - no. 1 piston) before taking everything apart.  Note also that there
are markings on the camshaft gears and crankshaft pulley for alignment
purposes in case anything shifts.  And if all else fails, hit the Workshop
Manual - in fact, you might want to read (study) it before you begin.  In
fact read the manual careful - after all I'm just writing this off the top
of my head......and likely missing something.....

FURTHER:

Be very careful....  I'm looking at a crankshaft (more likely a scrapyard
engine) replacement soon.  After looking through the Miata.net
correspondence etc., combined with my own experience, I am relatively sure
of what is happening.

The groove for the woodruff pin (which holds the cam belt pulley in place)
has a slight rounding of the groove at the engine end.  I'll try to
illustrate here with a side view of the pin - the rounding is at the base of
the pin groove at the end closest to the engine.

                                          __________________________________
___________________
                                          |
|
        ENGINE                   |     (note lower left)        WOODRUFF PIN
|   FRONT OF CAR
                                           \
____________________________________________________|            

This is likely due to manufacturing processes/methods.  I believe the pin
also has a slight rounding at one end at the corner corresponding to this
(mine was destroyed) ensuring a proper fit.  If this is not installed
correctly, the pin will not slide into place like it should.  The pin will
likely stick out a little bit - obviously not too noticeable.  Due to the
location of the bolt and pin this may not be immediately obvious.

What happens next is that the pulley bolt is torqued on but does not
actually tighten the pulley properly because the pin has not slid back far
enough.  The bolt stops at the pin and perhaps the other side of the pulley.
When the engine is running, forces due to belts, pulleys, valve train,
crankshaft etc. act on the loose pulley causing a slight movement.  The
resulting friction begins to eat away at the metal surfaces on the pulley,
crankshaft, woodruff pin and the pin groove.

My pulley and crankshaft are actually worn egg-shaped.  The damage results
in a loss of performance (due to retarded valve and ignition timing the low
speed acceleration is poor - the higher speed power is down also but not as
noticeable).

Mine has not broken off (yet) and I've "rigged it up" for the time being
until better weather and finances come around (been a rough couple of years
complete with a couple of moves due to career moves, economy etc.....).  A
little bit of machining, ingenuity, and extra woodruff pins (keys...) and
old feeler gauges sacrificed for the greater good have resulted in the
engine living for close to 40,000 miles since the fateful work being done.
I know this is "mickey-mousing" it but it is the best choice I have at the
time - besides we have another back-up car so I can put off the inevitable
for the time being.

Anyhow, I'm out of time and outta here!

Cheers






Reijo Silvennoinen    rsilveno@kootenay.awinc.com
'90 Mariner / MCA #36633
Cranbrook, British Columbia, Canada