Check that Belt!

Broken Belt Causes Holes in Two Cylinders

Jeff send me the following story of how a broken belt caused damage to
two cylinders after the owner (not Jeff!) continued driving for some time with a
broken belt.  This is the only time I have actually seen a photo of the
damage caused, but not the only story I know of.   A couple of years
ago I witnessed a 964 owner’s engine ‘blow’ on the track.  Heard later from
him that is was due to a broken belt.

 

bullet It all started at a Driver’s Education event in May 2001. The car had just
come off the track, a ’93 964 with about 80k miles on it…the owner left it
idling for awhile, to “cool down”. Jeff noticed it was ticking quite a bit,
and when he brought it to the owner’s attention, the owner replied that a
local shop technician had noticed it as well and said that it was likely the
valves were out of adjustment.
bullet Jeff had just purchased his 964 and wanted to compare performance being
that his 964 was stock and the other one had a chip and an intake
modification. The owner of the other 964 welcomed Jeff to drive his around the
paddock. Although this 964 had some modifications, it seemed that it was
lacking power. Jeff attributed this to the fact that he had just installed a
lightweight Cup clutch/flywheel, and it made quite the difference in
acceleration.
 
bullet Within a week or two, the owner took the car to an independent shop where
they adjusted the valves and basically performed a 60K service.
 
bullet After this service, the engine still had the “ticking” sound, but it
seemed that the car ran better.
 
bullet The owner went on to attend two more Driver’s Education events after the
valve adjustment. During the first session of the second event, several corner
workers (flaggers) reported a LOUD ticking noise coming from his car as he
came by each flagstand. He was black flagged and he came in the pits…he was
notified that there was something definitely wrong with his car and he needed
to get it off the track. The owner also realized that it had been lacking
power for a few laps.
 
bullet He retired the car for the weekend, and had it towed to the repair shop.
They pulled his engine apart, it needed two heads and two cylinders. The
pistons checked out okay.
 
bullet It seemed that no one had a clue of what caused the damage to the
cylinders and heads, until someone thought to check the distributor belt…and
wallah! It was BROKEN, and apparently had been for quite some time.
 

This is a prime and extreme example of the damage that could be caused by a
broken distributor belt. In this case, the secondary rotor had obviously stopped
it’s rotation on cylinder #5, the pictures provided are of #5 and #6. The
detonation was so bad that it actually burned a hole from cylinder #5 and into
#6.

The owner took this as a chance to upgrade and replaced all the pistons and
cylinders with a good used set and had 3.8RS heads installed, with custom chip,
exhaust and intake mod.

This engine now puts almost 290hp to the rear wheels! Now that’s what I call
turning lemons into lemonade!!

 

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