How
to Bend Valves in a Nissan VG30 EngineHow
to Bend Valves in a Nissan VG30 EngineEver
wondered what would happen if the Timing Belt snapped in your 300ZX? Wonder
no more. This article contains some pictures showing what happens when scheduled
maintenance is not adhered to.
It’s
not that owners would deliberately neglect their car, but rather, anyone can
be innocently caught out by buying a car with a tempered odometer.
Remarkably,
the car from which these engine pictures were taken, came through pre-purchase
tests with flying colors- with excellent scores for engine compression, transmission
performance, steering, suspension etc.
On
the fateful day, the car’s owner, hearing a flap..flap..flap.. noise coming
from the engine. As the car cruised up to within 200 meters of a garage, and
while the Z was shifting gear, there was a sudden whizzing sound, and the engine
stopped dead. “Uh..oh”!
The
worst fears were soon realised - the camshaft timing belt had snapped, and removal
of the cylinder heads revealed 24 bent valves. Each valve had hit the piston
with such force that the valve stem had bent right over.
Remarkably, the pistons were not cracked, but were heavily scored by the valves hitting them.
So
how much is each valve? Well, for starters, they are supplied ex- Japan. At
around $80 each, that makes it $1920 for valves alone. Ouch! At this stage of
the process, a second hand engine seemed a good alternative
Thirty
working hours later the car is back on the road again. “The engine I removed
has done alot of work... possibly 200,000Km or more.”said the mechanic.
Replacing an engine with a used or rebuilt one will generally cost in the vicinity of $6,000- $7,000. Work is specialized, and requires a very high skill level. If you are not 100% sure your odometer has not been tampered with, its good insurance to change that timing belt at a cost of around $400-$500.
Pics
(Click for full-size):
Yes, well when you remove the camshaft, the valves are supposed to sit back
in the head, but here you can see how bent the valve stems are. Looks like a
mushroom farm.
What else can you say?
