updated 5/15/02
(Name withheld by request)
My question is how where these cars driven prior to the gear/sprocket failing?
I think a lot of people bought these cars thinking they are designed to be
torched and beat on. Ford builds mustangs for that. Ford built these things for
the person who wants to feel like he has a fast car, but can lug kids and old
people around too.
Ford didn't stop selling the option because of the engine problems, they stopped
because so few where being sold, The boasting V8 was unimpressive in the shadows
of the competition. Not to mention, for the same $ you could get a crown vic
with a 4.6, police suspension, and more room from the same dealership.
The Phenomenon your speaking of (in my own opinion) wouldn't be specific to ford
sho motors. It is a problem experienced by a lot of overhead cam engines driven
very hard.
If the car was constantly full throttled since it was new, the gear could easily
break by 20k miles, and ford would warranty the work. Not too many people drive
their new cars like that. So the problem usually occurred after warranty ended.
That's probably why ford denies the problem.
The truth is, that with any performance rated car, from a sho to a corvette,
there are going to be people who do buy the car and beat on it from the time
they get it, until they break it. Then when it breaks, they act like it
shouldn't have broken.
But any real mechanic knows that if you full throttle anything all the time, it
will eventually break.
The cam sprocket transfers a lot of torque to the cam-a large mass. Often, the
gear is made of plastic, where all the other components are steel, and is a weak
point in the valve train. This is not just a problem with fords.
After a lot of abuse, teeth on the gear can break off, causing the valve timing
to slip. At worst, the gear completely shatters at high rpm, and the cam stops
after the chain binds up and strips the lower gear too. In this case, if the
engine is not a free rolling motor (meaning that if the crankshaft is not free
to rotate when the camshaft is not rotating), the pistons will hit the open
valves, bending, or most often breaking them, and usually destroying the piston
and sleeve. High grade cam gears are a no-brainer when building high horsepower
engines. Sure, ford should have made this gear stronger, but shouda, woulda,
coulda costs a lot.
same thing happened to my co-workers BMW M3. Cost him about 16k. eight on the
first hi-po motor that lasted him 13k miles when the ALUMINUM gear literally
shattered. And, eight to build it again after the gear failed. The gear had
about 80k miles on it because when he had his motor rebuilt the first time he
didn't replace the cam gears. He drives his car like it is a race car.
My advise is depending on how you drive, and the mileage of the car you bought,
it might be a good idea to replace the gears (and chain while your there) before
they have a chance to fail-if it has over 80-100k miles on it. That would be a
costly, of course. But a engine would cost a lot more, if that is the only fix.
The history of the car...who owned it, how they treated it is important
obviously. if you think it was treated nice, and for the most part your a
average driver, then I would say not to worry about it.....But if your right leg
spasms every time the light goes green, you might want to invest in a new gear.
Hope this mini essay helps a little...
(Name withheld by request)
Tim, it seems to me that the individual that wrote the mini-essay "off
the record" (4-26, V8SHO)- "the reason the V8-SHO motors cam sprocket
fails", is not very familiar with the SHO motor design or the specific
numbers (mileage, age, demography or quantities) on these failures.
First, our cam gears and the shaft itself are in fact made of steel, not plastic
or aluminum as suggested in the essay. It is of the same design as the newer
Mustang motors of which better then 90% of are driven much harder and more
frequently at WOT then the SHO. I have seen little in their list's postings that
deals with any type of cam issues other then the adjustments, grind and timing.
Why I ask do the Mustang motors with multi-overhead camshafts, driven hard from
day 1 not fail as the SHO? Or does Ford know something that they could share to
let us know that they have a greater then 10% failure of cam sprockets on the
Mustang engines? Consider this, the Cobra motor cost less then the SHO motor. I
have not read that the Mazda, Honda or Nissan's succumb to the same sprocket
failures even though a bulk of their motors are double-over-head cam motors and
mounted in sport-sedans and coupes that are driven hard. I would very much
invite the author to submit the documentation of the "other" overhead
camshafts experiencing the same sprocket failures.
In response to the profile or demography of the people that have experienced
this failure, I know of at least 3 failures to cam sprockets here in Ft. Smith
that occurred to 2 old ladies and a very conservative older gentleman. None of
these people had driven their cars in the manner the essay author described as
reason for the engine failure. The older woman had her's repaired at 38,000
miles as she recalled. Then there are others who have flogged their car from day
one with no ill effects with nearly 100,000 miles.
This list is not an exception or anomaly or pervasive to the trend of the
failures, but rather a limited, and I feel that needs to be stressed, A LIMITED
collection of the knowledge to how many have actually failed. Of the close to
20,000 V-8 SHO's produced, we have only around 500 of them posted to this group.
Many, many more SHO owners know nothing of this list, the NHTSA data base or
anyway to be heard since our production numbers don't even show up as a blip on
the radar to one of the top ten largest corporations in the world, Ford.
I would hazard a guess that the person that wrote the essay is in fact a
warranty issue or customer service Ford employee with very little if any
engineering or metallurgical design training. If they did, I would at the very
least feel we would have received an explanation as to why technically this is
in fact the only automobile engine to have the cam sprocket not
"shatter", "break off" or "fall off" but just have
the slave sprocket loose bonding to spin free on the second most important
rotational component in the motor. Then to allow this design to cause
catastrophic damage. The concept that the "large mass cam" is
responsible for this failure would be in direct contradiction to the design by
not attaching the gear to the camshaft by the usual tried and proven methods of
either a bolted flange incorporated into the casting itself or to the primary
drive sprocket. I would also expect to have it explained why this problem does
not occur on the other Ford performance engines of similar camshaft design.
So this is what a "possible" Ford response could be expected if they
were to supply any acknowledgment that this problem really does occur?
That would be very disappointing from such a World Class Corporation.
Carter Fujibayashi
'97 ES
Greenwwod, AR.
Cam sprocket failed November, 2001 at 94,000 miles