I can’t imagine a frozen Compressor stopping an engine unless it was idling. No belt is strong enough or tight enough to stop an engine sudenly if running down the street or road.
I understand your skepticism, Elly. But I’ve seen so many things that I would not have believed over the years that I accept the possibility of the bizarre.
You may recall that when NASA was investigating the Challenger disaster, the engineers said there was no way the foam from the suttle surface could have penetrated the wing. So they set up a test. Fired a small piece of the foam insulation into the leading edge of a duplicate wing at the velocity that they calculated the piece in the video would have hit. To everyone’s surprize, the foam blew straight through the wing leading edge leaving a hole the size of a basketball. Everyone was stunned.
Reality often surprizes us with the unexpected. This may be one of those cases.
I saw that test that NASA did. One engineer thought it could happen…and he spent a couple of years trying to convince other engineers that it could happen. F=MA. The mass of the object was extremely light…but the object was moving so fast…the F (Force) was enough to go through the wing. The piece of foam they used weighed just a few ounces…but was traveling at a few thousand miles per hour.
"I can’t imagine a frozen Compressor stopping an engine unless it was idling. No belt is strong enough or tight enough to stop an engine sudenly if running down the street or road. "
Elly, something tells me that OK4450 has a few more hours under the hood than you do. See his story about the Nissan above. I can’t think of why he’d make up such a thing. Imagine what you will.
In this case, there was no need to stop the engine completely or break anything. If that compressor seized up, the crankshaft took a jolt. That’s true even if the belt broke.
I’m not convinced that its the story. But it is not outside of plausibility.
It wasn’t that the object was moving so fast as it was the difference in speed between the wing and the foam piece at the time of impact. After all, it departed the shuttle assembly so at the time of departure, they were traveling at the same high rate of speed. The shuttle flew into the piece as it broke free and decelerated due to air resistance. I suspect what may have surprised the engineers was two-fold; the rate of deceleration of the foam piece (creating the magnitude of speed difference) at the time the shuttle flew into it and the structural integrity of the foam was mis-calculated. Hind sight is always 20-20 but it’s hard to believe they didn’t mock up this worst case scenario beforehand. I suspect they did attempt to model it but mis-calculated what “worst case” constituted…why emprically test? Our models show it isn’t an issue! My bad…
Edit, so I don’t get flagged for off topic, I’ll say that I’ve had first hand experience with V belts that were in new shape having enough grab in the pulley groove to present this kind of scenario. Never seen a serpentine belt hold up as well but like was mentioned, if there was wear in the timing components, anything is possible. It might not take much resistance at those forces to do some real damage.
NOVA has a great on hour documentary on the investigation of the Challenger disaster. Mike’s description of the scenereo, that one dissenting engineer struggling to convincethe others, is exactly accurate. The belief was that the foam would disintigrate upon impact. It went through the wing intact. There was no miscalculation invloved, just an incomplete mathematical description of how the foam would react.
Physics, largely the science of mathematically describing how matter acts when confronted with specific forces, is pretty imprecise. We’re good, but we’re often surprized. I believe that there’s a whole lot that we don’t know yet.
Regarding that story about the Nissan with the seized engine I would reinforce in that particular case it did not even suffer a compressor failure. It was the seizure of a small half dollar sized bearing on the idler pulley and the belt was almost new.
Even with a 1/2" drive breakover and cheater bar that engine would not budge nor would the belt even slip on the pulley no matter how much force was applied.
The gentleman who owned that car was stunned, and refused to believe me, when I called him only an hour or so later and told him the car was ready to go with only a bill in the low double digits instead of well into four.
Those belts are far tougher than one might think. Harley started using comparatively small rear drive belts on their motorcycles quite a few years back. Even locking the brakes up at speed on a near 600 pound bike loaded down with 400 pounds of passenger and gear won’t snap them or cause them to jump teeth.
Again, the crank jolting is theory but if there were looming problems in the valve train setup who knows what would happen.
The foam thing is about the Columbia.
The Challenger was the cold rubber o-rings.
The official stories are always what people should have known. But the thing is that given the complexity of these systems if we demand complete predictability we will never have them. In the Challenger case, the notion that people “behaved badly” by going on with the launch despite warnings about the o-rings is one of those classic 20-20 hindsight stories. O-rings were damaged ever single time a shuttle launched. Everyone knew this and everyone knew that cold mattered. All of these things take place within parameters of “accepted risk.” The launch was actually ok by normal operating procedures. The foam story w/ the Columbia was similar. Losing foam was fairly routine. Damage from losing foam was fairly routine. “Could have been prevented if…” stories are presented after the fact as rational reconstructions that are out of touch with day to day reality of getting things done. At some point we’re going to have to come to terms with the fact that we now produce systems that we can’t fully understand or control.
I alway get names confused. Sorry folks. It’s old age.
Both were tragedies, but the Challenger was appalling. Every engineer involved told them not to launch. That tragedy absolutely should not have happened.
ok4450, I have a terrible time beleiving this—Even with a 1/2" drive breakover and cheater bar that engine would not budge nor would the belt even slip on the pulley no matter how much force was applied.
cigroller, You are right “Elly, something tells me that OK4450 has a few more hours under the hood than you do. See his story about the Nissan above. I can’t think of why he’d make up such a thing. Imagine what you will.” I am just an old shadetree mechanic who did all my mechanical work for around 55 years. I also did some repair for others. Cars have been a hpbby of mine and I like to keep up with the latest trends. Now I can’t work on these new computer controled machines. However, many old facts and problems still exist. I have been around long enough to know that the theory of a compressor freezing up and slam dunking an engine is pure hochey. If someone can prove this to be the case, I will admit I am wrong, on here, in big, bold letters.
some day I am gonna post on here some of the stupid remarks that have bveen posted in the past. Example: “Ford finally found out how to make a 4 cylinder engine run smoother by spacing the firing of the cylinders closer together.”
"A torque Converter will never "reverse drive an engine " And we werent talking about turning the engine backwards. Talking aboutaen engine holding back a car on a downhill.
Believe it or not, the story is true. The guy had this car towed in from 25 miles out because he thought the engine was seized. The car belonged to his daughter, was purchased brand new, and the father had changed the oil in it every 3k miles. This car only had about 50k miles on it and was as new both in and out.
The car was dropped off at my shop along with a note. After examining it (starter motor would not budge it) something sounded odd to me. The engine was full of oil and appeared to be well taken care of.
Calling him on the phone he said it had never been run low on oil, used no oil, and was running like a new car right up to the second it froze up; which was when she backed out of the driveway.
The only thing I could think of was some freak metallurgical failure if what he was telling me was the truth and told him I’d get back with him when the motor was apart. He didn’t care. His attitude was that the motor is wiped, rebuild it, and hang the cost. He just wanted it fixed and said that I didn’t even have to call him again until it was done…
That evening I had a chance to look at it closer after failing to budge it again with the cheater bar and socket on the crankshaft bolt. Closer examination with a flashlight revealed a slight purple tint on the idle pulley cover and the light came on. I loosened the idler, removed the belt, and voila: it fired right up and ran like a sewing machine. This was followed by replacing the bearing in the idler and reinstalling the belt; about a 15 minute job for the entire repair.
His reaction was utter disbelief at first because he also was stunned that an engine would lock up over somethng so trivial.
I actually ran into something like this another time but for the life of me I cannot remember what type of car it was. Vaguely, I think it was a 4 cylinder Ford of some sort.
There was no miscalculation invloved, just an incomplete mathematical description of how the foam would react.
Right…He wasn’t wrong he just didn’t know the right answer. Makes as much sense…
I just had another thot. If that car was a manual shift car and the engine locked up, he must have slid the drive wheels also. (Never happened).
"MikeInNH March 7 Report
I saw that test that NASA did. One engineer thought it could happen…and he spent a couple of years trying to convince other engineers that it could happen. F=MA. The mass of the object was extremely light…but the object was moving so fast…the F (Force) was enough to go through the wing. The piece of foam they used weighed just a few ounces…but was traveling at a few thousand miles per hour. "
Sure about that? The shuttle itself was traveling less than 2,000 miles per hour, so how did the foam get the additional one or two thousand miles per hour of speed relative to the shuttle? And in the testing, how did they accelerate a piece of foam to such a speed? I’m pretty sure it just knocked off heat-resistant tiles without going through the wing.
Ultimately, the testing was completed within a matter of months, and the foam issue was the main focus of the investigation from the beginning. The final report was issued six months after the disaster. As someone else has mentioned, the Columbia disaster.
TT, to my mind a miscalculation implies correct and complete formulas but an error in using them. In this case I believe the formllas that described how the foam would react were incomplete. The former is an error, the latter a lack of complete knowledge.
Sadly, the result was the same. Good people’s lives were lost.