Interesting fun fact on fatigue; As a material is cyclically loaded, the fatigue strength is reduced (The more loadings, the lower the breaking strength). As one might expect, different materials have different fatigue characteristics.
With Aluminum, it follows the principle above, eventually to the point where even a very small cyclical stress will eventually break the aluminum. This is one of the reasons why inspections on aircraft are so important.
With steels and irons, however, they follow the basics above but have a bottom limit. This means that if you design a steel part that’s loaded at a stress level below this threshold, it will never break because of fatigue.
That is interesting, Joe.
Your boyfriend, who apparently destroyed your engine by running it out of oil sounds like a middle schooler (nothing is ever their fault either). However your incessant multiple posts to get ammunition to prove what a doofus he is are getting mildly annoying. And the Cutlas Cierra doesn’t sound like it is worth $1250.
Lastly, a safety inspection is only interested in spotting the things that will kill you or someone else, it doesn’t care at all about the things that will cost you money or lead to failing a safety inspection next year.
Someone should have opened the hood two weeks earlier when you heard the strange noises from the engine. If you can’t get your SO to check your oil you may have to check it yourself. Don’t let your next car run out of oil, old cars need to be checked frequently.
I’m not a metalurgist, but I don’t buy “metal fatigue” as a cause of failure of a motor. Metal is pretty tough stuff and in general metal last forever. Wear of metal parts due to usage or lack of lubrication I can accept, but in general metal is metal and it doesn’t change over a short time and 20-50 years is a short time as far as metal is concerned.
Metal fatigue is tested by bending a strip of metal until it breaks. So, take a strip of tin and bend it 90 degrees repeatedly. If it breaks after 10 bends that is the standard for that particular metal. Some metals will break faster and others slower in the same tests. Most of the wear in an engine isn’t subject to these kinds of forces and therefore metal fatigue isn’t really an issue. Someone is blowing smoke up your a–. And trying to use “metal fatigue” as something you can buy into. This is a bogus in this instance. Such a thing as metal fatigue exist, but it isn’t applicable to this case.
Personally, I’ve never seen a case of metal fatigue engine failure. I did see a case where an aged connecting rod broke on a 40s era Indian Chief motorcycle but the point could be made this was rider stupidity rather than a metallurgical fault.
He was doing a late night, high speed run with 2 Harleys and the sidevalve Chiefs were simply not designed for high revving, much less sustained high revs. The front connecting rod broke under the wrist pin and proceeded to cut the engine cases apart.
I think metal fatigue is a bigger item in the suspension system. Lug nuts, springs and other components can easily render an older car less safe for towing and carrying at it’s rated capacity. Why do older ars pull to one side, sag and literally, have their wheels fall off…metal fatigue. Frame flex in older pickups is generally why box frames have distinct advantages. Unfortuntelly, riding around with light loads using trucks to commute with has put manufacturers in a bind making their frames more compliment as the norm now, rendering them less functional later in life. So, use has as much to do as maintenance with metal fatigue. I would guess that driving a car at higher rpms would do the same to car motor components and maintenance would have less effect.
But, in general, we focus too much on the condition of a motor which can be more easily replaced then body parts when it comes to metal fatigue, use and maintenance. The motor world is upside down. It’s safer to take care of your body as well as the motor in considering metal fatigue ( or corrosion) then talking about or maintaining or obsessing about the motor alone.
Metal fatigue is a byproduct of changes or deterioration to a metal’s grain structure due to stresses in application. Like bending a piece of metal back and forth until it breaks. In modern engines it’s pretty well been eliminated due to modern design technology and melallurgy.
Dodge600, the reason low oil pressure usualy develops is due to wear. Oil pressure is created by the pump pushing oil through small spaces like those between the main bearings and the crankshaft surfaces. That creates a pressurized barrier for the crank surfaces to ride on, but as these surfaces wear the spaces become larger. As the spaces become larger, it becomes more difficult for the pump to maintain suffcient fluid pressure. Low pressure can result, preventing oil from getting providing those all-important fluid barriers.
I tend to think if a major engine component breaks, it was either due to neglect, manufacturing defect, or design error. I did see two crankshaft failures on Plymouth V-8 engines. One Plymouth was a 1956 and the other was a 1958. These crankshaft both broke at the same place. These events occurred in the early 1960s and I saw the cars in the service department of our local Desoto/Plymouth dealer. Supposedly, both cars were well maintained. I tend to think that this was a design error or manufacturing defect. I don’t think it could be attributed to metal fatigue.
One case of metal fatigue occurred on Volkswagen Rabbits built in Westmoreland, PA in the 70s. That pant has closed since. These models had A/C as an option and the Germans just hung another pully on the crankshaft, which was not under-designed; Europeans models of this car just did not come with A?C.
There were many “fatigue” failures of the crankshafts, mostly because it was under-designed.
I have not heard of camshaft caps breaking off. Cam journals out of line will break the cam but not the caps. If the bolts broke, I would guess that someone over-torqued them. If the caps broke, I would look for scoring on the cap and cam indicating oil starvation as RodKnox suggested.
As for the second question about the end-cap falling out, is it metal or plastic? Pressure build up in the crankcase from excessive blowby in an old engine, or a blocked PCV system, or both, can push out that cap. A plastic cap will have shrunk over the years making it loose.
By today’s standards, 176k is not a lot. I paid $8k for a car with 175k on it and have since put another 115k on the car. However, an '87 Dodge with 176k miles has outlived the vast majority of its siblings.
I don’t get the bit about VW Rabbits and crankshaft fatigue as I worked for VW during the late 70s and 80s and never saw this happen except in a few isolated instances.
In those isolated instances, there was always a somewhat recent service history which involved removal of the crankshaft pulleys.
If this was a common problem I never saw or heard of it during lunch or break time war stories and note swapping.
None of the Westmoreland cars were actually built in PA. They were just assembled there from parts that were Hecho en Mexico.
@ok4450 The only ones that suffered this fate were ones with air conditioner. The majority were sold without air.
It’s still news to me because the majority that entered the shop did have A/C and I even did a few A/C installs on them. It’'s OK and A/C is pretty much a necessity here.
The only problems we saw were related to the rubber mounting of the compressors and which was not one of the better ideas. The same could be same for SAAB’s rubber mounting of alternators.