Connecting rod failure, a true mystery

I have a 2014 Subaru Forester purchased from dealership as certified pre-owned at 60,000 miles. All maintenance and oils changes have been up to date. I had a recall and oil change done at the dealership two weeks ago. I was driving home over a small mountain range (30 or 40 miles at about 1,500 ft) that I went over earlier that day, but opening the throttle uphill started sounding funny. 5 minutes later, I pulled over and the engine sounded horrible. There was no oil leaking when parked for hours waiting for the tow truck and was towed back to the dealership. I got a call today saying the connecting rod failed, and there was no oil leak with full oil. I am under warranty and they will end up replacing the engine but I would like to know how this happened? Certified pre-owned means all oil changes/ maintenance was done on time at a Subaru dealership by the previous owner, so I’m stumped.

It’s a machine.

Machines break.



Agree with Tester.

Disagree that certified pre owned means oil changes and proper maintenance were done. I would trust documentation of the maintenance. Dealers inspect used cars and the ones that look good and have the best chance of lasting through the warranty get the certified sticker, the lesser ones go to another part of the lot or to auction.

BTW great that Subaru is standing behind the car and making it right


Sometimes the regularly scheduled oil change interval is not good enough. There is a severe service schedule and all cars fall under that. It’s not just miles driven. It’s time, type of driving, moisture in the air, dust, etc.

CPO may mean little or nothing. The previous owner (as with many drivers now) likely never raised the hood to check the oil between oil changes. Running chronically low is an engine killer. If it spun a bearing or seized the rod on the crank journal then neglect would be the cause of that.

Even if someone went through a full CPO checklist they have no way of knowing what has been going on inside of that engine before it was sent back for the inspection. It’s strictly wishful thinking.


Anything made by humans can fail. Sometimes quietly, sometimes spectacularly. If connecting rods never failed, new ones wouldn’t be stocked on parts store shelves.

You’re very lucky you have a warranty to buy you a new engine. I’d be counting my blessings.

Says who.

For a Subaru, it just has to pass this checklist

Consumers Research and Motorweek both say you should have the car inspected by your mechanic before buying it, even if it is a CPO.

I was using a lawnmower back in the 1950s when the engine just stopped. When I pulled the starter rope, there was no resistance. A disassembly of the engine showed that the connecting rod had broken. The mower had been well maintained and was not under load when it happened. I saw the same thing happen with a neighbor’s lawnmower several years later. Both mowers had Briggs and Stratton engines. Now there are millions of push mowers with these engines. I am sure that s fraction of a percent have connecting rods break.
When I was in high school, the service manager and head mechanic at the small DeSoto/Plymouth dealer wanted me to see an engine that they had removed from a 1958 Plymouth station wagon. The crankshaft.had broken. He asked me what I made the crankshaft break. I didn’t have that first clue. I asked him what might have caused the crankshaft to break. His answer was “Things happen”. (It wasn’t our car, fortunately.)
Some years later, I saw a crankshaft that had broken from an engine in a 1956 Plymouth. It had broken at the same throw as the first engine I had observed. These were Plymouth V-8 engines, and were known to be rugged engines. I guess sometimes things happen.

Had an axle break, at the break you could see there was a flaw in the metal. Stuff happens.

But, with some engines, they seem to have a habit of happening too often.
Many years ago, I knew a guy who bought a new Austin Marina coupe, circa 1976. It was a very nice-looking car, but its styling was its only good feature.

When the Austin was a few months old, the crankshaft snapped. The repair was made under warranty, and then it took… maybe… six months before the new crankshaft snapped. I think that BMC had a bad quality control program already, and more than likely, their crankshafts weren’t properly hardened.

The dealership gave him a very good trade-in value for that cursed Austin, but–unfortunately–he applied that value to the purchase of a new Plymouth Volare. The crankshaft in the Plymouth never snapped, but that lemon almost killed him a few times, due to its habit of stalling under load. When your engine stalls on the entrance ramp to the Interstate highway, it can be a white-knuckle experience.

And then, there were the rust problems that ate-away the Volare’s front fenders after 4 years…

yet there are quite a number of folks who has a nostalgia for the 50+ year old cars… as grass was definitely greener at a time :slight_smile:

@VDCdriver. I agree. There were some cars that had problems right from the day they left the showroom. Rust problems plagued the Volare and also the mid 1970s Honda Civics.
I once considered buying a Plymouth Volare. It even had a good rating by Consumer Reports. It had quite a bit of rear seat passenger space. The university where I was on the faculty had some Volares in its fleet. I drove one to a conference 60 miles away. It ran o.k. but it felt tinny to me. It really didn’t seem much better than the 7 year old Ford Maverick I was driving at the time.
You are right. There are some problems that plague certain model years of cars. There are also unusual problems.that may not be a.common problem.

That’s why I’m glad I drive a 58 year old car. Whenever I need a reminder of how much cars have improved, I get in my wife’s 2019 Hyundai.

my first car was ~5 year older than I was at the time… and while it was fun and might be fun to have it for a spin 30+ years later… I would not want that as my daily driver

I don’t drive more than 2000 miles a year anymore, all of it local, so it works for me and makes me smile!

I’m not there yet, @old_mopar_guy :slight_smile:
still adding low-5-digit on odometer annually

Glad it worked out for you with the warranty support. When my 2.5-liter legacy died at 11K miles in the 1990 it was also a con-rod that killed it. Your post illustrates why I buy Subarus but never recommend them to anyone who own them outside of the warranty period.