Mazda 2 1.5d engine failure

[lemonslap]

Hello all, my 56k mile mazda 2 had engine failure this weekend. Always serviced every 10k miles/10 months with the last service 600miles ago using Millers EE performance 5w-30 oil as always. The failure happened without warning at 2500rpm at full throttle in 3rd gear up a slip lane, I actually thought the gearbox had gone at first as there was a loud noise (similar to forcing a gear to engage) then bang, but the engine was running on 3 cylinders after this. I managed to limp the car 3 miles to the next motorway exit. Oil everywhere so I knew it would be terminal.

I recovered it back to my workshop and this is what I found:
Bottom of the sump:


Cylinder 4:


Big end bolt, other snapped:


Small end:


What do you all think caused it?

[gazza285]

Where's the piston? Seized in the bore?

[lemonslap]

gazza285 said:

Where's the piston? Seized in the bore?

Thanks for the reply gazza. Just about see the piston is this photo, didn’t try and move it to be fair. The bottom of the piston is missing where the gudgeon pin was. Still not sure where the rest of the connecting rod went! Now feel very sorry for the car following me…

[lemonslap]

More pictures:

[lemonslap]

[stevieturbo]

Nicely done.

Oil and servicing would seem largely irrelevant here.

It would be interesting to see the piston and if it has somehow seized in the bore.

Rods etc break, bolts break, although more unusual is it has ripped the small end apart, and the pin out of the piston. I've seen a few rods break etc, but generally the small end doesn't break.

Is this engine renowned for failures ? you may just be unfortunate.

[Grayedout]

First look I would say the piston seized, for whatever reason, the little end then shattered and then the conrod got smashed around and broke the big end.

[Olivera]

Everything is absolutely humped, so you're unlikely to ever get a definitive explanation of what broke first.

[Tony1963]

Olivera said:

Everything is absolutely humped, so you're unlikely to ever get a definitive explanation of what broke first.

There are people working for the manufacturers whose job it is to investigate engine failures if there’s a large warranty claim. They’re very good at their job, but I doubt they’d be interested in an out-of-warranty failure. “Disregard the impossible” was one tip the guy I met told me. He said that because many people try to explain failures by saying that impossible events have occurred, often to fit in with their own theories.

I think the above explanations based on piston seizure sound plausible.

[lemonslap]

Thanks all.
Not heard of this happening to one of these engines before, they are relatively rare as only made between 2015-18.
I’ve owned it for the past 2 1/2 years and to be fair it’s been a massive pain in the backside with the DPF. One of my mates has brought it off me and is going to replace the engine as I haven’t got time to mess about with it, once the old one is out I will try and grab it to do a bit more autopsy. Shame as when working , it’s incredibly economical. Also I just fitted new goodyear tyres, front brake pads during its service and even has a full tank of diesel!

[chrisch77]

My first though looking at that is to ask if the engine has ever taken in water and hydro-locked? It’s all too common that people think they have got away with driving a car through a flood because the engine is able to restart at some later point.

If a cylinder takes in water whilst running, then a bent con rod is a common result and the engine becomes a ticking time bomb waiting for either the rod to fail from bending fatigue or the imbalance to cause premature failure of the rod bearings.

[lemonslap]

chrisch77 said:

My first though looking at that is to ask if the engine has ever taken in water and hydro-locked? It’s all too common that people think they have got away with driving a car through a flood because the engine is able to restart at some later point.

If a cylinder takes in water whilst running, then a bent con rod is a common result and the engine becomes a ticking time bomb waiting for either the rod to fail from bending fatigue or the imbalance to cause premature failure of the rod bearings.

Thanks Chris, not during my ownership, i’ve had it since 24k miles and 2 years 6 months. Haven’t found any evidence of it previously as i’ve changed thr air filter myself during servicing.