(ENGINE RUNS!!!!) Broke down my engine block and changed the engine

[jvictormp]

Originally Posted by 11_335D

Bingo on the "rodless" piston comment, I have the same view as you. I'm not sure why some "members" are critiquing my assessment when I've been pretty close on potentially finding a root cause. I would like to state I am by no means an EXPERT in engine building/failure analysis/mechanical engineering/etc but I do enjoy building high revving naturally aspirated engines as a HOBBY and have had my fair share of successes and failures. I enjoy contributing to the forum to help others but not to judge others contribution.

jvictormp, Thank you for taking the time to upload all the photos and videos, hopefully a root cause will be identified if not we all learn something from this.

Don't take it badly, it's normal to discuss ideas in the board. You should see when the subject is rod bearings

[jvictormp]

Originally Posted by drrust

Thanks for taking the video. It maybe a trick of the light, but that small corner (semicircular area) may indicate the presence of a fatigue crack. It's hard to tell for sure as much of the surface has post failure damage.

And a fatigue crack would lead us to something?

[drrust]

Originally Posted by jvictormp

And a fatigue crack would lead us to something?

A fatigue crack can slowly grow. Once it gets to a critical size the part can no longer handle the loads and failure occurs. It is usually designed around, but there can be several factors that exasperates formation. These can be surface finish, internal features or residual stresses.

[jvictormp]

Originally Posted by drrust

A fatigue crack can slowly grow. Once it gets to a critical size the part can no longer handle the loads and failure occurs. It is usually designed around, but there can be several factors that exasperates formation. These can be surface finish, internal features or residual stresses.

Nice!

You think that it could have happened during the hydrolock in 2019?

I don't know if I mentioned, but when the injector got stuck open, I turned the engine off, and I remember trying to start the engine after that.

Sometimes it started and ran roughly, sometimes it didn't even turn, making a knock sound, that I don't know if it was the engine itself, or the starter, or even the relay.

And I tried that several times, in an interval of two days, when I decided to tow it again to a shop, where I found out it was the injector.

Maybe that little fatigue occured that day and survived until now?

[Davisca455]

@jvictormp

You said you were going offshore, do you work for Petrobras?

[jvictormp]

Originally Posted by Davisca455

@jvictormp

You said you were going offshore, do you work for Petrobras?

Yes, I proudly do.

[Davisca455]

Originally Posted by jvictormp

Yes, I proudly do.

Small world!
I work for Schilling Robotics.

https://cdiver.net/news/two-schillin...-rrc-robotica/

[jvictormp]

Originally Posted by Davisca455

Small world!
I work for Schilling Robotics.

https://cdiver.net/news/two-schillin...-rrc-robotica/

Nice!!! Your robots have been diving around here. Small world!!

[Redd]

Originally Posted by jvictormp

Maybe that little fatigue occured that day and survived until now?

That is certainly possible. I stand by my analysis. It's clear to me that the rod is bent which can only mean compressive forces, nothing else. The only way to get a compressive force is liquid flooding the cylinder and hydrolock. Since your car was not in a flood, and it was only one cylinder, that only points to injector stuck open.

So yes it is likely that the damage was originally caused by the hydrolock incident in 2019 but the rod only failed now.

[drrust]

Originally Posted by jvictormp

Nice!

You think that it could have happened during the hydrolock in 2019?

I don't know if I mentioned, but when the injector got stuck open, I turned the engine off, and I remember trying to start the engine after that.

Sometimes it started and ran roughly, sometimes it didn't even turn, making a knock sound, that I don't know if it was the engine itself, or the starter, or even the relay.

And I tried that several times, in an interval of two days, when I decided to tow it again to a shop, where I found out it was the injector.

Maybe that little fatigue occured that day and survived until now?

Can't say for sure, your current engine is a mystery with the 2010 block.

[jvictormp]

Originally Posted by drrust

Can't say for sure, your current engine is a mystery with the 2010 block.

I was looking for some signs of a 2008 engine, and couldn't find. All the stamped dates I found were 2011.

I guess this engine was completely replaced some time.

I'm a little curious about the camshafts that showed some signs of oxidation, which makes me think of them being out of engine someday, instead of being an engine closed from factory all of its life. Or maybe I'm overthinking, and the oxidation would be normal even in a factory untouched engine.

[Assimilator1]

Originally Posted by 11_335D

Bingo on the "rodless" piston comment, I have the same view as you. I'm not sure why some "members" are critiquing my assessment when I've been pretty close on potentially finding a root cause. I would like to state I am by no means an EXPERT in engine building/failure analysis/mechanical engineering/etc but I do enjoy building high revving naturally aspirated engines as a HOBBY and have had my fair share of successes and failures. I enjoy contributing to the forum to help others but not to judge others contribution.

jvictormp, Thank you for taking the time to upload all the photos and videos, hopefully a root cause will be identified if not we all learn something from this.

Sorry mate, but despite the few piston contact to valves, their is no way that mild contact with the piston would break the rod, I just think you're wrong. As a tech of many years I've seen far worse damaged pistons from snapped cambelts or slipped chains, and none of them broke the rod, including engines where the valve head snapped off and was embedded in the piston or the head (I'm sure some of the latter may have had slightly bent rods though, but none broke). A rod is far stronger than even 2 valves.

A flaying (broken) rod could have easily pushed the piston back up a little a few times after the valves had pushed it down. Before breaking off further down, as victor said.
No offence meant by me contesting your idea, on the face of it, it might have been a plausible idea.

jvictor and drrust
Interesting stuff, one thing neither of you guys mentioned is that their seems to be a dark patch on the rod shown (which is also on the small end of it) on the photos of post #191, you can see it clearly in the 1st, 3rd and 4th photo. Although it isn't at all on the 2nd, so is it just a trick of the light?
If it really is a dark patch, then that would indicate a fracture some while prior to failure (the dark patch being 'exposed' metal, either oxidising or simply absorbing contaminants. I'm sure drrust will be familiar with that ).
If it is a sign of a fracture, then I think you're on the money victor regarding the previous failure of an injector. As you and Redd said, maybe it (partly) hydrolocked that cylinder, but not quite enough to break the rod instantly, possibly bend it and severely stress it, which sooner or later lead to a crack, and which soon after lead to it breaking.
You mentioned that sometimes it didn't even turn, that sounds like hydrolocking to me, and the knocking you mentioned might have been detonation due to the large amount of fuel causing very high compression.
Did the knocking sound like an old diesel engine knock?
How many miles was it again between the injector failure and the rod failure?

victor - could you take a short film of the small end of the rod's break?

Btw, re the oily valves, I don't suppose the oil breather exits near to cyls 1 and 5 intake??

Incidentally, in some ways this reminds me of an engine I blew up (entirely my fault! ).
About 13yrs ago I had an e36 323i (redline ~6300 RPM), I was driving along a dual carriageway (a highway to US folks ) doing 70mph, I went to change down from 5th to 4th to overtake someone, but somehow I ended up in 2nd!! Needless to say it massively over-revved the engine before I managed to dip the clutch! I saw the rev counter go off the scale beyond 7000 RPM, about 7300 I reckon!, I actually winced expecting the engine to blow up there and then, but it didn't! I thought, wow! I was lucky to get away with that!

But a few months later driving to a nearby port to go on holiday to France (75 in 5th), their was a faint boom and the sound of 'gravel' being thrown under the car, quickly followed by a big plume of smoke behind me, the back end weaving, knocking and the dash lighting up like a christmas tree! (it would happen going on holiday!!).
After I stopped a quick look under the bonnet showed I could see daylight through the block to the floor! (I later found out the rod had snapped in 1/2 and nearly carved the block through!). Interestingly that cylinder had oily valves, although (annoyingly) I never pulled the piston out to see why, but that engine did burn a fair amount of oil, it's replacement used virtually none.
Oh btw, the block was in a particularly bad way, because after I stopped and shut it off, I realised I was stopped in a bad place, the engine was knackered anyway, and their was a layby just 100-200yrds up the motorway. So I fired it back up again and crawled up to the layby! lol (low revs of course).

Anyhow, the point of my story is the rod broke quite a while after the stress 'event', at the time I was doing about 17k/yr, so probably a good few thousand miles.

[jvictormp]

Originally Posted by Assimilator1

jvictor and drrust
Interesting stuff, one thing neither of you guys mentioned is that their seems to be a dark patch on the rod shown (which is also on the small end of it) on the photos of post #191, you can see it clearly in the 1st, 3rd and 4th photo. Although it isn't at all on the 2nd, so is it just a trick of the light?

Not a trick of light, definitely a different surface aspect, but not sure if a dirty path or something. Unfortunately I'm not at home for 20 days, so I can't take more photos until then.

Originally Posted by Assimilator1

You mentioned that sometimes it didn't even turn, that sounds like hydrolocking to me, and the knocking you mentioned might have been detonation due to the large amount of fuel causing very high compression.
Did the knocking sound like an old diesel engine knock?
How many miles was it again between the injector failure and the rod failure?

There was no running with knocking.

When it started, there was no knock, but a rough idle and throttle response (did not move the car, only in neutral).

When it failed to start, the sequence I observed was:

Press start button, hear knock one time, no turn in the crank, no starter noise.

There was about 7000km between injector failure and rod failure. And two track days.

Originally Posted by Assimilator1

Btw, re the oily valves, I don't suppose the oil breather exits near to cyls 1 and 5 intake??

I think the oil breather sits towards the back of the engine, cyl 4 and 8.

Originally Posted by Assimilator1

Anyhow, the point of my story is the rod broke quite a while after the stress 'event', at the time I was doing about 17k/yr, so probably a good few thousand miles.

That's annoying. I thought that a rod, when fatigued, would fail in the next few kilometers.

[drrust]

Fatigue cracks can grow very slowly. All depends on the loads.

https://en.m.wikipedia.org/wiki/Fatigue_(material)

[Redd]

Originally Posted by jvictormp

That's annoying. I thought that a rod, when fatigued, would fail in the next few kilometers.

With stress fractures anything can happen. You basically got 7000 free kilometers on an already damaged rod.

[jvictormp]

I guess there is nothing more to discover on this engine, right?

Can we conclude it was due to injector stuck open, hydrolock, fatigue on rod, and catastrophic failure on rod?

[jp1984]

Originally Posted by jvictormp

I guess there is nothing more to discover on this engine, right?

Can we conclude it was due to injector stuck open, hydrolock, fatigue on rod, and catastrophic failure on rod?

Would it have occurred the same way if the first event had not happened?

[jvictormp]

Originally Posted by jp1984

Would it have occurred the same way if the first event had not happened?

You mean, if the injector had not stuck open?

If we are concluding it correctly, no, it would not. The rod would be as healthy as the other 7 rods, and that engine would probably run more 200,000 miles redlining everyday without changing even a single bearing.

[jvictormp]

Look what I found in my old media! Me trying to start the engine with the hydrolock!

[atopa2002]

Originally Posted by jvictormp

Look what I found in my old media! Me trying to start the engine with the hydrolock!

was expecting to practice my portugues on the idrive

[jvictormp]

Originally Posted by atopa2002

was expecting to practice my portugues on the idrive

I can't give myself to that confort. Need to be always practicing english.

[jvictormp]

About the ARP bolts, let me know your thoughts.

They were installed AFTER the fuel hydrolock, so they didn't suffer the most critical force.

Now, when the rod broke, they did not suffer any force at all, right? Even the rod bearing of cyl 5 was flawless.

I measured them all - can't remember the measure right now, it was about a week ago-, all of them had equal measures, so no yielding.

Should I really spend some time going out to find someone who tests them for fissures?

I'm only buying ARP lubricant, and the ACL bearings.