Blown engine theory

[kmh001]

Mate I am truly sorry to hear about your misfortune and I understand your need for an explanation. I commend the guys for searching for an explanation. But I don't buy the hydro lock theory one little bit, it's fanciful at best. I also think it's curious that no body has asked if the supposed hydro lock was caused by excessive flow from a WI system?

Cylinder pressures will produce the same results, you don't need to have a fluid in there to bend the rods. I don't understand why cylinder pressures are being overlooked in this discussion. Probably because cylinder pressures aren't going to make money for the theorists who have something to sell.

The most useful thing I can add is that I've had the low-rpm high-load studder a few times, usually while cruise control is active. It produces a metallic rattle with a James Bond smoke screen out the back. Perhaps I've been a whisker way from the catastrophic result you had? I don't know, but based on discussions I've had with Mazda engineers in my view it's a software issue and I won't be spending money on any WI or other snake oil solutions anytime soon.

[Cosmic3MPS]

Your comments on WI I think are unfounded as very few cars with meth have blown. I am one of the lucky few . WI is certainly not snake oil and is a technology that goes back to fighter planes in WW2 and the benefits are proven. There is no way in hell the amount of spray going through this system could hydrolock the motor (it would undoubtedly be vapourised once it reaches the cylinder anyhow). Good business is to find the real solution and market that. Those that sell crap and tell lies will disappear quickly. Who are these 'Mazda engineers' and if they have answers why don't they step forward with their theories? They can maintain a cloak of anonymity on a forum like this. OK to sh!t on ideas as long as you can disprove them or have a valid alternative theory.

[kmh001]

You're not the only person to spend money on a damaged engine. I've rebuilt a few blown engines and I've learned a few things along the way. My comments were intended in good faith and I'm sorry you didn't take it that way.

BTW I'm not dismissing the theory of WI. A B52 carries 12 tons of water and burns it all in 60 seconds during takeoff. So what? We're not at war. We should be able to tune these engines without band aids like WI.

[Jmac]

The most useful thing I can add is that I've had the low-rpm high-load studder a few times, usually while cruise control is active. It produces a metallic rattle with a James Bond smoke screen out the back. Perhaps I've been a whisker way from the catastrophic result you had?

High-load low RPM stutter - actually noticed this tonight.
What is the significance? (please enlighten me)

[Nexus]

I am finding the oil control theory fairly convincing myself - the motors are hydrolocking on oil after some kind of catastrophic failure of the oil control / pcv system - oil getting sucked through the engine.

I am struggling a little to understand how PCV valve alone could flow enough oil, how it could fail so completely to do it's job, or where else the oil could come from - I understand that there are two possible routes for it to take as far as getting sucked through goes (?)

The melting around the oil control ring ring land strikes me as just plain bizarre. I have previously read that some US modders with catchcans were catching quite a lot of fuel as well as oil - if they emptied their can and let everything settle there was quite a lot of fuel in there.


So the questions seem to be how is the oil getting up top and how is the fuel getting down below?
Is there any way the HPFP could be causing fuel to get into the bottom end?

That Cosmics had oil all through the cooler and exhaust seems to point in the direction suggested here, and the severe knock with smokescreen described by kmh001 below sounds very much to me like a less severe event without the hole-in-the-block result, which is perhaps made that much more likely the more severe your mods.

... I've had the low-rpm high-load studder a few times, usually while cruise control is active. It produces a metallic rattle with a James Bond smoke screen out the back...

[Cosmic3MPS]

You're not the only person to spend money on a damaged engine. I've rebuilt a few blown engines and I've learned a few things along the way. My comments were intended in good faith and I'm sorry you didn't take it that way.

BTW I'm not dismissing the theory of WI. A B52 carries 12 tons of water and burns it all in 60 seconds during takeoff. So what? We're not at war. We should be able to tune these engines without band aids like WI.

Not sure how I should take a comment like WI is snake oil. More confusing is this post that shows WI is a proven technology (only to be used in war time of course). WI will of course be a useless defence if oil-hydrolock is occurring but that does not negate its anti det properties. It is also not restricted in operation by the Mazda electronics but can be delivered consistently regardless of what the ecu is doing. Add to that cooling and cleaning effects and you have a solid enhancement for FI engines.

[Nexus]

Following thought re: fuel getting into the bottom end somehow

Let's say a certain amount of fuel has made it's way into the bottom end by unknown means - HPFP doing something wack, or however. If it wasn't happening, it wouldn't be in oil catch cans...

Let's say that fuel slowly builds up, perhaps at cruising, until there is a great enough concentration of it that it lights up under the pistons. Perhaps the oil control ring land is the ignition point for this wayward fuel.

If there is sufficient fuel to ignite under the piston, that's potentially going to create a huge crankcase positive pressure.

Could that not account for oil being forced through the PCV patchways, into the intake and from there produce hydrolock?

Piston temps would very quickly increase abnormally because the oil spray underneath that is supposed to cool them is actually an area of ignition.

So pistons start melting and oil is forced through producing hydrolock and the rest is history...No PCV valve failures required, just massively abnormal crankcase pressure.

[Wardski]

I think its great to look at all of the theories.. The hardest thing here is to prove it..

I doubt you'll have any Mazda techies coming forth with info on this, as if the oil theory is to blame for the KA-Boomskies, then this would probably warrant a total recall, and Mazda would have to spend up big on a total engine re-design..

In my mind, I think the oil theory could be a major cause, but I also think its one of many chain reactions to the first action.

I still believe that the rods are being very slightly bent in the first action (but within tollerances allowing the motor to still function for a small period), which then causes the chamber breach, and allowing oil to get past the seals and causing a hydrolock.

Alternatively, unburnt fuel would also be able to escape past the seals into the crank at WOT at low revs. This fuel is then able to ignite under the cylinder head causing enough heat to further weaken and compromise the rods.

Either way, I consider the rods and the head pins to be the weak point in the MZR 2.3ltr engine.

[kmh001]

Not sure how I should take a comment like WI is snake oil. More confusing is this post that shows WI is a proven technology (only to be used in war time of course). WI will of course be a useless defence if oil-hydrolock is occurring but that does not negate its anti det properties. It is also not restricted in operation by the Mazda electronics but can be delivered consistently regardless of what the ecu is doing. Add to that cooling and cleaning effects and you have a solid enhancement for FI engines.

I'm just opposed to WI because it's an inelegant and outdated solution. To take the aviation analogy a bit further, aircraft engine designers stopped using WI decades ago because engine technology advanced to the point where it's no longer needed.

Using the aforementioned B52 example again, with 1940's technology it takes 8 engines, 12 tons of water and copious amounts of fuel to lift an 83 ton aircraft into the sky. Today we have 350 tonne aircraft doing it with 2 engines and a fraction of the fuel. I'd prefer it if we didn't need WI because our developers got with the times and did a better job.

For the guys pushing the limits with race engines WI is fine, but for a daily driver I just think it's an undesirable alternative to better design. That's why I call it snake oil.

I'm also a bit skeptical of the guy on MS forums who keeps wheeling out these implausible theories whenever he has something to sell. And I don't care for his scaremongering.

One of the problems with these discussions is they can be too narrow and some of the less experienced younger guys treat these issues like they've never happened before. And there are a multitude of aftermarket companies that perpetuate myths to exploit their inexperience.

Many of these issues are not new at all. For example 20 years ago I ran a V8 with a 5 litre catch can which would fill in about a month. That's normal. Although with today's engine tolerances you would expect it to fill less quickly.

Fuel in the oil is also normal. Every piston engine has fuel in the oil. If you run a catch can it will collect the fuel and other light-weight vapors because that's what it's designed to do. It's not an abnormality.

I'm not claiming to have the answers, I'm just saying I've seen these diagnostic discussions explore outlandish theories so many times and they always come back to a normal explanation and solution when the appropriate expert gets involved (I don't mean me). So with that background I'm automatically cynical of theorists, especially those with something to sell.

If you hole a piston you're going to get oil right through the engine. That's entirely normal, but this is the fist time I've ever heard anyone suggest the oil caused the hole. I've had experience with excessive oil entering the intake. My old V8 again, it used to push too much oil through the pushrods and the rocker covers would full with oil to the extent that it poured through the pcv and into the intake. The smoke out the exhaust was incredible. The engine had a similar 9.4:1 compression ratio, but no bent rods and no holed pistons.

Detonation bends rods and holes pistons all the time and that's what I think the problem is. I really don't understand why this is being ignored. I'd prefer to focus on why the engines are detonating.

Jmac to answer your question I think the low-rpm high-load studder is the same detonation that blows these motors. If it's a less severe occurrence you just keep driving and forget about it, if it's a more severe occurrence you have a broken engine.

That's just my opinion and I have no evidence to support it other than the lack of evidence to the contrary. I'm happy to be proved wrong.

As for the fuel burning in the crankcase theory, I've worked with large diesel engines that have a proclivity for crank case explosions and have explosion plates built into the crank case to mitigate the destructive effects. I've seen what happens when they explode and I'm certain that if any combustion occurred inside our crank cases there would be a hell of a lot more damage than a bit of melted piston. The results would be catastrophic. Again I say BS to that theory.

[Nexus]

.... The results would be catastrophic....

How exactly does a hole in your block not qualify as catastrophic?

A certain small amount of fuel in oil sure. Lots of it, hell no. Enough for it to ignite? Hell no. It doesn't have to burn explosively - it's diluted with oil once it's in there. It just has to reach a concentration where it ignites and create abnormal temperatures and abnormally high crankcase pressures.

Snake oil, BTW, is traditionally considered a total fabrication that has no effect whatsoever. Since WI clearly has an intended and proven outcome, there's no grounds to call it snake oil.

If you want to call it a band-aid, I think that could be reasonable.

...If you hole a piston you're going to get oil right through the engine. That's entirely normal, but this is the fist time I've ever heard anyone suggest the oil caused the hole...

Have you actually read the MS forums article in detail? The engine they pulled down did not have holed pistons. There is no suggestion whatsoever that oil caused a holed piston.

I know this is a contentious subject. Please lets try and keep this thread focused, civilised, and addressing the various data without going off half-cocked etc.