I was refering to water injections use as a performance enhancer not to clean.
 

Lowers intake temps, supresses detonation, etc, etc...

Steve
Michigan

Re: Do not use water to clean carbon from motor! Big pic warning.
 

I would agree with s4for73- I don't think that it was a carbon problem. At least there is no clear evidence that there were any large chunks that had ceramicized, which would be the only way that they would be hard enough to cause dimensional interference sufficient to bind up that rod.

I would be inclined to think that the water charge alone was sufficient to cause the rod to bind and possibly fracture the area around the bolt/ cap shoulder. If you were using a vacuum line to draw water into the engine, then a full down-stroke of a piston would possess sufficient vacuum to carry a 101% (or more, of the minimum ratio) water charge into the cylinder. Also, the missing carbon chunk on the valve may have been caused when the rod let go and there was a momentary hyperextension of the piston in its bore.

Thirty-some years ago, when I was still just a lad in high school occupational training, I did a 1 month internship at an aircraft engine shop. One of the old-timers there worked on an assortment of WW2-era aircraft engines. Included in that group were some enormous 18 cylinder radials, which had often been equipped with water injection. My boss showed me some of the problems that water injection can produce, and it was a truly frightening subject to contemplate. Let's just say that there were more than just a few of those engines that were rendered useless due to an over-enthusiastic application of water.

I came away from that experience with the clear instructions that water should be introduced into an engine by misting only, and only for brief intervals.

Sorry for your bad luck, Chad T.

I don't think it was hydrolock....
 

The water vaporized immediately when I ran it through. I just dipped the vac line in water with the engine idling until the engine slowed a bit then reved the motor and pulled it out. I Did this a few times and maybe ran a cup or 2 of water through the intake. This was a week before the car broke and I drove the car daily. I just don't see what else it could have been.

Or do you think there could have been damage done when I did the water that just didn't show up for a week?

Car ran much better with no stumbling after I did it until I went to pass a car on the freeway. Then it stumbled briefly and started knocking. Never heard any pre-ignition or knocking and from the looks of the heads and plugs it doesn't seem like it was running lean or anything.

The piston spins freely in the bore as if it's not connected to anything. Gonna have to get a look at the bottom half.

Thanks M. Samson

Chad

hmm, i've cleaned a few american v8's with water or seafoam poured
 

directly into carb. They key is a hot engine. Water will vaporize when doping this if you have a nice hot engine and dont dump a huge volume in. It cleans pretty well, I use water to clean out small engines, lawnmower and such. When it somes to cars I use seafoam for that purpose and its worked great for me though i've only used it on carbed engines and not the audi.

If it was going in in small volumes, gradually and engine was kept running I dont think it hydrolocked, i'd hazard a guess that somehow some of that carbon jammed up your piston even though that seems like a really weird situation considering that wasnt a huge solid chunk letting go in there more of a large flake.

Re: Do not use water to clean carbon from motor! Big pic warning.
 

GM's top cleaner worked nicely for my 4ringer...Just change oil and filter afterwards.

Re: I don't think it was hydrolock....
 

Chad T-

Sorry for the delay in responding. I've had a very busy day.

I didn't mean to imply that you had hydrolocked your engine. What I meant was this: it is certainly possible, and even very easy, to damage an engine with even modest amounts of liquid water.

If a person studies their physics, you can easily discover that the conversion of water to steam involves an expansion factor of 1600 times per unit of volume. Think about that. _Sixteen Hundred_ times! I won't bore you with the mathematical calculations involving compression factors, velocity, etc., but suffice it to say that it is not very difficult to increase an engine's compression ratio _Hyper-dynamically_, if even only momentarily, through the introduction of water. We're talking a dynamic compression ratio easily 2 times (or possibly a bit more) that of diesel range. In other words, instead of a compression ratio of 8 (or so) to 1, it wouldn't be difficult to have one of 40 (or more) to 1 through steam expansion.

Now you know why a car runs noticeably better when it is raining- you have perfectly vaporized water (and not too much of it) and it boosts the compression a bit.

My old boss taught me some rough calculations and showed me their real-life examples- that's what I meant when I said it was really frightening to contemplate. Some of those old radial engines with 1-inch thick castings had cracked as if they had been filled with water and then frozen. Really scary stuff.

So, yes it was/ is possible that you could have cracked something which wouldn't have come loose until it was stressed further. Like maybe put under _full_ boost or something...

Added to this mix is the fact that the Audi 5-cylinders have -3rd and -4th order vibrations (deep, intense) which are more potent and of slightly longer duration that of 4 or 6 cylinder engines. I remember reading some technical analyses several years ago which suggested that even excessive rod bearing wear could precipitate rod failure due to these types of vibrations.

In any event, I hope this clears things up a bit.

-MS

That makes sense I see what you are saying. :-)
 

I'm looking forward to seeing what goes on with the broken pieces underneath.

Re: I was refering to water injections use as a performance enhancer not to clean.
 

Normally you mix water with methanol when doing water injection for performance..
You can safely clean an engine by injecting water, if done correctly..NEVER stick a vacuum line into a container and suck in the water, that can definitely cause a hydrolock situation to occur! If you do it, use a fine mist only and do it in short increments..
I agree with the seafoam cleaner technique; much safer and seems to work like a mild soap by surrounding the carbon deposits and lifting them from the surface...

Re: Suck in water HYDROLOCK
 

<center><img src="http://www.quattro123.com/EngineClose.jpg"></center><p>I only offer my story, which may have some relevance the way the explanations in this thread are going.

I Hydrolocked a 10 V with it parked on an incline.

Auto ramps, parked for a month, turn the key and CLICK. nothing.

STUMPED.......big time.

What happened was the car had a leaky head gasket in the # 5 (back) cyl. YOur case looks like no cracked HG.

The piston was just below TDC and enough coolant leaked into the ring area so when I keyed the starter a slow: "rhun" and nothing else except CLICK, CLICK when I turned the key was to be heard.

I tried to turn over the engine by wrench on the crank bolt: nothing. no turn. Locked.

In hindsight, I suspect having the spark plug out of # 5 would have completely avoided the problem, but who knew?

Taking the plug out would have saved me $1000 repairing the motor.

A shop tore down the motor and loosened the bearing caps and said the motor turned over slowly and nothing looked damaged.

The engine ran after the repair.

i have no idea if you bang happened after short idling or whether incline or other factors led to your situation, but I suspect the water ingested from the cup was enough to speed up the failure of that rod.

This all could be coincidental too. You could have detonated under boost (bad OR cheap gas (I know you used 93 octane, so said the pump))
leading to this failure.

I popped a Saturn motor at the track.
Downshifts oil starved the pump / bearings and the motor failed later on. It got noisier and sounded great at idle (no load) but sounded like marbles when driving (increasing load on engine) until it popped at about 2,000 RPM.

Either way, you're rebuild should cure the issue and be a good learning experience in making your Avant go really fast :-)

-Scott by BOSTON

A little clarification....
 

Since this post has gotten many veiws I feel the need to update the info. After getting in to things further it appears that the motor crossfired (fired to the next cyl instead of the one it was supposed to) due to the PO having the wrong dizzy rotor installed.

I originally thought that the water cleaning loosened up some carbon which caused the problem but I think it was merely a coincidence. The motor ran great for 2 weeks after the water cleaning. I was just sitting on a time bomb running 24 lbs of boost with the wrong (wide tipped) rotor.