Chad T

Hey Guys,

I just got done removing the cylinder head from my 200 20v and now have an idea of what might have happened.

About a week ago I had ran some water through a vacuum line to clean some of the carbon out of the motor. (I know I know. Stupid!)

The car ran great after I did it but the water must have knocked a bunch of chunks loose and they didn't get burned up. Check out all of the carbon around the piston of the cylinder that had the rod poke through the block. You can also see tons of carbon at the top of the next cylinder.

<img src="http://members.aol.com/clag500/Carbon">

Looks like a big chunk fell off of the intake valve in this next pic and may have got wedged in there and bent a rod. I'll know more when I get the bottom end out but that is my best guess at this point.

<img src="http://members.aol.com/clag500/valve">

Something to think about if you are planning water injection as well. This is what happened to the motor.

<img src="http://pictureposter.audiworld.com/21509/broke.jpg">

AudiSport4000

Well, at least we know what happened now .
After we had talked at the Ohio meet I was kinda stumped about what happened.
Im not very familiar with the water injection stuff, though.

Good luck the rest of the way

Chad T

Yeah seems to make sense that that's what happened.

Water injection uses a fine mist in the intake to cool the air and allow more boost. Adding this to a motor with a lot of miles can cause the same thing.

I was just trying some hillbilly motor cleaning trick. It removes the carbon but it dumps it all into the cylinders.

I actually noticed while reading the Bentley that Audi recommends using an additave to remove the carbon from the engine preiodically. It was called Autobahn something or other.

The sad thing is I have 5 cans of bg44k (supposed to be the best for removing carbon buildup) but I did the water trick while waiting for them to arrive.

I've been taking tons of pics. I'll get a motor r&amp;r thread going here soon.

Chad

SteveAngry

I've used both with great results over the years.

BTW, water injection when used properly is fine.

Anyways, that sucks. Good luck on the rebuild. You find a bottom end yet?

Steve
Michigan

itsav8

Chad..next time go to the local FLAPS (friendley auto parts store)..&amp; use seafoam. Or I used GM top engine cleaner before.
Breakes up the carbon &amp; blows it out the tail pipe like a James Bond smoke cloud.
It injects in the vacume line to the manifold..great stuff.

But at least you know not to use the water thing again.

But keep us posted on your progress.

blackthunder

BTW, water injection when used properly is fine.


similar to steam cleaning an engine ?

Spray warm misty water in the air intake or something similar ? Or are you talking some totally different ?

Just curious

S4for73

Very nice pix. Looks like normal carbon deposits. I can not make the connection between the carbon and the loose/broken rod. Good luck! It would have to have been a very large piece of carbon to actually been smashed between the piston top and the cylinder head. This would
have surely smashed your plugs down to nothing! And they would not have fired after that.

Chad T

Well it looks to me like it could have filled up around the edge of the piston and got jammed in the "squish" area around the outside of the cyl where tolerance is very tight. You can actually see a big chunk in this area.

I guess I won't know for 100% but I should have a better idea when I get the rod out to look at it. Car went from running fine to knocking to completely broken within a few minutes of run time.

Chad T

I just meant water injection on an older motor can loosen up big pieces of carbon in a similar way to this.

I think I have a bottom end lined up. An AAN with approx 70k miles on it.

mcorrow

Drove our A6 2.7T through about 8 inches of water, then found out later that the air intakes are at the bottom of the bumper... sucked water up into the engine, destroyed both turbos, bent rods, etc.....
Looks like you may have gotten enough water into the cylinder to make it fail...

good luck, keep us posted...