AMGTestDriverNJ

Hey guys, I know I don't post here too often but I know you guys are the most technically inclined w/ the 55k motors so maybe you can help. I have no idea what caused this to happen. My motor is completely stock, had it not been, they would not have covered it under warranty. This is an 03 model, w/ approx 61k on the clock. It was initially in for valve cover gasket leaking on both sides of the motor. I then find out today that on the test drive it threw a misfire code and upon removal of the head they found a cracked piston. I don't know what to think or what could have caused this. I did some searching and found one or two other people have run into this but they have done modification. This is a stock engine! I'm baffled, what could the problem be? Is it okay to just replace the piston? Should I replace all of them? There was a good amount of carbon build up which leads me to believe that combustion isn't happening correctly. Any further than that I'm lost. I am worried that my car won't run properly anymore and that it is just a matter of time before it is a complete waste. What else needs to be done to be sure that everything is in top shape? What would you do if you were me, or not do? Please any help would be greatly appreciated. Tomorrow I am going back down now that the entire motor is out of the car (this morning the block was still in the bay) and take pictures if that will help anyone determine what I might do/check to make sure everything is back and running properly. Thanks for your time and information I appreciate it.

MB_Forever

Did you buy it new or used? If used, maybe the previous owner had it modified or abused it then returned it back to stock.

If the dealer will fix the car under warranty, then I don't think there is need to worry. Most dealers warranty their work.

AMGTestDriverNJ

Yes it is under warranty thankfully. However, it seems based on the limited info I got on the boards that people who have delt with these type of issues have typically either replaced the entire bottom end or atleast did all of the pistons. I feel like its foolish to put in one new piston given the labor rate to take the motor out if not for warranty service, and that it would make more sense to replace all of them. Is it even okay to put one new piston in? Don't they have to machine the cylinder walls again for the rings to seat properly? Idk maybe I'm just bugging out a little bit but it hurts to see your motor all torn up like that. Does it make sense to replace all the pistons? Should I take the cracked one and have better ones made? JE maybe?

Yacht Master

Odd that the missfire code came up while the dealer had the car.
I don't like the sound of this. BTW was it cyl #5?

BMWEATR

The 2003 motors were the first yr and had some issues like BLOWING UP issues. I threw a rod through my block and it was stock, they put in a new crate motor direct from AMG. it seems they should just give you a new crate motor?

slavik

wow....crazy to hear....you were just telling me 2 days ago how your car has been in the shop for 2 weeks now for valve seal work....turned out to be something much bigger...best of luck on gettting it back to normal.....makes me worry about my car...

Max.H

hmmm, you can replace all 8 pistons with brand new cast pistons they will seal the best and more suitable for long time use. You can also have some forged pistons installed and increase the bore, but the rods may need modification to use a full floating wrist pin. You should pickup some extra ponies for sure. btw all engines will have carbon build up on top of the pistons. thats normal.

btw where was the piston cracked? on the ring land? or by the wrist pin? my question is did it shatter or did it lean out and melt right through the edge of the piston and cause damage to the cylinder wall. that would tell us alot. and help determine the cause.

LZH

I think if he had cylinder damage he'd be getting a new motor. No need to replace anything other than what is broken. I'd be interested to hear why the piston cracked...that is the most important thing to find out...

MARK CUMMINS

+1 Where is the REAL History from the first owner....Pulley?/Mods?
Then Returned to Stock and then Traded in or Sold

With a decent tech...NO signs of Modded...

Jakpro1

Here's the best part though!!

Benz doesn't sell "one piston" and DON'T let them tell you otherwise.

The kit is an ENTIRE bottom end. Minimum is all 8 slugs but if I am not mistaken it's new crank too I think.

Few years ago, the kit ran low 20k ish believe it or not.

Glad it happened now bro!!

OzE55

I'd suggest you DONT even attempt to find out if the car was previously modded. You dont want to give the dealer any way out of this. Ensure you have an extended warranty.

CynCarvin32

I have watched my local shop foreman do 2 piston replacements on kleemann modified cars. Kleemann could not figure out how to tune a post smog pump ecu flash car and a lean mixture ended up causing detonation and a cracked piston. Both cars had one damaged slug and the parts are available. Its done quite often as the piston is the first park of the 55k motor to break when you have fuel mixture issues. Also its not rare to see a stock car fail like this. I have talked to about 2-4 people who have had an oem failure like this and it seems to be more common in earlier build cars.

The damaged slug was replaced and the car was sent on its way.

If its just one and the cyl wall is ok just replace the one and be done.

Edit I just read he has a warranty. I should add that the cars I spoke about were fixed under warranty. The factory likely will not replace the motor unless the cyl wall is damaged. They also wont change out the 7 good slugs. They replace cracked cranks on cars with 500 miles and send them on their way so why would they change and entire bottom end on a car with 61k miles?

CynCarvin32

With the nikasil coating on the cyl wall you cant really do much boring work to fix a scored wall. If it is that bad you will end up with a new motor. If it just cracked and left no visible damage you will likely get a new cyl, rings etc and be send out. I have seen this happen twice and I watched on motor be fixed during the course of 3 days. If they have to machine the block its new motor time.

Go look in the normal E55 forum (W210) and there is a guy there who seems to likely have a cracked piston as well. His car is a Kleemann kompressor W210.

chiromikey

the air pump reflash even left some unmodified cars running lean and i have my suspisions about this one. if i had let mine go without luckily finding a service manager that actually knew our cars, i'd likely have run into the same problem being discussed here.

mkonei

DO NOT use cast pistons on a forced induction car....thats a recipe for disaster.
OP...Did it brake the near the compression ring? excessive carbon buildup on the piston will cause detonation. If the engine was burning oil, that will cause detonation as well. detonation = broken ring lands

chiromikey

i agree and wouldn't use them if i had a choice but iirc the oem pistons under the oem blower are cast...

AMGTestDriverNJ

I believe so yes. Do you have any insight on that?

AMGTestDriverNJ

Yea I wish they would. Unfortunatly for now I'm just getting a new piston and spark plugs? I KNOW they are going to have to go through this again, I just know it. Take the head off, remove the block. There cost effective warranty policy just wastes everyones time but there is no fighting it.

AMGTestDriverNJ

They are claiming the cylinder wall is fine. They also told me that they have never seen this happen before, in this manner anyway. They said usually they either break apart completely into pieces or it actually can break through the block. This piston was cracked all the way across the top from one side to the other. It was still in there but it was clear that it cracked all the way through. Seems odd to me....

AMGTestDriverNJ

Yes, I did buy this car used w/ 24k on the clock 2 yrs ago. Now, as far as your question, its funny because I debated doing a ton of modification to the car, cooling, tensioner, pulley ect. Not long after, I decided rather to spend my money on the warranty and enjoy the car longer w/o having to worry. Just so happened that a few days after that I lost a belt doing nearly nothing and I had the car flatbedded to dealer. I'm expecting full warranty coverage so I'm not worried. The car had just been through a however many point inspection before they could sell me the warranty and the car is serviced regularly at the dealership and trust me I'm **** about getting that stuff done. They come back to tell me they aren't going to cover it because the stock pulley was "lose" and they claimed that the lubricant they found whatever type of rod that it sits on was not lubricant they use and therefore I either must have had a pulley or had the car worked on by someone else. Neither of which were the case. In any event, it made me start to think that whoever had the car before me did play around w/ a pulley possibly and whoever put the stock one back on did a ****ty job. With that being said, the car had been in atleast 10 times for service/issues ect and I always ask them to check belts pulleys everything. So for them not to have noticed this along with my 1000 point warranty inspection was a little ridiculous. I fought it and fought it and finally they did the work under warranty, but not w/o a fight. But it is definatly still a possibility the car had a pulley @ 1 point........

AMGTestDriverNJ

Your kidding? So what do they do with the other 7 keep them for other customers who break pistons? This can't be a normal thing could it? I want the rest of those damn things what can I do to get them to do all of them? help me out on this! I'd love a new crank and pistons thats like 1/2 a new bottom end!

AMGTestDriverNJ

Is it okay to just replace one? Is it likely my car will run the same after they fix this? Should I be worried about beating it around on the highway now? I would hate to be nervous to beat on it. I thought thats what these cars were made for!? I just want it to work the way it should I don't care how they achieve it. although a new bottom end would be great!!

AMGTestDriverNJ

P.S. I don't think I mentioned this before but, they told me that they switched the coil packs and there was no problem with them. Does that narrow it down any? What causes these types of problems? I assume its a timing issue of some sort? Sorry for my ignorance I know some but not enough. Thanks for your responses thus far I look forward to hearing more from you guys.

AMGTestDriverNJ

Thanks for the heads up I appreciate it. Maybe it was the carbon build up? They will surely clean all that junk out of there right? Being as the entire engine is out that is a standard procedure right?

AMGTestDriverNJ

guys, what happened?! I need your expertise come back!