C32 rebuild advice, piston cracked
It was running great for 4 months, till the idler pulley jammed, belt snapped on the freeway. Could not stop immediately and I did the dumb move of driving for another 5km before exiting at the next off ramp.
Got the belt / idler fixed, car was running good again for about 800km, and then the misfiring started, and started burning oil.
Tocut the story short, piston at cyl 5 was cracked ( pic attached)
Now my options are:
1. Get a second had engine- proving to be very difficult as these engines are rare in this part of the world
2. Engine rebuild
So I'm going to go with a rebuild. I known a machine shop which can re-bore the block ( which is mildly damaged)
The question is, do I rebore and install larger 6 pistons ( and which pistons?)
Or
Reborn and sleeve the 6 pistons.
Another which in found out, the crank pulley is an oversized Kleemann piece which has to be changed as well ( rubber part is coming loose , will probably go back to stock size)
Scarpping the car would not be an option , and shipping a c32 engine is going to cost as much as doing the above.
Thx in advance guys.
Last edited by bikz; Jul 14, 2016 at 07:33 PM. Reason: Picture added
Last edited by Khan 55; Jul 15, 2016 at 02:58 AM.
Just emailed Mahle, cp carillon and wiseco.
Just to clear up, one of them said the block is Alusil bore that will only work with the special copper coating . What does that mean?
Last edited by Khan 55; Jul 18, 2016 at 06:29 AM.
Option 1:
Buy original 1x piston which will cost RM 2700 (USD681) all in all, 3 weeks to ship from Germany to Malaysia.
Bore all 6 cylinders, and the machine shop will re-sleeve with cast iron (no one does alusil here) and balance it. So the other 5 cylinders will be reused
Question - do the pistons come with alusil coating as well? will cast iron sleeve make much difference?
Option 2
CP Carrilo will fabricate all 6 for about USD1500 (so with customs tax would come upto USD 2000). they have the most helpfull so far. they will coat with which ever coating that is request.
But shipping will take about 6 weeks.
Option 3.
Mahle will fabricate for upwards of USD2000a, and they would prefer one piston be shipped to them. so time would take easily 9 to 12 weeks for the whole process.
Although i would love option 2 or 3, time and cost matter alot
So i am going to go with option 1, that is one piston and rebore and resleeve all 6 cylinders on the block. Would this be a good or bad decision?
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Option 2 would be most viable if time were on your side. Just google the type of piston AMG uses. Then google wear properties of aluminium to cast iron but hey Toyota engines were made that way back in the day. Nowadays everyone uses aluminium cast blocks because of their weight being the number one benefactor. Other properties are there as well like corrosion as compared to cast iron.
The Best of Mercedes & AMG
http://articles.sae.org/10507/
above is a good read on how the 6.3 litre engine block cylinders are made and more insight on Mercedez using steel rather than aluminium pistons in their newer style engines. I will look for info on the older generation V8 and V6 engines.
Here is a great read on M112/M113 blocks for anyone who is interested. Great help this information is and many thanks to Signal to Noise on writing this article
http://www.fitzhughmedia.com/MBF/rebuildable.html
You can also google Wolf Gang's ML page for more insight on your engine.
So thanks to you I have learnt more. Aluminium pistons indeed but the block was cast around the sleeves of this engine. They did mention they are aluminium type sleeves but they made with different material. Then after they are made the coating is applied to them by dipping them for an hour into an MB type of bonding agent. None the less, should you take the time to read the above, you will be able to make a good decision. Good luck and do respond to us once your engine is done and rebuilt.
Last edited by Khan 55; Jul 28, 2016 at 05:32 AM.
The issue now is the freakin piston which i had ordered from Mercedes (took 3 weeks to arrive from Germany)
- on the box its part number is correct (there is no part number or the piston as far as we can see)
- but it is different from the pistons in my car (different dome volume , old 9.6cc, new 19.7cc, different weight - by 30gm)
- this car has had a engine swap (im the third owner), but from the engine number it does look like a c32 amg (plz correct if im wrong)
11296160164xxx
- here are some pictures of the two pistons.
So does my engine have a different block, or was the piston that was delivered to me wrong?
Anyone has pictures of their C32 AMG Piston Head

The issue now is the freakin piston which i had ordered from Mercedes (took 3 weeks to arrive from Germany)
- on the box its part number is correct (there is no part number or the piston as far as we can see)
- but it is different from the pistons in my car (different dome volume , old 9.6cc, new 19.7cc, different weight - by 30gm)
- this car has had a engine swap (im the third owner), but from the engine number it does look like a c32 amg (plz correct if im wrong)
11296160164xxx
- here are some pictures of the two pistons.
So does my engine have a different block, or was the piston that was delivered to me wrong?
Anyone has pictures of their C32 AMG Piston Head

You obviously cannot just chuck it in with the rest as it will be like running on two different size shoes and obviously a big problem. The same issue the engine will experience.
You obviously cannot just chuck it in with the rest as it will be like running on two different size shoes and obviously a big problem. The same issue the engine will experience.
There doesn't seem to be a part number etched on the the Pistons, at least not a mercedes number. There are some numbers on it, maybe I have to contact the manufacturer to confirm.
my c32 is sitting idle now with a bent rod. other than that is been exceptional. i didnt realize bad fuel injectors around 100k miles should get replaced as i had a stuck open injector that caused a hydrolock on cyl 1 and caused my bent rod. note to others if your on original injectors at 100k miles or more you should probably get them replaced....its pretty cheap maybe 500 bucks total from an indy shop with bosch injectors.
M112 N/A pistons don't show AMG inside, only mercedes logo
Look at the pictures for comparison between C32 piston on left and C320 piston on right.
Thats why you have had piston failure... There was a lot ot stress on these weak pistons with high compression ratio
My guess is that you have 3 alternatives (except buying whole engine)
1. Return that C32 piston and exchange it for C320 piston and drive it easy
2. Ask me to ship you one USED C320 piston and again drive it easy
3. Buy a set of WISECO pistons for C32 at about 1300$ (ask RobertAMG fo how to do it)
my c32 is sitting idle now with a bent rod. other than that is been exceptional. i didnt realize bad fuel injectors around 100k miles should get replaced as i had a stuck open injector that caused a hydrolock on cyl 1 and caused my bent rod. note to others if your on original injectors at 100k miles or more you should probably get them replaced....its pretty cheap maybe 500 bucks total from an indy shop with bosch injectors.
Look at the pictures for comparison between C32 piston on left and C320 piston on right.
Thats why you have had piston failure... There was a lot ot stress on these weak pistons with high compression ratio
My guess is that you have 3 alternatives (except buying whole engine)
1. Return that C32 piston and exchange it for C320 piston and drive it easy
2. Ask me to ship you one USED C320 piston and again drive it easy
3. Buy a set of WISECO pistons for C32 at about 1300$ (ask RobertAMG fo how to do it)
i managed to source an engine for a good deal (with the gearbox). i used one of those fibre optic cameras and confirmed that the "new amg" pistons were the right one, like the one you have posted. the car is runnning well now. (only problem is the REAR SAM -> any idea if it is the same as other W203?)
however, now i have a bunch of stuffs which i am not sure what to do with:
1. Engine block - has been resleeved (cost quite a bit), and rest of the engine part from supercharger till the flywheel)
2. 5 x C320 pistons which are in good condition
3. 1x C32 piston (brand new, bought it from merc dealer, AMG / Mahle ) -> cant be returned as it was a special order item)
4. 5x piston rings (band new -wanted to change the older pistons rings)
5. 6x conrod bearings (brand new)
6. Kleeman oversized pulley (which my car originally came with -> changed it with an original pulley)
So basically i have a whole engine, with new parts, and only lacking one freaking piston.
Based on ur suggestions, i am now contemplating of doing either:
1. just keep everything as spare,
2. rebuild the engine and swap it into my SLK 230 R170
either:a. getting the C320 piston from u
b. getting a set of new Wiesco pistons (dont have the cash now though)
3. rebuild the engine with C320 piston and sell it off to someone who is willing to use is it slow
4. Sell parts seperately.
I think you will not be able to use the old engine for parts, only salvageable parts will be the camshafts
I guess best will be to find one 320 piston and close the engine, at least will be one complete unit till the time you find what to do it
I think you will not be able to use the old engine for parts, only salvageable parts will be the camshafts
I guess best will be to find one 320 piston and close the engine, at least will be one complete unit till the time you find what to do it
that's good news for the reae Sam. how about the front Sam, is it interchangeable with other w203 as well?
in that case, I think I might as well make the engine complete. how much would it cost for your c320 pistons ?
Best is to take front sam from facelift car, you will gain 2 more options:
1.mirrors folding when the car is locked (if you got folding mirrors)
2.cornering fog lights
Will check how much will be the postage for the piston to Malaysia
Best is to take front sam from facelift car, you will gain 2 more options:
1.mirrors folding when the car is locked (if you got folding mirrors)
2.cornering fog lights
Will check how much will be the postage for the piston to Malaysia
Only problem now is the Auto Headlight function does not seem to work. Is there a way to make it work, or does that involve coding via STAR as well?
and thx for the advice, i got my self a front sam from the face lift version. but how do i get the folding mirrors and cornering fog lights to work?
and is the piston still up for grabs?









