Hi, I'm just wondering if anyone out there can assist with a question I have regarding piston rings for the Mercedes M104 (IL6 3200) motor?

My question is....are the piston rings for the M104 the same as the M112?

According to all the data I can find they are dimensionally identical (i.e. an 89.90mm bore and the same 1.5 / 1.75 / 3 mm (compression / compression / oil control) ring thicknesses and as an aftermarket part share the same part number.

My instinct tells me that they would be interchangeable, however it is possible that they're not!

If anyone has any knowledge on this topic that would be great.

Of course many readers may just ask "why don't you just get the right ones to start with?" Simple, I am in Australia, the parts here are hellishly expensive so I choose to buy all my parts online...unfortunately none of the online suppliers will send these to Australia! I purchased all my other engine parts from Autohous Arizona at a very reasonalble price but they do not stock piston rings. I have however found a supplier of M112 rings at a reasonable price (The rings here are US$580 for an aftermarket set, the supplier I have found is a quarter of that!).

O.K. , thanks in anticipation,

Richard.


P.S. for information.....


A 112-030-03-24

and the part I apparently need is:

104-030-82-17

I think the rings are likely not the same. The M112 has a silicon-aluminum cylinder bore while the M104 has a cast iron bore.

Thanks, I had a feeling the composition of the bores would come into play. The next question I ask is are the rings backwards compatible, ie will the 112 rings go into a 104 but not visa versa? Or would 104 rings be suitable in a 112 but not visa versa?

Any ideas?

Sorry that last post really sounded like my original question...the reason I ask is that aftermarket parts (hastings for example) share the same part number across the 104 / 112 range.

From that I assume that there is some commonality beyond dimensions but it may be that the interchangeability is a one way street on the genuine part.

Any ideas?

If memory serves me correctly the M112 uses a low tension piston ring. That bit M/B in the ass and they warranteed a lot of re-ring jobs because of oil consumption problems. Not sure if they updated the rings to more tension or just put in a new set of low tension rings for warranty. Personally I wouldn't use the 112 rings in the 104 engine unless it was a drag motor running a vacuum on the crakcase.

Thanks, it looks like its 104 rings then....now all I need to do is find a cheaper supplier who will ship to Australia....any ideas?

Find a forum member willing to make the domestic (i.e. US) purchase of the piston rings for you, then arrange a shipping (and payment) method that suits you both.

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Thanks G-Benz...I had thought of that but don't want to inconvenience anyone to any degree. Anyone out there happy for me to make a purchase and have the items sent to your address for you to forward to me? Best payment method for me is via Paypal.

Richard.