OM60x Piston oil ring expert - Page 2 - PeachParts Mercedes-Benz Forum

ah-kay · #16 05-20-2014, 12:38 PM

Jt20 thanks for the info. I am very prudent when I fix cars. I do not use the most expensive parts and I cross reference generic parts for my application. This oil ring has the same specification as the 1987 300D I am rebuilding. Oil ring comes in different form and shapes, some with spring coil, some with oil expander, some without expander. The original MBZ oil ring uses spring coil. I can source it from Europe for 1 ring only. I have a set of this Beck/Arnley ring set. The spec is the same, 87mmx3m. I measure the ring gap and it is within spec. The ring is beefy and it doesn't look like I need anything behind it. However the box comes with oil expander. That is why I am puzzled. There is no way I can fit the ring PLUS the expander. May be the vendor box them regardless.

ah-kay · #17 05-20-2014, 12:43 PM

Quote:

Originally Posted by moon161

How many parts are harder to access and service than a piston ring?

or phrased another way,

How many parts have greater associated labor & machining to replace?

or more simply, what is the cost of being wrong about this?

What is cost & lead time for OEM ring set?

So most simply:
What is the cost of being wrong?

compared to-

What is the cost of being right?

I'd be at the local benz parts counter. Load up on free cookies & coffee while you wait, if it will make you feel better.

fully understood. The ring is spec'ed for the job. I am very confident of that. I posted the question to solicit confirmation. Doesn't look like I am getting any except one.

OM603 · #18 05-20-2014, 02:11 PM

That oil ring is not correct, it is a generic, simple and inexpensive that's why it's "beefier" and will not fit with the expander ring behind it! There is a reason MB decided on the design they did.

Will it fit into the groove of the piston, perhaps but only because it's not larger that the groove. Will it function in the same manner as the MB design, no it cannot.

As far as any diagram, these generic cheap parts all have the same thing, multiple simplistic line drawings that cover every possible permutation of applications, they are far from definitive in any way shape or manner.

In all probability Beck/Arnley sourced the rings based on the dimensions of the piston grooves that's the 87 mm X 3 mm "spec" you're referencing, it's the absolute minimum information required. If all oil rings were created equal there would only be one oil ring design available! Beck/Arnley is the original URO Parts!

The Goetze ring sets are less than $40 a set from Pelican, $240 for six sets. How much are you saving if the Beck/Arnley don't work out?

The failure of the attempt to solicit confirmation as to the suitableness of using the parts you've described might be understood that no one else has ever decided that such a decision was "prudent"? Perhaps something to consider?

good luck!

jt20 · #19 05-20-2014, 03:02 PM

I have to agree here. Regardless of the different life cycle this ring might see in a gas engine (higher heat, higher velocity and acceleration), it does not justify its use here. The design will not function the same as the coil expanded ring.

The original oil rings are really quite fragile. This 'weakness' allows them flexure in more than one degree of freedom. Up stroke requires the upper band to twist at the same time as flexing out while allowing the lower band to reduce contact.

A more rigid ring will not 'give' in the same manner or respond as quickly.

That does not mean it won't "work", however.

Quote:

Originally Posted by OM603

There is a reason MB decided on the design they did.

Will it fit into the groove of the piston, perhaps but only because it's not larger that the groove. Will it function in the same manner as the MB design, no it cannot.

ah-kay · #20 05-21-2014, 12:01 AM

Well, I heed the warnings and look at the waverly oil expander one more time. It was my mistake, assuming both the oil and expander rings will not fit into the groove. I decided to put them on and mount the whole piston inside the piston ring compressor. I tighten the compressor and I am surprised that both rings fit inside the groove.

I push the piston inside the cylinder and all is well. So it was my bad observation, assuming the waverly oil expander cannot be compressed enough to go into the groove. The Beck/Arnley part is the correct part but it is not name brand so to speak. Thanks for all the help and comments.