Piston Rings
Manufacturer: Hastings
Part Number: 2M7382
Let me just start off by saying that these parts can now be found in several places. I got mine from Summit Racing. There may also be oversizes available, but was able to get away without boring my engine, so I didn't pursue it any further.
One thing that jumped off the page when I first looked at the box label was this:
I've been speculating for a while now that there are other applications with parts that will work on the ecodiesel engine. I already know that the Sprinter 3.0 engine has close to (if not the same) piston and rings. It looks like the Mercedes 2.0L diesel also uses the same rings. All this increases the options for rebuilding these engines, and the pool of available aftermarket parts. Hopefully others will add their findings as well.
The Hastings rings are all cast iron with a Moly coating on the top ring, phosphate on the middle ring, and chrome on the oil ring. One important difference I noticed was that the factory top and middle rings appeared to be rectangular, or possibly half-keystone, whereas the Hasting rings are both internally beveled. I tried to take a couple pictures to show the difference, but couldn't get the camera to focus.
Factory specifications for end gap are:
This seemed pretty tight to me (especially the oil ring). Once again, outside the factory spec, I could not find any other end gap specifications for this engine.
I finally called Hastings, and they gave me a spec of 0.25 mm to 0.50 mm (~0.098"- 0.020") gap on all the rings. Additionally, I found several articles stating that the 2nd ring should be at least 1.25 times larger than the top ring for oil management reasons, so that was my starting point. After measuring the rings in my engine on all cylinders, I found the following range of end gaps:
Top Ring: 0.013"-0.014"
Middle Ring: 0.017"-0.020"
Bottom (Oil) Ring: 0.010"-0.012"
This fits pretty nicely into the range specified by Hastings, and is close to the 1.25:1 ratio middle to top, so I am not going to overbore this engine.
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3/01- Quick Update
I installed the rings on the pistons last night, and started to put the piston/rod assemblies into the engine. The oil rings caused me a bit of a problem. For the first piston I installed, I used an older style ring compressor, and ended up trapping the oil ring in-between the tool and the block, damaging the ring.
The spring sits so far out from the piston, and has no dimensional stability, so it is easily trapped outside the ring land (especially at the end gap). Because the old-style ring compressor completely surrounds the piston, I was unable to see that the oil ring was stuck outside the piston. This is the older style I'm talking about:
To solve this, I started using my newer ring compressor:
There is a small gap near the handle when it is installed, so by positioning the oil ring gap in that opening, I can confirm that it is not hung up, and is fully compressed. I was actually able to catch the problem a couple times with this tool while installing the other pistons. It's a little hard to see, but here is what the gap looks like when properly compressed (circled in blue):
I was able to install the rest of the pistons successfully, but I had to order one extra set of rings before I can finish this part.