Full Rebuild - need assistance with PISTON RINGS

[ScottieB]

Hi All.
I bought a 1986 K75C at the beginning of the year as a project.  I bought it from some old rooster who has it stored in his barn covered in crap. It hadn't been ridden since 2011.
I pulled EVERYTHING apart (valves, pistons, etc) and had it cleaned, deglazed, cylinders honed, etc.
I ordered a new set of rings (along with many other items) from KHOLLANDPARTS.COM, but the rings don't fit. They do, but not in the correct order. The bottom is fine; the second fits as it should, but the top is too thick to fit in the groove. Hmmmm. I swapped the two around, and both fit fine. This is odd as the ring with the "inner chamfer" is supposed to be in the second (middle) groove, and the other ring with the word "TOP" is supposed to be in the top groove with the "TOP" facing up.
Any advice would be greatly appreciated.

Cheers
ScottiB

[Laitch]

Were the ring grooves scraped, cleaned and any burrs carefully reduced with a file? Did the original #2 ring have a bevel on its top interior edge? #1 is the main compression ring; a significant part of its function is to transfer combustion heat to the cylinder walls. I wouldn't be swapping the positions of #1 and #2. This problem should be taken to kpartsholland.

[ScottieB]

Were the ring grooves scraped, cleaned and any burrs carefully reduced with a file? Did the original #2 ring have a bevel on its top interior edge? #1 is the main compression ring; a significant part of its function is to transfer combustion heat to the cylinder walls. I wouldn't be swapping the positions of #1 and #2. This problem should be taken to kpartsholland.

Thanks for the feedback. I don't intend to swap the rings permanently; it was just done as a reference point.  I've been in touch with Khollandparts, but haven't had a reply from them for 5 days.

[Laitch]

What is the height of replacement rings #1 and #2?

[frankenduck]

The pistons and rings changed in 6/88. Did you get new rings for old pistons by any chance?

(I don't know the details of what changes though.)

https://www.realoem.com/bmw/enUS/showparts?id=0574-USA-10-1986-K569-BMW-K_75_C_0564,0574_&diagId=11_4684

[Laitch]

The pistons and rings changed in 6/88. Did you get new rings for old pistons by any chance?

You can see what was purchase by going to this link at kpartsholland. The height of the rings will tell the story of what he received.

[ScottieB]

Thanks for the replies.
I don't have a digital calliper so can't accurately measure the thickness.
I ordered part number 11251460994
https://kpartsholland.com/products/repair-kit-piston-rings-k75-new-11251460994

As specified in the description, this part number is supposed to be for models before 02/88.
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I emailed pics and further details and specifically asked for a reply from "Thom" at Khollandparts.com yesterday, and hoped he would reply overnight, but he did not. It has now been 6 days.  He's just ghosted me...unless of course he's on holiday. Seriously doubtful as I didn't get an "out of office reply".

Cheers
ScottieB

[Martin]

It's well worth getting a set of digital calipers, once you have a set you'll wonder why you didn't get them sooner. They can be had for under $30 try auto part suppliers or hardware shops. If your willing to wait they can be had cheaper from Ebay Aliexpress or Temu.
Regards Martin.

[Laitch]

I don't have a digital calliper so can't accurately measure the thickness.

I don't understand how you can be involved in doing a total engine rebuild without having a micrometer and vernier calipers unless somebody else is doing the rebuild and you are only paying for it. If you're just paying for it, then the mechanic should be ordering the parts based on what measurements of the mechanic are determining is needed.

The KPH (kpartsholland) part number seems to be the correct one for the age of your Brick, but if the engine is not the original then that could change things. KPH states the buyer needs have a clear understanding of what is owned when ordering parts. There were KS or Mahle pistons used in these engines. The pistons and rings the two types used had differing dimensions.

Working with a vendor thousands of miles away—or even in the same region—can be frustrating even with Internet access, as you are discovering. The reason many of us participate in these forums is that dealers and service departments can be disappointing so we've taken on the responsibility of repair ourselves. It can be a rough ride sometimes. Consider getting the measuring tools described here to help verify what you are receiving from vendors.

What is the odometer reading of your Brick? I suggest you run the VIN through the VIN checker at realoem and let us know what it discloses about the age of your Brick.

[frankenduck]

It's easy to tell when a brick motor was made. The date of production is cast into top right rear of the engine block and is very obvious when the lower half of the airbox is removed.

For example, the block for my K75 built on 2/20/95 (from VIN decode) was cast in the last quarter of 1994.

[ScottieB]

I don't understand how you can be involved in doing a total engine rebuild without having a micrometer and vernier calipers unless somebody else is doing the rebuild and you are only paying for it. If you're just paying for it, then the mechanic should be ordering the parts based on what measurements of the mechanic are determining is needed.

The KPH (kpartsholland) part number seems to be the correct one for the age of your Brick, but if the engine is not the original then that could change things. KPH states the buyer needs have a clear understanding of what is owned when ordering parts. There were KS or Mahle pistons used in these engines. The pistons and rings the two types used had differing dimensions.

Working with a vendor thousands of miles away—or even in the same region—can be frustrating even with Internet access, as you are discovering. The reason many of us participate in these forums is that dealers and service departments can be disappointing so we've taken on the responsibility of repair ourselves. It can be a rough ride sometimes. Consider getting the measuring tools described here to help verify what you are receiving from vendors.

What is the odometer reading of your Brick? I suggest you run the VIN through the VIN checker at realoem and let us know what it discloses about the age of your Brick.

The odometer was missing.  However, it's last registration date showed 89,800 KM. In the four years leading up to the last registration date, our govt registration data shows it had been ridden a grand total of 1000 KM (620 miles). I live in New Zealand, so we most likely got the EU version rather than the US. Given our geographic isolation and a shithouse weak currency, freight/shipping of parts here is almost as much as the parts themselves.

The engine was manufactured in the last quarter of 85.
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[ScottieB]

Here's some more interesting information:
Here's the FULL image of the stamp on the block.  Note the "K1".
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Here's the screenshot from our department of transportation website with VIN, Engine, Serial #'s, etc.
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