Topic: OM617A piston questions

I have a very enthusiastic foster nephew? (I guess that's how he would be termed) with an OM617A that he has taken apart.  Apparently the ring lands are worn.  Top ring is .008 outside spec, 2nd ring is .004.  The question he is asking me about is ring groove repair shims which I had never heard of and thusly cannot provide advice.  Can you shim the rings in the turbo OM617 and if so, what caveats exist for doing so?  He says pistons are expensive for the thing and I really don't have any knowledge of that either.

1990 RX7 "Mazdarita" 
1994 Jaguar XJ12 (Winner C-Class 2013 Sears Pointless)
1964 Sunbeam Imp (IOE 2013 Sears Pointless)
1980 Rover SD1 (I Got Screwed 2014 Return of Lemonites) (Sold -> Houston.  Gone and forgotten)

Re: OM617A piston questions

cheseroo wrote:

I have a very enthusiastic foster nephew? (I guess that's how he would be termed) with an OM617A that he has taken apart.  Apparently the ring lands are worn.  Top ring is .008 outside spec, 2nd ring is .004.  The question he is asking me about is ring groove repair shims which I had never heard of and thusly cannot provide advice.  Can you shim the rings in the turbo OM617 and if so, what caveats exist for doing so?  He says pistons are expensive for the thing and I really don't have any knowledge of that either.

Send a message to Rob(Type 44) here on the forum.....He is an MB guru.....And one helluva nice guy,to boot...

40+x Loser.....You'd think I would learn......
5x I.O.E  Winner   1 Heroic Fix Winner   1 Org Choice Winner
2x  I Got Screwed Winner    2x Class C Winner
(Still a Class B driver in a Class A car)

Re: OM617A piston questions

Yeah, I thought about him.  I have his email.

1990 RX7 "Mazdarita" 
1994 Jaguar XJ12 (Winner C-Class 2013 Sears Pointless)
1964 Sunbeam Imp (IOE 2013 Sears Pointless)
1980 Rover SD1 (I Got Screwed 2014 Return of Lemonites) (Sold -> Houston.  Gone and forgotten)

Re: OM617A piston questions

when I needed some rings to fit an obsolete piston, I went with Hastings. The nice lady on the phone helped me find individual rings close enough to what I needed and it was cheaper than buying sets

https://www.hastingspistonrings.com/ring-finder

I also used a ring groove "cleaner" loaner from Oreily's to cut the radial wall depth a little deeper to fit the rings that were available.

I've also seen (and repeated/reinstalled) where someone used the scraper ring from a 3-piece oil control ring as a spacer/shim for a traditional top ring essentially mimicking a gapless ring.

This was back when I was rebuilding A-series engines and actually staying within the $500 rules

Re: OM617A piston questions

Total Seal is in Phoenix, and will cut ring grooves to match off the shelf rings. They will also make custom rings, but the price difference is a wash.

I called them to find this out.

That guy

Re: OM617A piston questions

DirtyDuc wrote:

Total Seal is in Phoenix, and will cut ring grooves to match off the shelf rings. They will also make custom rings, but the price difference is a wash.

I called them to find this out.

I like this idea better than shimming rings. It's a diesel... Compression is key. A low compression gas motor is a smoky, low power hot mess. Bad compression on a diesel is a stubborn no start. One of these scenarios is to be expected in Lemons, the other is a buzzkill.

#888-Hong Kong Cavaliers Benz S500: formerly known as OMG Racing #140...
Judges Choice and Regional Award winner! Chuckwalla '12, Buttonwillow '13, BFE GP '15, Miller '14 & '15, Sonoma '13,'14,'15,'17, '18. Inde '16,'17,'18. Other foolishness: Finisher of the inaugural Lemons Rally, in the black Jag.... and IOE in the Super Snipe back in '12.

Re: OM617A piston questions

BigBird wrote:
cheseroo wrote:

I have a very enthusiastic foster nephew? (I guess that's how he would be termed) with an OM617A that he has taken apart.  Apparently the ring lands are worn.  Top ring is .008 outside spec, 2nd ring is .004.  The question he is asking me about is ring groove repair shims which I had never heard of and thusly cannot provide advice.  Can you shim the rings in the turbo OM617 and if so, what caveats exist for doing so?  He says pistons are expensive for the thing and I really don't have any knowledge of that either.

Send a message to Rob(Type 44) here on the forum.....He is an MB guru.....And one helluva nice guy,to boot...

Thanks for the kind words... I gotta admit, this kid sounds like he's dug further into a 617 than I've ever needed to, guru or not smile

#888-Hong Kong Cavaliers Benz S500: formerly known as OMG Racing #140...
Judges Choice and Regional Award winner! Chuckwalla '12, Buttonwillow '13, BFE GP '15, Miller '14 & '15, Sonoma '13,'14,'15,'17, '18. Inde '16,'17,'18. Other foolishness: Finisher of the inaugural Lemons Rally, in the black Jag.... and IOE in the Super Snipe back in '12.