Piston rings not sealing?

[Sealik]

I finally figured out why my engine hasn't been cooperating; I simply have not been "challenging" it enough. I have hired a few "motivators" to educate her...

 

 

... she will be graduating from LZ22 School, and moving up to LZ23 University soon. That'll learn her :devil:

 

 

NPRs?

You might want to check the clearance between the rod (small end) and piston.

Mine was about .012"...down from about 3mm on stock config.

The Z22 rod is wider than the Z24... could be a little tight in your Z24 piston.

 

Also changed the chrome rings to cast iron

[docbainey]

Didn't read all this thread, just bits and pieces. Did see chrome rings mentioned and maybe not re-bored only flex honed? Chrome rings are only good in fresh bore/re-bore. If you're trying to freshen up a motor without a re-bore always use cast iron rings. Chrome rings need a basically perfectly round hole or they never seat. Moly is a little better, but cast iron is king in a worm bore, they don't last, but they'll work.

[femtnmax]

Read thru your hassle. Many good points made. Bottom line is all the rings did not seat properly. As mentioned, the rich fuel mixture can let the rings glaze over...Yo gotta fix the fuel issue before re-ringing the engine.

The old ring ridge left at the tops of each cylinder as shown in your photo should have been removed; that's real poor the "machine shop" did not even tell you or correct this detail. Even a shade tree mechanic knows to remove cylinder ridge.

The new pistons/rings with correct fuel mixture should fix the oil burning.

 

The "old" trick to seat poorly seated rings is to run the engine to operating temp, then with throttle at steady 2000+ rpm slowly sprinkle in about a teaspoon of BonAmi kitchen cleanser....you want the old original formula...not the new product. Then take the vehicle out and run it kinda hard for 15 or 20+ miles. Then back home and change the oil. Chevy had BonAmi listed as a factory approved ring-seating method when they first started producing the high nickel blocks and had trouble with rings not seating. There have been many examples since then of top racers such as Smokey, Grumpy, etc sprinkling a little "magic dust" into their race motors on occasion. It does work, I would not over do it tho.

Glad to see your redoing the pistons/rings.

[docbainey]

[.

 

The "old" trick to seat poorly seated rings is to run the engine to operating temp, then with throttle at steady 2000+ rpm slowly sprinkle in about a teaspoon of BonAmi kitchen cleanser....you want the old original formula...not the new product. Then take the vehicle out and run it kinda hard for 15 or 20+ miles. Then back home and change the oil. Chevy had BonAmi listed as a factory approved ring-seating method when they first started producing the high nickel blocks and had trouble with rings not seating. There have been many examples since then of top racers such as Smokey, Grumpy, etc sprinkling a little "magic dust" into their race motors on occasion. It does work, I would not over do it tho.

Glad to see your redoing the pistons/rings.

 

The old BonAmi trick, read about it many times.

[MicroMachinery]

As far as the running rich goes, that didn't incident didn't take place until I'd put a few thousand miles on the engine. In contrast, I broke the engine in with a Weber 32/36 that was jetted for a smaller engine; it was actually running pretty lean for break in, which I think is what contributed to the outside 2 cylinders not seating. The center two looked ok, seeing as though they were getting all the fuel.

[MicroMachinery]

So, what did you do with your z24 pistons to make them work, Sealik? Did you ground something down?

[Sealik]

So, what did you do with your z24 pistons to make them work, Sealik? Did you ground something down?

 

About 1mm will be shaved from each side of my Z22 connecting rods...just to obtain stock clearances

[MicroMachinery]

Why didn't you go with the chrome rings?

[datzenmike]

If the block has been carefully and accurately over bored then you can use a chrome ring. Chrome rings are hard and don't wear in much so they are no good for a quick hone on a worn bore. Here a cast iron ring is much better for a quick break in and seal but they don't last because of this.

[MicroMachinery]

I'm just worried about running into the same issue that I'm trying to defeat. I'm having the block bored and honed in a professional, legitimate machine shop, so I needn't worry about a shotty job. Like I said, though, I want it right. I'd lose my shit if I rebuilt the engine and ended up burning a bunch of oil again.

[femtnmax]

I'm just worried about running into the same issue that I'm trying to defeat. I'm having the block bored and honed in a professional, legitimate machine shop, so I needn't worry about a shotty job. Like I said, though, I want it right. I'd lose my shit if I rebuilt the engine and ended up burning a bunch of oil again.

If the shop is using Sunned equipment or similar quality brand to do the bore/hone you should not have any issue. After the machine work wash the cylinder bores with hot soapy water, rinse thoroughly and wipe dry to prevent rust. Don't over oil the cylinder walls or piston skirts...no oil on the new rings. Break the engine in kinda pushing it a little at first then harder...they say most of ring break in is within the first couple hundred miles, so don't go easy on it...get into it a little. Run it up down some hills like you said you had done, and do it right off the bat. There are 100 opinions how to do the details, sounds like your on top of it already.

Glad to hear progress!!

[Sealik]

Why didn't you go with the chrome rings?

 

I did already....they failed.

No doubt the unshaved rods etc. (?) contributed......who knows... :blink:

I have no faith in my 'machinist' and don't need another rebuild.

Somewhat of a 'used bore' now...so I'm going with a ring that will seat quicker.

Not sure if this will hinder or benefit the life of the cast iron rings...but...the top ring is 2mm compared to stock 1.5

[MicroMachinery]

Alright. Did some work today..

Ready for round 2..

[Farmer Joe]

you know, i was gonna ask you about this thing at canby..

 

kept forgetting til now...

 

wonder if youll find anything interesting?

[MicroMachinery]

#1 and #4 Cylinders are very sooty. The two middle ones are clean as a whistle. I just got my cast rings in the mail(not gonna test my luck with the chrome ones), so it's just a matter of tearing it down and getting it to the machinist at this point.

[Farmer Joe]

soot in the cylinders?

 

well i guess theres the oil...

 

wonder what the rings on 1 and 4 look like...

[MicroMachinery]

Had a couple minutes before work, so I went and took the clutch and a few things off.. drained the oil, etc.. if I can steal away this week sometime(family's up from southern California), I'll hopefully get the pistons out.

[MicroMachinery]

So. The verdict is in. Everybody ready?

 

Somehow, some way, the oil control rings on cylinders 1 and 4 overlapped during piston installation. I have no idea how this happened, seeing as how it's never happened to me in the past(First time for everything, right?). I was a little concerned at how easily the rings I used would "jump" over each other, but I should have triple checked(I always double check) due to the concern I had. Cylinders 2 and 3 stayed put, but yeah.. 1 and 4 rebelled.

 

On a brighter note, the internals were all beautiful. Very clean, and the bearings were clean and free of galling or scuffing. B)

 

The temptation is to just have it re-honed and throw a new set of rings in, but since I've got the pistons, let's just take it to the next level: LZ23. Let's do this!

 

 

 

A quick question for the pros out there: During installation, what's the easiest way to make certain that the oil control expander ring stays butted? It hasn't been an issue in the past, but this time was a fluke that I'd rather not repeat. Is it as simple as the feeling of the piston sliding down the bore? I noticed when I pulled them back out, #1 and #4 were very easily dropped out. #2 and #3 were pretty firm in the bore. I don't recall there being difference in the feeling when I installed, but perhaps it's something I overlooked. Any guidance would be an arrow in my quiver. Thanks again! :)

[ddrum]

If you go through the Z24 engine build thread I'm still not done with, you'll note there is a big problem with piston rings from all manufacturers these days. Half the time you put them in and they're too wide. I filed down .030 over rings to fit my .020 over bore for that very reason.

 

I still go by the Datsun bible specs: .004 for each inch of bore on the top ring, .003 on the second ring. Multiply those two and you'll have the desired end gap.

 

Not trying to thread jack but, the same thing has been happening to me i bought a set of std Hasting piston rings for my L20b and the ring gap is too wide, then i bought some Sealed power and they are a little tighter but not tight enough. And i dont know where to get .25mm over rings.

[I'm BLUE]

It's def nice to have a closure especially on this kind of situation ... nice Job man happy fer ya :thumbup:

LZ23 ... that put's a smile on me face ... ! :cool:

 

When I rebuilt my L24 ... I was soooo worried about the oil-rings "jumping" and piston rings moving out of the degree'd indexed positions (the one you saw on the stand lol) that I wen't OCD and pulled all the pistons out to check the rings again before sealing up the engine :lol: . I almost did it twice ... :lol: .

 

I haven't ran said engine at all so we shall see hahah (gotta wait for my current l24 in my 240z engine to go bad first before trying haha)

 

Although I probably shouldn't have ... I used some "Grant" rings ... The oil control rings had green painted on one open end ... and red on the other open end ... for the overlap's verification's very purpose (I think). I have def not seen all company's do this method but I haven't overhauled/rebuilt enough engines on my own to really know :confused: :rolleyes:

 

Good work bud :hyper:

[Sealik]

I gave my machinist a copy of this.....

 

 

Why don't you get them to install the pistons after they bore it out....?......You are boring to 89mm....correct?

Somewhat cover your ass if there are any issues in the 'near' future.....

[MicroMachinery]

Yeah, I may have them do that.. they kinda have this thing about not installing parts that they sell you(I see their point), but I know the guys over there well enough. Like I said before, it's never been an issue for me in the past, as I've built a number of engines, but for some reason, these ones must have just gone rogue in the ring compressor somehow.. perhaps the design made them more susceptible to having the expander ring ends "jump" over one another..

 

Now that I think about it, I remember filing the ends flat because they came to points that wanted to not butt up. It must have worked on 2, the other 2 it didn't.. I'll just have to be a little more picky about the rings I use in the future. Live and learn.

[MicroMachinery]

When I rebuilt my L24 ... I was soooo worried about the oil-rings "jumping" and piston rings moving out of the degree'd indexed positions (the one you saw on the stand lol) that I wen't OCD and pulled all the pistons out to check the rings again before sealing up the engine :lol: . I almost did it twice ... :lol: .

 

That's a healthy fear to have. Ask me how I know :lol:. Even after double checking, I ended up in this situation. There's no such thing as being too careful or taking too many precautions or measurements when it comes to engine building. Thanks for the encouraging words B)

[TENDRIL]

bump to find later as i think i might have a problem similar on a kade 

[jesusno2]

Dude i remeber when i first fired my fresh KA in my 720 it smoked like a son of a bitch just a bellowing cloud!! I ended up pulling the engine back out. And nothing was wrong the ring gap was perfect nothing broke just oil EVERYWHERE! Even up in the intake. I bought a set of hastings rings for it and all was fine. The NPR ring i used were just junk im guessing not enough tension to seal. I have carillio chrome ring with this new KA im building i finished the bore with 220 grit stones in hopes they will seal up