BrandenZ Posted December 28, 2011 Share Posted December 28, 2011 Short version of a long story: Picked up a junkyard F54 / P78, which looked like this once disassembled: Upon further inspection, the head was clearly warped, but the deck seemed to spec out fine. Swapped on a known good head, brand new headgasket -- leak down numbers come out great, no more than 10% across any cylinder, and with a less than 5% variance across all 6. Same with compression, 160-165 across the board. However, immediately upon getting it back on the road it was fogging up the entire neighborhood. After a few miles and WOT runs, the smoke seemed to be infinitely less pronounced, but upon pulling it back in the garage and yanking the plugs, I found #2 to be oil soaked (smoke even came out of the combustion chamber right when I pulled the plug), and #5 to have a very tiny amount of oil residue on it as well (although nothing I'm really concerned about, esp compared to #2). All I can think is rings here. Or maybe a stuck ring on #2 if the motor sat in the junkyard for a long time? What perplexes me is why the leakdown and compression numbers came out so spot-on awesome. Given the amount of oil I seem to be burning in just that 1 cylinder, and the fact that the plug looks nearly fouled after a few miles on the road, I'd expect some kind of smoking gun (aside from the obvious smoke!). The motor runs extremely strong and I'd never suspect a problem if I didn't look in the rearview while making pulls! Any ideas or thoughts on anything I could possibly try that doesn't involve pulling the entire motor again and completely disassembling it and re-ringing it? Thanks! Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 28, 2011 Share Posted December 28, 2011 The bottom ring scrape the oil, the top rings seal the cylinder. You can have bad oil rings with good compression rings. When the engine stops, typically two cylinders have valves pretty far open, one the exhaust and one the intake. I think a couple more could be cracked open also, depending on where it stops. So at least two cylinders are exposed to the atmosphere and will get some rust, from what I've seen. You might have rust damage in #2. Maybe some oxidation of the aluminum piston also. No advice, just a comment. Did you see any rust in the bores when you had the head off? Quote Link to comment Share on other sites More sharing options...
BrandenZ Posted December 28, 2011 Author Share Posted December 28, 2011 Not especially, but given the oil + coolant milkshake explosion due to the warped head and obliterated headgasket, it's a big hard to say. Here's a shot of #1 and #2 (left) right after I took the head off. Granted, this was after I also rotated the crank to TDC, so it isn't exactly as it sat in the junkyard... Thanks for the response... you're probably right, blown oil ring and OK comp ring. At the end of the day, I think the answer is that I should've re-ringed the darn thing before ever putting it back in, especially given it's unknown history. Would've cost me $30-40 and a few hours. :-/ Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 30, 2011 Share Posted December 30, 2011 Except you forget that when you pull the rods you gotta buy new rod bolts as well... Quote Link to comment Share on other sites More sharing options...
BrandenZ Posted January 8, 2012 Author Share Posted January 8, 2012 Update: Pulled the motor again and popped out both the worst and best piston. The problem was 100% stuck rings. In cylinder #2, which appeared to be the most oil soaked from reading the plug, both compression rings spun freely, but the oil ring was completely compressed and stuck shut, so much so that it took tapping against the ring gap with a flathead to free it. The #1 cylinder, which appeared to be the least oil soaked, actually also had a stuck oil ring, but it was stuck uncompressed and protruding out of the ring land, it also took almost no pressure by hand to free it. My best guess is that this is fallout from it being a junkyard motor, which probably sat out in the elements for an extended period of time. That said, anyone have any suggestions for good replacement rings? From what I understand, the 81-83 N/A 280zx (F54s) use completely different rings than the 280z and also the turbo 280zx's. Unfortunately, MSA wants $250 for the set! I can't seem to source a Perfect Circle set at all that isn't oversized, and the only other vendors I can find (eBay) aren't leaving me with much confidence that the rings that are delivered will be _specific_ to a 81-83 N/A 280zx. :-/ Quote Link to comment Share on other sites More sharing options...
rejracer Posted January 8, 2012 Share Posted January 8, 2012 Check out a product called Auto-RX I've used it on 3 vehicles so far, and I've been happy with it. I've noticed an improvement in compression over a period of 5000 miles. This stuff will only make a difference if the rings are gummed up, it's not a miracle additive. From what I've read about it, it's designed to slowly clean the rings over a period of 2 oil changes, it's not really geared for cleaning up tarnish as some oil system cleaners are. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted January 8, 2012 Share Posted January 8, 2012 Hastings makes good rings, call a local machine shop, they should run ~$60 or so. I've posted the part number for N/A 280z rings before, but I'm not sure that's what you need. You can look up the P/N on hastings website. Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 8, 2012 Share Posted January 8, 2012 Just curious, since I haven't rebuilt any engines, but why don't you just clean up the rings and ring lands you have and re-use them. I understand the "while I'm at it" or "it would be foolish to have it apart and not" principles but if you didn't break any and the other four cylinders were good, why not? The compression and leak-down numbers looked good. Or just replace the oil rings. Quote Link to comment Share on other sites More sharing options...
Lazeum Posted January 8, 2012 Share Posted January 8, 2012 I know it costs money & time but you should check everything such as cylinder bores, honing condition on bores, piston clearance, etc. or problem might come back soon. If you replace the rings, make sure your pistons are well clean otherwise you have some more problems in the near future. I had issue with my engine and I'm currently rebuilding it, it is a very demanding process but I encourage you to do it right. Since you've removed pistons, I would also change rod bearings at least with new ones Quote Link to comment Share on other sites More sharing options...
BrandenZ Posted January 10, 2012 Author Share Posted January 10, 2012 Rej -- Thanks, but since I've already got it pulled and apart, I'm going to go the proper route. Perhaps if I knew of this stuff before, I would've given it a whirl! Letitsnow -- I'll check out the Hastings rings! Unfortunately from what I've read, the 280zx rings are different, so I need to be careful there, as most everything I can find is 75-80... NewZed -- If I were trying to solve this in a weekend or on a budget, I wouldn't see much of a problem with this. Heck, when I discovered it that night, I was fairly tempted to do exactly what you mentioned. However, given that this is the 3rd time I've pulled this junkyard motor, I decided that even my time is worth the extra money to make sure it's right this time! I'm tired of buying headgaskets that see 10 miles and get tossed! Lazeum -- Agreed. I'm gonna get a ridge reamer and honing tool. Everything specs out such that boring does not appear necessary, but the original cross-hatching is gone, so definitely going to take the time to re-hone the cylinders. Also new rod bearings as you mentioned, along with new rings, and also ARP rod bolts (thanks Tony, I would've missed that one). Thanks all for the comments and suggestions! I'll report back once I get all of the parts in and get it back up, running, and hopefully not fumigating the neighborhood! Quote Link to comment Share on other sites More sharing options...
letitsnow Posted January 11, 2012 Share Posted January 11, 2012 Part numbers are on this page, scroll down until you find it. The numbers for turbo, 81-83 n/a, and 75-80 are all there. http://www.hastingsmfg.com/RingFinderMasterDetails.aspx?AppMACD=NISSCART&AppMOCD=NISSAN%20Cars%20&%20Trucks&AddText= Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 11, 2012 Share Posted January 11, 2012 I haven't seen an L Block yet that needed a ridge reamer, but people tell me sometimes the F54's get a ridge... Never seen it personally though. Nissan oil control rings are notoriously weak--that is "low tension" and prone to get stuck if they sit for a prolonged period. Low tension rings means more horsepower for you to use instead of being wasted as friction scraping the cylinder Walls. For years my #5 was like that, oil is cheap compared to the cost of even a halfarsed freshening... Eventuall with enough hard miles of driving (40,000 at 17psi) they seemed to rectify themselves. Nomore fouling or excessive consumption for me. I just couldn't bring myself to crack open an engine with only 40,000 KM (what's that, 24,000 miles???) when I knew it was a stuck ring from sitting in my yard under a tarp for 5 years before I got around to using it! Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted January 14, 2012 Share Posted January 14, 2012 Never seen a ridge either..........just something that comes off with mild rubbing and carb cleaner. Quote Link to comment Share on other sites More sharing options...
BrandenZ Posted January 20, 2012 Author Share Posted January 20, 2012 Hey guys -- I have everything needed to get this back in business... _except_ the rings. I'm having a terribly difficult time sourcing the correct rings for an N/A 280zx. Autozone, Advance, and NAPA all say they can only get the chrome ring set -- can't even order the cast ones any more. Does this look good: http://www.carpartsdiscount.com/auto/parts/81/nissan/280zx/pistons_connecting_rods/piston_ring_set.html?3593=62169 I _assume_ that because this is a $164 list, even though it's only selling for $26, that it's the entire set -- not just for 1 piston. What I can't find is a cross-reference to Grant to ensure this is a NON-chrome set. If any of you have a good source for a set (that isn't the $200+ dollar one from MSA), please let me know! Or if the set linked above looks good, happy to hear that as well ($26 is great!). Thanks! Quote Link to comment Share on other sites More sharing options...
Lazeum Posted January 20, 2012 Share Posted January 20, 2012 (edited) I had very good experience with Andy Carl from www.clarksdiscount.com even if I was in France. His service was spotless, quick & very responsive. Not sure thought he would have cast rings alone. You would need to check. Since he's carrying ITM pistons with cast rings, you might find what you're looking for. [edit]: found this on the site Edited January 21, 2012 by Lazeum Quote Link to comment Share on other sites More sharing options...
BrandenZ Posted January 20, 2012 Author Share Posted January 20, 2012 Awesome, thanks Lazeum. According to their website, they have a set of non-chrome Hastings rings in stock for my application. My only concern is that it doesn't specify turbo vs non-turbo, and it says something funny "use with #4 main". Do you happen to have Andy's contact information? Feel free to PM if you want. I'd like to call or email and see if I can ensure correctness (very paranoid given the difficulty in finding an appropriate set). Thanks again! Quote Link to comment Share on other sites More sharing options...
Lazeum Posted January 20, 2012 Share Posted January 20, 2012 (edited) No problem to share the email here since it is the one you can find in the contact info on the website. info@clarksdiscountautoparts.com Please, tell him you're coming from me: Mathieu in France. He did a good job so I believe it is good for him to know that happy customers spread the news about it Edited January 20, 2012 by Lazeum Quote Link to comment Share on other sites More sharing options...
BrandenZ Posted January 20, 2012 Author Share Posted January 20, 2012 Great suggestion! Carl responded to my email super fast, with the exact information I was looking for, as well as a screen capture confirming with his parts catalog that what I was looking at on the website was the correct ring set. They're ordered and should be on the way soon! Thanks Mathieu, you rock! Quote Link to comment Share on other sites More sharing options...
Lazeum Posted January 21, 2012 Share Posted January 21, 2012 (edited) No problem... I've mixed Carl and Andy. I'm buying too many things and I'm mixing up names... (Andy is the tool guy selling me Chicago Pneumatics tools in UK ) Carl (since it is his real name this time) received some orders from me on Monday, parts were at my place on Friday on the other side of the world Shipping is usually quick! Edited January 21, 2012 by Lazeum Quote Link to comment Share on other sites More sharing options...
BrandenZ Posted February 16, 2012 Author Share Posted February 16, 2012 Just wanted to update this thread in case it helps someone else in the future: All pistons and rings on the pistons pulled, every compression ring spun freely and virtually every oil ring was seized. It just so happened that the oil rings in the two cylinders that were heavily consuming oil were seize "shut" and more clamped in around the piston (less gap), and the others were seized in more of an open (more gap) state, which I assume is why this condition wasn't present across the board. Two of them that were stuck the furthest open actually managed to leave some scoring across the cylinder walls where the sharper edges from the ring-gap sat on the oil rings. I using the Hastings ring set as mentioned above (Thanks again, Lazeum!). The top rings are cast as opposed to the moly that came from the factory, but at least they're not chrome, and the fitment was perfect. Measured out the gap across all cylinders, completely within spec. I used FLEX-HONE per the recommendation of this page: http://datsunzgarage.com/rebuild/ Cross-hatching turned out great, and the scoring disappeared as well! Two tools absolutely essential to this process were a ring spreader, for removing the old rings and also installing the new ones, and a ring compressor (not sure of the official name here) which basically looks like a big aluminum cuff that can be expanded to fit around the piston top and compressed on it to compress the rings and allow for easy installation back into the cylinder without risk of scoring the walls or popping a ring out. Also went ahead and put in new bearings as well as ARP rod bolts to avoid the potential for disaster with the torque-to-yield stock bolts (Thanks for the heads-up, Tony!). All in all, the rebuild went smoothly... Except for that bloody chain tensioner! I used the block of wood trick (that I've done several times now with success), but somehow across the process (probably from flipping the block upside-down and rightside-up for the ringing process so much) it managed to slip just a hair. I couldn't manage to get the cam gear lined back up... so off went the front cover! 3 hours of basically wasted time later, I had it all re-assembled with a fresh gasket (thanks, 24 hour autozone). She fired back up almost immediately, and with no issues, even with just 4 degrees of timing dialed in (being conservative to start on the high compression combo). Aside from an initial smoke-screen, the rings appear to have done the trick with what only appears to be extremely minimal smoking even though I haven't had the opportunity to attempt to seat the rings. Unfortunately, I did not put the front cover back on with sealant at the corners per the service manual (DOH!), so the front cover is now leaking. As such, I haven't had the opportunity to fully seat the rings and report a complete success, but all initial indicators are extremely positive. I'll update this thread again once the gasket issue is resolved and I have the opportunity to seat the rings, read the plugs, and run a hot compression test. Thanks again to all for the assistance here... she's so close! Quote Link to comment Share on other sites More sharing options...
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