Kia Nu engine: now what?

So, my DD is a 2014 Kia Rondo (the 2nd generation that's Canada-only.)  The engine is a 2.0L Nu GDI.  123,000 km (70,000 miles): yup, thoroughly out of warranty.  We've been enjoying the car a lot, but today the nice man at the dealer told me my bad engine noise is piston slap, and he offered me a new shortblock ($7145 installed after tax) or a used longblock ($4159 installed after tax.)

So far, nobody's suggesting Kia would like to step up and buy me anything.

Searching online quickly brought me to this thread: https://grassrootsmotorsports.com/forum/grm/hyundai-criteria-for-longshort-block/99297/page1/

I was wondering if there has been anything new on this subject since 2015.  This thread was about the 1.8L Nu, so I'm also wondering if the problems transferred over to the 2.0L.

Advice? Anybody?

Only 70k in Canada? No 100k? Weak... that suck bro. Sorry to hear that. I’d try to find that engine in a wrecker yard, or, see if another Kia motor will swap in. Get it running, sell it, and never go back to Kia... I guess. I thought they were coming up in the world. Try raising hell at the corporate level?

Drive it until it dies? Or perhaps a second opinion...

Run it until it goes "bang" and discharges little pieces of piston and valve out the exhaust. That might not be for 100,000 more miles.

10w-40 high mileage with lucas and run it.

Yeah you can get away with years and years of piston slap, especially if it goes away when the engine warms up. Also, piston slap can be fixed with new piston rings. Look into the cost of a re-ring job from an independent mechanic.

Old Chrysler 2.2/2.5L engines were famous for piston slap. I had a number of them that went well past 200K mile mark. I would still be on the phone trying to get it replaced.

Paul

GameboyRMH said:

  piston slap can be fixed with new piston rings.

Not usually.

The Suzukis I drove for years had bad piston slap and they usually ran for many miles like that. I would just drive it.

Piston slap has almost nothing to do with rings. Rings are moved by the piston, not the other way around. It's a skirt-to-bore clearance issue. As the engine warms up, the piston thermally expands by a hard-to-predict amount, and so does the bore. Skirt clearances and skirt profiles (not perfectly cylinder) are sized very carefully to keep slap down at all thermal conditions without causing too much interference (scuffing), but also while reducing friction. Seems like some engineer got the design wrong or parts aren't being machined correctly. 

I work on bigger engines with liners, so slap is a big deal to us because the liner will "ring" like a bell and causes cavitation to erode through the coolant cavity into the bore. On a parent-bore automotive engine, slap is mostly just annoying, but can cause long-term wear problems. 

Suprf1y said:.

Not usually.

The Suzukis I drove for years had bad piston slap and they usually ran for many miles like that. I would just drive it.

maschinenbau said:

Piston slap has almost nothing to do with rings. Rings are moved by the piston, not the other way around. It's a skirt-to-bore clearance issue. As the engine warms up, the piston thermally expands by a hard-to-predict amount, and so does the bore. Skirt clearances and skirt profiles (not perfectly cylinder) are sized very carefully to keep slap down at all thermal conditions without causing too much interference (scuffing), but also while reducing friction. Seems like some engineer got the design wrong or parts aren't being machined correctly.

You're both correct on the topic of piston slap as a design issue, but when piston slap arises or worsens later in the life of an engine (which from what I understand, is what's happening here) it's usually initiated by severely worn rings allowing the piston to rock back and forth more in the cylinder, increasing skirt-to-bore contact. To be fair if this isn't dealt with relatively quickly the engine will likely need an overbore to be brought back to factory levels of piston slap, but that would be discovered in the process of a re-ring job.

I'm learning a lot here, and I appreciate it.

For further clarity, this noise started maybe 10,000 km ago and I initially addressed it by doing one of those spray-can cleaners for the top end of a GDI engine.  Based on the crap that came out of the exhaust, I'm sure that helped the engine, but it did not change the noise, which is why I ended up at my friendly dealer's yesterday.  I asked the service tech if this was a common issue, and his reply was, "If you had asked me a month ago, I would have said No. Since then, I've had three."

So I'm wondering if this 2.0L Nu is succumbing to the same syndrome as the older Nus in the previous thread.

On the subject of oil: Can I really jump from 5-20 to 10-40?  And WHICH Lucas?  I would want to get it right, and they've got a lot of kinds of magic goop out there.

In reply to GameboyRMH :

No that's not happening here. It's a low mileage 4 yr old motor, but either way, it has nothing to do with rings.

I wouldn't jump to a 10W-40, especially not in a colder climate (meaning starting the thing below 30 - 40* F).  I'd consider trying a 5W-30 or something that's just a little thicker to see if it makes any difference though.  Maybe a 0W-40 (they tend to be on the thinner end of the 40 range).  

I still have to disagree, the rings do not allow or disallow the piston to do anything, including slap. The piston will do whatever it wants, and the rings are free to move within their grooves. Piston secondary motion analysis (slap FEA) usually doesn't even include a ring body.

The only exceptions being if a ring gap is too tight and high cylinder temps (say a 100 shot of nitrous) cause the ring to butt, scuffing the bore, and creating a crazy amount of resistance on the piston. Or if a ring is so worn and/or broken that it twists under or above the groove, filling the gap between piston and bore. See ring-land breakage issues on other engines. 

This thread is obviously some sort of phishing scam, the Rondo is 100% bulletproof and indestructible.  I refuse to believe otherwise.  

RONDO THUG LIFE FOREVER!!!!!

In reply to pinchvalve :

That's a first gen Rondo, which everybody knows is bulletproof.

His is a second gen. It's becoming obvious now they tried to do too much too early and it's just too much awesome all at once, even for the pistons. I'm surprised he hasn't blown the welds on the intake yet

do NOT jump to 10-40 and lucas. Jeebus... that E36 M3'll be as thick as sludge. Use a quality oil in the range for the engine and drive it until it explodes. That engine is in a ton of cars (Fortes, Elantras, Rondo's, Soul's Etc) and are pretty cheap at a scrap yard. keep driving it until you have an issue (not just noise). The main issues with the 2.0 GDI nu's has been bearing failure and still not a common enough occurance for panicking. 

GM LSx truck engines show this sign around 100k miles and will make that noise for another 300k miles. It would not be something I'd be worried about. 

I have a hard time believing a 70k kia 2.0L is bad, can you do a proper seafoam treatment, let it sit overnight, then fire it and take it straight down the 401 to say port hope and back?

It'll smoke like a banshee till courtice but then start clearing off, would definitely rule out carbon knock

I'm not opposed to this idea.  Could you define a "proper Seafoam treatment"?

forward this thread to corporate.

I'm not opposed to that idea either.  This diagnosis, if that's what it is, just came in yesterday, so we're still in Chapter 1 of the story.

My Elantra developed a knock in the 1.8 at 85k Miles.  While waiting a for a long block (they were back ordered)  I tried to get it to blow, but it held up to plenty of abuse and was still going strong when it was replaced.

Because it was US, they ended up replacing the long block.

The explanation I received was that the friction reducing coating was coming off a piston skirt causing the knock. The dealer didn’t do anything beyond removing the oil pan and valve cover to take photos to send to Hyundai, so they didn’t tear it down to inspect it. 

I would stick with factory filters and a good quality oil with a high mileage/extended interval additive package in the recommended weight to avoid affecting the performance of the variable valve timing system, and run it until it fails. 

Take a bottle of Seafoam, (not the aerosol), feed it to the engine thru a vacuum port, make sure the engine is hot, I prefer to do it at the end of day, let it sit over night, first thing in the morning fire it up and drive immediately.

Be aware it will smoke like you wont believe, the highway drive after the overnight soak  , really seams to get rid of any carbon build up.

Thanks, w-r-n, and to everyone who has participated so far.

Considering options at this point, before I go back to the dealer for a conversation higher up than the service writer.  I enjoyed finding out from Joe Gearin in another thread that GRM has >4.5M unique viewers a year.  I have to think that that factoid plus this thread will count for something with somebody somewhere.

I don't know how seafoam is going to correct, or even affect piston slap. Maybe somebody can explain it to me.

And despite Bob's self assessment of being the real oil guy, his likewise dubious assessment of 10W40 being thick as sludge may be another slight exaggeration. I'm not sure that it's use would make any difference, positive or negative.