09 4.6 Broken Valve Spring?

[Peveto]

I've had my '09 V8 for the better part of 6 years and ~80k miles. Purchased used (CPO) in 2011 with 36k miles, and just rolled over 120k miles in the last couple of weeks. It has been a relatively painless few years, i was subject to the ABS module failure/recall, and some typical early 2009 Model Year electrical issues (tilt/telescope failure, audio problems) all of which were fixed via recall or under the original warranty. No powertrain issues to speak of. I change my own oil, always using Hyundai filters and 5w20, at or before the 7500 mile interval.

Right at the first of the year, on the way home from the office, I rolled to a stop at a red light and felt a slight stutter/misfire. No CEL illuminated, and it was a one time event, so I thought little of it. Haven't had any problems further until last Friday, 1-6-17.

Leaving the office to head to lunch I drove out of the parking lot, and as the car warmed up (say, on the road for 10 minutes or so) it started misfiring/missing/stumbling terribly. I immediately thought "i've burned up a coil pack (cause I used to drive a VW, and this happened often)". Turned back around, drove the few minutes back to the office and parked the car. Went upstairs, called my dealer and made an appointment to drop the car off later that afternoon. Limped the car over to the dealer in the cold and snow (yeah, it snows in Dallas, and we all freak out and drive like maniacs) and dropped it off.

Dealer called Saturday and said, replaced spark plugs (which I had asked them to do), and still had a slight misfire, but was much better. Coil packs all test good.

Called Tuesday and said, still misfiring, but also doesn't appear that #8 cylinder injector is firing. Hyundai service/tech line says ECU will turn injector off if it detects misfire. Technician working with Hyundai North America to determine if software reflash of ECU will turn injector back on.

Called today to say #8 Cylinder has a broken valve spring (I neglected to ask if it was intake or exhaust side), and that they would attempt to replace the spring without pulling the head to the tune of ~$1k, but if they had to pull the head it would be significantly more.

I've seen a couple of threads here and there about broken valve springs, but no real further data about the repair or replace (especially for those of us that are out of warranty). Anyone have any further insight?

Thanks!
--Peveto

 

[balfor]

If it is a broken spring I would expect it to be roughly the same misfire/rough idle all the time. The fact that your misfire changed with plugs and seemed to come and go in the beginning would point to something electrical like the coil or injector, possibly a sensor. Also, sometimes a broken spring can leave the valve hanging down enough in the cylinder to be hit by the piston and then it is game over.

It also sounds odd the ECU would kill the injector with a misfire code, sounds like that makes it hard to diagnose issues. So is the injector firing now that they have spring as the cause? You might want to take it to another dealer if you don't trust their estimate.

 

[tfrazier]

I have an 09 and the same happened to me. I bought it used with about 80k. I experienced a couple instances over the next 10k miles where it almost felt like the trans was slipping. Took the to the shop, and it got a clean bill of health.

Driving down the freeway (cruise control set to 65), it began to shake like I was losing a tire. I pulled off and notied the CEL blinking. Got to an autozone and it said cylinder misfire in cylinders 2,4,6,and 8. Got the valve cover off, and sure enough, #8 has a broken valve spring.

 

[[icon]]

Just had this issue. After dealer threw plugs and a coolant temp sensor at it, then started wanting to replace injectors, ECU, etc. I pulled it and took it to a reputable shop. Within hours they had tested out coil packs, injectors, compression, etc and diagnosed broken valve spring on #6. 90k on 2010 4.6. Bought used at 55k.

 

[Audio]

Yep... And if the valve drops into the cylinder and scores the cylinder wall, you could be in this boat with me, too lol:

 

[Peveto]

Man, that's a rough picture. Lucky for me I didn't drop a valve, but the broken spring turned into an $1800 repair, including a set of plugs and an oil change. Have been trouble free (knock on wood) since!
--Peveto

 

[Audio]

Man, that's a rough picture. Lucky for me I didn't drop a valve, but the broken spring turned into an $1800 repair, including a set of plugs and an oil change. Have been trouble free (knock on wood) since!
--Peveto

did the head have to come off? Getting the valve covers off and accessing all of the springs is really easy in these things. I'd be kind of irked if popping a valve cover off, replacing a single $10 valve spring, and doing $80 worth of spark plugs, even with an hour of labor for the plugs, and an oil change that honestly even with labor shouldn't be more than $120..... that's just a lot of cash. That's nearly $1500 labor to change a valve spring that should take them maybe 2-3 hours beginning to end.

 

[Wafu]

I have a 2009 4.6. I have a second valve spring that has broken in the past two years. My car has done 129,000. Its a terrific car. And my last one was cylinder 8 right at the back. Is this a common issue with these cars over 120,000. Am I going to suffer this problem frequently?
I have replaced it with a OEM spring, but not confident another will not go....
Any advice, i do not want to get rid of the car.

 

[Big shot tazzo]

Def seems like a common problem . I have a 09' 4.6 and it's doing the same thing . My car has been sitting in the shop for 3 weeks . Spark plugs changed , coil packs changed . If it's something as simple a gasket I'm gonna be pissed.. really think they're trying to get me to trade my car in