techs/mechanics/DIY'ers chime in

[Audio]

Ok so... I have let my head clear a bit after a break down and would love to brainstorm on this one while I go through my own diagnostic process:

What happened: car started to misfire suddenly which I original attributed to a coil going out(had it happen before on COP cars), then stalled out at a light and would not re-start. It would do a single click like a dead battery.

This is where it gets weird to me. All electronics/lights worked perfectly while in this "dead batter" type state. Car would not restart or do more than a single click at all, even while attempting to jump start.

My idea at first was a bad battery. Coils are sensitive to voltage, a bad battery will pop them one by one quickly(again, I've seen it, so I felt good about this).

I then had the battery tested where I got the "good but needs a charge" which almost always means alternator issues.

This all makes sense so far but I'm still skeptical. Alternator goes out, car can't provide enough voltage, a coil pops, misfires, dies, battery too drained to restart car (though my multimeter shows 11.8v immediately after it died).

Anyone else have any other insight on the issue? a cam or crank position sensor also come to mind, but I'm going to start with charging the battery, see if it will start or even crank, and go from there.

Thanks in advance for any info or suggestions!

 

[dougmcp]

All kinds of things can happen if you do not have the correct voltage available for the components to function.
Although I'm guilty of this sometimes, I would not over think this yet and start with the basics:
1) Battery needs to be about 12.2v to start the car and get the electronics working properly.
2) Alternator output at 1500 rpm needs to be between 13.8v and 14.5v. Anything less than 13.8 will not charge the battery and anything over 14.7 will boil the battery.
You need a digital voltmeter to perform the tests.
These need to be correct before you get to the next steps if you still have a problem.
Battery age is nearly irrelevant as they are a little like light bulbs, some last for a year some last for 8 years.
Here is a battery state of charge chart:

 

[Audio]

Thank you. I agree about over thinking. I always over think when it's my own car, but for customer cars I always reassure them and start with the simple stuff lol. Battery has been tested, so next step is to give it a good charge, start the car, and test the alt. Here's to hoping a new alt and coil will cure my issues as anything bigger is going to really dig into the saving account. Luckily the alt for this car isn't terribly expensive and I can get my hands on coils for about $65

 

[dougmcp]

I wouldn't bank on the alternator being a problem yet.
Recharge the battery and measure the voltage, 12.7v is fully charged. You should load test it to know if the battery is OK.
If you don't have a load tester, put the voltmeter on the battery and start the car and watch the voltmeter, it should not drop below 11.5v if it does your battery is suspect
After that test the alternator output and get those behind you before considering the cost of alternators, coils etc.

 

[Flarfignewton]

Hook up a code scanner and see if you have any codes stored. If it developed a misfire, there should be some sort of code in there to help guide where to look. Although I don't know exactly how long it went from misfiring to stalling and may not have had enough time to throw any codes. Apart from that, checking the battery, alternator and starter in that order would be my next course of action. Seeing as you've already tested the battery, it's probably not that.

 

[Audio]

Alright guys, thanks for all the brain storming, I have completed the diagnosis..
Side note: I get an error in trying to connect my scan tool to the car, which has no problem connecting and communicating with any other car, so there's that little shitty piece of information.

Now to the issue:
Battery, alternator, starter, etc all fine. No charging system issue at all.

Upon trying to crank the engine by hand, we found it hit a brick wall at the same spot every time and I mean a big one. So with the engine feeling seized up, it was time to inspect for major mechanical failure. pulled spark plugs and scoped down in the holes to find that the second cylinder on the drivers side had a valve dropped. Upon removing the valve cover I found a valve spring broke in half, the valve down in the cylinder, and the rocker laying in the head.

So, while staying optimistic that this was not a huge issue, it kind of was. Will be pulling the head and tearing it down to do all new guides and seats etc and replacing the busted spring.

I'm just going to say, on the topic of things that annoy people about their cars, there are some petty little things people bitch about, but there is no excuse for a mechanical failure of this magnitude on a modern engine. None. And now it's all out of pocket for me because god forbid they honor their big bragging point 100k warranty on anyone but the original owner.

/rant.

 

[dougmcp]

Wow that's a big change from a battery problem.
The warranty for the second owner and all subsequent owners is 5 years/50,000 miles so depending on the year and mileage you may still be covered.

 

[Mark_888]

I'm just going to say, on the topic of things that annoy people about their cars, there are some petty little things people bitch about, but there is no excuse for a mechanical failure of this magnitude on a modern engine. None. And now it's all out of pocket for me because god forbid they honor their big bragging point 100k warranty on anyone but the original owner.

I am not sure what model year you have, but there many problems of the sort you have described reported for 2009 and maybe 2010 model year 4.6 engines. Those problems have been documented in this forum.

 

[Audio]

I was not disputing that others have documented similar issues. I'm saying it shouldn't be an issue, let alone one that apparently is common enough that the small portion of the customer base that joins this forum has had multiple members with this type of issue. I think it's far more reasonable to say I'm annoyed that a valve spring breaking is a somewhat known issue than people who say "well, the finish on my wheels didn't last" for annoyances was my point. Not sure what you're getting at with "Those problems have been documented in this forum" as if I should have somehow searched the forum before I ever had a catastrophic failure to somehow prematurely know it was going to happen and to which spring.

 

[dougmcp]

Will you be doing the work on this yourself and/or with the help of a friend or will it be going to a shop for repair?

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[Audio]

I do this for a living, as much as I hate working for free, I will not be paying a shop either lol.

So yeah, it will get done between other jobs. I might get a few more hours in on it tonight. I'm just going to take it slow since I have another car to drive in the mean time and nothing frustrates me more than having to fix my own shit lol.

 

[dougmcp]

If it's real bad there are plenty of low mile 4.6's at the recyclers in the $3K range.
Also sent you a PM.

 

[Mark_888]

I was not disputing that others have documented similar issues. I'm saying it shouldn't be an issue, let alone one that apparently is common enough that the small portion of the customer base that joins this forum has had multiple members with this type of issue. I think it's far more reasonable to say I'm annoyed that a valve spring breaking is a somewhat known issue than people who say "well, the finish on my wheels didn't last" for annoyances was my point. Not sure what you're getting at with "Those problems have been documented in this forum" as if I should have somehow searched the forum before I ever had a catastrophic failure to somehow prematurely know it was going to happen and to which spring.

Obviously it should not have happened. The Tau V8 was brand new in 2009, and at some point I believe they fixed the problem in later production runs. A fair number of engines were replaced under warranty.

- - - Updated - - -

If it's real bad there are plenty of low mile 4.6's at the recyclers in the $3K range.
Also sent you a PM.

2011 is the most reliable year for the 4.6.

 

[Audio]

Well, here's my update:
Engine is a brick.
After putting the car on the back burner for a bit to get customer cars, a flip, and house shit taken care of, I got the head off last night to find what I feared. There is a mar in the cylinder wall so we changed gears from repair to replacement and the engine will be pulled at some point here. I guess if I'm dropping a new engine in, I'll look for a slightly later model when the part number on the valve springs changed as I'm sure they updated them to not be brittle pieces of crap lol.

 

[Audio]

In case anyone gives a flying f*ck, 2011 4.6 in it's way now. Should have it in about a week and a half and I should have the old one out sometime next week to prepare for it. I'm thinking coffee table for the old block.

 

[Mark_888]

Not sure what you're getting at with "Those problems have been documented in this forum" as if I should have somehow searched the forum before I ever had a catastrophic failure to somehow prematurely know it was going to happen and to which spring.

I was assuming you purchased the car used, after many reports of problems with the 2009 4.6 were already posted on this forum. But maybe you did not know about this forum before purchasing the car.

I am not in any way excusing Hyundai for the 4.6 engine problem, but the Tau 4.6 was a completely brand new engine design for Hyundai in 2009, which is the kind of situation I typically like to avoid with both engines and transmissions.

 

[Audio]

Agreed. I typically avoid first year cars as well when there's a major drivetrain or electrical change. BUUUTTTT my basic searches prior to buying this one turned up very positive results and I didn't see anything about valve spring issues prior to purchase. Oh well, the 2011 engine should cure this hopefully