Cold Start Engine rattle

[TruRed1]

Started my '09 Genesis 4.6L Tuesday morning to head to work after it sat for a few days over the holiday weekend. OMG. Engine shook all over the place, Engine light was on, thought the thing was going to explode!
I backed it out of the garage, stopped and pulled it right back in. No way was I getting on the highway like that.
The dealer suggested towing it in...thank god for my AAA.
Two days later they still have it - claiming the oil pressure was 3x higher than it should have been, which caused all the shaking. Perhaps. Supposedly after running in their shop, they claim the pressure returns to normal.
I told them I didn't want this happening again, so they are still troubleshooting. They tried an oil pressure regulator, which they claim requires the car to sit overnight so they can start it cold in the morning. They suspect tomorrow morning they'll be removing the valve cover and looking in there. Anyone familiar with this?

 

[Sayantsi]

Are you using synthetic oil?

 

[viguanna]

I have never experienced this but I will say my 3.8 V6 is really loud for the frist 3 seconds after cold start up. Once oil pressure builds up it goes away. The engine has never run rough during this time and I have never seen the check engine light on other than for a self test. I have read other posts where people have said similar to my experience. My car only has 2400 miles on it and its done this since new. I let Hyundai know about this when I did my new car survey. I was really impressed with the amount of technical questions they gave me to answer. I Let them know about the common speedo reading way fast issues, bouncy suspension on uneven road issues and engine rattle at cold start up.

I am not sure on the V8 but with my technical background, with BMW and volvo, tells me there is a serious lacking of a anti oil drain back valve in these engines. I think all the oil is draining back to the pan overnight and that results in a very dry start up. I am not too bothered by this with the 100000 mile warranty, I know I am covered if the engine ever comes apart.

Keep us updated on what the dealer says or does. I also agree with Sayantsi, I have read on other posts that say full synthetic oil is really important in these engines and help alot of the "noise" issues.

 

[bnajack]

When I had my V8 Genesis, this happened three times.

The first time, at about 10,000 miles, I thought the engine was coming apart; the tow truck driver thought so, too. When it got to the dealer, it cleared up after about 1-2 minutes running. When they checked for codes, it showed a random misfire.

The second time, it cleared up in about a minute and I drove it to the dealer. They determined it was bad gas after they did a fuel gravity test.

The third time it cleared up and I drove it to the dealer and the codes showed another random misfire.

This was discussed on a thread abour a year ago

 

[ctrcbob]

When I was out in Roswell last December, morning temperature was 11F, my Genesis made a hxxx of a noise for about 5 minutes, until the engine warmed up. On other mornings, when the morning temperatures were between 20F and 25F, it again made noise, but not for as long.

My Genesis just does not like cold weather, but will probably spend a month out there in either December, January or February, depending on how well I recover from a recent operation.

 

[Dano4.6]

2010 4.6 Genesis was in the dealer for 4 days to fix driver seat as it was making a grinding noise going backwards only. they lubed the worm gear and its better for now. Also had it in to fix, for the 2nd time, the power tilt. which by the wasn't fixed as they claim the tilt module is on back order country wide. Must be an awful lot of problems with the power tilt to be out of parts country wide??? Anyways, they didn't know when the parts would be available and I needed the car for the weekend. so I picked up my car and started it and I thought the engine was going to bust through the hood. the car was shaking like crazy, and smoking out of the exhaust and making all kind of noise. after about 3 minutes it quieted down. no engine warning lights, nothing other than it seemed like it was running on 3 cylinders rather than 8. Dealer claims the car was sitting Idle for 24 hours and all the oil drained to the pan and there was nothing to lubricate the lifters.. told them I didn't agree as I've had the car sitting for 3 days without using it and this has never happened. then they questioned me about the oil and that they didn't have record that the oil was changed. Told them I changed the oil and filter at 2300 mile and used Amsoil, as I do with all my cars. Well the Genesis has only 8400 miles so I know it's not the oil. Dealer is to call me back when the power tilt modules comes in, unfortunately he had no idea when as Hyundai corporate has not provided any ETA....

This is my first Hyundai and I'm concerned I may have a POS lemon on my hand... we'll see...

 

[mikec]

Dano - did the dealership drive your car out from the service area to the front/customer area and shut it off for a few minutes before you took it? If so, that might be why it ran horribly when you re-started it: when cold-starting, the Tau V8 dumps in extra gas... if it isn't driven very far, this gas can collect in the intake pipes... then next time you start, it's waaaayyy rich leading to a shaking engine and black exhaust. There were posts on this a few months ago.

It's never happened to my car (yet?) - I've started it to move it out of the garage while I clean/move stuff in the garage and then re-start it a few minutes later to park it again. It's never had the issue described above. One member on this site, has a Borrego (I think that's what it was) which uses a Tau V8 and when he experienced this, his dealership explained the problem.

mike c.

 

[Dano4.6]

Hey Mike c. - no the dealer didn't move the car. it was parked next to their service building on a slight incline. so it's plausible that the oil completely drain to the pan, but what's disconcerting is that I use Amsoil and that should provide sufficient lubrication to the lifters. It was just very strange. the car seems to be doing ok now, well maybe. I've noticed now that when I'm stop at a red light or stop sign and I accelerate that there's a slight vibration felt on the center console armrest and a low noise similar to that of riding over road ripples/washboard or those warning bumps as if you were coming up to a sharp curve in the road. I'm heading up to the Tennessee/North Carolina mountains this weekend and I'll see if this gets any worse.

 

[mikec]

The Tau V8 uses what Hyundai calls "HLA" or "Hydraulic Lash Adjusters."

These are similar to the "lifters" used in pushrod engines in that they "fill up" with oil to expand, removing any lash (clearance or slop) in the camshaft+follower+valve assembly. Functionally they are hydraulic springs - using oil as the working fluid. When the engine is OFF, any camshaft lobe in the "open the valve" position is applying force to the assembly... which can squeeze the oil out over time. Next time the engine is run, the squeezed-out oil means the HLA is compressed, leading to lash between the camshaft and the follower. That lash will in turn lead to a clattering/ticking sound - similar to an old pushrod engine with collapsed lifters or a old engine with mis-adjusted manual valve clearances. It should not cause significant engine vibration though, and certainly not exhaust smoke.

A few seconds of engine running re-pressurizes the HLA reducing the lash back to zero and the engine should be quiet again.

My car often sits for days at a time - it's not my daily driver - and I've never heard start-up clatter. Even when it was parked for a week in freezing temps while visiting the folks in Utah... it started right up, ran quietly & smoothly. I use Mobil 1 oil; off the top of my head I don't remember what weight I used. It's whatever the owners manual recommends - on the thicker end of the recommendation. I've never tried Amsoil though I have no reason to doubt it.

mike c.

 

[mike813]

My 2009 4.6 with 20k miles is at the dealer for the same issue. I've had the rattle/misfire probably a half-dozen times over the last year, including yesterday afternoon at cold startup. I'll post back here if the dealer finds anything new.

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[ed123]

Never heard of this issue, let us know result??

 

[Rey]

I had my first cold start rattle this morning at 33000 miles. At first it sounded as though there was much more wrong than just dry lifters. It sounded more like a bad rod. Engine light illuminated, but I could not grab the code number with my ScanGuage, and I could not turn the light off either.
Stopped the motor, checked the oil. It was topped with fresh Mobil 1 #5/20. Ran the motor again listening to motor sounds with a mechanics stethescope. On second start-up the sound was diminishing quickly and I could not isolate the source of the noise.
I suspect this is a drain-down anomaly, which occurs when conditions are just right. It may have to do with cam shaft/lifter position on shut off.
Presently, I am "rebooting" the car's ECU to shut off the check engine light. I do this by disconnecting the batter terminals and then connecting the positive and negative terminals together. Note, the batter wires are too short to make a direct connection, so I use a jumper wire. I also insulate the battery posts from the battery wires by laying some heavy towels across the top of the battery.
Has anyone found a TSB (technical service bulletin) on this?

 

[mike813]

My dealer wasn't able to find a service bulletin and didn't find anything "wrong" with my engine. They were able to duplicate the problem on my car and one other V8 at the dealership by starting the engine, cutting it off immediately, and then restarting. I let them flush the injectors and change the oil and now i'm just careful to not run the engine for less than a minute. This does seem like a strange problem to have - that shaking and sputtering can't be good for engine life. Hopefully we'll have a solution some day, and hopefully before these cars start hitting 100k miles.

 

[Rey]

Follow Up: I think the problem is an anomaly related to the Hydraulic Lash Adjusters draining under unusual conditions. This subject is noted in the factory shop manual under the engine mechanical section. The condition occurred when I moved the car a foot or so with a cold engine, and then shut it off - the noise arising the next morning when I restarted the car. All is well now. If this reoccurs, I will take it to the dealer and ask that they let the car sit overnight, and then start.

 

[MHT]

I exsperienced this problem for the first time this morning. The car did not drive right the entire 5 mile trip. When I got back in the car for the return trip home the car started up and ran just fine. I do not know if it was due to a drop in temperature or not as it had started ok at other times when it was colder outside than it was yesterday.
I have to talk to the service manager today about the map update so I will also inquire about the bad start and car not running right.
My car is a 2010 4.6 V8 and I have only had it six months. It has been back to the dealer once for the Tilt Steering issue and other than that I have not had any other problems.