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2010 Elantra Engine Valve Rattle

53K miles on car; Third owner, and second owner bought as a certified pre-owned from Hyundai dealer. When starting up the car cold, it will idle normally but after approximately 25-30 seconds it will start to make a chattering or rattling engine noise. Reminds me of loose valve train rattle. The noise tends to go away after a short time, but while the engine is still warming up if I goose the throttle it will make the noise again briefly. Or if I start to drive, very slowly - parking lot driving speed, rather than driving to get up to traffic speed, I can goose the throttle and hear the rattle after I let off the gas pedal. After the car is warm, even at start up and idle, it doesn’t seem to make this noise or not nearly as loud. Two independents and one Hyundai tech heard it, and Hyundai tech said it was an out of adjustment issue and not harming anything. I’m naturally suspicious of dealer tech when there’s a warranty out there. Anyone have experience with this kind of issue?

You’re the third owner of a vehicle with only 53,000 miles on it? And the engine makes noise?

I sounds like a problem with the engine from the get-go.


It could be excessive valve lash and if so that needs to be adjusted as over time it can be damaging to valve train components. Valve lash is a maintenance procedure and it’s not a warrantable repair.

If by some chance the rattle is something other than excessive lash that may not be warrantable either if it’s due to irregular oil changes and no records to back up claims to the contrary.

Three owners in about 50k miles would make me a bit antsy also and I tend to agree with Tester. Sometimes the words “certified pre-owned” is nothing but lip service used to sell cars.

Could it be piston slap?

In any event, a car that has had 2 previous owners in 53k miles (or less) may have been a problem child from the beginning.

Thanks for the comments. Because we bought the car hoping to keep it awhile and everything else on it appears to be in good or better condition (based on a mechanic inspection), we’d like to try and fix this noise. So it seems the next step is to have the valve train adjusted. Not happy about what the cost might be. It just seems odd that if it is valve train, the noise is not there right at start up but takes 30 seconds to appear. Wouldn’t valve lash begin at start up?
Thanks again, and if you have an idea on cost of a valve adjustment on this car, that would be helpful.

I was poking around in AllData. I noticed that the clearances for the engine coolant at 80 degree C are 3-4 thousands more than the coolant at 20 degrees Centigrade. So the valve clearance increases as the engine warms up which would go counter to your noise indication. The procedure is not too complicated to check the valve clearances but the procedure to change the clearance involves changing a lift bucket shim (at least the lifter bucket does not need to be changed).

If you have the valve clearances checked and any adjusted, have the mechanic look at the timing belt tension. Have him/her look for any lost motion as the crank is turned against the cam gear. The belt tensioner is set in a nonstandard way that might allow timing belt slap.

As to price, you should shop around. Make sure that the shop you pick has the shims available. This might be a job for the dealer.

Hope this helps.

Maybe an issue with the variable valve timing mechanism which could possibly be caused by irregular oil changes from one or both of the previous owners?

I would try Shell Rotella. It’s a diesel oil that has more cleaning additives to clean variable valve screens and ports. May fix problem cheap.

dont own a car that requires valve adjustment during the warranty period. you would think that valve adjustment which is required to keep the warrantied engine running right would be covered. i seem to recall older porsche engines that needed constant valve adjustment. but they had 12k warranties?

If it does require adjustment, check warranty paper work and call service department to see if it’s covered.

I still wonder if it’s the VVT.

I’ve worked with mechanical lifter engines for decades with various makes and have never, ever seen one case where valve lash adjustment was covered under warranty.

The only exceptions were many, many years ago where a couple of makes (SAAB and Subaru) would advise the customer to bring the car in at a 1000 miles for a complimentary free service and valve lash check/adjustment at that time. After that you’re on your own.

If it is due to the VVT that may not be warrantable either depending upon the oil change regimen; unless Hyundai decided to Good Will any repairs. On a 3rd owner I wouldn’t hold my breath on that one.

Toyotas have had issues with VVT cam pulleys rattling or clicking due to a clogged oil screen or VVT valve, likely due to inadequate oil changes.

Thanks again for feedback.
Dealer already took position it’s an “adjustment issue” and not covered by warranty. Sounds like there’s no way to find out otherwise until the engine is opened up a little, and by then I’ll be spending money on the fix. I’ll research the VVT issue and hope that gets me good info. My hunch is it’s not related to the timing belt because if it were one of the two dealers that listened to the car would’ve said “hey, we need to $change$ a timing belt tensioner” but they did not.