Piston Slap? - 2006 Elantra

I have a 2006 Elantra GLS Automatic sedan with only 9500 miles on the
odometer. Motor oil used is Mobil 1 5W-30 synthetic with OEM Hyundai
filter - change interval is every 3K or 3 months, so oiling should be
the problem with this observation.

For some time, possibly since we bought it in December 2005, I've
noticed a tick, or a very light knock, when the car is initially
started and placed into Reverse gear in the morning while backing out
of the garage. The noise is not present in Park or Neutral at the
initial start up with the engine a "no load" condition. After 5
minutes or so of driving, this noise goes away entirely. I don't have
any experience with piston slap in an engine, as I've never owned a
car previously that had this problem - no GM 3800 V6's or V8's! But,
this sounds like it may be a piston slap in the Elantra, especially
since the noise disappears after warm-up.

I realize that today's engines are not designed like engines in the
past in an effort to reduce reciprocating mass, to reduce internal
friction, and improve fuel mileage. Modern pistons don't have full-
length skirts, or practically any skirts at all, these days, and this
design implementation can lead to piston slap.

First of all, does this sound like piston slap? Or, does the VVT make
noise when cold under load? And, is this somewhat common with the
Beta II engine?

I've noted significant discussion on piston slap on the Lexus boards
with the Toyota V6 engine, thus it's certainly not just a Hyundai
"problem." I understand that piston slap is not a serious condition
"per se," as many engines that suffer this go over 200K without any
serious problems.

 

I have a 2005 accent 1.6 CDX bought new. I am quite a heavy user about
20,000 miles a year. At 25,000 miles the engine check light started to come
on after 1 minute from cold. I took it to the garage where I bought it and
they read the codes which said "miss fire on 1,3 and 4". It has a five year
warranty. They said it was electrical and changed the leads. I light came
on again…many times. Always the same…about 1 minute after a cold start and
always the same codes. Eventually I started to get cross and they asked me
to bring it in for a complete testing and to see if they could reproduce
the error. After one day the told me it had piston slap and they would
replace the pistons.

After fitting new pistons I did 3000 miles and the engine was using about
half a gallon of oil in 600 miles, they admitted the engine was totally
useless. They installed a brand new engine and at the moment I’ve done 2000
miles and all seems well but I will wait ‘til about 20,000 miles to see if
the check engine light will come on again…

I like riding in my car………when it goes.

 

I don't recall noticing this before, but your description doesn't trouble
me terribly, either. It's quite possible it's piston slap. And you're
right; modern engine designs lead to this sort of thing occurring. The
GM
3.1/3.4 engines were actually fairly loud. The four cylinder Subarus I
see
in our shop make a similar knocking noise. Mostly, I think it's just
that
there's enough clearance when the engine is cold that the piston doesn't
quite tightly fit the cylinder.

If you're unsure, mention it to the dealer on your next service visit and
leave the car overnight for them to start in the morning. Don't let them
know you think it may only be a minor issue. Wait for them to give you
their opinion. That way, they won't know going in that you're willing to
accept a "normal operation" conclusion.

 

I think they also use much shorter piston skirts nowadays to keep
friction down and this lets the piston rock a little more in the
cylinder, particularly if the cylinder is at the outer spec limit and
the piston at the inner limit.

Matt

 

This could also be caused by the hydr. lifters. They can be noisy
until oil starts to warm up and it is fully circulated through the
system. It sounds like a knock or a tick. It's normal and not
dangerous to the engine, if that's what's causing the noise.
Bill
Bill

 

This car has mechanical lifters, so it's not the oil pressure buildup issue
you reference. But it is possible that the valves may make a little more
noise due to thermal contraction.

 

Actually wondering about what the mechanism is for 'piston slap'. I had
this interesting recent experience with my 10 year old 5 Horse Briggs &
Stratton mower. It still started easily & ran fine UNLESS I shut it off hot
& then tried to restart. Almost felt seized & fresh oil quickly turned dark
with metal flakes.
Took it apart & found the bottom of the piston skirt in 2 spots was
starting to rub on the lower part of the cylinder walls -piston slap?. Now
it never did this until last week in all the years I used it, so I kind of
figured that perhaps the rings had worn enough for that piston to slop
around enough to hit the walls.
I hope that's not the mechanism in these Elantras.
BCinBC