Knock, knock, who's there? Piston slap, Thats who. (1 Viewer)

[knorrena]

My new to me 2004 lx470 has cold start piston slap. I read of only one other account here on mud and was hard pressed to find any other accounts. We test drove two lxs: a 2003 and a 2004. The 03 was dead cold when it started and had no knocking on start up. The 04 (the one I ultimately wound up getting) was driven from the lot to the sales shack before I got to hear it, thus I never did get to hear it on a cold start.

The 04 has 36000 miles on it, and its a nice truck with no other probs. the sound is definitely a knock. I have heard a few leaky exhaust manifolds in my time and I would be very shocked if it were a leaky manifold.

So what do I do? The truck still has some warranty on it (6 years and 110000kms) and is heading to the local lexus dealer on friday, but how do I prepare an argument for them to repair it? Should I just live with it? Its nagging at me. I really like the truck save the knocking.

Karl

 

[campoj2]

I thought I had the "slap" but it turned out to be an exhaust leak and I am happy about that.

The ultimate question is, will they fix it or do they consider it problem? I would press them to show you something in print that says that piston slap is normal or acceptable. Didn't that truck cost $70K new?

Good luck and let us know how things turn out.

 

[e9999]

unusual, I would think....

Oh man, if the LXs are starting to sound like GMs.... sheesh...


how cold are you talking about? Like way below freezing?


I would think you could easily make a case that this is not normal nor OK for a vehicle in that class. Is this a Lexus warranty?

 

[d0ubledown]

if its under warranty, you should not need an argument for them to repair it. they should repair it. at least wait to hear what they find. regardless, its a newish truck under factory warranty, so anything thats not right will mechanically will be covered under warranty. if it needs a new motor, they will put one in on their dime. piston slap is not normal...and any lexus dealership or tech that says it is ought to be reported.

 

[1loudLX]

I can pickup the exhaust manifold leak on cold start from across the lot. I heard a LX start up last night and I was a few hundred feet away. Its pretty common, I'd check into the manifolds before trying to tear apart the engine to fix the slap.

Let them change the manifolds under warranty and hopefully that should solve it. If not, make sure the dealer you go to services 100s and 120s regularly so they're somewhat familiar with the motor. I'd also recommend speaking with one of the head master techs before they tear into your motor. Make sure he knows what he's doing and isnt going to half azz it.

 

[dclee]

OK, does this sound like the symptoms:

Start up on cold, idles fine in Park or Neutral. As soon as a gear is engaged (forward or reverse), the idle drops and the engine starts warbling, almost sounds like a diesel. I think it's the exhaust leak, but not sure...

 

[knorrena]

Its cold here - about 5*F. It knocks the moment it starts and sounds like somebody is knocking on a thick solid wood door.

The dealer is the only one in town, and they have a fair reputation, so we will see.

Hmmm, you guys present a very compelling case for the exhaust manifolds. I will take a video of a cold start tomorrow morning and post it; lets let your ears be the judge.

 

[1loudLX]

Thats the best bet, make sure its not a cellphone though!

 

[Topoguide]

There are a couple of threads here that address the different ticking sounds LCs make. I thought I was one of a very select few with a piston slap for a while, but this thread has some good info, and others that have the piston slap.

I think the video should tell for sure. On the 04 it is unlikely that it is the manifold leak, in 03 they changed the exhaust manifold to fix that problem. If it is the piston slap here is some info (mostly quoting myself from the above mentioned thread):

Piston slap happens on colder days (less than 45 or so degrees), the colder it gets the more it sounds like a deisel, but as soon as the engine starts to warm up the slap goes away. If it is determined to be piston slap it is OK to leave it be, the only option to fix is to tear into the motor. There are other opinions about this being OK, but Toyotas official story is that is a normal behavior on some vehicles. Also many other manufacturers have this issue now, such as Subies, GMs, etc.

From my research here is the story on the piston slap: The problem is the piston design has a shorter skirt to save weight to produce more power this requires a slighltly offset positioning of the connecting rod to the piston to keep it from slapping. For Toyota some of these parts are at the edge of tolerence so when the engine is cold that piston slaps until it heats up enough for the metal to expand and have a better fit. Any extra wear should be very limited (but possible) and won't be noticed until a lot of miles are put on the truck, not that I have studied or seen studies on any possible extra wear if there is any.

That said you can do a couple things. Run a lighter weight oil in winter, run synthetic oil, keep it in the garage, add a block heater, and if you don't like any of those come join me in Phoenix where the days you have the sound are very limited. Of course you can always take it to Toyota and see what the will do for you, if you do please post back and let us know what happens.
​

 

[scottm]

My '03 does knock on cold starts, usually temps in the teens or below after sitting all night in the garage. I'm running Shell Rotella Synthetic, 5W-40. A block heater isn't an option as this is my wife's rig, I'd be replacing extension cords weekly.

Any jobs in Phoenix?

 

[9toys]

My 2000 Tundra, 2004 Tundra and my 99LC have all have had the momentary knock on cold mornings from day one. The 2000 had 107k on it when I sold it. The knock never changed. The '04 Tundra has 60K with no other issues. The LC is at 140K. Changing oils from 10W30 to 5w30 and to synthetic made no difference. I don't worry about it anymore.

 

[e9999]

admittedly, not that easy to do something about.
Unfortunately, that does not mean it's a good thing to have. Nobody wants oval wear in a cylinder. The question is how much is there, of course. Fortunately, it's not as if we have to have our engines rebuilt all the time because of this.
Would give me stomach cramps, though...

 

[Kanaljen]

Wow... my first thought goes to expectations of an LC/LX..

I expected to get the best built SUV when settling for the LC; reason for piston slap is something I can understand but never justify!
Ans, it sounds like it's more than a one-in-a-million-type issue and it sounds like some owners settle. I wouldn't increase mpg and power derived from lighter pistons if it came with the potential, yet rare, cost of piston slap..

I've never had any abnormal noises during start-up but I'm in warm country; never drops below 35 even in the winter. After reading this, I will keep my ears pinned when up in the mountains...

Keep us up to date, it'll be interesting to heard how the dealer handles this..

 

[r3run33]

i have what is i believe the piston slap also but toyota/lexus does not believe it to be a issue. With my vehicle it has to be cold; 20's at start up and does have a destinct diesel sound. Now it does go away after warm up; someone on this board from colorado took it much more seriously and tried to get lexus to fix. as with mine i think my truck is the best vehicle out there and its just something you have to live with. I'm not saying that yours may need repair but having many other vehicles before and actually dealing with a jeep lemon law problem; this does not bother me. I have an 06 lx470 45k miles.

 

[BManning`]

Any jobs in Phoenix?

About 9, with 365,000 people competing for them!

 

[Topoguide]

About 9, with 365,000 people competing for them!

Yep... that about sums it up down here. But plenty of homes available...

 

[Matador98]

My 2000 Tundra, 2004 Tundra and my 99LC have all have had the momentary knock on cold mornings from day one. The 2000 had 107k on it when I sold it. The knock never changed. The '04 Tundra has 60K with no other issues. The LC is at 140K. Changing oils from 10W30 to 5w30 and to synthetic made no difference. I don't worry about it anymore.

Ditto, it's a common problem on the 2uzfe, and more prevalent on the Tundy (or it could be because there are more Tundra's than LX/LC on the road). Check out tundrasolutions for more on it.

It's really not a big deal, IMOP.

 

[pokie1313]

A co-worker of mine has a Tundra with the slap.

First, the Master mechanic at the dealer said it was the crank bearings, so they replaced those, for about a thousand bucks!
Well, the next cold day he started his truck and knock knock knock! When he took it back, they offered to give him a deal on installing a new short block.

An independent Toyota guru said it was piston slap and not to worry.

It sure is easy to tell people not to worry when it isn't your engine that sound like it's about to throw a rod!

In contrast to previous suggestions in this thread, he switched to dino 10W30 (from 5W30) and has had no more knocking over two winters.
We are in central Oklahoma and it gets cold here, but not for long. Also, we have lots of jobs available in oil and gas, wind energy, and construction.

 

[1loudLX]

I'd love piston slap, give me a great reason to stroke the motor a few extra cc's

 

[Topmounter]

Does Toyota make replacement parts that solve the issue? If they don't consider it an issue, then I'd think they would just replace it with factory parts that might exhibit the same behavior.

I've done a cold-start on my '01 at -15F and had no piston slap noise... just the speedo cable noise which I had on my 62 as well. It's funny how the LC has some very specific multi-generational idiosyncrasies... err I mean heritage!