onsknht

MBA only unfortunately... Lexus didn't design the engine, Toyota did and piston slap has been a common theme from 3 out of 4 most recent engines I've bought from them. The only engine that did not have piston slap was in an i4 camry, it made all sorts of other noises though!

Piston Slap this day in age is not uncommon to any engine on the market, engines have changed substantially over the years and I've watched, listened and owned quite a few over the years... There is basically no harm in this occurring as it is for the most part built into the design, but there can be other problems that cause the noise, but the engine has to wear out first.

You'll need a degree in metalurgy over engine design to understand this.

I think where you're going wrong here is again you're confusing the two distinct noises... Pistons are aluminum, cylinders are steel, the block is aluminum, rods and crank are forged steel, etc., etc. etc. All of these parts expand and contract at different rates and the engine designers purposely allow for these changes to occur... That said, any noise you hear after 10-15 minutes of warmup (should really be gone in 90 seconds) is not the diesel knock/piston slap noise, it is more than likely the valve train which doesn't diesel knock or piston slap.

That is because you're being told what it is by SERVICE WRITERS not SERVICE TECHNICIANS and the techs can only tell you what the service writers want you to hear... The service writers manage the shop, they are in charge of all the numbers and turning a profit, the techs do the work that makes the money. If you really want to know what is going on (your issue sounds valve related to me) take the car to an independent guy and pay him to find the issue... Then take it to Lexus with the diagnosis and see what they say.

I will now show you what Engine Designers and Piston Slap all have in common. GM has been the hotbed of piston slap more recently and guess what??? TOYOTA AND GM SHARE ENGINE ASSEMBLY PLANTS!

Piston slap is nothing new to piston driven internal combustion engines and compressors. It is the secondary (sideways or perpendicular) movement of a piston against the side of a cylinder bore where the primary movement of a piston is intended to be parallel (up and down) to the cylinder bore. All piston driven internal combustion engines and compressors have a certain amount of piston slap.

Excessive piston slap occurs when the clearance between the piston and the cylinder bore is too great. The piston to cylinder bore clearance becomes too great either through wear, mismatched pistons and cylinder bores at manufacturing or, a combination of both. The audible noise associated with excessive piston slap is due to the perpendicular impact of the piston against the wall of the cylinder bore. Audible piston slap is typically loudest when the engine is first started up. The pistons then expand with heat reducing the piston to cylinder bore clearance thus, reducing the perpendicular impact of the piston against the cylinder wall and its resulting noise.

In the case of the famous GM piston slap engine defect, the piston design with hypereutectic (high silicon content aluminum alloy) pistons, reduced or ELIMINATED piston skirts (to reduce reciprocating mass), and a higher ring pack to reduce unburned fuel mixture on the sides of the piston crown have made piston to cylinder bore fit much more critical. The amount of tolerance (variation or margin) in allowable clearance between the piston and cylinder bore to prevent audible piston slap has been reduced by a factor of at least 50%. Consistently hitting the narrower margin for piston to cylinder bore tolerance has not happened for GM during mass production. Thus, some engines have no audible piston slap and some have piston slap on only one or two cylinders. What might have looked really good in testing of hand built engines in the lab hasn't transferred to the production line of this corporate giant.

Make no mistake about it, while a lot of these engines don't appear to be driving rods through the blocks, the ones with louder and longer duration piston slap will wear out before the ones that are basically quiet. The perpendicular heavy impact of the piston against the cylinder wall over time will not come without a price. This is also why GM has released a recent TSB saying that opening 4 quarts of oil to add to your crankcase between a 7,500 mile recommended oil change interval (1 qt per 2K miles on an engine with 36K miles or less is "NORMAL". After 36K miles, all bets are off (there is no abnormal oil usage rate). This is why the now common offer of an engine component letter extending your warranty to 5 years or 100K miles is basically worthless. If the piston isn't laying in the oil pan in pieces, the engine will be operating "NORMAL" according to GM.

VroomVroom

I've heard the same from Lexus service folks that I heard from GM service folks...basically nonsense. My beef with these guys is that they either don't care to learn the cause or it's just easier to stick their heads in the sand and pretend it doesn't exist. I believe this is more a function of dealers than manufacturers, but in this case I think the significant difference is that there have been transmission failures but no engine failures.

I think this can be explained by the fact that the engine isn't under any load when in park.

Like I posted earlier, both of our cars do this. It's only a cold-start condition, and is identical to the three previous-gen GM trucks we owned. I've been following this issue for almost five years now, with tons of valid and invalid information being posted on many forums. The explanations from onsknht certainly mirror those of others I've read, including posts from a GM field engineer. While I'm surprised and a bit disappointed to see that Lexus is affected by it, I still have yet to hear of any mechanical failures as a result.

I guess my biggest disappointments are that a technological design change hasn't somehow resolved the issue and that dealer service departments aren't directed to share consistent information. Nonsense about injectors and timing chains is just that...nonsense...and does nothing to instill faith on the behalf of customers. Ok...one more too. Over the past two years I've ridden in many other V6 and V8-equipped vehicles with sophisticated engine designs (Audi, Mercedes, BMW, Ford, Honda) - none of them seem to have the problem. I know generalizations like this are often inaccurate and certainly unfair when mentioned alone, but what's different about these engines vs. the Toyota and GM ones?

RXGS

iTrader: (2)

do u think that lexus will address this, along with the transmission problem with the 08?

MD350

Me too, owned 6 Honda/Acura products within the past 10 years. Never had this sound. My wife's new Pilot purrrrrs in all driving conditions. Oh well, this is something I have learned to live with. Not worth my time running to the service department only to be told it is normal.

MD350

In my opinion, Lexus says the engine noise is normal and I don't think there is an offical fix to the tranny flare. So, the answer to your question is no.

onsknht

No... The 2GR-FE series motor will always have piston slap to some degree. It may be possible that some of the "clackity-clack" from the valve train is dampened.

Look fellas, I had a 4 cylinder Toyota truck years ago and it made horrendous noises... It sounded like it was chewing itself up from day one. This engine today is regarded as one of Toyota's MOST DEPENDABLE motors every produced. All of these engines sound like crap but many have them have gone hundreds upon hundreds of thousands of miles without ever being opened!

What most here want is their cake and they want to eat it too! That's fine and these cars are very expensive not to demand this, but what you need to consider is there is always a tradeoff. Take piston slap for example, do you want a high mileage AND high performance engine or do you just want the mileage and not the performance or vice-versa??? Toyota engine designers gave both performance and mileage at the expense of a little noise... I have no doubt they could have made the engine whisper quiet in all instances, but I think you'd all be a little peaved then that it gets 15% worse mileage and maybe only like 240HP? Why? Because they would need to increase rotating mass with skirted pistons and use different materials that probably cause greater friction to quiet the engine.

I do believe there are some cars out there (like dunnojack) that could really benefit from some valve train adjustments/replacement parts, there will always be some extreme cases... Basically, if your engine sounds about the same as any other 2GR-FEs, I wouldn't get into too much of a knot.

osokuko

Another good write up on piston slap ons, I thought everyone would like to see the piston as shown in the manual. There’s not much below the wrist pen all the mass mostly the rings are above the wrist pen. I guess this allows for higher RPM’s. I can see now that yes there will be some slap or a slight knock sound due to no shirts.

MD350

You do know more than I do when it comes to engines. Of course, I am upset to spend this kind of money on a rattle box. Why is it that Honda can build a much quieter engine and still have the power?

onsknht

They don't... The 2GR-FE will spank Honda's 3.5, there is a tradeoff going to V-tec and SOHC... Sure it's quiet, but it lacks torque and only gets moving in a real narrow band.

The Honda will kill the Toyota in gas mileage though.

I wouldn't be upset at the racket unless it's real loud (this may be touching on a tolerance subject and is therefore very subjective, everyone has a different perception of "loud") then I'd take it in and have them prove the noise was normal. I've said before, my past engines V8, V6, i4 from Toyota have been a little noisey, but they've been trouble free... I truly think Lexus "misunderestimated" the amount of noise. You very well may see improvements from a cabin/sound deading perspecive or changes to actually quiet the motor. The Toyota Camry guys haven't made a sound about piston slap or valve train noise?

onsknht

Thanks! However, the image I have stuck in my head of the actual pistons in the engine are even thinner than the ones pictured in your diagram. Even the most current shop manuals tend to reuse images from prior years... It's a V6 engine and they're showing how to insert the piston, they're all marked. I used to buy shop manuals for snowmobiles because they were like $20 and throughout the years, they showed the same pictures over and over, when something was model specific was the only time they changed.

I thought about looking for an image to post, if I can find one I'll post it.

onsknht

Here's some polished up photos... This is the IS motor, the main difference is the addition of direct injection, so imagine the injectors pointed directly in the cylinders do not exist... The basic intake may be a little different but I think the injectors in the intake are located similarly on the ES.

Note the pistons, there isn't much too them and they typically arent all chromed up, but then again there usually isn't blue and red led lighting in an engine either.

Look at the valves and the cams and the springs and the rockers and the... Well that's a lot of stuff moving in there.

MPLexus301

iTrader: (3)

Seems like it has been rehashed a good bit here, but there is nothing wrong with the engine and it's not going to fail on you. This is simply part of the design of the GR engine. Look across 4Runner and Tacoma, Camry, Avalon, and other cars that use the GR block and you're going to hear people complaining of the same issue- ticking, knocking, or almost a diesel sound at times.

This is a characteristic of this engine, and if it bothers you so much, you probably should have not bought the car.

That said, it's not going to affect the performance, longevity, or your ownership experience.

ES350Bob

The knocking/tapping noise is very annoying and is due to a mechanical issue of improper valve lash adjustment just as diagnosed on both my ES though repairs were denied.


I found this for LS owners with it, ES owners notice it mostly in AT in D range.

Maybe taking in the LS TSIB may get something done for ES owners with it.

http://www.lambros.net/tsib/2007LS/L-EG014-07.pdf