e-Mel

Just wondering if anyone having the cold engine start-up valve tapping noise has considered trying an engine oil additive such as Rislone (there are others too). I've had very good results with this in the past (though admittedly on older vehicles). Their website states it will not void new vehicle warranties (don't know how Lexus feels about that). I am not recommending the product - only wondering if anyone has considered it. I realize these are very new cars and should not need additives to operate flawlessly.

amf1932

Lexus, just like most auto manufacturers do NOT want you to add any kind of additives to the crankcase.

Lexmex

Your vehicle is way too young to use anything. I have and still use some for racing, but unless you have a problem with the engine as opposed to noise, no need to use them.

wanderer99

The fact that your considering using additives on your brand new engine should tell you something is wrong. Using a 'patch' solution such as this isn't going to fix anything. Someone should suggest this to their service advisor when mentioning the noise issue - I think they'd be stunned!

onsknht

This "noise..." I think ya'll are behind the times a little... This is an "all" aluminum engine. It really isn't "all" but the block and the heads/castings etc. are. The pistons have been aluminum for some time, no need to carry dead weight... And now the block et al are aluminum. I respect Bob and his issues and even the tech's comment, but I think they're mis-guided... Aluminum transfer's noises differently and I think Toyota is finding out traditional noise dampening isn't working with the "new" engine... Further aluminum reacts differently to Hot and Cold than traditional materials, folks face it, you're an R&D group... These cars will be flawless during your time of ownership even though they may be annoying at times. I've heard my 3.5 sound like the neighbor's dog's ***** slapping together, yet at other times it sounds like grandma's sewing machine... We need to adapt or Toyota needs to adapt to our gripes, it's as simple as that.

e-Mel

This is not something I am considering. Fortunately my engine does not have this noise issue and lately it's been pretty cold in the mornings here in NJ. I was merely asking if anyone who was experiencing this noise would consider an additive.

savon

I agree with you. In my opinion, increasing horse power and using aluminum has increased engine noise. I think that is why a lot of people especially previous ES model owners are disappointed with engine noise level. My toyota camry has less noise on idle than my new ES. Dont forget that a lot of people were complaining about lack of engine power in old ES models. Well, we got the horse power we wanted. Lexus listened to us. There is a limit on what technology and engineers can do. My major disappointment is not the engine noise but transmission failure in some cars and build quality. I hate to say it but my 8 years old camry is better built than my new ES. I didnt have a single rattle or interior noise during first 2-3 years.
I hope lexus addresses these issues otherwise they are going to lose customers.

MD350

Here is $1,000,000 question. How much engine noise are Lexus owners willing to live with in return for more horse power? I personally want the horses. But, I can understand some others want the smoothness.

My wife's Sienna has the 3.3L engine in it. I personally don't like the performance. I heard Toyota is dropping the 3.5L engine in the 2007 Sienna. I, again, would take more power over some noise in the van as well.

Coming from a 270 horsepower 2004 Acura TL, I do like the power in the new ES 350 and am willing to listen to some engine noise in return for a lot of juice and great gas mileage.

e-man

So you guys are saying that more power equals more engine noise? Uh, please don't take this the wrong way, but that makes absolutely no sense. My engine is rated at 300 hp and I don't hear the noises many are experiencing with the new ES 3.5 (although maybe that's not a fair comparison because I have a V8). What about the poster above who had a newer Acura TL with 270 hp? Did that V6 make a lot of clatter? How about the new BMWs that are making close to 300 hp? Do those engines make unattractive noises? I think not.

MD350

My TL did run a little rough when very cold, but smoothed out when hot. The ES gives a little more horse and better gas mileage than the TL.

Overall, the ES runs a lot smoother than the TL. I think it is going to be personal preference. Coming from an older generation ES, the new ES may seem very rough and loud. But, coming from a sporty car like the TL, the ES is very smooth.

onsknht

No only pointing out there's a difference in design compared to previous models... Iron or aluminum, there's a difference in design. The aluminum block is probably reinforced differently than an iron block and therefore a different resonnance or frequency of noises are being emitted.. Could Toyota mitigate the noise, I believe so and I bet there will be changes incoporated in later build dates.

wanderer99

How do you find the ES350 engine compared to the your Sienna XLE engine?

amf1932

When a new engine is designed by Lexus, or for that matter all manufacturers, they run all kinds of tests to determine whether they pass ALL the test parameters that they deem acceptable. This includes the materials that the engine block is composed of......iron or aluminum. I'm sure that the resonant frequency is part of the testing procedure. The fact that some of the owners are plagued with tapping, rapping noises, does not indicate that the engine materials would have to be changed. I'm sure that Lexus will NOT change these basic materials in future builds.....but there is the possibilty that they'll modify certain parts in the 2008 ES's.

Lexmex

I have more power than stock and at idle I hear more engine noise.

onsknht

Valves or Piston Slap????

Noisy engine? It might be "piston slap"
by Jim Kerr

Knock, knock, knock, knock. No it's not the neighbour at the door. It's the disturbing sound of piston slap coming from your car or truck's engine. Is it a problem? Maybe - it depends on whom you talk to. During the last couple of years, I have had hundreds of inquiries about piston slap. Let's look at what causes the knock, and why it is much more common now than in the past.

In simple terms, piston slap occurs when the piston is forced rapidly against the side of the engine cylinder wall. The more clearance between the piston and cylinder wall, the louder the knock. Controlling piston slap is a complex process. Too little clearance between the piston and the cylinder wall and the parts will score and fail. Too much clearance and you get a knock. It doesn't help that usually the piston and cylinder are made of different materials and have different expansion rates.

Several features are used in piston design to reduce slap. To keep the piston close to the cylinder yet allow room for expansion, the piston skirt (the part that slides against the cylinder) is tapered - it is bigger at the bottom than at the top. The top of the piston expands more, where the extra clearance is, because of higher heat at the top of the piston. The bottom always remains close to the cylinder.


Pistons are also made oval shaped. The large part of the piston is close to the cylinder, while there is clearance on the smaller sides. As the piston expands, heat is transferred into the smaller sides, so the piston becomes more round. Thus, the large sides of the piston always stay close to the cylinder and piston slap is avoided.

There are several other piston features to counter piston slap, such as offsetting the piston pin position, but I think you get the idea. Too much clearance between the piston and the cylinder and we hear that Knock, knock, knock.

In the past, the sound of piston slap meant trouble. Worn cylinders, damaged piston skirts, or cracked pistons were common causes, and all meant expensive repairs. Now things have changed.

Engine designs have changed to make them more compact, lighter, with less internal friction, and higher revving. To do all this, piston design had to change, and some of the major changes are shorter piston skirts and straight piston skirts. The short, straight skirts allow the piston to rock more in the cylinder, and we hear it as piston slap.

Closer manufacturing tolerances have helped reduce piston clearances and slap, but some engines need more piston clearance to allow for piston expansion. During the first few minutes of operation, the piston can expand several thousandths of an inch, yet clearances are typically in the one to two thousandths of an inch. Fortunately, the cylinder also expands, or we would find pistons seized.

On vehicles built in the last decade, piston slap that occurs for a few seconds on cold start is quite normal. My own vehicle, with only 30,000 km on it has piston slap for about 5 seconds when first started on a below freezing winter morning. Service information from General Motors states "A cold Piston knock which disappears in 1.5 minutes should be considered acceptable". From experience, I have found that piston slap that occurs only during cold starts and lasts only for a minute or less causes no problems. Just don't place a load on the engine until the pistons have expanded and the clearance has been reduced.

Speaking of clearance, we normally find piston to cylinder clearance in the .0005 inch to .002 inch range. A human hair is typically about .002 inches thick, so you can see the clearances are very small. Some manufacturers are using special coatings on piston skirts to reduce friction. This enables them to reduce clearances even less and prevent piston slap. Ford V8 overhead camshaft engines use coated pistons; so does the Corvette Z06 high performance engine, as well as other manufacturers.

A good example to show the advantages of coated piston skirts is the Corvette. Clearance specifications for the coated pistons are from minus .001 inch to plus .001 inch. You read correctly; minus clearances! The piston is actually larger than the cylinder on the skirt sides of the piston. That coating has to be slippery! As the engine warms up, expansion in the cylinder block gives more clearance.

The correct engine oil can help reduce slap. Good oil takes up some clearance and is not easily scraped off the cylinder wall during cold starts. Sometimes, changing oil brands or viscosity can reduce a cold start piston slap.

If you suspect your piston slap is excessive, then there is an easy method to locate which cylinder has the problem. Before starting the engine, remove one spark plug wire and short it to the engine block. When the engine is started, that cylinder has less pressure pushing the piston sideways. If the knock changes, or is gone, then that is the cylinder with the problem. If the knock is still there, try another cylinder at the next cold start. It takes a little time, but it is much better to locate where the problem is before disassembling the engine.

So is piston slap a problem? Not for most engines built in the last decade and if the noise is there only for a few seconds during cold start. If the knock is in an engine of older design, the knock continues, or it is there during acceleration, then engine work is in the future. The worst part about piston slap is trying to explain that a cold start knock on newer vehicles can be normal, especially when you try to sell your vehicle!