Hearing a rattle noise at low gear acceleration.

[arash]

Oh yours gets worse as temperature goes up? That's the opposite of what others are seeing and it could be something more significant than piston slap. That rattling noise for me only happens on a cold engine at lower revs and goes away completely in all circumstances on a warm engine. I'm also not sure how the main bearing is involved in piston slap, since the piston is hitting the cylinder wall, though I know nothing about how engines work.

 

[Vision83]

Oh yours gets worse as temperature goes up? That's the opposite of what others are seeing and it could be something more significant than piston slap. That rattling noise for me only happens on a cold engine at lower revs and goes away completely in all circumstances on a warm engine. I'm also not sure how the main bearing is involved in piston slap, since the piston is hitting the cylinder wall, though I know nothing about how engines work.

I don't think there is a censuses on when/how the sound is occurring. Some have it in park, some when warmed up, some when cold. Some have it all the time.

From what I have seen it is most common when the engine is under load from 1500-2500 rpm And some report it going away after it is at temperature.

I am not 100% convinced it is piston slap... We have seen that reported and it may be. But it really could anything internal.

I think this is best explanation until more information comes out.
May (or may not be) caused by an issue with something in the crank/oiling passage/main bearings.
(I was told main bearing redesign)

 

[KyLandcruiser]

I’ve observed that if I use certain fuels such as Marathon/Top Tier Fuel I don’t notice the noise. If I run Marathon long enough the noise for some reason seems to disappear or become less noticeable. The past few mornings I haven’t noticed the sound.
Has anyone else noticed this ?

 

[arash]

I had a chat with an AI that dropped a lot of knowledge that put my mind at ease about this. Thought I'd share.

I also later asked about diesel engines because I'd guessed those would have even more piston slap than gas engines, and I haven't heard of diesel engines failing due to cold start piston slap.

Question: How typical is it for modern engines to have piston slap when the engine is still cold that goes away when the engine is warmed up?

Piston slap when cold that disappears once warmed up is relatively common in modern engines, though it varies significantly by design and age. Here's what you should know:
Normal vs. Concerning:

• Many modern engines, especially those with short-skirt pistons designed for reduced friction and weight, exhibit some cold piston slap
• Aluminum pistons expand more than iron cylinder walls when heated, so the piston-to-bore clearance is intentionally larger when cold
• Light tapping or knocking for the first 30-60 seconds that fades as the engine warms is often normal

Factors that increase likelihood:

• High-mileage engines (100,000+ miles) as wear increases clearances
• Engines with hypereutectic pistons (common in many modern cars for efficiency)
• Direct injection engines tend to be noisier overall, making piston slap more noticeable
• Some manufacturers like Subaru, GM (especially LS engines), and certain Toyota models are known for this characteristic

When to be concerned:

• If the noise persists after full warm-up
• If it's suddenly gotten much louder
• If accompanied by excessive oil consumption or loss of power
• If it sounds more like a heavy knock rather than a light tapping

Many manufacturers consider mild cold piston slap a normal characteristic that doesn't affect engine longevity. However, if you're concerned about a specific noise in your engine, having a mechanic listen to it can provide peace of mind and catch any actual issues early.

Question: Do diesel engines have even more cold start piston slap? And would Toyota design the engine so this piston slap would not cause wear to the pistons or cylinders over time?

Yes, diesel engines typically have more pronounced cold start piston slap than gasoline engines for several reasons:


Why diesels are worse for piston slap:

• Higher compression ratios (16:1 to 23:1 vs 10:1 to 12:1 for gas) require larger cold clearances
• Heavier pistons due to the need to withstand higher combustion pressures
• Different combustion characteristics - diesels have more abrupt pressure rises during combustion
• Longer warm-up times - diesels generate less waste heat, so they stay "cold" longer
• The characteristic diesel "clatter" is partly piston slap mixed with injection noise

Regarding Toyota's engineering approach:


Modern manufacturers, including Toyota, design engines to accommodate cold piston slap without causing significant wear:


Design features that prevent wear:

• Piston coatings - Many modern pistons have anti-friction coatings (like molybdenum disulfide) on the skirts
• Optimized piston profiles - Pistons are slightly oval and tapered when cold, becoming round at operating temperature
• Offset piston pins - Reduces the side thrust that causes slap
• Precisely calculated clearances - Engineers model thermal expansion to minimize slap while preventing seizure

Why cold slap doesn't typically cause wear:

• During cold operation, the engine is under light loads - most wear occurs under high heat and load
• The oil film, even when cold and thick, still provides cushioning between surfaces
• The "slapping" motion is more of a rocking than a hammering impact
• Modern oil formulations include additives specifically for cold-start protection

The key insight: Engineers accept some cold piston slap as a trade-off for:

• Better fuel efficiency (less friction from tighter hot clearances)
• Improved emissions
• Longer engine life under normal operating conditions

Toyota, known for reliability and longevity, wouldn't design an engine where normal cold-start characteristics would compromise durability. The T24A-FTS in your Land Cruiser is engineered to handle hundreds of thousands of miles despite the cold start noise. The fact that the slap disappears when warm actually indicates the design is working as intended - the clearances are closing up properly with thermal expansion.

I asked some more followup questions which you can view and even ask your own questions here: https://claude.ai/share/7b7820ef-fa00-4df2-bd77-39acfbf668be

 

[RGV Land Cruiser]

Posted this on another thread:

Engine Death Wobble

Have the same engine tick issue, but it happens every single day for me. Kinda kills the vibe to cruise with the windows down.

 

[RideWithYanu]

I like the sounds of the little sewing-machine engine.

 

[Doggman1525]

Fun thread, now let me introduce you to my friends Dunning and Kruger...

I can't help but think this is one of those situations where more than one thing can be true at the same time. Absolutely there are owners who's vehicles have serious defects that will lead to early failure. This is as true of the LC as any vehicle. It sucks, blows and stinks all at the same time. That's why we have warrantees, guarantees, lemon laws and lawyers in the world. You have my full sympathies and support that, after laying down your hard earned money, you deserve to be made whole for any such loss by the manufacturer.

Now does this mean every click, rattle and hum is a harbinger of doom that will leave you stranded in the desert to die of thirst and starvation? Probably not. Fact of life: Internal combustion engines make noise. The T24A has been around for a while now and from what I've read it's never been accused of purring like a kitten. Between direct and port injection systems, fuel pressurizers, multiple pumps, turbos, waste gates and a thousand other parts I've never even heard of if you're going to crawl into the engine bay with a stethoscope looking for a sound to make you anxious you're going to find one.

Try applying Bayes Theorem. This forum encompasses 4-5k highly engaged, highly motivated to report and share members who either have a specific ax to grind but more commonly just love our trucks and want them to be perfect. We are more likely to raise issues with each other and with the manufacturer because we love our babies (and per my comment above, don't want to die stranded in the middle of nowhere).

Now, I haven't run the statistics but my intuition is that in this and maybe a half a score of similar threads there have been maybe 2 or 3 owners per who have been able to document truly serious issues that have escalated the dealer for major repairs or at least discussion thereof while the rest of us are mostly just pearl clutchers commenting and looking for reassurance.

A handful of serious cases out of 5000 members isn't exactly an epidemic and it would be a mistake to extend the assumption that all ~50k+ LC owners in North America are prone to this level of hypervigilance. More likely their vehicles are making most if not all of the same sounds and they just don't care that much as long as they are not late for work and can keep driving. Yet, there's no been rash of broken down Landcruiser backing up traffic or filling up dealer's garages, at least not to my knowledge.

So, you can see how there can be both catastrophic outcomes at the anecdotal level but systemically there may be whole lotta nothing going on. Toyota's been in business and making money for a while, I think they know that that if they sell 30 or 40k of a model even at a low failure rate they will still get at minimum hundreds of unhappy customers filing reports under the best of circumstances and yet that's not cause to treat this as a systemic issue, at least not one that we all need to be up sweating bullets over every night.

Now, I don't entirely dismiss the logic that Corporate has its motivations to keep things under wraps and protect the brand, but, and I apologize in advance to those who do not fit this description, my experience is also that dealership mechanics are not great at saying "I don't know" when they legit don't know something and are prone to just making up a bull$#!t answer to get you to you shut up and go away. Hardly the sort of thing that recalls are built upon.

At the end of the day could Toyota be redesigning the main bearing and plan to replace all the T24A-FTS blocks? Sure, it's possible. I'm open to reassessing my analysis as new data comes in but am I confident that some floor jockey at a dealer in Nowhere'sville USA has the direct line to HQ in Aichi where the big decisions are being made? No. Now, if you and Mr. Sato are bestie's on Insta then by all means please give us the inside track...

 

[EOD Guy]

Fun thread, now let me introduce you to my friends Dunning and Kruger...

I can't help but think this is one of those situations where more than one thing can be true at the same time. Absolutely there are owners who's vehicles have serious defects that will lead to early failure. This is as true of the LC as any vehicle. It sucks, blows and stinks all at the same time. That's why we have warrantees, guarantees, lemon laws and lawyers in the world. You have my full sympathies and support that, after laying down your hard earned money, you deserve to be made whole for any such loss by the manufacturer.

Now does this mean every click, rattle and hum is a harbinger of doom that will leave you stranded in the desert to die of thirst and starvation? Probably not. Fact of life: Internal combustion engines make noise. The T24A has been around for a while now and from what I've read it's never been accused of purring like a kitten. Between direct and port injection systems, fuel pressurizers, multiple pumps, turbos, waste gates and a thousand other parts I've never even heard of if you're going to crawl into the engine bay with a stethoscope looking for a sound to make you anxious you're going to find one.

Try applying Bayes Theorem. This forum encompasses 4-5k highly engaged, highly motivated to report and share members who either have a specific ax to grind but more commonly just love our trucks and want them to be perfect. We are more likely to raise issues with each other and with the manufacturer because we love our babies (and per my comment above, don't want to die stranded in the middle of nowhere).

Now, I haven't run the statistics but my intuition is that in this and maybe a half a score of similar threads there have been maybe 2 or 3 owners per who have been able to document truly serious issues that have escalated the dealer for major repairs or at least discussion thereof while the rest of us are mostly just pearl clutchers commenting and looking for reassurance.

A handful of serious cases out of 5000 members isn't exactly an epidemic and it would be a mistake to extend the assumption that all ~50k+ LC owners in North America are prone to this level of hypervigilance. More likely their vehicles are making most if not all of the same sounds and they just don't care that much as long as they are not late for work and can keep driving. Yet, there's no been rash of broken down Landcruiser backing up traffic or filling up dealer's garages, at least not to my knowledge.

So, you can see how there can be both catastrophic outcomes at the anecdotal level but systemically there may be whole lotta nothing going on. Toyota's been in business and making money for a while, I think they know that that if they sell 30 or 40k of a model even at a low failure rate they will still get at minimum hundreds of unhappy customers filing reports under the best of circumstances and yet that's not cause to treat this as a systemic issue, at least not one that we all need to be up sweating bullets over every night.

Now, I don't entirely dismiss the logic that Corporate has its motivations to keep things under wraps and protect the brand, but, and I apologize in advance to those who do not fit this description, my experience is also that dealership mechanics are not great at saying "I don't know" when they legit don't know something and are prone to just making up a bull$#!t answer to get you to you shut up and go away. Hardly the sort of thing that recalls are built upon.

At the end of the day could Toyota be redesigning the main bearing and plan to replace all the T24A-FTS blocks? Sure, it's possible. I'm open to reassessing my analysis as new data comes in but am I confident that some floor jockey at a dealer in Nowhere'sville USA has the direct line to HQ in Aichi where the big decisions are being made? No. Now, if you and Mr. Sato are bestie's on Insta then by all means please give us the inside track...

Very well stated!

I do agree, there are those, unfortunately, that truly do have issues/problems/failures from the factory and I think Toyota will try to make it right with those affected. I think there are dealers that will move heaven and earth to make it right and there are dealers that will tell a person anything to get them out the door. Dealership's employ both Mechanics and Technicians/parts changers. If you get a Mechanic, they normally find the issue, give sound advice as to the root cause and possible courses of required/needed repairs. If you get a Technician/parts changer, they normally can't replicate the issue and send you on your way or load up the parts cannon and get your permission to fire it.

I also believe there are some that have read a post (somewhere) and they now believe they have catastrophic issues due to a noise that's hard to hear but It's there "I tell ya". They have read where it's good for your engine to change the motor oil to a higher weight viscosity because "no way an engine can run on that thin oil and thicker oil will increase engine life" but they fail to realize the total circumstances to which a thicker oil would be beneficial (tolerances).

And my favorite........ I just spent "insert price here" (50k, 60K 70k, 80k) on a new vehicle and there is a terrible noise when poke a stick into the cooling fan. (satire here)

 

[RGV Land Cruiser]

Very well stated!

I do agree, there are those, unfortunately, that truly do have issues/problems/failures from the factory and I think Toyota will try to make it right with those affected. I think there are dealers that will move heaven and earth to make it right and there are dealers that will tell a person anything to get them out the door. Dealership's employ both Mechanics and Technicians/parts changers. If you get a Mechanic, they normally find the issue, give sound advice as to the root cause and possible courses of required/needed repairs. If you get a Technician/parts changer, they normally can't replicate the issue and send you on your way or load up the parts cannon and get your permission to fire it.

I also believe there are some that have read a post (somewhere) and they now believe they have catastrophic issues due to a noise that's hard to hear but It's there "I tell ya". They have read where it's good for your engine to change the motor oil to a higher weight viscosity because "no way an engine can run on that thin oil and thicker oil will increase engine life" but they fail to realize the total circumstances to which a thicker oil would be beneficial (tolerances).

And my favorite........ I just spent "insert price here" (50k, 60K 70k, 80k) on a new vehicle and there is a terrible noise when poke a stick into the cooling fan. (satire here)

EOD Guy, thank you for everything you have shared and done on this forum. Personally, you have given me several ideas and answered a lot of questions I have had. Please keep it up!

This is my first Toyota and I shared my ticking video on here because another member recommended it. I thought the sound was something normal and it usually goes away after 15 minutes. Whether or not it is by design (more than likely is), it's something that Toyota needs to address because I have seen several differing opinions and answers on here.

However, I am that person that the dealership and Toyota has been saying anything to or "can't replicate it" so can't fix it to move along. Offered this video to both and neither wanted it. Maybe I've had bad luck with these folks, but that's why I'm posting it here to see if anyone has had this issue and hope maybe someone from corporate sees this and responds. The thread is here: Engine Death Wobble

 

[EOD Guy]

My intention wasn't to make lite of your obviously legit issue.