That's not promising, with the second engine block and still issues. How was carbon buildup determined as an issue or symptomatic?

I have a 2025 but only 9000 miles on it. Did the first dealer oil change at 7000 miles, but I did oil changes at 500 and 3500 miles myself. Hoping to prolong the engine life as much as possible.

 

The asst Service Mgr couldn't answer that. I got the name of the mechanic but I'm not sure they will let me talk to him. He supposedly has worked on nothing but Hondas for 30 years.

 

Out of curiosity, what were your oil change intervals?

 

5-6,000. They tell you 10,000, but the dashboard says 5,000.

 

Tear it down twice(!) more for carbon buildup? I think that is grounds for demanding a new engine. I would have called no more as soon as the second rebuild was proposed. Problematic Carbon buildup should not be happening at that mileage, as long as the engine is being maintained as directed.

 

The first problem was the cylinder scoring discovered at 19,000. at 25,000 they tore it down, discovered carbon deposits, cleaned, reassembled, drove it, tore down a second time this same visit, and discovered carbon again!

 

I can add that I find my engine lately has been noisy. To the point that my family has been commenting on it.
It is particularly loud on cold start, almost like it's knocking a bit. Not a sound I am accustomed to in my vehicles. It will quiet down after a short period of idling, but still, the sound should not be expected at 5500 miles (Just under 9000km).

 

I do remember hearing about some people having outright engine failures on this new engine. Not extremely widespread, but they exist.

 

There was a member on here last year who had a camshaft failure, but IIRC they sort of admitted the first two OCI's were >10,000 miles and ~13,000 miles. Should the camshaft have failed even with that kind of neglect? Maybe, maybe not.

 

Factory fill, I had a lot of Moly still at over 9k first oil change (did oil analysis). There was a very high level of copper, but they said it could be from the newly installed parts, copper they said was radiator wear iirc, it went down after second oil change but still elevated.

Possible, not bashing Amsoil (I use for convenience) but their "high quality oil" (from them, not me), their best Signature series runs out of anti wear around 13k miles (oil analysis proven) but they state it can go like 25k... Also their branded oil filters to help go the 25k allows more dirt to pass thru at lower microns.

Might be better now but late 2000s, Mobile was having bad oil analysis and OCI suggestion was no more than 5k, a lot of oil consumption and engine failures in the Subaru community - that's where Rotella T6 (diesel oil) became popular.

 

There was a very high level of copper, but they said it could be from the newly installed parts, copper they said was radiator wear iirc, it went down after second oil change but still elevated.

Blackstone Labs believes (and I tend to agree on this based on my own experiences) that the J series engines exhibit elevated copper levels when they're lower mileage and this goes down as they break in. I noticed this when I had one done on my Accord at 30k compared to my Odyssey at 111k. The copper levels in the Accord were noted as being elevated, while the copper levels in the Odyssey were more normal. Blackstone says this is a common pattern they see with the J series engine samples they get in.

Moly is a good thing and part of why doing an early "break-in" oil change is a thing of the past.

Should the camshaft have failed even with that kind of neglect?

How do you know a 10k or 13k OCI was neglect? Did you do an analysis on their oil to determine it was no longer capable of protecting the engine and should have been changed sooner? It very well could have been, but we can't make such assumptions when it's proven time and time again that oil can in fact last that long or sometimes even longer.

 

Blackstone Labs believes (and I tend to agree on this based on my own experiences) that the J series engines exhibit elevated copper levels when they're lower mileage and this goes down as they break in. I noticed this when I had one done on my Accord at 30k compared to my Odyssey at 111k. The copper levels in the Accord were noted as being elevated, while the copper levels in the Odyssey were more normal. Blackstone says this is a common pattern they see with the J series engine samples they get in.

Moly is a good thing and part of why doing an early "break-in" oil change is a thing of the past.


How do you know a 10k or 13k OCI was neglect? Did you do an analysis on their oil to determine it was no longer capable of protecting the engine and should have been changed sooner? It very well could have been, but we can't make such assumptions when it's proven time and time again that oil can in fact last that long or sometimes even longer.

I've seen first-hand what maintenance neglect can do the internals of an engine. Replaced many over the years. Not really interested in yet another oil discussion. I really don't give a flip.

Also I ended the question with "maybe, maybe not".

 

UPDATE: "Thank you" to everyone for your replies! I appreciate all of you! More bad news: I got my Pilot back but the service director is mailing my shop report. He said the new block has scoring on walls but not bad enough to replace block again. Pictures of everything have been sent to Honda engineers and they don't know what is causing the problems! My repair order is being left OPEN. Plus, there is another of the SAME ENGINE in the shop with the same issues! Yikes! My wife is hoping for a recall.

 

How many miles are on the new block ?
Just Re-read the 1st post, so is there only 6K on the new block ??

I would think you may want to ask the shop check periodically, if they are willing, maybe during routine services..
Especially since they left the repair OPEN...

So update this thread when you can.
Hoping for the best outcome for you...

 

What is your VIN? I’m curious because engine block machining may have been bad for a period. This is NOT good news for Honda Owners. My 2025 Pilot had 2 recalls already Fuel Software update & Brake Pivot Pin. FWIW I also changed my oil more frequently.

Keep us posted. And thanks for informing us. Good luck 🍀!

 

Sorry so long replying! VIN 5FNYG2H75SB020812

 

Man, I hope they just give you a new engine at this point. Probably would have cost less money overall for them at this point.

My 25 Pilot Trailsport has been at the dealership for over a month with a transmission fluid leak right at the transmission transfer casing. Honda takes quite a long time to approve of any major warranty repairs. The dealership just got approval to tear open the transmission. Hopefully it is nothing serious. At least you got a loaner SUV. The dealership gave me a loaner Accord. Haha

 

Dang. So sorry you’re going through that! I also have a 2025…19,000 miles. This is my 3rd pilot and 5th Honda. Have never had engine issues in my time owning Hondas, only transmission. I do have a couple of friends that have had blown engines at high miles with the older generation pilots. Sounds like you drew the short straw. I hope Honda makes it right.

 

Hello, Our 2023 Pilot Touring model has 49k miles. Oil changes with Mobil 1 oil and filter. No problems yet. Mostly highway miles.

 

Using Valvoline oil

 

oh boy '25 touring here. No problems yet at 7k. Just dipping my toe in to hear the tea.

Out of curiosity, I see some of you are mentioning some sort of oil analysis for metals? Are you getting this info yourselves? Why? or is there some indication to do this?

 

This needs a critical path analysis:

Scoring and carbon build-up suggests the carbon build-up is a result of excess oil entering the combustion chamber due to the scoring.

The question is what caused the scoring?

There are only two ways into the combustion chamber. First is through the intake valves and intake plenum and air filter. Second is through the fuel injector. Abrasive foreign material can enter through either way.

Replacing the block should have eliminated the air intake path if the mechanic was thorough in preparing and cleaning it. That leaves the fuel path, which includes the high pressure pump - and there is some history on this causing abrasive foreign material to enter the combustion chamber over the past few years.

 

From what I understand Excess carbon can also build up in piston ring grooves. With this build up there no longer a slight gap for the rings to expand into when they heat up in operation and they expand to the point they lock up in the ring groove, sometimes even breaking the ring land in the piston. Could be the gas direct injection on the new J35 causing this one?

Fltmech

 

2025 Pilot Black Edition, my 3rd Honda, having come over from another brand recently.
I’ve owned a 1977 Civic 5-speed CVCC bought used with very low miles then a brand-new 1980 Accord hatchback LX.
No issues whatsoever with either vehicle. NONE!
My 2025 Pilot BE is an incredible vehicle, it handles very well and the steering is light and precise with great on-center feel. The 3.5L V6 is a terrific engine, along with the 10-speed transmission which is as smooth as can be.
Luv my Pilot! 🚙

 

Scoring of cylinder walls occurs from bad pistons or rings. Poor castings end up in catastrophic failures. I'm a die cast die maker and casting issues would be poor fills or cracking. Scoring comes from motion of the pistons. Someone is giving you bad info. I have 25K miles on my 2025 Pilot Touring. There are many problems with it but the engine is OK so far. I made a mistake buying a honda...

 

Trade it in.

 

.

 

Maybe you should starting talking to a lemon law lawyer regarding your circumstances

 

When life gives you lemons, make lemonade!