[Kaminski54]

I’ve looked far and wide online for pictures showing the condition of the intake valves with regards to carbon buildup as mileage adds up. I changed my spark plugs and boots and threw a scope into each cylinder and was finally able to obtain pics of the intake valves, crosshatching, and pistons. Hopefully, this will help others with this concern as I have been unable to find pictures anywhere else online.

I was honestly surprised at how clean the valves were. Crosshatching looks like a brand new engine to me and I’ve never seen pistons/combustion chambers that clean! I’m not worried about fuel dilution after seeing my engine’s crosshatching. I use nothing but 93 octane top tier fuel. I’m tuned with a Ktuner stage 2. Have been for about 50k miles. Also, all oil changes are with Pennzoil Platinum or Ultra (if I can get it) 0w-20 or 5w-30 at about 30% oil reading on maintenance minder.

As a side note, any comments on the black spots at the head/block head gasket junction… pics 7, 8,and 9? I know these 1.5T engines blow head gaskets around 90k frequently. I’m hoping it is just carbon buildup as I would think if it was coolant, that spot would be clean. Like a steam clean. But there is almost no carbon anywhere else, which is puzzling. Any opinions? Hoping some mechanics could weigh in on those carbon deposits or possible head gasket issues.

Again, I hope this helps others as carbon buildup and fuel dilution issues have been a hot topic of discussion with these Direct Injection motors with no visual evidence to prove or disprove their existence.

 

[mtts60]

The valve stem is not anything to worry about. It's the valve seat and that part of the valve itself that contacts the seat that's the concern.

 

[Powell_87]

Thank you! Good to see actual condition of the valves. These pics are as rare as hen’s teeth!

 

[Kaminski54]

Rare as hen’s teeth indeed! 🤣 I looked for hours upon hours for pics or evidence of carbon deposits and fuel dilution wear problems, and it just doesn’t exist. So much talk with no real world data to prove or disprove these valid concerns. Finally decided to go for it myself and share with the community. I hope this helps others and sparks new debate and opinions.

 

[ThrillHill]

Wow, haven't been able to find these type of pictures anywhere!

I have a 2018 2.0T engine with a bit over 70K miles. Mostly Top Tier fuel, although occasionally I get gas from BJ's if I'm out food shopping or the like. For oil, I used to use Quaker State Ultimate Durability 0W-20, although I switched to Pennzoil Platinum 0W-20 a bit over a year ago which they claim protects similarly to 5W-20 (have been asking around on Bob Is The Oil Guy about those claims)

When it's hot for extended periods, I tend to use 93 octane to help manage knock control, which I think should help somewhat with head gasket concerns? I've yet to see any boroscope pictures or the like of 2.0T engine carbon buildup, but your pictures give me some hope.

 

[Kaminski54]

So glad this helped you! I looked everywhere for months and months and couldn’t find anything. Tons of carbon buildup discussions and forums but never any evidence. I figured some pictures would pop up eventually but they never did. I had the chance to finally obtain them myself and did so. I’m shocked at the lack of carbon on the valves, but was equally shocked by almost zero carbon in the combustion chambers. I’ve never seen combustion chambers so clean!

 

[slimm1469]

A rare find. What kind of fuel?

 

[Kaminski54]

93 Top tier only. Usually Exxon, Shell, or Marathon.

 

[ThrillHill]

I’ve never seen combustion chambers so clean!

Assuming this is a result of the Top Tier fuel detergency requirements. Obviously, a test control would be someone who DIDN'T use Top Tier fuel, but I'm unsure that someone who wasn't concerned about fuel detergents would somehow be concerned enough to check for carbon buildup deposits.

 

[WiiMaster]

In some cases premium can have more additives vs regular (ex: Shell's V-Power NITRO+) so that would make for a good comparison as well.

 

[Kaminski54]

For sure. Now we just need to wait another 5 years for a neglected 1.5 or 2.0 to provide pics. 🤣 It is either the fuel I used or my tune has something to do with it. More complete burn? Just guessing. 🤷🏻‍♂️

 

[WiiMaster]

Yeah, IMO these pictures are only partially useful when they're not a stock engine. It's good to at least have something out there, but the best photos would be on a stock engine that followed Honda's recommendations (ie: 87 octane, factory tune).

 

[MisterHooman]

Yeah, IMO these pictures are only partially useful when they're not a stock engine. It's good to at least have something out there, but the best photos would be on a stock engine that followed Honda's recommendations (ie: 87 octane, factory tune).

A factory tune car should look better in the same conditions! An aftermarket tune almost certainly increases blowby. A catch can would help somewhat with that though.

Too many variables to expect the same results for each car. For example, long trips vs short trips or Top Tier fuel vs generic straight from the refinery are a few examples.

 

[Kaminski54]

Yes, a stock tune with regular gas would be nice to compare. Most of my trips are 20 minutes or more so that probably helps as well. Still, regardless of the tune, gas, and trip distance, I have never seen a combustion chamber that clean. If I didn’t see it myself I would think it is impossible. Do you guys think the small black spots near the head gasket is just carbon?

 

[Powell_87]

Any chance you had an oil analysis done during the life of this Accord? The doom and gloom of oil dilution would be mitigated if it results in such a minor carbon build-up.

 

[Kaminski54]

I never did. Bought the car used with 34k miles on it. To me, the stronger evidence against fuel dilution leading to wear would be the excellent condition of the cross hatching of the cylinder walls. I definitely have oil dilution as my oil dipstick rises from mid level with a fresh oil change to above full after about 5k miles. Obviously the dilution hasn’t impacted wear, at least on the cylinder walls.

 

[Powell_87]

I was just thinking if you are still looking for thoughts about the potential carbon, it might be good to put this info on BITOG. You get lots of feedback, maybe even some info. They love this kind of stuff.

 

[Kaminski54]

I’ll definitely do that. Thank you!

 

[KayGeeP]

Top tier fuel wont help in any way alleviate the carbon fouling issues plaguing GDI motors.

Fuel gets sprayed directly into the cylinders, none of it makes contact with the valves or intake. Better quality oil, sooner oil changes (not waiting until the maintenance minder tells you to change it) have a bigger impact on slowing carbon fouling, it's inevitable..... And of course we have the elephant in the room..... Aftermarket Oil catch can. (Soma car makers, like Mazda, have a factory catch can installed by no way for it to be emptied...

 

[Kaminski54]

Yeah, my carbon comments or questions are regarding the combustion chamber, not the valves. The valves are relatively clean by what I can only assume is an effective PCV/EGR system. I’ve never seen a combustion chamber that free of carbon. Maybe it is top tier fuel, maybe it is my tune, but most likely is the design of the engine. Although I don’t specifically know what engineering feats would result in such a clean, carbon free combustion chamber.