What type of gasoline were you using?

 

Don’t be too sure. I had a Honda Odyssey with that engine and after 46,000 miles it started misfiring. It turned out that Honda did a bad job with the piston rings on three of the cylinders. The engine was rebuilt under warranty, but if you do a search under Honda 3.5 V6 misfire, you will see all the past and current issues, including a class action lawsuit.

 

That's the fault of VCM, which Honda was peer-pressured into implementing on the J35. The 6MT Accords that don't have VCM don't have this issue.

 

Its certainly true that more things can go wrong with Turbo

 

This 100%. The J35 has been around awhile and in multiple models in both the Honda and Acura lineups. The issue with the VCM was explained to me by the Honda mechanic I use but it was a while ago so not sure I will have this 100% correct. The shutting down of three of the cylinders causes them to cool and when they are called on to engage again, it mimics a cold start causing extra wear on the piston rings.

 

Wanted to share an update since a lot of folks have been describing that same “feels like it’s about to stall” issue at low speeds.

Mine’s a 2019 RDX SH-AWD with around 86k miles when it started happening. The car would hesitate or jerk a bit under sudden acceleration to a high speed (such as merging onto a highway from a stop or accelerating to higher speed after being in traffic). No check engine light, no overheating, just that weird stumble when hitting the gas.

Brought it to a local Herb Chambers Honda dealer and they found a cylinder 4 misfire that stayed put even after swapping coils. Leak-down test showed bubbles in the coolant system, and after tearing it down they confirmed a head gasket leak between cylinders 3 and 4.

The good news is the head and block were both fine, so no cracks or warping. It just needed a new gasket kit and seals. Everything was fully covered under my extended warranty, and the total came out to around $3,600 with zero out of pocket.

The new gasket kit they used was part number 3101987 CPC, which the tech said is the updated version with improved sealing around the coolant and combustion rings. Hopefully that means this won’t come back down the line.

This thread actually helped me a lot when I was trying to piece together what was going on. The info here gave me enough detail to walk into the dealership with a clear description and the right tests to ask for. Really appreciate everyone who shared their experiences because it definitely saved me time and money.

If anyone else feels that hesitation but no codes or CEL, it’s worth getting a leak-down test done early. Mine never threw a light but was already leaking internally. Catching it early probably saved me a much bigger headache later.

 

Curious - which Herb Chambers Honda location?

 

Herb Chambers Seekonk, MA

 

I’ve used them for decades. Tim Islip (SA) is a pretty good guy and I know one or two of their techs. It’s good to know that are at least now aware of this issue.

 

Did you happen to notice if the level in the coolant reservoir was going down?

 

Always premium from Costco.

 

Also, did you get any forbidden milkshake in your oil? Hopefully not but wondering if it's noticeable before the failure becomes catastrophic.

 

Yes, the coolant reservoir was completely empty,. The video they showed me had milky oil in the cylinders.

Honestly, I think this is a ticking time bomb for all owners. The fact Honda is tight lipped about it, means they are hoping to get through this as unscathed as possible. They are hoping the head gaskets fail after the power train warranty so they don't have to cover any of it. They may cover some out of good will. But the majority of people will be SOL soon. I'm sure the 2026 RDX will be the last of its generation. And then 6 years later, Honda/Acura will be out of the woods, at least for the RDX. The 1.5t engines in the accords, civics, cr-v's are screwed.

 

Thank you, that's something we can keep eye on and maybe get a heads up that something is going on.

 

What oil was used and how often changed?

There is a theory going around that LSPI could cause it, but I doubt it.
short OCI is recommended.

 

Think you guys are making this into a bigger deal than it is.

4355345343463 things contribute to a Head gasket failure, from issues during assembly, a wastegate failing and oversboosting, a thermostat failing and causing the car to overheat, etc.

I've not see any HG issues with these motors making tons of power in Accords and so on.

 

1.5T had much more sales than 2.0T, thats why it might seem that issue is more common in 1.5T.

there are number of post for 2.0T Honda.

I personally think fuel dilution and LSPI could be one of the contributing factors coupled with a bad block/gasket design

 

Also oil change intervals that are more than 4-5k miles…

 

That whole thought to me is wild, I know oils/filters have advanced but going 10k on them is wild to me.

Spend the $35 it takes for Mobil 1 and a good filter and give yourself some added insurance.

 

From ChatGPT, take it for what its worth. I dont think its completely wrong…

older oil is more likely to cause LSPI, especially if its not API SP//SQ. SQ is ideal, if you can find it…






How fuel dilution leads to head gasket issues

• Thinned oil: Excessive fuel in the oil thins it out, reducing its ability to properly lubricate engine components.
• Increased friction: Poor lubrication leads to more friction between moving parts.
• Overheating: Increased friction generates more heat, which can cause the engine to overheat.
• Warped components: The excessive heat can cause engine block and cylinder head components to warp.
• Gasket failure: Warping creates gaps where the head gasket should seal, leading to a head gasket failure.

How LSPI leads to head gasket failure

• Detonation and pressure spikes: LSPI causes premature, uncontrolled combustion (detonation) that generates extreme pressure spikes inside the cylinder.
• Stress on internal components: This sudden, out-of-sync pressure places tremendous force on internal engine components like the piston, connecting rod, and crankshaft.
• Component damage:
  • Connecting rods can be bent or broken.
  • Pistons can crack.
  • Rod bearings can be battered.
• Head gasket compromise: The combined stress from these events can warp the cylinder head and/or engine block, creating gaps that the head gasket can no longer seal, resulting in a blown head gasket.

 

Probably not, but like you said, more frequent oil changes goes a LONGGGGGGGGGGGGGG way in regards to this.

LSPI is a whole different issue

 

yeah, but as oil gets older the chance of LSPI increases. Only in API SQ
latest standard they are measuring aged oil ability to prevent LSPI.
most people now run SP oils, which are only tested to prevent LSPI when they are new, so those
that run longer oil changes could be having more LSPI events.

LSPI causes excessive pressure in cylinder, and if you have badly designed block/gasket, it can blow it…

we dont know full picture, but I will attempt to do what I can to prevent it:

1. Higher octane gas
2. One grade higher oil
3. change oil 3-4k miles
4. Change coolant every 50k/5 years


may not prevent it, but maybe reduce chances…

 

The only thing I keep coming back to is this: why didn't the K24 and J35 have this issue? Or did they? Just feels like the newer motors aren't 'overbuilt' like they used to be.

I keep thinking about that video of the guy who tried (and failed) to seize up a CR-V K24 by running it with no oil. I doubt you could do the same thing with the K20C and L15.

 

k24 was not Turbo if I am not mistaken?

Turbo produces higher pressures inside cylinders, you need good seal to keep all that pressure inside and now blow gasket.
also poor design of the block and head gasket is likely the culprit.

some are blaming head bolts that are stretching, could be the case as well with Honda saving few $ on cheap head bolts

 

I mean they both had their own issues, K24 had chain tensioner issues and J series had trans issues, granted that was not motor related but as an entire car, there were issues.
The issues are more related towards "smaller" motors needing to be more fuel efficient AND make power, thus forced induction.......


Yupp exactly......
large contributing factor is def the snail

 

K23 in RDX 1G was turbo and did not have these issues! I might be in the market for an RDX and the CPO seems very appealing due this thread.

 

Didn't those have issues with the variable turbo flap/throttle body or whatever it used to open/close the exhaust housing off.

Every motor has issues, big and small.........

 

K23 in 1G RDX is just a K24 with a turbo slapped on it. Actual displacement for K24 is 2349cc.

Matt, the thing you're referring to is the eyebolt on the turbo actuator wearing out. When the bolt hole gets too big it throws a code. Plenty of posts about it although at 207k miles I've been lucky to not deal with it so far.

I've been dealing with plenty of oil leaks on this motor but that's the biggest issue I've had. This weekend I'll be changing out a leaking oil pressure sensor for example. But this is by no means a catastrophic failure the way a failed head gasket is.

Everything else I spend my time on is suspension or steering-related. All that said, I'm fortunate to have bought the car in essentially new condition (purchased @ 53k from a family member who bought new and did all dealer service). I've seen and worked on other first-gen RDXs that are in very rough shape due to lack of maintenance.

 

Ah yes, I couldn't remember the exact issue with those. I was just using that as a reference point to show everything has issues.
People are up in arms about a few cases related to the thread topic, I still don't think it's some massive issue though.


There's a dude on Honda-Tech that has a cool 1G RDX too. Probably not many of them out there.

 

1G engines are getting old, some are getting issues with Turbo waste gate. It was overall reliable engine.

 

Tim is the man! When me and the wife were carpooling and driving 80 miles a day, He saw my 2016 Accord often for oil and tires. Most of the time now with my RDX I'm seeing Malainne Costa, and she's fantastic.

Posts on AcuraZine, Drive Accord, and CivicX may make it seem like the sky is falling but we are all enthusiasts and only people with the issue posts, so the signal-to-noise ratio will be off.

I appreciate everyone's tinfoil hats, especially because not only are we all hyper niche by being on an RDX forum, this can get echo-chamber-y since now we're all on the same thread for a specific issue in a specic generation/trim. I'm not going to give Honda the benefit of the doubt and act as if they're infallible, but it is extremely telling to me that the "fix" was basically a part revision that's inline with mid-cycle refreshes, hence the "G02" part number. I would love to be a fly on the wall to see what the engineers discovered, any high mileage testing, or if there was any internal reports about this, especially because someone posted earlier that after contacting Honda directly they covered a portion of the repairs. It might just be a "keep silent but if people come in, take care of them" issue and not a full blown recall.

100% in agreement - can't make an apples to apples comparison with NA Honda engines. My KSeries 05 Accord (197k miles) and my JSeries 16 Accord (140k miles) were basically bulletproof engines, but once you add in a turbo it is a different ball game.

According to my research the K20C4 is an acura tuned version of the CTR engine. Different head, different cooling passages, and different turbo tune. It's possible that we can look at the updated head gasket as "we found a tolerance or material improvement". It's unfortunate because it's an easy jump to conclude "Are all four cylinder engines a ticking time bomb!?!?" after this, but it's not like the K20Cs are EJ25s.

The L15B7 (1.5T in Civics and CR-Vs) issue was Fuel dilution in cold climates, right? I think I read that it was fixed with a software update and an extended warranty. I don't recall them having head gasket issues like we are experiencing.
Then there were the K20C4 and K20C3s in Accords but I was reading about Carbon buildup, Wastegate rattle, oil leaks around timing/cam cover, and higher than normal oil consumption. I still have my Drive Accord account and I see "my 2.0T is flawless at 120k" posts. At least in the Accord, the engine seems solid.

With the RDX the engine runs hotter, makes more boost, and I read that the cooling layout is slightly different. Heck, the RDX is a heavy sumbitch as well - and Sport+ Mode runs the engine way harder than an Accord does lol. All that to say... it's interesting to me that our pre-revision RDXs are having this issue post 75k but, I'm at least glad that there's a part out there and Honda shops have a resolution in place.

 

No niche here, I just happen to hop on here as well as being active on Honda-Tech and just generally in to cars.
See plenty of Accords with 400/400 on upgraded turbo kits and all with 0 HG issues.

 

Updated part number might not be necessarily fixing the issue if design of a block is the root cause, Honda might be trying to bandaid the gasket to be more durable but its not clear if new design is any better, time will tell. I know some parts took multiple revisions before they got it right.
they keep it tight lip, and dont seem to want to pay for it out of warranty, especially if you are over 100k miles

 

According to this thread on the CRV forum, head gasket failures are a big problem. Much more so than we're seeing here so far.

​​​​​​https://www.crvownersclub.com/thread...ailure.242558/

 

yeah, there are more problems in 1.5T head-gaskets in online forums.
However, the number of sold 1.5T is a lot bigger than 2.0T, so statistically you might see more problems reported online.
Its hard to say if 1.5T is more prone than 2.0T without Honda proving statistics

 

Who did you call to complain, because my '19 did not give me any warnings, no limp mode no engine lights until it forced me to pull over on the side of the road. Currently sitting infront of a shop waiting to be towed to a second shop because the first shop did not want to touch it