It is Honda's turn to handle head gasket problems on new dual motor hybrid design introduced in 2023. https://www.go-parts.com/garage/engine-cylinder-head-honda-civic-honda-accord-honda-cr-v-2023-2025?srsltid=AfmBOoqm5I38lGu-zCmkyKWlZopEBI74YjciMM21KhzpyossbcTy9tke
it amazes me that these geniuses can't get it right. it must be the bean counters, the engineers can't be this bad
It's the first twin electric motor for Honda who did not license Toyota technology likeFord did. Thermal cycling that was not present in Otto port injected versions of the engine is the likely cause as is the most logical case with gen3.
They went from a naturally aspirated engine to a direct inject; turbo charged engine. Engine start/stop systems probably compounds matters. Higher pressures and heat spots contribute to the issues along with customers that have a closed hood policy. I'm paying someone to maintain the car; so I don't need to check anything. Just my take on things. They're making it out of the warranty period, just doesn't meet customer expectations; which are very high - considering the cost of new cars these days.
It isn't their first power-split hybrid system. It first showed up in the previous generation Accord and the Insight3. And Toyota licensed Ford emission controls that they really wanted. The reality was that Ford developed their system independently. Toyota just beat them to the patent office. And they both ended up paying Paice. No turbo in the hybrid. "The primary cause is suspected to be the frequent on-and-off cycling of the gasoline engine in a hybrid system. This repeated heating and cooling (thermal cycling) puts significant stress on the head gasket, potentially causing it to fail much earlier than expected." Guessing the direct injected engine that showed up in the 2023 Accord runs hotter.
Thermal cycling is caused by the rapid loss of temperature when the engine shuts off in Ready which returns when it restarts. I have seen 40 degrees drop when in traffic or when "idling".
The 1.5L and 2.0L engines are having head gasket issues; not just on the hybrids. They have been known to make those size engines to be bullet-proof in the past - w/o head gasket issues. The differences I noted above (#4); no issues with intake manifold fuel injection on those same engines in the past. For clarification purposes; Hondas first gen hybrids wasn't a power split unit. They simply removed the torque converter and placed an electric helper motor; so the engine needs to run to move the car. IMA, integrated motor assist. The engine was downsized and optimized; that's why they were never able to achieve the same numbers as a Prius, though they were as gutless as a Prius. Honda later copied/engineered a similar Toyota's setup. Honda did beat Toyota to the marketplace with the first mass production hybrid; Honda Insight. For the record; those engines didn't pop head gaskets and they also turned-off the engine when stopped. I believe I had a 1.3L in that old Civic hybrid. Lost the traction battery around 75K miles - replace under warranty; sold it and bought my first Prius.
Honda can only claim first hybrid in North America as it arrived a year before the Prius as a 2000MY. Toyota had been mass producing the Prius in Japan since 1996. IMA was just a mild hybrid system, and it was likely rushed going by the battery issues some models had. Honda does have another full hybrid besides the power-split multimode; well, they actually claim two. It is a parallel hybrid similar to Hyundai's, Toyota's Hybrid Max, and others. It arrived before the power-split in the Jazz/Fit hybrid, which managed to outsell the Prius in Japan for a bit. Then Honda made a performance version of it with two motors on the rear for AWD. I think we got an Acura with it at one time. On the OT, how new are these engine designs? Total redesign, or just the previous model modified to have direct injection?
It could be the automated machining is out of spec or more likely bad head gaskets. Was the engine overheated? Decades of engines with iron blocks and aluminum heads which put more stress on the layer between them, surviving. Water cooling and all aluminum should be easy. Also the general public is the problem, as they will find a way to break things no matter what.
I was forced by the Climate Industrial Complex (and the 'vid) to buy an eensy-weensie little CUV in 2020 - a 1.5l turbocharged Direct Injected FWD car - but I got it for several thousands off because my beloved government was trying to lock everyone and everything down at the time, and the dealership was desperate to move something - ANYTHING off the lot. It was a nearly base model GMC Terrain. I was not hopeful that this would be a good addition to my stable but I've been very pleasantly surprised that in 6y and over 100k it's had zero issues. Nothing. The only time it's been to the dealership is when I replaced my beloved 2009 GMC Sierra..... The little SUV-let still gets over 30mpg, goes 130mph (or so I'm "told" :lol: ) and it's sorta fun to drive in its own way. HOWEVER (comma!!!!) I KNOW how direct injection works, and I have NO INTENTIONS of EVER letting the car go much beyond 3000 miles before changing the oil (recommended OCI=7500) and the very first thing I did to the car was to disable the dumb-A.S.S. I check all fluids every fill up and I've changed the air filters at 2x factory recommendation. If this car ever tests positive for the Prius Disease - I will notice immediately and start cleaning stuff in the intake. I was briefly tempted by an oil catch can, but I figure I'm going to go into the top end and clean the valves anyway before 200K, and even though the motor is oriented 90-degrees off of how it SHOULD be - getting to the head is so simple even Millennials can do it. Succeeding generations can probably do it even better but they're too lazy to go out and buy their own food - a situation that will probably be self-solving later in their lives. BUY.....a HONDA? Nope! I'll stick with GM for now. It's like politicians. One brand isn't really much better or even much different than the other in the year of our Lord 2026 AND there's a GM dealership in nearly every town - not that I've NEEDED one very often...... One brand is ALWAYS more expensive than tha other one though.....
Honda has a history of head gasket problems when overheated. However gen3 Prius and the 2023 and newer Honda hybrids don't need overheating to blow head gaskets. It is the stress hybrid thermal cycling creates combined with the Atkinson cycle that took Corolla's reliable 1.8L ice engine with egr and created head gasket problems without overheating on gen3 Prius. Granted low tension rings would cause excessive oil burning in earlier ice engines including Camry, Rav4, Corolla and others but those engines did not have bead gasket issues or thermal cycling with Atkinson cycle valve timing. Toyota figured it out on the gen4 1.8L engines; Honda is still working on it. On direct injection by itself? No thanks. Give me Toyota's dual injection to keep the ports clean with direct injection's advantages and Toyota's more recent electric motor driven intake valve timing which can effectively run in two modes.
I don’t think thermal cycling in hybrids is any issue. Any engine in North Dakota used year round gets extreme frequent thermal cycling. Toyota hybrids have run hundreds of thousands of miles with no signs of head gaskets failure. The cycling is mostly within a narrower temp range. Toyota specified an improved head gasket for the gen 3 I think. I would use a Felpro “made for the repair environment” in other words less than ideal surfaces. I doubt any common auto machine shop can equal the factory Toyota cylinder head finish and flatness. Not even close, look pretty isn’t a spec.
You obviously never spent any time in the air force. "Shine it must; fly it might" I had a lot of friends that worked maintenance on aircraft and had to keep the brass happy.
