Hi

I'm planning to upgrade my NX 300h to 350h/450h.

Engines of 2GR-FKS/FXS have common productions problems like cylinder head leak,timing belt cover leak
water pump fault etz.

Starting from which year those faults were fixed?

Did Lexus built these engines also in Japan?

Thanks,Jukka

The 2GR V6 is not used in the NX350h/450h+. It uses the A25A 4 cylinder engine. When it appeared in the NX's cousin the 2019 RAV4 it had some issues with the electronic thermostat/valve which was fixed before this engine made it to the NX. This engine is also somewhat susceptible to moisture buildup (milky oil) if used mainly for short, cold weather trips. The solution here is simply to change oil more often when used in this type of severe service condition. Other than people complaining this engine is noisy, I'm not aware of any systemic issues with this engine.

Sorry

I made mistake.
I meant to upgrade to RX350h/450h.

Br,Jukka

Well, the answer remains the same since the RX uses the same engine(s) as the NX now. RX350h/450h+ uses the same A25A engine as the NX350h/450h+, and the RX500h uses the same T24A as in the NX350. The 2GR is done, obsolete, had a great run despite some of the common issues you mentioned.

Sorry again

I mean RX350h/450h till 2022.

Br,Jukka

LOL, ok, the 4th gen RX is probably the best forum to ask questions about this vehicle, but since I'm familiar with the 2GR...

I don't think the timing chain cover leak was ever fully addressed as it was a design/assembly issue that was only corrected on different newer engine designs. On those that did leak, simply resealing it properly usually fixed the issue for the life of the engine. Mine never leaked on my 3rd gen RX after 14 yrs, but to be honest I had the water pump fail early under warranty (which was one of the issues you mentioned) and its possible that the timing cover was resealed at that time too, I don't remember. The water pump was revised during the 3rd gen RX era, so this I think is not (as much, any water pump can fail) an issue for the 4th gen RX. My replacement water pump never gave me any issue. Regarding the head gasket leak, I recall that wasn't a very traditional type of head gasket failure where it fails from the inside. Mostly it was caused by corrosion on the outside of the engine where the edge of the gasket was exposed to road salt and such and gradually deteriorated from outside to in. Solution, if driving on salty roads, keep underneath and engine clean (good advice for all parts of the car). Early versions of these engines also had some issues with VVT gears flying apart and destroying the engine (around time of 2nd gen RX). If I recall, the gears were updated before 3rd gen and made them less likely to blow up, but they still had issues with VVT gear rattles as the engines got on the old side (150,000m +) and could still fly apart, but the revised version I think was more reliable and gave plenty of warning to get fixed before anything outright failed. My RX they rattled just for a second perhaps once or twice a month at this point, when they rattle for several second on each start then that's when repair becomes a priority. I believe by the end of the 3rd gen run the gears were updated again with even better results, so I don't think this was a big deal with the 4th gen RX. Early versions of the 2GR also had rubber VVT oil lines that ruptured, but this was corrected with steel lines I think around the 2012 RX, so well before the 4th gen RX came around. These engines also were a bit notorious for some piston slap noise when the engine was cold. Lot of people didn't like that, but it was just a characteristic of this engine that had nothing to do with reliability. Outside of the issues mentioned, these engines were extremely reliable if a bit leaky at times. It was quite difficult to make them burn oil, and the rotating assembly was very robust.