JDM salvage engines from Japan

No vin on a JDM engine so no way to check history or mileage. Salvage yards here routinely remove vin plates on US engines so origin stories can be murky.

With that said, my local independent hybrid shop likes them from a source that requires purchase of ten at a time.

The only way they could be better is if they did not use low tension rings. And if they really have 50k-60k miles as advertised.

 

What's the miles? Was the EGR system ever cleaned? Water pump original? What's your oil consumption like?

 

Consensus here seems to be to replace the water pump around 150K, at the latest. They have been failing around that amount of miles. Plastic impellor starts seizing.

Is the coolant level stable? That said, with your miles and maintenance, it's pretty much certainty the head gasket is letting go.

 

Most gen3 head gaskets go out slowly with the first severe rattle in the morning which may not repeat for weeks. 15,000 miles later the rattles may cause slight coolant loss or rattling after a minute wait at a traffic light. Rarely is there an overheat ever.

Carbon buildup from the rings, marginal pcv and egr design combined with large thermal swings (cylinders cooling off 30-50f because of the engine on off cycles) over 125,000 miles or more are culprits. All of which were redesigned in the far more reliable gen4s.

Keeping the rings free with 5k (max from day 1) oil changes and avoiding traffic jams or long idles helps.

Blatant overheating will kill any engine. However Toyota cooling systems are very good and overheat warnings are there if heeded.

Gen4 Cylinder Insulators and Revised Coolant Passages:

 

Periodic EGR cleanout is paramount to head gasket longevity, my 2 cents.

 

The stopping and starting of the egnine is NOT a flaw. It's the way it was designed.
Any car that is "city" driven will have more wear than one that is drive "highway" miles.

Look how long police car engines last...because they run all day/night. Very constant.

 

Yes, any engine, not just he Prius, if it runs constantly, should last longer.
It's why every manufacturer tries to get it to operating temperature quickly and keep it there.

If you call it a "flaw" for everyone engine, okay, but not JUST for the Prius.

 

No problems in 2nd or 4th gen, only 3rd with its carbon-clogging EGR.

 

No egr on gen2 plus a completely different 1.5L engine. It used an elaborate coolant system in an attempt to have consistent temps and warm up faster. Gen2s are often oil burners. Conventional oil used at 5k intervals. Brake booster failures but no serious hg issues.

Gen3 was a new hybrid design as a 1.8L engine. Low tension rings and other design flaws to reach a stretch goal of improved mpg. Many Toyotas had low tension rings and became oil burners. Gen3s often burned oil early in their life cycle. Toyota changed pistons and rings free if burning exceeded 1 qt in 1200 miles. With synthetic oil and a doubled 10k interval, along with two free changes to reinforce that interval, people could run out of oil between changes and not qualify for the engine work. Egr intake before the cat. Inverter and brake booster failures. Egr clogging occurs especially on oil burners but it is egr sticking open that caused mild rattling. A software fix was offered.

Toyota fixed the serious issues partially by the 2015 gen3 and significantly by 2016 gen4. Including major work to solve gen3s thermal cycling cylinder wall temperature issues.

 

2nd gen didn’t, 4th gen learned from 3rd gen Guinea Pigs, made major improvements to it’s EGR system.