Buy a Used Gen 3? (Another form for advice, help a newbie out!)

Well you see that dozens of people are not jumping in with advice.
That is because this is TOUGH call.

Most who visit here like/love their Prius but most of them were obtained at or near to new.
A used Prius often is not a good financial deal over the long run.......and sometimes even over the short run.
Some are traded in perfect condition because of an "upgrade" but some are traded in because the owner is disillusioned because of repeated problems (this is true of any car make and model) and you often can't tell which it is.

Consider this VERY carefully and price and test drive other small fuel efficient models too.

 

If the Exhaust Gas Recirculation system and intake manifold is not thoroughly cleaned, by 120K miles at the latest (preferably under 100K), the head gaskets tend to blow, with tiresome regularity, somewhere around 150K~200K. If the symptoms are ignored long enough a bent piston rod can happen as well, from accumulating coolant in cylinder.

Also, the 2010 through 2013 model year, and partway through 2014, have weaker piston rings and a piston design which is more prone to oil consumption, starting around 100K.

 

If the coolant level is low when you check it, it’s not the one for you. The head gasket is already compromised. If the miles are extremely low for the year (think 2012 with 20k), be worried the battery could cause an issue. Long idle periods can cause harm to the battery.

 

Too, a savvy seller might top-up coolant and/or oil, just before test drive. Tread cautiously.

 

I wouldn't listen to people who try to scare you off from buying a used prius. Any used car may or may not be a mistake. Sure, the battery will indeed fail one day, but that could be 6 months from now, or 10+ years from now. Know your budget and stick to it. I bought my 2010 for 7K at 108K miles, and have put 40K miles on it myself. This car has had to deal with 10 brutal Texas summers and 1 fridged Minnesota winter, and the battery is still going strong (obviously not 100%, but still going).The only major repair I've done was because the mechanic screwed up royally on a simple job. Make sure to include battery replacement in your maintenence budget. As you would with any used car, know your common failure points. And check them on any vehicle you're considering before you buy.

I personally had a good experience buying a 7 year old prius (at the time I bought it), I know others have had unfortunate experiences too. But if you like the car, you can take care of it, and you know what too look for when buying used, it'll likely be a great choice.

 

The number of used Gen 3 for sale in my area with low coolant levels in the picture would beg to differ.

To the OP, do not take my statement as a scare tactic. I love my 2010 with 238k. I am 25k past an engine replacement and would not trade my car for anything.

 

OK, gotta ask:
I know what a head gasket is and how it works.
I also know what the EGR system is and how it works.
Ditto for the intake manifold.

What I don't understand is how not servicing those two things somehow causes the head gasket to "blow".

I've seen this claim made on here several times but never any attempt at an explanation.
It doesn't make any sense to me.

 

Is that a scare tactic ?
Neither were my comments.

MOST non-hybrid models don't come with a ~$2000 part that is guaranteed to fail at a reasonably "young" age.
Many non-hybrid models with similar age and mileage and reasonably good fuel mileage can be had at a lower initial price.

Just trying to paint a reasonably accurate picture here.
Not trying to scare anybody off.

 

I have seen attempts at explanation. The ones I've seen generally focus on temperature; they're structured sort of like this:

• The effect of EGR is to reduce peak combustion temps (which is, of course, true; that's how it reduces NOx formation, which is what it's there for);
• So, restriction of EGR means peak combustion temps higher by some amount, leading to
• head gasket damage, Q.E.D.

There's an obvious gap in the second to third step where the quantitative part is missing: how much higher? and what temp is needed to damage the head gasket?

I have never seen an explanation attempt here that seriously tries to address that gap, which is why I'm still unconvinced of the claim. But that's the explanation that's usually offered.

A variant explanation I've seen a few times is that it's not the restriction of EGR flow, but that the partial occlusion in the EGR cooler reduces its heat exchange efficiency, so the EGR delivered to the intake is less cooled, so higher temp, so gasket damage, Q.E.D. Again, the quantitative part is missing (and my guess is the contribution here would be even smaller than in the first explanation, so I'm even more doubtful of this one). But I've seen both explanations.

 

The EGR is supposed to cause a reduction in combustion temperatures. With the intake and EGR cooler plugged, it is alleged the engine can “locally overheat” causing damage to the head gasket, normally at cylinder one or two, since those are the most plugged ports in the intake. It’s an unproven hypothesis so to speak.

 

Be prepared to clean the EGR system at about 100K miles. But since you have mechanical experience, you shouldn't have to worry. That's what the mechanic screwed up on for me, so if I had to do it again, I'd want to DIY. Not sure how the EGR is on newer models. But its a great car. As long as you inspect the vehicle before making a purchase, I'll you'll make a good choice.