Second major update:

I was waiting for my mechanic to finish all his research before he calls me, before I ask about the head gasket. Turns out he checked everything else first, because he just didn't feel a Toyota should blow a head gasket on such a well-maintained engine. It was in fact, a blown head gasket.

He looked into it and found a few rare cases of this happening on 3rd gen Prius models, mostly high mileage and taxis (150k-200k miles), that had the same problem. Every single one was the number 2 cylinder. He's fairly certain this is a defect that Toyota must be aware of, but since it takes so long for it to occur and is so rare, they may not care to do much about it, especially since they released the 4th gens already. He also found that 3 valve lifters were damaged and clattering (I noticed that sometimes my engine sounds a little like a diesel when idling).

So my options were to either fix it ($4,300), replace the engine (short block, $8,000 to $9,000, or long block at $13,000 to $14,000), or a get a different car. I feel confident that as long as I keep maintaining the car well, I can go another 200k to 300k before another major issue, including this one, if I repair the head gasket. I also feel it's the least expensive option in the long run, since I am still just under 2 years from paying the car off.

I went ahead and green-lighted the repairs. Head gasket + all lifters (since it's a lot of labor just to get to them and they themselves are not expensive to replace) + new coolant and oil + new high-tone horn (it died recently) + new plugs + cabin air filter (yes, I know, it's easy. But it's even easier when they do it all at once!). This will also give him a chance to check on the rear main seal leak I developed a while back (I posted that one under my first problem detected thread).

Part of my decision was also due to the fact that no one's done this before and I think it would be just fun to see how far the car will go before it's really not worth the effort. A lot of stuff on the car are things no mechanic has ever seen. One thing my mechanic is planning to do is look at the piston rings for carbon deposits. It's a bit of work but worth it for him (and me), and on his dime thankfully. We're both fans of longevity, and how long we can run a car with good maintenance and service.

I'm curious to see how many miles I can accumulate before the next major issue!

 

Ouch, blown HG it is. I was rooting for ya to hit 500k

Well, thanks for keeping all of us posted, your car is providing the rest of us with alot of useful info!

In the spirit of your "problem detected" threads, I will create my own "first problem detected thread"

 

Hey Raidin, thanks for the update as always, and sorry to hear about the repair bill

I tagged the user danlatu in some of your threads on Priuschat and he offered some insight.

I'm linking all the posts here so that you don't miss anything, as some of the threads you weren't quoted in so you won't get the notification, and so that others may find it here as well.

https://priuschat.com/threads/courie...2#post-2679708

https://priuschat.com/threads/just-a.../#post-2679695

https://priuschat.com/threads/rough-...4#post-2679503

https://priuschat.com/threads/rough-...4#post-2679580

https://priuschat.com/threads/oil-ca...-knock.179588/

 

Thanks a lot, Vegas. Gonna go look at everything now.

I also wanted to update that my mechanic discovered that there are certain cases mentioned by hybrid mechanics who cited the water pump allowing for intermittent overheating leading to head gasket failures. The claim is that the water pump, once it starts going bad, will intermittently fail, where overheating occurs just below the temperature that the warning light comes on at, so there's no real warning. Over time this has caused head gaskets to fail in 3rd gen Prius models they saw. With this in mind, we decided to replace the water pump, since there's no labor involved while the head gasket job is being done, and since I plan to keep running the car for much longer.

FYI: cost of the pump is roughly $500, labor is almost the same on its own (RepairPal confirmed this).

 

Final update:

Got the car back Wednesday (2/28), and have been driving it as normal since. So far everything is running perfectly.

Laundry list:

1. Head gasket job
2. New water pump
3. New spark plugs
4. New thermostat
5. New valve lifters (all 16)
6. Both coolants changed
7. Oil and filter change
8. High-tone horn replaced (died previously)

Total was just under $5,400. Let's see how far I can go before my next major issue!

 

glad you got the ct back, raidin!

if it lasts another 300k, then $5400 is worth it.

i plan on keeping my ct for a long time too

 

It's really good to see that you believe in the CT that much to spend that kind of money to have it fixed up ready to go again especially since you're in the courier business and it's all about cost per mile. I'm in the trucking business and we're always calculating cost per mile also. $5,400 is a big amount to spend on a high mileage car even though some of it repairs are basic maintenance.

 

Wow, 25k OCI's!? You are brave. In my experience with many vehicles even 10k is pushing it. Not the oils ability to maintain but the amount of carbon buildup. Does not make sense to circulate that dirty oil considering how cheap oil is in engines like this. I just got mine and will be switching to Mobile One full synthetic. I am a huge fan of Liqui Moly's anti friction treatment. Fantastic cold start protection. Upwards of 90% of engine wear happens at cold starts and the product is excellent. I use it in all my vehicles. Amazon sells it and lots of great reviews on BTOG forums.



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The way I look at it, anything cheaper than a new car is better. My first major repair at nearly 400k is really good imho, and at $5400, is not bad considering all the things I did, which should help the car last much longer. Once the car is paid off, a few repairs bills here and there are better than having constant car payments from constantly replacing cars + any repairs on top of that. That was my original plan.

I did a lot of oil tests with Blackstone Labs to make sure I am ok going that far on my oil. But if the car develops a problem, like the head gasket failure I just had, then a long OCI could just make things worse. I did it because it saves me a lot of money. 25K OCIs vs 10K OCIs is $400 a year saved. I've decided to scale down to just 15k OCIs for now, especially since my mechanic noticed the first signs of sludge forming.

I'm going to look at that anti-friction treatment too. At my mileage though, it may not be worthwhile.

 

Would not hurt if you are trying to get another 300 out of her. Liqui Moly also makes an excellent engine flush. MMO works very well too. I don't do extended OCI's because of the sludge issue. Not worth it vs a little extra money for more changes.

 

At each of my 20-28k OCIs before I switched to a set 25k, I asked my mechanic to look inside the engine and see if he sees anything wrong, including sludge. He also checked my oil filter for filtration issues. I kept going because we hadn't seen anything, but now we have. My first 80k miles on my CT were on 5k OCIs, believe it or not, just to avoid sludge, but turns out it wasn't a real concern.

Yes, I am trying to get as many miles as possible out of my car. I will spend whatever I have to to keep it running, unless that cost goes above and beyond a new car. Even $5k a year is better than a new car with payments and having repair costs or extra fuel costs (since very few cars fit my needs and get near 50 MPG). Right now I anticipate maybe $5k every 2 years, maybe 3, in total repair costs. That's a very good deal considering how I drive.

 

So I'm wondering if you HAD stuck with the 5K miles OCI, would you have avoided the current $5k+ repair bill?

The costs of the synthetic oil and oil filter at 5K OCI is WAY less than $5K. Especially if doing the oil change DYI.

BACK when I had my 2000 LX470 before I traded in for a new LX570 in 2013, I changed the oil in the LX470 RELIGIOUSLY (It got it's first oil and filter change at around 2500 miles) at 5K intervals. There was no signs of any oil sludge nor anything mechanical issues at 280K+ miles at trade in (trust me, the Lexus dealership looked it over head to toe). I did the same for my old 1995 Volvo 960 sedan since new and sold it in 2013 with some 185K+ miles with no engine issues.

I just think changing the oil and filter at 5K intervals is easy to do and is a very cheap way to prevent any potential engine issues down the road. If you are just leasing the car for a couple of years and then return back to sender, then no need to do the 5K OCI. Just do whatever is required by the lease.
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I feel that you can go at least 10K when using Synthetic Oil.

 

I doubt that sticking with 5k OCIs would have made a difference. The problem occured, it was just exasperated by the long OCI. I doubt much harm was done because of that though. The amount of coolant in the engine isn't going to do much. Remember that I took the car to the shop as soon as this happened, and long OCIs won't cause a head gasket failure anyway (which is due to overheating or age).

Also, using some rough math, had I stuck with 5k OCIs since day one, I would have spent just above $3,000 more than I did. A head gasket job is just over $3,000. I paid more because I fixed a few other things as well to save on labor down the road. I feel I basically got a free head gasket job thanks to what I saved with my long OCIs. I'd do the oil changes myself, if I had the time, but unfortunately I work too much, and am not allowed to do it where I live anyhow.

The manual calls for 10k OCIs, and synthetic is the only oil you can use anyway (0W-20 is synthetic only). The oil I use is rated for 15k OCIs (which is the OCI I will switch to now).

 

How long,, or maybe I should ask.. How many miles are you planning to put on this vehicle before replacing it?