SCV6 overheated and then catastrophe

Hi everyone, I am hoping to get some input on a situation that just occurred on a trip with my 2015 LR4 HSE Lux.
The vehicle has ~113k on it and has been mostly highway driven along the east coast from FL to NJ it’s entire life, 42 service records that were all completed at the dealer. We just got the car back from a service at our local shop where they changed the spark plugs and the cylinder 4 coil due to the P0304 code that it threw a couple days ago. A few months ago we had a warning of ‘low coolant’, so we took it in and they said it had a small leak at the water pump, crossover pipe, and inlet neck. We had all of these items replaced along with all other hoses and associated bits and pieces.

Fast forward to yesterday... driving down the highway and the warning of high engine temp came up, a few seconds later the engine began to stumble (similar to when the coil pack went bad), and then a few seconds after that the car was engulfed in steam/smoke as it shut itself off and I coasted the the side of the road. Upon lifting the hood, the entire engine bay was covered in coolant and engine oil. I mean everything from the air cleaner boxes and down. All of this happened in a matter of about 30 seconds and had zero indication of poor driving manners before it occurred.

Any ideas of what this could be? Obviously overheating, but why all of a sudden and why so dramatic of a failure???

All of the previous work that was done is covered by a 3 year warranty, and the shop has been great to work with. Is there reason to think that any of that work could have led to this?
Any input is greatly appreciated.
Thanks!

When they did the crossover pipe, did they do both the front and rear, or only the front? You'll need to investigate what failed - if it was something that was in-scope of your prior work, then the warranty should come into play.

Thanks for the reply, both crossover pipes were replaced. They weren’t both leaking, but we discussed the scope of work prior to the repairs made and I requested that they replace anything that could be related to the cooling issues so as to not have trouble with them later.

I got a call from them today and they said they have looked over the entire car and couldn’t find anything wrong with any of the previous work that would suggest it had a part in the engine failure. The suggestion is that it’s is ‘possible head gasket is blown’ but... it could be internal engine damage that would require a new/reman engine. I have no reason to think that they aren’t being honest with me about it.

The car is in near perfect condition otherwise, so if it is worst case scenario, I’m trying to decide if it will be worth it to replace with new or reman engine. Thoughts?
Thanks

They can't find the source of the catastrophic coolant leak? Is this the same shop that supposedly did the previous work? Sounds like a crossover failure to me. Did you get the old parts back when they did the original work?

Hi Joe, I did not get the old parts from them after the previous work was completed. This is the same shop.
The latest update is that they don’t see any exterior hoses, clamps, pumps, gaskets, etc or other areas that would identify as ‘the leak is from here’... and this pertains to the coolant and the engine oil.

The consensus from the shop is that the fluids are being ‘belched’ from the engine, and most likely due to a blown head gasket allowing the fluids into the combustion chamber before being expelled out the intake/exhaust. Does this sound viable? Make sense?

That doesn't sound plausible to me but I'm not a mechanic. To lose that much coolant that quickly doesn't sound like a head gasket. I suppose anything is possible but I suspect they may be trying to cover their tracks for the previous work that may, or may not have been done. Either way it sounds like you will be needing a new engine but I wouldn't be trusting those guys to do it. Hopefully you can find a decent local shop for a second opinion. Sorry for your loss.

Thanks. We are discussing having the car taken to another shop for a somewhat unbiased opinion on the diagnosis. I agree with what you’re saying about covering tracks, and I’m also trying to stay logical in that I have had a good relationship with this shop and not experienced any lack of integrity or issues in the past.
So, I guess that leads to the question of how much does a new engine cost these days? And can I get my new Toyota in the same color of white as the LR4? Lol

Wow - does not sound good. Really sorry to hear about this.

I agree with Joe77 - I can’t imagine the mechanics can’t locate the source of that kind of major leak. Only so many places the coolant can be coming from.

The explanation you were given does not make a lot of sense to me. Belching up through the intake is not going to spray stuff all over your engine bay. The only way coolant gets sprayed all over is from a coolant pipe bursting.

If there really was engine oil around, that means something else happened (probably in addition to the coolant leak). I’m guessing a major coolant leak and overheating followed by head gasket failure (probably warped heads), though I’m still not sure why the oil would have been spraying around like that.

Need pics

Thanks for all the replies. I am going to the shop on Monday and will get some pics to post here for more input.

I found the receipt and parts list for the previous work on the cooling system. I’ll post the pic of it here. I very specifically remember talking about and agreeing with them replacing both crossover pipes, but only see one listed on the receipt.

If it is a rear crossover pipe issue, what would I look for that may be the ‘smoking gun’ as to blame? Outside of obvious physical damage...

A side note, the radiator was replaced at ~80k miles (currently at ~113k) This was prior to our ownership of the car, and the service report didn’t give anymore detail about the rest of the scope during that job. However, when we had the vehicle inspected pre-purchase we took it to a different dealer and had them look it over to confirm that the service records reflected good quality work. Our feedback was that it looked fantastic and *almost all parts were new. Could the rear crossover been replaced then maybe?

A big part that has me confused about the whole thing is the absolute sudden turn of events that went from perfect operation, cruise control at 70mph, to ‘engine overheating, stumbling, and complete shut down’ ALL within 30-45 seconds. I’ve never had anything like that and have had cars overheat in the past. ‍