So I was driving on the freeway 2018 CX-5 137k miles, and out of nowhere car wouldn’t accelerate, all sensors went into malfunction mode and engine light flashing. Pushing the gas pedal it just went down and nothing happened. I pulled over and turned off car, wouldn’t turn back on.

Towed it to the Mazda dealer and after a day or two they are telling me that the recommended repair is an engine replacement because the piston and intake valve hit and piston is damaged. They haven’t given me any additional information. See video for damage https://tvidnow.com/nAuh5mP

can you give me some more insight into this? Why would this happen suddenly with no warning signs? Is an engine replacement the only solution to this problem? What are the alternatives?

the car had a recall about the PCM needing reprogramming but seems like it could’ve been connected to this issue, and this repair was supposedly done on my vehicle in 2019.

anywho, any insight is appreciated so I can figure out what to do next. Thank you.

 

Yup well sorry to see this but unfortunately at your miles it happens and not anything to do with the engine design or ECU commands. The only was to determine the exact cause is a full engine disassembly. The downside it you are out of warranty and a disassembly from any experienced engine builder that can examine "All" the damaged parts (much more than what was superficially found) to determine the exact cause!

I have seen dozen from my own customer's bringing their engine to be rebuild. A piston eating a valve is not as uncommon as many think. LOL




A guess only based on the very limited information is a valve spring or springs broke or on the guessing list and less likely a cam lobe(s) went flat?

 

@Callisto Thanks for your post, so what do you think would be the best thing to do from here? I still owe a pretty substantial amount on the vehicle, so I'm thinking that a repair is the only option for me. What would is cost on average to for engine repair/rebuilt/replacement? Sounds like you have a lot of experience so I'd love to hear your thoughts on it.

 

In this case there is no way as I said to know the extent of the damage. It will cost your to have the engine torn down. You would be better off finding a low milage engine with a warranty from the several businesses that offer it . Then find a simple mechanic to do an R&R of the engine. Not the dealership which cost much more.
The head itself will need to be complete rebuilt other wise know as a valve job. And several parts in that rebuild will need to be replaced. If the short block had any metal that went through the lubrication system it will be a complete short block rebuild and possibly machining of the crank? And then there is the question is applicable about the balance shaft assembly if it was damaged or compromised. more $$$$ etc etc its is the unknown that is the question of cost ?

I recommend Find a low mileage engine!!!

ASE &
** owned and operated my own Performance engine machine shop for several years