80,000
2016 CX-9 GT Coolant Leak Rear of Engine
- Thread starter BinDerSmokDat
- Start date
I wonder if all 3 of these leaks are really the same issue or not. We really need some more information!
The first one sounded like a block porosity issue or a cracked block, in which case I could understand replacing the whole engine.
The second one is still a mystery. Did the dealer say why they need to replace the entire engine?
The third sounds like a head bolt or head gasket, although the explanation is not clear. Lots of engines are made of aluminum these days and case and head bolts don't normally back out. This happens so rarely that when it does, it tends to be news (Ford 4.6 V8's had issues with spark plugs blowing out, for instance). Even if it did happen, I would think you could replace and/or retorque the bolts without junking the entire motor.
The first one sounded like a block porosity issue or a cracked block, in which case I could understand replacing the whole engine.
The second one is still a mystery. Did the dealer say why they need to replace the entire engine?
The third sounds like a head bolt or head gasket, although the explanation is not clear. Lots of engines are made of aluminum these days and case and head bolts don't normally back out. This happens so rarely that when it does, it tends to be news (Ford 4.6 V8's had issues with spark plugs blowing out, for instance). Even if it did happen, I would think you could replace and/or retorque the bolts without junking the entire motor.
Ya sorry, I’m not that savvy with cars. It’s basically a head gasket issue. Note sure why it started leaking all of a sudden though.
What kind of warranty is your trusted shop offering you on their repair ? If you already are covering the costs under 3rd party warranty i would get it done at a dealer, especially for such low mileage and age. You will likely get better warranty for the repair, will be able to better diagnose the source and may even drop in a brand new engine instead of a repaired one.
That’s a good point.
I posted this on another thread but seems to be similar:
I have a 2016 Mazda CX-9 with 115,000 miles. Just the other day I felt the car starting to misfire and jerking and then noticed the temperature needle moving up to about 250 degrees but did not hit the red area or give me a check engine light. I let the engine cool down and checked my radiator reservoir and it was empty. I bought the Asian Coolant for Mazda and filled the reservoir. I drove it a little and it started going to about 200 to 210. So I stopped. I could not see any coolant leaks from the bottom of the car. I ordered a thermostat and replaced it. It ran fine for a week and then started doing it again.
I took it to the dealer they said that there was coolant on the backside of the engine probably when I replaced the thermostat. They cleaned it off and told me to come back next week. I brought it back the next day because it was getting hot again. They kept the car and called me back the next day and said they notice a leak on the back of the engine and that they need to take the head off and send it to get inspected. They called me yesterday and said the head was good but they did see coolant in #2 and #3 cylinders and suggested I replace the entire engine! Cost is $7500. So they don't know where the leak is coming from and their solution is to replace the engine and that should fix it. I would certainly hope so. Have anyone encountered a similar problem?
I have a 2016 Mazda CX-9 with 115,000 miles. Just the other day I felt the car starting to misfire and jerking and then noticed the temperature needle moving up to about 250 degrees but did not hit the red area or give me a check engine light. I let the engine cool down and checked my radiator reservoir and it was empty. I bought the Asian Coolant for Mazda and filled the reservoir. I drove it a little and it started going to about 200 to 210. So I stopped. I could not see any coolant leaks from the bottom of the car. I ordered a thermostat and replaced it. It ran fine for a week and then started doing it again.
I took it to the dealer they said that there was coolant on the backside of the engine probably when I replaced the thermostat. They cleaned it off and told me to come back next week. I brought it back the next day because it was getting hot again. They kept the car and called me back the next day and said they notice a leak on the back of the engine and that they need to take the head off and send it to get inspected. They called me yesterday and said the head was good but they did see coolant in #2 and #3 cylinders and suggested I replace the entire engine! Cost is $7500. So they don't know where the leak is coming from and their solution is to replace the engine and that should fix it. I would certainly hope so. Have anyone encountered a similar problem?
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- Canada
Their suggestion to replace the engine without knowing where the leak is sounds typical of a dealer who's goal is to maximize profit. Since you're well out of warranty, I'd suggest going to an independent shop to see if they can pinpoint the cause and recommend a different course of action. Otherwise, if you do end up having to replace the engine, try to source a used engine from a wrecker, swap it in, then trade in the vehicle or drive it into the ground. My $0.02.
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- 2015 Mazda 3
I'll throw in the update on my 2016 Mazda CX-9 Signature which had 64000 (at 3.5 years), so just over the 5yr/60,000 mile warranty. I wrote on this thread back in March 2020 that I got a coolant leak, took it to the dealer and they said the engine needed to be replaced, at my cost. I couldn't believe it - never heard of replacing an engine with such low mileage, plus I had bought the Signature which was the top trim level when it first came out, and I had purchased two other Mazda 3's including a 2018 that I had recently purchased from that same dealer.
Mazda wouldn't approve the new engine, instead offering to cover just the minimum to repair it. It took weeks of back and forth with the dealer - note this was during covid so I understand some of delays - they tried to fix it and they had the head machined; didn't work and the engine ended up being further damaged. My understanding is the dealer blamed the machine shop and forced them to pay for the new engine.
After around 2 months they gave me back the car and it was a disaster - airbag lights, no cruise control, multiple warning messages - they told me it would sort itself out. I couldn't accept the car with airbag lights on, so I returned it and it took them another month or so to figure out the issues - they told me reinstalling the software fixed it.
So 93 days later we finally got the CX-9 back with a new engine. The whole situation has left me with a sour taste on Mazda, which is disappointing. I do enjoy driving Mazdas, and I've gone out of my way to do some videos on youtube (not monetized) like
to help others with some of the basic maintenance which have received some positive comments.
Anyways, I'm not looking for nasty responses please - I'm just posting this to share what happened in my situation in case it can be of help to others.
Mazda wouldn't approve the new engine, instead offering to cover just the minimum to repair it. It took weeks of back and forth with the dealer - note this was during covid so I understand some of delays - they tried to fix it and they had the head machined; didn't work and the engine ended up being further damaged. My understanding is the dealer blamed the machine shop and forced them to pay for the new engine.
After around 2 months they gave me back the car and it was a disaster - airbag lights, no cruise control, multiple warning messages - they told me it would sort itself out. I couldn't accept the car with airbag lights on, so I returned it and it took them another month or so to figure out the issues - they told me reinstalling the software fixed it.
So 93 days later we finally got the CX-9 back with a new engine. The whole situation has left me with a sour taste on Mazda, which is disappointing. I do enjoy driving Mazdas, and I've gone out of my way to do some videos on youtube (not monetized) like
Anyways, I'm not looking for nasty responses please - I'm just posting this to share what happened in my situation in case it can be of help to others.
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- Canada
Thanks for providing your experiences and creating those videos - I'm sure they will be a great help to others.
If you'd like, you can also voice your concerns/frustrations in these threads:
Dealership service
Corporate service
2017 CX-9 with 115K miles. Cracked block. There were no leaks in the system that led to undue heat on the block to cause the crack. First symptom was coolant draining from the block. Coolant didn't mix in with the oil, but was spewing out of the right rear of the block under the H20 pump.
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New here
I have a 2017 Mazda CX-9 Touring bought it at 19k miles currently at 53.8k miles. Last night noticed coolant leak underneath it near rear of engine. Nothing visible on engine or under hood but clearly visible under car. Praying cracked engine block is not the case but I don't feel great about it after reading this thread. Wish me luck
I have a 2017 Mazda CX-9 Touring bought it at 19k miles currently at 53.8k miles. Last night noticed coolant leak underneath it near rear of engine. Nothing visible on engine or under hood but clearly visible under car. Praying cracked engine block is not the case but I don't feel great about it after reading this thread. Wish me luck
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- Canada
Do you have any pics of the leak, or the area where you noticed the leak? I think those pictures might be helpful to others. The good news is that your car should still be covered under the factory warranty.
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- Mazda CX-9 Signature
So do you see coolant stain dripped to the bottom of the engine or on the floor?
Better take it in and it get documented before your 60k powertrain warranty is up.
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- Winnipeg Canada
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- 2017 CX-9 GT
May I ask what year your CX-9 is? I've heard some say this is an issue with 2016 models, but could be that they're just first to experience this.
Is that "top" part the head? Is it just a case of the head bolts coming loose? I suppose that could also cause damage to both the block and head, but if the shop says they can repair it for around $3000, that sounds like what a head gasket replacement might go for. Do they need to machine the head?
I wonder if Mazda has changed the head bolt torque spec over the hears. That might be something we should try and figure out.
mchu123's is a 2016. His engine was replaced.
Several now have been 2017's. The only details that have been provided are there is a water leak coming from the block near the water pump. Nearly every post about this issue follows a similar trajectory:
1. Post about water leak
2. Follow up post about requiring engine replacement
3. If we are lucky, one final post confirming the engine replacement.
Nobody has provided any more detailed information. I'm sure everyone on this forum would like a picture or confirmed diagnosis as to what exactly broke. It's almost like Mazda is making people sign an NDA with the consistent radio silence that occurs, or everyone is dumping the car as soon as they get it back...
... or the people this happened too don’t have enough technical knowledge or know enough about the issue to be able to elaborate further.
i am sure if Mazda wasn’t replacing the engine under warranty that we would hear a bit more. But for most, the investigation ends when Mazda acknowledges the leak and offer a new engine for free.
i am sure if Mazda wasn’t replacing the engine under warranty that we would hear a bit more. But for most, the investigation ends when Mazda acknowledges the leak and offer a new engine for free.
It sounds like there is an issue with the cylinder head developing cracks. Cracks in the head could cause both the coolant leak and the compression loss issues. Someone in another thread found a CX-9 for sale with a new engine, which the dealer explained was required because the head had cracked. That dealer also stated there is a redesigned cylinder head out now to address the issue. The parts database seems to support this, as the current part number is PY8W10100A and there are multiple superceded part numbers.
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- Winnipeg Canada
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- 2017 CX-9 GT
A crack in the head requires a full engine replacement? I would think a crack in the block would make more sense. The block also has a superceding part number: PY8W10300A
Interestingly, when you look at the head, it also states that those who bought this part (the head) also bought some other parts including the head gasket (expected) and engine block (Um, no... I wouldn't expect that....).
My guess: The head bolts somehow get loose and damage the block's head-bolt threads (plus other things) making the block unusable. It leaks because the head gasket is not properly secured in place and probably breaks. I sure hope I'm wrong though!
Interestingly, when you look at the head, it also states that those who bought this part (the head) also bought some other parts including the head gasket (expected) and engine block (Um, no... I wouldn't expect that....).
My guess: The head bolts somehow get loose and damage the block's head-bolt threads (plus other things) making the block unusable. It leaks because the head gasket is not properly secured in place and probably breaks. I sure hope I'm wrong though!
There was a thread elsewhere on this forum where the entire long block was replaced rather than just the head after diagnosing a cracked head. The explanation was that the head cannot be removed and replaced with the engine in the car. If this is true, it may be cheaper for Mazda to pull the engine and just replace the whole thing rather than pay dealer service rates to swap the head.
