As most regulars might know, I have bought a CPO Mazda CX-9 two years ago, it is a 2010 model which has a 3.7 Duratec engine. I researched the car a lot (or so I thought) to make sure it is easy to service, stuff like oil, ATF change, brakes etc. What I overlooked was the water pump. I have the repair manual and was trying to figure what is involved in changing the serpentine belt and I realized that the water pump on this engine is driven by the timing chain and it is internal to the engine. To change the WP, you have to take the engine and transmission out of the car, around 12 hours of labor involved.
A search on the net also shows that the 1st sign of the water pump failing could be leaking coolant in the oil and engine destruction without even showing any early warning for coolant leak from the weep hole.
So, as you see, at 50K miles and driving close to 20K miles a year, I get the feeling that I am sitting on a time bomb. I consider WP failure almost a routine maintenance issue. The minimum bill if I figure it our early is $2K and the max is a new engine. I also don’t have much faith that the mechanics would be able to get the engine/trans out and put it back in without causing some other issues (from leaks to wires/connectors). I don’t have the best of luck with other people working on my cars.
So any thoughts that can calm me down a bit or should I start looking for another car and get rid of this one.
That Duratec engine is common to many Ford products as well as Mazda. There are a ton of those out there, and you don’t hear about too many people complaining about them or destroying your engine, do you?
Every Chevy Cobalt 4 cylinder out there, some Cavaliers, Chevy Equinox 4 cyl., for that matter any GM product with the Ecotec family of engines has a chain-driven water pump. All Chrysler 2.7 and 3.2 engines have a chain driven water pump. There are quite a few other makes and models out there that use a chain driven water pump. You’re not alone.
Most people will go their entire motoring lives without experiencing catastrophic water pump failure. My experience is that internal water pumps seem to fail less than conventional belt driven ones. But that’s just me, I have no data to back that up.
I don’t think of water pump failure as routine maintenance. We replace them with timing belt service because we’re there, but at 100K miles it’s not too common to see a leaky one. So lets say you go 150-200K before you need one. That’s about the normal life expectancy of a car. It should last as long as you drive the car.
I wouldn’t worry about it.
The water pump bearing with chain drive experiences much less side force than with belt drive and should be very reliable.
I can’t figure out from your post if you’re having a problem or just want to change it because you consider the water pump to be a routine maintenance replacement item. If the latter, it isn’t. You should have no reason to be concerned about it unless it fails.
Thanks for the comments, it is reassuring.
TSM, I am not trying to change the WP as routine, but most cars I have had, have needed a new one around 100-120K miles, so that is why I count it as a wear and tear item.
I know there are a lot of chain driven water pumps, but I think having to take the engine and transmission out to change one is extreme. There are reported failures, but not many. Mazda is not a high volume manufacturer, so I am not putting much faith in that part, if this was a Camry, the story would be different.
I think at this point I am going to take my chances, just use synthetic oil and do the coolant change per owner’s manual and see what happens. Shopping for a car is a bit painful not factoring in the added cost, so I prefer to stick to what I have got.
I’d stay on top of the engine oil and coolant changes and try to relax a bit.
That being said, I think the design of a chain driven water pump is an idea that sucks no matter what the failure ratio is.
Equally sucky is the amount of labor (a.k.a.$$$$) to change it.
Unfortunately, automotive history is littered with seemingly benign parts that decimate the bank account because of replacement costs.
Wow. Thanks for bringing this issue up anyway. I’d never have guessed a water pump replacement would require removing the engine and transmission. Except maybe in a specialty performance car. I wonder if there is a simple way for prospective buyers to tell which cars/engines require seeming unnecessary stuff like engine removal to replace the water pump, or you just have to check in a repair manual, car by car?
From what I hear newer Mazdas like this are a pretty reliable car, so you’ve got that going for you OP. And the direct gear drive is probably less stressful on the water pump bearing, so that’s another thing in your favor. Cross your fingers and check the oil for signs of coolant contamination I guess is the best course of action. Best of luck.