Turning an engine 90 degrees for use in a different application usually results in fairly harmless engineering compromises. It’s why Nissan 350Zs starve their front two cylinders of air, and why you can’t simply use a front-wheel-drive LS4 V8 from a Grand Prix GXP in an old Camaro without some modifications, but neither of these quirks are anywhere near catastrophic. However, notice I wrote “usually”? There’s an exception to every rule, and Ford cars and crossovers equipped with 3.5-liter and 3.7-liter V6s are an exception, because they can be mechanically totalled due to simple water pump failure. Here’s how.
On most cars, the water pump is driven by either the serpentine belt or the timing belt/chain, two arrangements that have their own pros and cons and take slightly different approaches to water pump replacement. In the case of the former, losing a serpentine belt means you also lose drive to the water pump. If this happens, you may notice a 12-volt charging system fault light on the dashboard before the car starts to overheat, or notice heavier hydraulic power steering if your vehicle’s so equipped. Another plus besides these pre-overheat warnings is that if a serpentine belt-driven water pump starts to leak, replacement it is generally fairly easy because it’s bolted to the outside of the engine block. For instance, a 2008 Toyota Camry with the 3.5-liter V6 engine uses this arrangement, and even though you need to pull an engine mount to change the water pump, book labor time comes in at a reasonable 4.2 hours.
In the case of a vehicle with a water pump driven by the timing belt, that belt will have a fixed replacement interval and the water pump almost always gets changed with the belt as part of a preventative maintenance regimen. The 2008 Honda Accord V6 uses this arrangement, has a timing belt interval of 100,000 miles, and the whole job requires just four hours of book labor. Not too bad for a timing system-driven pump swap.
Screenshot: YouTube/C.L.S. All-In-OneHowever, then we get to Ford’s transversely mounted 3.5 liter and 3.7-liter Cyclone V6. While timing chains from non-German manufacturers are generally maintenance-free for the life of the vehicle, Ford went with an internal water pump design, i.e. the water pump is driven by the timing system like on the aforementioned Accord (except a chain instead of a belt).
This wouldn’t be a huge problem if water pumps lasted forever, but they don’t. Seals can age out causing leaks, water pump drive bearings can wear out, and plastic vanes on the water pump impeller can break. I’m not going to clown on plastic water pump vanes, as bits of plastic in cooling passageways sound less bad than having bearings in a metal impeller pump go bad, leading to the vanes chewing up their cavity and sending bits of metal everywhere, but I am going to highlight why Ford’s specific design has some serious flaws.
Firstly, access to the pump takes a while if you need to change it, as this extremely helpful DIY video from YouTube channel C.L.S. All-In-One shows. On an all-wheel-drive 2011 Ford Flex with the naturally aspirated 3.5-liter V6 engine, water pump replacement calls for 10.8 hours of book labor. 10.8!
Assuming a relatively inexpensive labor rate of $120 an hour at an independent shop, that’s definitely more than a grand in labor alone. Turbocharged models are even worse, with a 2011 Flex Ecoboost water pump replacement calling for 12.3 hours of labor. However, that’s assuming a water pump suffered from vane failure or if a water pump leaks caught early enough from the tiny weep hole to not cause further damage. There’s another failure mode that could be much worse.
Remember those seals we talked about earlier? Well, because the water pump on a transversely mounted Cyclone V6 is driven by the timing chain, on the other side of a series of seals and bearings from the coolant sits an oil-lubricated cavity for the timing chain. If you’ve ever seen the results of an internally blown head gasket, you can probably see where this is going.
Should the seals fail and an owner keeps topping up the coolant instead of dealing with the problem, coolant can mix with the engine oil, potentially resulting in engine damage due to compromised lubrication. In the event this happens, and it certainly has to owners, the most sensible path forward is replacing the entire engine with a good used unit. This Ford Edge owner’s story runs along those lines, stating that “I ended up having the entire motor replaced” due to coolant mixing with oil.
Taking a look at complaints owners have made to NHTSA, it seems that this worst-case scenario can get seriously expensive, and it certainly isn’t a fluke event. This 2010 Flex owner was quoted $5,000 for engine replacement, and that seems to be on the medium end of things. Some owners claim to have been quoted upward of $7,000 for engine replacement due to water pump failure, and even in today’s market, that’s entire used car money.
If you have a 2011-2019 Ford Explorer, 2007-2018 Ford Edge, Ford Flex, Ford Taurus X, 2008-2019 Ford Taurus, 2010-2012 Ford Fusion Sport, 2007-2016 Lincoln MKZ, 2007-2018 Lincoln MKX, Lincoln MKT, Lincoln MKS, 2017-2020 Lincoln Continental, 2008-2009 Mercury Sable, 2009-2013 Mazda 6, or 2007-2015 Mazda CX-9 with one of these engines, water pump replacement could be in your future.
With older and especially high-mileage models, chances are it isn’t worth much if it’s knocking on the door of 15 years old. It’s no secret that depreciation happens, but as cars reach that well-used point, a big repair can sometimes cost more than half of the vehicle’s value.
For instance, assuming $1,296 in labor, a list price of $152.91 for an OEM water pump, fresh coolant to top up the system, and a few miscellaneous shop supplies like RTV gasket maker to reseal the timing cover, this repair will end up hitting the $1,500 mark on the low end if you catch the failure early.
Some owners are reporting repair bills costing more than $2,000 to fix a failed water pump, possibly due to higher labor rates. On a 200,000-mile 2011 Ford Flex that’s worth $3,900 in good condition, that’s a tough pill to swallow for a best-case scenario in which water pump failure is caught early and treated before coolant can mix with the oil.
Lots of Fords with these transversely mounted 3.5-liter and 3.7-liter engines were great vehicles when they were new, and I have a particular soft spot for the Ford Flex. However, I probably wouldn’t recommend a high-mileage car with one of these engines, and if you do find a Flex Ecoboost you want in nice condition, it’s a good idea to keep a few grand around for water pump replacement so you won’t be caught off guard with a crazy repair bill.
Top graphic credit: Ford
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My work vehicle is a de-copped Exploder PI with the 3.7. Sometimes, I could swear I smell coolant.
I always have this moment where I wonder what happened in the engineering meeting for things like this.
Water pumps fail. Timing chains shouldn’t. Why drive the failure prone element that could fail with the part that should never have to be serviced? Especially since water pumps have a failure mode that could destroy the lubrication system (and the engine)?
I know the answer was cost and packaging. But you think Ford would have learned something from Chrysler’s 2.7L V6 debacle.
They did learn. They learned the cost of failure and selected their preferred failure point based on the fact that it was the most profitable.
This is clear to owners and mechanics but is unlikely to be considered by anyone at a corporate level. Doing so isn’t part of any P&L calculation that matters. It was beyond the warranty and car companies sell new cars, not used ones. Never forget that fact and learn to appreciate any longevity that exists as the gift it is—or at least factor it in to your budgeting calculations.
Just say no to transverse V6’s 🙁
The Chrysler 3.6L Pentastar V6 has the same issue in FWD applications.
4 hours for an Accord timing belt??
So, you’re telling me that it’s only 2 hours after you get that $@#%* crank pulley bolt loose?
Volvo inline 5 turbos FTW. You can remove the timing belt without having to remove the crank pulley bolt.
I had to do one on our Volvo wagon plus water pump and I was done in four hours even though it was my first timing belt replacement, went super slow and triple checked everything. Now that I know what I am doing I can get it done in one hour if ever need to do it again.
Timely article with the earlier one today asking for 3-row advice.
This precise problem occurred around 180,000 miles on my parents’ Flex and around 190,000 miles on a sibling’s Flex, and is why we no longer have either. Quite upsetting because they’re decent vehicles otherwise.
“Achilles” would be a great name for a car if it weren’t for karma (and car reviews).
For that matter, so would “Karma.” Oh boy.
Had the timing belt go out on my wife 2014 Flex Limited EcoBoost engine at 110k miles & thankfully the dealership offered (honestly damn near insisted) to do the water pump at the same time. It wasn’t cheap but it’s been running like a top since & she loves the car so I think it was well worth the money. I appreciated the dealership pushing me on it & it only took a few minutes of googling Ford Flex water pump to know why.
My wife’s younger sister is 16 and just got a 2011 Edge as her first car. 🙁 I *think* the small business they bought it from (that used it as an occasional delivery car) already had the water pump done, though. Fingers crossed, at least.
I have a 2012 Explorer that my son drives that has 235k miles on it, and my brother and I replaced the water pump on it a year ago. It isn’t that it’s hard, it’s just that it takes so long to actually get to it. You may as well plan to change out every wearable part anywhere along the path, because God forbid you have to get back in there again. I would plan a solid two days, and definitely have another car to drive just in case anything goes wrong.