When does a 3.5L water pump leak? | Ford Explorer Forums - Serious Explorations

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When does a 3.5L water pump leak?


Elite Explorer
May 10, 2024
Reaction score
City, State
Around, CT
Year, Model & Trim Level
2016 Base 4WD 3.5
I knew going in before purchase of this 84k vehicle that a water pump was likely in my future. I pressure tested the cooling system twice when cold and it would hold pressure all day long if I let it. Huh? So tested twice when hot and again it held. Double huh? But I could smell the hot coolant with engine running, so I started thinking maybe head gasket or coolant pipe under intake.
After getting it home I started digging into where this leak was. It took a while to find exactly where the weep hole was located and using the flexible camera of my scan tool could tell that was the leak point. But only with engine running would it leak. Triple huh? Once I got the pump out I checked for shaft looseness and it only had maybe a couple thousands of play in it. So that is my story and am sticking with it because no more leak with new pump.


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From what I have read, a water pump failure can happen any time after 60k-80k miles. Be thankful that you got an early warning sign of the leak. Many times the pump fails catastrophically and takes out the engine.

My coolant drop started in the high 80s, got it replaced in the low 90s via ESP luckily.

had just picked up a 16 sport with 134k on it still had the orginal pump had it done at 142k wasent leaking but id prefer to have it and the chain done before problems arry. on my 14 piu(rip) it started to go i wanna say at 107k dident get it done till 121k

Typically the water pump start weeping anywhere between 100-150k, but I've heard it happening as low as 60k. I'm sure age is starting to become more of a factor at this point. We have a giant multi-page thread regarding the water pumps on these 3.5's here. Your lucky you caught it when you did. An untrained eye could easily miss it.