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I'm changing the head gasket on a 99 ranger. I don't know why it overheated in the first place. There has to be a cause, right?

I was cleaning up the top of the engine block to put the heads back on and noticed this hole in the water pump gasket.

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Also the outside of the water pump has spots on it that you might expect to see it it had been exposed to water.

Do I need to replace that gasket? The hole doesn't go all the way through the gasket. It's maybe 3-4mm deep. Could the water pump be bad and that is what caused the blown head gasket in the first place? A water pump is only $40 but I'd prefer not to do any more work than I have to.

*It might be worth noting there are some rust flakes down in the flutes (? the holes on the top of the engine block that you can look down into and see coolant) so maybe it's a good idea to take off the pump anyhow to get some of that out of there?

EDIT - It looks like I got very lucky. I'm not a mechanic and don't really know what I'm doing. That little gap in the gasket got me to replace the water pump, even if my motivations were wrong. Well the old water pump was WRECKED! I doubt it was able to push much coolant and maybe it was what caused the engine to overheat in the first place.

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    It will never be easier to get to that pump… – dlu Jul 26 '16 at 19:32
  • Do you know if you have to replace the bolts or torque to a certain value? – dolphone bubleine Jul 26 '16 at 19:43
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    Not off hand. It seems unlikely to me that you'd need to replace the bolts, and I'd suspect that the torque value is just "the usual" for a bolt of that size and whatever the material it is going it is (e.g., it might be lower for aluminum than for cast iron). – dlu Jul 26 '16 at 19:45
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    Wow, that pump looks horrible... – I have no idea what I'm doing Jul 27 '16 at 8:23
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    OMG! I so want to use an emoticon, but I have no idea how. I would investigate whether the proper coolant was used. I've never see even a stamped pump rotor degraded to that level. wicked You can imagine that pump didn't pump. Might make a good Margarita or Bloody Mary, but certainly isn't going to circulate coolant. – SteveRacer Jul 28 '16 at 4:19
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There are typically two ways to tell if a water pump is bad.

  1. The water pump won't turn.

  2. The water pump is leaking.

In the event of a water pump not turning, the belt driving it will usually be ruined so that's usually easily diagnosed. With the belt off of it, the water pump should be able to be turned by hand. If the water pump is leaking, that's also pretty evident once you've gone as far into the engine as you have.

To agree with dlu's comment, you'll never be closer to the water pump than you are now with the work you've already done. If you've successfully replaced the head gaskets then replacing the water pump should be no problem. If the pump doesn't leak and it still turns freely then you can just replace the gasket if you think the hole is something to worry about.

When that close to the water pump, you may as well just replace it since they are not built to last the entire life of the car. Most timing belt replacement kits come with a water pump as well as they go hand in hand when replacing. (thanks, dlu)

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    Water pumps are "consumables" – don't know about your vehicle but on a VW diesel 100,000 to 200,000 miles on the water pump is about all you can expect. Since changing the water pump is more or less the same project as doing the timing belt, they tend to get replaced every belt change or every other one. So, you might give some thought to the miles you've got on the vehicle and consider replacing it "just in case." – dlu Jul 26 '16 at 19:55
  • @dlu I'm not sure if your comment was meant for me or not, but I agree. When that close to the pump you may as well just replace it since they are not built to last the life of the vehicle. I've added that to my answer. +1 – Dalton D Jul 26 '16 at 20:45
  • There is another failure I've experienced. I had a water pump with plastic vanes. The vanes cracked, and if they were spinning, were not spinning at the appropriate speed. Everything looked fine from the outside. I've also heard about the vanes wearing down, but I don't know if that's still a thing on modern water pumps. – rpmerf Jul 27 '16 at 12:18

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