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HELP! Water Pump keeps leaking after 3 different installs!!

Discussion in '3rd Gen 4Runners (1996-2002)' started by tommyCO, Sep 13, 2022.

  1. Sep 13, 2022 at 5:30 PM
    #1
    tommyCO

    tommyCO [OP] New Member

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    Hey Everybody,

    I am about to lose my mind here... Very long story short:

    Replacing my timing belt, water pump, cam/crank seals, tensioner, pulleys, etc, etc on my 1997 3.4L 4runner. After basically reassembling everything the first time and minutes away from starting my truck the water pump started leaking badly once the coolant level got high enough to enter the block and water pump! I took mostly everything apart again, put it all back together for a second time and same story... Then took it apart again and re-installed for a third time and SAME PROBLEM!

    The water pump is leaking in the bottom left (if standing in front of the truck, opposite side of the thermostat) everytime.

    The first time I tried the metal gasket, no FIPG

    Second time, ONLY FIPG

    Third time, FIPG + Paper Gasket

    After looking at both the block and the old water pump closely today it appears there is some fairly significant "pitting" that occurred on the old water pump when I removed more of the old gasket from it.

    Is it possible the old water pump fused to the metal on the block over time and when I removed it actually pulled metal from the block and damaged the mating surface for the new water pump on the block?

    It seems like this may be what happened as after closer inspection the block appears to have a tiny bit of damage in the place where the leak has been persistent.

    OR - Is it possible the replacement water pump was not machined to the correct spec in that spot and buying another could solve the issue??

    Also, the old water pump WAS NOT LEAKING before doing this job. I was do for a change and trying to be pro-active.

    ANY INPUT is greatly appreciated! Thanks in advance!!

    image_6483441 (1).jpg
    image_123923953 (6).jpg
    image_123923953 (7).jpg
    image_6483441.jpg
     
  2. Sep 13, 2022 at 6:29 PM
    #2
    negusm

    negusm New Member

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    Did you use an AISIN water pump?

    If not, that's most likely the problem.

    That pump also comes with a metal gasket with an integral rubber gasket.

    No gunk should be needed.
     
  3. Sep 13, 2022 at 7:01 PM
    #3
    Dillusion

    Dillusion New Member

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    Assuming pic 2 & 3 is the old pump?

    Need a gasket of some sort between there.
     
  4. Sep 13, 2022 at 7:14 PM
    #4
    Ahdofu

    Ahdofu New Member

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    Apologies if you have already ruled some of these already
    1. Have you confirmed that it is really a leak from the mating surface of the water pump and not from one the hoses? ex: oil cooler hose?
    2. If this is really caused by the leaky mating surface, did you assure yourself that you had removed all the old gasket material, .., etc from the engine block and bolts completely before installing the new water pump? I typically use something like a hobby knife with a straight edge to remove the old stuck on gasket material.
    3. If the mounting surface is clean and the gasket is new, then the next possibility could be that the water pump's housing is warped. Not sure whether this is easy to decipher or not by examining the water pump's contact surface where the leak is occurring.
     
  5. Sep 13, 2022 at 8:11 PM
    #5
    tommyCO

    tommyCO [OP] New Member

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    Hey everyone,

    Thanks for your reply's!

    To answer some questions and further clarify:

    - New water pump installed was Toyota part number 16100-69398

    - New water pump did come with the metal gasket. No FIPG was used, and it leaked.

    - Pic's 2 & 3 is the old water pump that come out. There was a paper gasket with FIPG on the old water pump that was removed.

    - The leak is NOT from a hose. I actually ended up replacing the oil cooler hose that connects to the water pump to be 100% certain it was not that. I can say for sure it is leaking at the mating surface of the block and water pump. All old gasket material has been cleaned and removed. Upon putting on the new water pump for the first time the surface was completely stripped and cleaned.

    - If the water pump mating surface is warped am I completely screwed?

     
  6. Sep 14, 2022 at 6:02 AM
    #6
    Daddykool

    Daddykool Photography enthusiast

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    This may be a bum suggestion, but since you're in so deep, would it be worth re-trying the original pump with a new OEM gasket (the one negusm mentioned) after cleaning it up really well? If that doesn't leak, it may at least tell you the block is ok.
     
  7. Sep 14, 2022 at 6:26 AM
    #7
    2Toys

    2Toys Imperial Star Cruiser

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    This looks to me, from the pictures, to be a corrosion problem - mostly on the water pump side, but a little on the mounting face on the block. The inside edge of the removed water pump where the coolant flows is corroded. Your question about the water pump mating surface on the block being warped: not likely it is warped, but could be leaking because of the corrosion from the old water pump. There does seem to be some pitting on the block side in the picture. Maybe some Permatex applied to the area where pitting is seen and then reinstall the replacement pump with a new or serviceable metal gasket. Should you use the Permatex, you may want to let that cure a bit before filling the coolant system.

    Regarding the possibility of the replacement not being machined to spec - possible, but not likely. Especially if you bought the water pump directly from Toyota.
     
  8. Sep 14, 2022 at 10:22 AM
    #8
    Dillusion

    Dillusion New Member

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    I'd try the permatex. I'm going to agree the block looks a little beat.
     
  9. Sep 14, 2022 at 3:52 PM
    #9
    tommyCO

    tommyCO [OP] New Member

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    DaddyKool - Thanks for the suggestion. Not a bad idea to test if the block is in fact warped/damaged!


    2Toys - I like this: "Maybe some Permatex applied to the area where pitting is seen and then reinstall the replacement pump with a new or serviceable metal gasket. Should you use the Permatex, you may want to let that cure a bit before filling the coolant system."

    Dillusion - Thanks for your input as well!
     
  10. Sep 14, 2022 at 4:45 PM
    #10
    McSpazatron

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    Dobinson IMS Warn Bumper CaliRaised Sliders 265/70 K02s
    Not sure about the warping possibility, but I wouldnt go there until you deal with the pitting

    Do you think the leak is coming from this area? (Pitting at bottom of pic by locating pin)9558CB84-AF35-40F0-833F-D11476DD7231.jpg

    I bet this corrosion pitting spans the inside and outside of the main sealing/compression portion of the gasket. The coolant would have a straight shot out of the engine if that’s the case. If it were me, I’d focus on filling these pits with Permatex. I’ve heard thin applications are recommended, it’s probably worth researching the best way to apply it. My suspicion is that you want to build in material into those pits by spackling it with a razor blade so only the pits have permatex in.

    But please dont take my guess for it, permatex might have some specific suggestions, or even products made for that purpose.

    edit: the pitting that’s occurring in a curve shape around the locating pin actually looks like the shadow of the compressing part of a gasket. If that’s the case, the gasket wont ever be able to seal until the pitting is addressed.
     
    Last edited: Sep 14, 2022
  11. Sep 14, 2022 at 8:51 PM
    #11
    tommyCO

    tommyCO [OP] New Member

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    Thanks McSpazatron, I really appreciate your input. I think my plan is a thin application or two of Permatex on the pitting and let that cure. Then a new Aisin water pump (just to be sure) and metal gasket. Won't be able to get to it until next week, but fingers crossed!..
     
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  12. Sep 14, 2022 at 8:52 PM
    #12
    tommyCO

    tommyCO [OP] New Member

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    If anyone else has any other suggestions I am all ears!
     
  13. Sep 14, 2022 at 9:49 PM
    #13
    negusm

    negusm New Member

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    If you got a TOYOTA pump from a dealer, it IS an AISIN pump.

    If you got a TOYOTA pump from Amazon or Ebay...there are counterfeits running around and sometimes you can tell because the impellers are cheaper.
     
  14. Sep 15, 2022 at 6:28 AM
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    2Toys

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    I would not let the Permatex cure without the water pump being installed. You will need a smooth surface on the Permatex to interface with the water pump to prevent leaks. The only way to get that is when the Permatex is wet.
     
  15. Sep 15, 2022 at 7:29 AM
    #15
    standard

    standard New Member

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    stock so far, what could he possibly need
    The mating surface on the block should look like the mating surface on the new pump. To me it looks like the block is scored and pitted, it this correct? If you try or tried to prep the block with sand paper or steel wool, did you back this with a strait flat piece of metal? Even a scraper can cause divots if not used carefully.
     
  16. Sep 15, 2022 at 7:38 AM
    #16
    standard

    standard New Member

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    stock so far, what could he possibly need
    if i were trying to fix this i would prepare the block surface for a coat of jb-weld flowed into the low spots and then made flat when it is cured, and then use the gasket. it will seal if it finds good mating surfaces. the problem i see with permatex is relying on it to take up the space that shouldn't be there, and i don't know how to do that without introducing permatex into the pump body. does that make any sense? it seems to me that the iron is eroded, if that's true i'd be inclined to repair the iron surface.
     
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  17. Sep 15, 2022 at 10:14 AM
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    Dillusion

    Dillusion New Member

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    Permatex is fine some don't come with gaskets and tell you to use it.

    Used Permatex on my old Camry before and no issues. Just make sure its cured before starting her up.
     
  18. Sep 16, 2022 at 4:47 AM
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    Ahdofu

    Ahdofu New Member

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    Thanks for looking into this. Since you used a Toyota part, I now very much doubt that the part is warped. Your earlier conjecture seems to be right on. Having said this I am still baffled as to why you still got a leak by adding coolant having installed the water pump with FIPG. I would have thought that the FIPG would have worked to seal that area even if it hadn't cured simply because the engine wasn't running.
    If you were to run a razor's edge on the engine block where the leak is occurring, can you confirm that all is flat and nothing is protruding? Obviously where there is pitting, the edge will just slide over it and that is OK.
    One other thought. Make sure the threads on all the mounting bolts are clean and corrosion free. This way you will not get a false torque reading in installing them.
     
  19. Sep 16, 2022 at 8:14 AM
    #19
    iamincrediboy

    iamincrediboy New Member

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    It looks like the original seal was on its way to failing due to the edges of your old pump and block surfaces. Like @standard mentions rebuilding that and then putting FIPG is likely your best bet. Something like this https://www.jbweld.com/product/steelstik-epoxy-putty-stick and just form it as smooth and consistent with surrounding shape as you can get. Pretty certain you arent going to clad weld right there.
     
  20. Sep 19, 2022 at 1:00 PM
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    DaveB

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    The corrosion is so thin jb weld it very smooth. The block shouldn't have any digits. Use a gasket glue on both sides when jb is cured. There is a brush on style I use. A very thin bead of permatex seal like very thin should cure it. Not sure what antifreeze you used but it's eating the gaskets I wonder what else it's eating now. Dexcool does that crap too.
     
  21. Sep 19, 2022 at 7:44 PM
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    negusm

    negusm New Member

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    Yeah, I'm thinking that someone is running the wrong antifreeze. Mine at 250k miles doesn't look this chewed up.
     
  22. Sep 22, 2022 at 7:44 PM
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    standard

    standard New Member

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    stock so far, what could he possibly need
    yeah that's a good point and worth checking out. need to follow the manufacturers directions on this. On some sleeved diesels the wrong coolant can bubble against the water side of the sleeves and corrode them to the point of failure.
     
  23. Sep 23, 2022 at 8:33 AM
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    DaveB

    DaveB New Member

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    Toyota metal is specific. If you run wrong coolant it will react as if it was a chevy lol. Since they love thier dexcool so much and don't warrenty when it eats the gaskets and motor early.
     

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