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Time To Replace Water Pump?

Discussion in 'Early CJ5 and CJ6 Tech' started by Eric, May 29, 2022.

  1. May 29, 2022
    Eric

    Eric Member

    CA
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    Symptoms: On cold start with radiator full, engine starts and runs fine. No apparent water entering upper radiator tank. Also, no water appearing from weep hole area. As engine warms up, eventually it "seems" that water is entering upper tank, so cap is put back on. After a short while, steam begins escaping the overflow hole under the cap and engine is turned off. Three hoses feel hot (upper radiator hose and both heater hoses) but lower radiator hose feels warm near engine and cold near lower tank. My guess: Thermostat opened as it should and let hot, expanding water enter upper tank giving the appearance of water moving. Also guessing water pump is not moving water and that accounts for cold feeling lower hose.

    Questions: First, is my logic sound in above analysis? Second, is there a way to verify pump is moving water without removing pump? (I suppose I could remove upper hose and see if water gushes out when engine runs.) And lastly, would a radiator flush kit be wise to try before replacing pump?

    Independent of all that, anyone want to go out on an endorsement limb and recommend a replacement pump in case I need to go there? (F134, by the way.)
     
  2. May 29, 2022
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    I would lower the water level in the radiator about one inch. Then restart and leave the cap off. As the engine heats and the thermostat opens, you should see water movement, although slower at idle. It may push water out. Let it. Maybe up the idle speed a bit so you can watch.
    Steam doesn't bother me, that's from hot water.
    If the radiator level is full, before the thermostat opens, it will push water out.
    Does your F4 have the 90 degree by-pass hose ?
    It's not needed but will help circulate water.
     
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  3. May 29, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Walck's should have the water pump. Water pumps usually leak before they wear out....it would take a lot of hours to actually wear one out. If the radiator was truly full that's way too much, as Jim noted it's designed to have air space for expansion. Chances are you don't need a new water pump.
     
    Eric likes this.
  4. May 29, 2022
    Eric

    Eric Member

    CA
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    Thank you, both. I'll include a photo of my water pump. The radiator started full and the steam escaped for a while before settling to a level below the core (tops of tubes showing). I know not to mess with the cap while engine is hot... had that drilled into me in Auto Shop YEARS ago when they still offered that class. There is no 90 degree bypass. I will start it this morning with water lower but above the core. What is still bothering me is the cold feeling on the lower radiator hose. In my thinking, once thermostat opens, all hoses should eventually be similarly hot to the touch. Thank you for the tip on Walck's. Was looking at an Airtex on RockAuto. Pulley did not have holes to bolt on fan, and several other venders use a similar photo.
    water pump side.jpg
     
  5. May 29, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    The water circulating through the radiator and coming out the bottom will be cooler.....that's the whole idea with the radiator. Now exactly how much cooler I don't know but if it wasn't cooler the engine would keep getting hotter and hotter. Do you have a temperature gauge? What is the thermostat temperature rating?
     
  6. May 29, 2022
    Eric

    Eric Member

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    I've never changed the thermostat so I have not determined the temperature rating yet. Yes, the lower hose should be somewhat cooler than the upper, but even after steam is spewing, the lower hose feels like ambient air temperature. I will put a termperature gauge on my list of future purchases as I see it references in lots of the threads I read. Thanks for the help.

    I think I will invest in a new radiator cap, also. Can't hurt.
     
  7. May 29, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Your steam escaping is almost certainly because the radiator was full with no room for expansion. At least that is how I interpreted what you wrote. You should have a 7# radiator cap by the way. Either a 160 or 180 degree thermostat would be what you need, probably 180 would be better, although if your Jeep has emission stuff I'm not sure what it should have. How is the fan belt adjustment? Good and snug?
     
    Eric likes this.
  8. May 29, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor

    East Tennessee
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    If you still have a problem after doing what was suggested above I suggest pulling out the thermostat and testing it. You can test it by placing it in a pot of water with a thermometer, watch as you heat the water and see if it opens and if so at what temperature. A kitchen thermometer will work for this.

    As already said water pumps usually start to leak before they actually wear out, and there is not much in them to go wrong other than the seals, if it is spinning it should be moving water.

    A stuck thermostat, or a clogged up radiator is more likely a culprit than the water pump provided the pump isn't leaking.
     
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  9. May 29, 2022
    Eric

    Eric Member

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    Belt is perfect. Thank you for the numbers on the cap and thermostat. No emmissions equipment. I ran it without cap and low level in upper tank. Once water started enting upper tank, things got hot in a hurry. (Several minutes of idling.) So I am guessing thermostat works but will use Oldpappy's advice and test it on the stove. Assuming it works, I think I might invest in a radiator flush kit as they are not too expensive. Do you have any thoughts on those? Picture of one manufacturer's kit attached.
    flush kit.PNG
     
  10. May 29, 2022
    Eric

    Eric Member

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    Thanks. I think the thermostat is working, though I do not know the termperature range it is set for. I am thinking of a radiator flush kit to force water out of the system by introducing it through a heater hose and out from the upper tank. That might dislodge any minor blockages. Probably removing the radiator and having a professional shop look at it would be the best? Trying to save a buck, but don't want to be penny-wise and pound foolish.
     
  11. May 29, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    Well, you're having maybe 160 or 180 degree water starting to merge with maybe ambient? temperature water so yeah it's going to start heating up quickly. But did it want to or did it overflow? Or did the level rise noticeably?
     
  12. May 29, 2022
    boopiejones

    boopiejones I can’t drive 55

    California east bay
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    When you say “things got hot in a hurry” do you mean the engine overheated, or just that the hoses and radiator feel hot? Assuming the engine isn’t overheating, I don’t really see anything wrong based on the way you’re describing the situation.

    as for the radiator flush kits, I bought the same prestone one on Amazon for $3. Looks like it would work just fine, but I ended up just holding a garden hose up to various hoses/openings on the engine and flushing it that way.
     
  13. May 29, 2022
    Eric

    Eric Member

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    It did rise about an inch but I could hear the boiling water and there was so much steam I shut the engine down. Is that rise attributable to expanding water or functioning pump? Thanks.
     
  14. May 29, 2022
    Eric

    Eric Member

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    What I meant was that once the water started flowing into the upper tank, the upper hose and heater hoses got very hot almost immediately. One of the things I need to fix on my radiator is the overflow tube under the cap. It looked like a steam pressure washer coming out of the tube. I'll add a photo of the broken tube and if you can imagine a high pressure spray of water/steam emerging from there. Finger is pointing to the section of the tube welded to the side of the radiator. The upper section coming from under the cap and toward me is where the geyser was spraying. I am considering ust using 1/4 inch rubber hose for that (hose clamps, of course).
    overflow tube.jpg
     
  15. May 29, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    Based on this the radiator being partially plugged is sounding like the culprit. The water level shouldn't rise much nor should there be that much steam.
     
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  16. May 29, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    Now let's hope you don't have a blown head gasket that is causing this.
     
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  17. May 29, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    This is why I'm saying let's hope it's not a blown head gasket.
     
  18. May 29, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    I'm assuming the upper and lower radiator hoses are ok? Not soft or collapsing?
     
  19. May 29, 2022
    Eric

    Eric Member

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    Correct assumption. Hoses are fine.
     
  20. May 29, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    If it was mine I would pull the lower radiator hose off with the radiator in place and see what you can flush into a bucket, basically to get an idea if possible of what the situation is and to help determine if the radiator (it must be) is truly plugged up. Obviously look for any loose particles in the hose or the inlet of the water pump.
     
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