Did I put the wrong seals in my pump

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  • Outaouais sailor
    Senior Member
    • Jul 2015
    • 39

    Did I put the wrong seals in my pump

    I hope someone can help me figure out my problem.
    My A4 has been overheating, keeping me at the dock.
    First I changed the impeller in my Oberdorfer pump. Still overheating. Then I noticed there was a fair bit of water leaking from a weep hole on the bottom of the pump. Struggled with the bolts, got the pump off, replaced the seals and put the pump back on.
    I followed the instructions from the manual but was confused by the fact that one of the seals I took out had a metal casing, a brass bearing housing.
    Now it seems to be leaking from a new place, a rectangular slot on top of the pump.
    When I removed the seals, one of them had a brass bearing housing. The replacement seals are the black plastic kind with little springs.
    To be clear: There used to be a thing that looked like this, only with brass housing instead of steel:
    Product No. - CSOB_00_463
    I removed that, replaced it with a black plastic seal.
    Is that where I went wrong?
    Do I need to order that part and replace the outer seal with it?
    Hope someone can help!
    Thanks
  • ndutton
    Afourian MVP
    • May 2009
    • 9777

    #2
    Here's what I think is going on:
    • Your shaft is scored and needs replacement, should have been done with the seal replacement. Having new seals on a damaged shaft will not stop the leaking. For water to leak out from the areas you describe it has to get past the seal nearest the impeller.
    • Don't be influenced by the different construction and appearance of the new seals vs. the old. The black seals are correct, only new generation.
    • The seals are not bearings. The bearing in your pump is a carbon or bronze sleeve bearing and should be checked for play (indicating wear) when your new pump shaft is installed. The part number you referenced in this and the other thread is for a different pump, the MMI 501 or 502. Your pump is an Oberdorfer 202M.
    • The simple solution is to spring for a new Moyer Marine 502 flange pump. Consider that your pump is quite old and in addition to the worn and damaged parts you're dealing with right now you likely have wear in the impeller cavity which at some point will affect the performance. We will all be replacing our pumps sooner or later.
    Edit:
    Here is the spec sheet for the Oberdorfer 202M series pumps. On the right side of page 2 is an exploded view, item #12 is the sleeve bearing (completely different from the seals). Item #10 is the grease cup which should be twisted clockwise regularly to lubricate the shaft and bearing avoiding damaging wear. The last time I twisted mine it bottomed out so just yesterday I reloaded it with grease.

    Edit #2:
    I don't think this leak is the cause of your overheating. Have you done an acid flush? When was the last time the water jacket side plate was removed for inspection? Do you have a valve in the bypass loop?
    Attached Files
    Last edited by ndutton; 07-24-2016, 11:07 AM.
    Neil
    1977 Catalina 30
    San Pedro, California
    prior boats 1987 Westsail 32, 1970 Catalina 22
    Had my hands in a few others

    Comment

    • JOHN COOKSON
      Afourian MVP, Professor Emeritus
      • Nov 2008
      • 3501

      #3
      Take it easy.
      Work list:
      (1) Rebuild the pump with a new shaft. This should stop the leak. If it doesn't it means you have torn the new seals up with the old shaft or the bearing that Neil mentioned is shot.
      (2) Now let's get to the real problem - overheating. Since you are currently at the pump end of the cooling system check to be sure the water inlet is not partially blocked. Once the pump is pumping correctly and the intake is clear take the hose off where it connects to the hot section from the manifold and start the engine rev it up and direct the output somewhere safe. It should be like a garden hose. If it isn't the pump output is poor or there is a flow blockage in the engine. Report back. Do you have a thermostat? The most common causes of overheating with good water pump output are thermostat stuck closed, water flowing around the engine through the bypass, blockage in the exhaust system* You could also try clamping the bypass and force all the cooling water through the engine.

      TRUE GRIT

      * Also crud in the water passages
      Last edited by JOHN COOKSON; 07-24-2016, 11:53 AM.

      Comment

      • Outaouais sailor
        Senior Member
        • Jul 2015
        • 39

        #4
        Thanks very much for this advice.
        I boiled up the thermostat last year and it responded as it was supposed to do.
        I'm going to try clamping the thermostat bypass. Is that the hose to the starboard of the thermostat housing, or to the port? It must be the one to the port, eh?

        Comment

        • Outaouais sailor
          Senior Member
          • Jul 2015
          • 39

          #5
          I just did some research and see the clamp goes on the starboard side.
          I will try this and see how it goes.
          A leaky water pump would be acceptable to me in the short term. I have a bilge pump. It's the overheating that's driving me mad since it's keeping me at the dock. I should have tried the clamping already.

          Comment

          • sastanley
            Afourian MVP
            • Sep 2008
            • 7034

            #6
            OS, yes..the stbd side. the hose on the port (on top) is hot exit water from the block enroute to the manifold. You should see markings on the t-stat housing labeled "WP" for water pump and "MAN" (I think) for Manifold..The water pump is the very first thing in the system, and the manifold is the last part of a RWC'd engine before it goes to the mixing tee and down the exhaust.

            I don't remember seeing it so I'll add an explanation of the 'bypass' hose as I understand it.

            Its job is to supply water to the exhaust system when the t-stat is closed (i.e. cold engine). Sometimes this route is easier than going thru the engine (if t-stat is stuck or there is crud in the water passages) and more water goes thru the bypass than normal and the engine overheats. Clamping the bypass forces the cooling water thru the motor..make sure you are still getting water out of the exhaust during this experiment...The rubber exhaust hose can handle the heat for a short period (I don't know exactly how long, if the engine is cold a few minutes, if already warm, maybe only a minute ), but the various exhaust parts will melt eventually without water being injected from the mixing tee.

            Oh, and +1 on the Moyer 502 pump. I found one used, but they are worth every penny...they pump way more water than the Oberdorfers..and if you are thinking about needing to plop down a couple boat bucks to repair your obd, I'd just assume get the Moyer pump!
            Last edited by sastanley; 07-26-2016, 11:43 AM. Reason: typos
            -Shawn
            "Holiday" - '89 Alura 35 #109
            "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
            sigpic

            Comment

            • JOHN COOKSON
              Afourian MVP, Professor Emeritus
              • Nov 2008
              • 3501

              #7
              Let's review the water flow in a RWC engine.
              After the cooling water leaves the water pump it sees the T fitting. At this point the cooling water has two options: flow through the engine or go around the engine by way of the bypass. What determines which route the water will take? The thermostat. The original A4 thermostat is a two stage thermostat. It opens to allow more water to go through the engine and at the same time blocks the bypass so all or most of the water does go through the engine. This is accomplished in the thermostat housing. There is a depression in the top of the thermostat housing where the bypass hose connects to it. As the thermostat opens and expands part of it is rammed up into this depression which blocks the bypass. With the bypass blocked water will flow through the engine (remember the T fitting) and cool the engine.
              What can go wrong? There are three most common. (1) The thermostat doesn't open (2) So much crud in the cooling passages in the engine that enough water can not flow through the engine to cool it effectively even with the thermostat wide open. (3) The depression in the thermostat housing is corroded away so much that the bypass is not effectively sealed when the thermostat is open. (MMI offers a brass thermostat housing) As a result the cooling water takes the easy way at the T fitting and flows around the bypass not through the engine.
              Ok, so now what? (1) Test the thermostat by heating it in a pan of water to see if it opens correctly. (2) Acid flush to clear out the cooling passages in the engine. Open the side plate and clear out as much KRAP as you can. Tear down the engine and hot tank the various pieces. (3) Clamp the bypass to see if the engine runs cooler. Get a MMI thermostat housing. As an alternative put a restrictor and or a valve in the bypass hose. This mimics the action of the two stage thermostat.
              Notes: Even with adequate water flow through the exhaust system the engine may run to hot because to much water is going through the bypass and not through the engine.
              This does not address other problems such as low water pump output, down stream blockages in the manifold or exhaust system.

              TRUE GRIT

              Edit: Shawn beat me to it!
              Last edited by JOHN COOKSON; 07-26-2016, 11:59 AM.

              Comment

              • sastanley
                Afourian MVP
                • Sep 2008
                • 7034

                #8
                Yeah, but your explanation is more thorough.
                -Shawn
                "Holiday" - '89 Alura 35 #109
                "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
                sigpic

                Comment

                • Outaouais sailor
                  Senior Member
                  • Jul 2015
                  • 39

                  #9
                  Gentlemen,

                  I had to spend a number of days packing and unpacking my significant other's belongings so I wasn't able to get to the boat to try out your ideas until today.
                  Some good news and bad news.
                  Good news: I took off the pump, put it back on and it seems to have stopped leaking. I suspect it wasn't properly seated.
                  Good news: I ran the boat for quite a while with the bypass hose clamped off and the temperature did not rise above 180.
                  Bad news: It still stalled out after 20 minutes and I had to wait a while before it would start again.
                  Now I am thinking it might be a bad coil?

                  Comment

                  • JDK
                    Senior Member
                    • Apr 2016
                    • 137

                    #10
                    Sounds like you are making progress......glad your pump leak stopped, that's a bigger problem than it seems cause when the inner seals finally go it'll leak raw water into the crankcase motor oil......not good

                    Comment

                    • JOHN COOKSON
                      Afourian MVP, Professor Emeritus
                      • Nov 2008
                      • 3501

                      #11
                      Originally posted by Outaouais sailor View Post
                      Gentlemen,
                      Bad news: It still stalled out after 20 minutes and I had to wait a while before it would start again.
                      Now I am thinking it might be a bad coil?
                      If you get a no start again pull the big wire from the coil out of the distributor and while holding it near the engine to ground it, and turn the engine with the starter to see if you can throw an arc. 1\2'" blue-white arc is good. You will find out real quick whether the coil is the reason for the no start.
                      Remember to close the raw water valve when you crank a no start engine.

                      TRUE GRIT

                      Comment

                      • Outaouais sailor
                        Senior Member
                        • Jul 2015
                        • 39

                        #12
                        Thanks, JDK and John.
                        I need to learn to check the coil.
                        You take the wire off the centre of the distributor cap and hold it near the engine block?
                        Why shut off the water intake valve?

                        Comment

                        • JOHN COOKSON
                          Afourian MVP, Professor Emeritus
                          • Nov 2008
                          • 3501

                          #13
                          Originally posted by Outaouais sailor View Post
                          (A)You take the wire off the centre of the distributor cap and hold it near the engine block?
                          (B)Why shut off the water intake valve?
                          (A) Yes. Turn the engine with the starter to see if you can throw a spark.
                          (B) With out exhaust pressure to blow it out water will accumulate in the exhaust system and back up into the engine and land in the cylinders. Not good.

                          TRUE GRIT

                          Comment

                          • Outaouais sailor
                            Senior Member
                            • Jul 2015
                            • 39

                            #14
                            Gentlemen,
                            I replaced the coil, took her out for a run and she quit after 20 minutes, as usual. Temperature, with bypass clamped off, never exceeded 170 F.
                            So this is a diagnosis challenge.
                            Motor quits every time after 15-20 minutes of running OK.
                            Will start again later.
                            My plan: clean the carb and see if problem persists.
                            Sound like the right move?

                            Comment

                            • ndutton
                              Afourian MVP
                              • May 2009
                              • 9777

                              #15
                              Where did you get the replacement coil?
                              Neil
                              1977 Catalina 30
                              San Pedro, California
                              prior boats 1987 Westsail 32, 1970 Catalina 22
                              Had my hands in a few others

                              Comment

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