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Epoxy as crank case filler

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  • Epoxy as crank case filler

    Hello, I'm rebuilding the compressor pump on my air compressor. It is an Quincy model 310. Water has built up in the crank case and finally degraded the roller and Babbitt bearings. I would like to fill the bottom of the crank case with epoxy while the crank case is tilted so that it raises the floor of the crank case in one corner opposite the drain. This will allow water that builds up to move to the drain and into an extension of the drain pipe, also will allow a more complete drain of old oil. My question is, what epoxy and survive immersed in oil. Any one have some knowledge on epoxies? Thanks. Rod Williams

  • #2
    a number of people have reported using jb weld to fix cracks and holes in their oil pans. your application is much less demanding.

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    • #3
      I would also say JB Weld. But I would JB some screws through from the bottom of the case so the JB filler has something to grab onto if the bond to the inside of the case fails. You will have to perfectly clean the case of course, where the JB is going to puddle- especially if you've been using a synthetic lube. Don't let the level of the epoxy come too close to the sight glass or you may change the way it reads.
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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      • #4
        I have a couple of 310's... I think the answer is to simply change your oil if it becomes "milky". If the water is separating it's not being used much; Mine is fully emulsified. Water IN the oil is not the same as "in the sump" as a layer, and will still mess with your bearing. Are you using a quality oil like DTE or the Quincip synthetic that can absorb some water?

        Last Quincy I rebuilt (340) I used Glyptal to seal the entire inside of the crankcase. The hardest part? getting the old oil out of the castings. I literally boiled it for hours in a caustic solution, and repeated a couple of times. You will have the same problem with epoxy.
        Last edited by lakeside53; 01-14-2020, 11:43 AM.

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        • #5
          You could use fiber glass mat and resin to coat the bottom of the case. I haven't seen it react to oil.
          Helder Ferreira
          Setubal, Portugal

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          • #6
            [How about just putting a shim under the whole compressor unit on one side. I am sure it will still run fine with a 5 or 10 deg. tilt.

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            • #7
              I'm with wdtom44 on this, a tiny bit of tilt would be much easier. Changing the oil more often right after stopping the machine when it is warm would help.

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              • #8
                I used JB weld on a suzuki dirt bike crank case once. It held up for a few years until I junked the bike. The secret was to have very thorough cleaning and preparation. I "warmed up" the metal a bit by sticking a light bulb in there. The epoxy was cured rock hard in half a day. I was able to drill and tap it, etc.

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                • #9
                  Originally posted by quadrod View Post
                  Hello, I'm rebuilding the compressor pump on my air compressor. It is an Quincy model 310. Water has built up in the crank case and finally degraded the roller and Babbitt bearings. I would like to fill the bottom of the crank case with epoxy while the crank case is tilted so that it raises the floor of the crank case in one corner opposite the drain. This will allow water that builds up to move to the drain and into an extension of the drain pipe, also will allow a more complete drain of old oil. My question is, what epoxy and survive immersed in oil. Any one have some knowledge on epoxies? Thanks. Rod Williams
                  JB and most epoxies won't work. The iron crank case will expand and contract more than the JB and the oil will infiltrate around the edges and eventually it will come loose. I did that once and it floated up in the oil. They make an aviation grade flexible epoxy sealant fuel and oil proof that self levels that would work better but I would, as others have recommended, tilt it instead.

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                  • #10
                    Originally posted by quadrod View Post
                    . . .I would like to fill the bottom of the crank case with epoxy while the crank case is tilted. . .
                    You could do that with molten lead. It won't bond to the case, but it doesn't need to. It will stay put as long as the pump is upright.
                    Southwest Utah

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                    • #11
                      Yes JB Weld will do what is required although you will need to roughen up the surface to assure proper adhesion and clean the surface very thoroughly to be certain a proper bond has been established.

                      Personally I would just use a good quality synthetic compressor oil and change it more often. Change it right after the compressor has stopped. One of the attributes of compressor oils is that they are designed to shed water so that it will separate if left standing for any length of time. You need to drain the oil while it is still an emulsion in order to remove it all.
                      I would also change it more often if you are not getting the compressor hot enough to evaporate the water from the oil during normal use. This can be an issue when the duty cycle of an air compressor is very low. Just like your car, short trips usually require more frequent oil changes.
                      Home, down in the valley behind the Red Angus
                      Bad Decisions Make Good Stories​

                      Location: British Columbia

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                      • #12
                        Another one that works very well in these applications is Marine-Tex. We used to use it to repair corroded liner lower counterbores in Caterpillar engines. It stood up very well with hot engine oil on one side and hot coolant on the other. The main thing with any of these epoxies is to scratch up the surface it is to bond to very well and get it as clean and oil free as possible before applying the epoxy. Once it kicks off you can machine or sand it to get a nice surface finish and oil, antifreeze or diesel fuel won't affect it in any way.

                        Larry - west coast of Canada

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                        • #13


                          Any nr of industrial epoxies are made for this, and cheap in quantity.
                          Expofer 402, and 34D hardener, in Spain, for one, from Feroca.
                          Really made for sealing fuel tanks, but great for mounting $$$ bearings, same ratings as hysol 3xxx at 20xthe price.

                          Look for your industrial suppliers fuel tank sealants, imho...

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                          • #14
                            I had already thought about tilting the pump unit. The way the sump is designed has the oil pick up tube and screen are right on the bottom and the drain sits about a 1/4" up off the floor. Water collects and is picked up and mixed with the oil and when draining you can't get it all out. Last oil change I changed it twice an still had a lot of contaminated oil left in bottom. I also thought about the lead idea. My plan is to boil the crank case in water with dawn soap or some mildly acidic degreaser we use at work. I figure anything I do will help. I talked to the folks at JB Weld and was told that there epoxy will survive immersed in oil and up to 550 degrees as long as it is allowed to fully cure first. Thanks for the replys.

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