Changing the Rear Seal on an MD2030B

I believe this HOW TO was originally posted by Kris Hearst (What If) in the files section of the old Mantatech site. If I’m not crediting this article to the right person, please feel free to correct me…Regardless it is an excellent example of a “How To” article that can add huge value to new site. 

Replacing the rear seal on a Volvo Penta MD2030B engine

  1.  Turn off battery.
  2. Shut off raw water intake.
  3. Shut off fuel if warranted.
  4. Drain oil from engine.
  5. Remove exhaust hose from mixing elbow on engine.
  6. Obtain two 4’ long 4 by 4’s and two 4’ long 2 by 4’s, or 6 4’long 2 by 4’s.
  7. Use on 2 x 4 to take weight off of saildrive.  We did this by getting two eye bolts with 1” of thread.  These slid into two slots on either side of the saildrive.


  8. Use 4 by 4’s or double 2 by 4’s to take weight off of engine using lifting eyes. wiki-changingseal3
  9. First, tie ropes around boards tight to engine.  Then remove the bolts that hold the engine mounts to the fiberglass frame.  Next you use brute strength, or a spare 2 by 4 to pry up the ends of the boards, and slip something under them to lift the engine.  We used the classics.  That is books – Catcher in the Rye, East of Eden, The Old Man and the Sea, among
  10. Now the weight should be off the engine and the saildrive.  Remove the bolts holding the saildrive onto the engine, and slide the engine away from the saildrive by sliding the support boards.  Make sure all your electrical line, fuel lines, water lines, are OK, and don’t get pinched or pulled.
  11. Once the saildrive is separated, we tied another line through the empty bolt holes for added assurance to make sure the saildrive was supported by the board.  This is a good idea, as you will be working over the top of it, leaning on it, and bumping it a lot.  You can see the extra lines tied on in the second picture.
  12. Now the work begins.  Take off the bolts that hold the flywheel housing adapter on.  There are 8 of them.  The have plastic washers on them.  One of ours had a plastic bushing on it. If yours does, make sure you memorize which hole it was in.  The washers are used to electrically isolate the saildrive and flywheel housing from the engine.  Don’t lose them. 
  13. Once the bolts are off, remove the flywheel housing adapter.  You will see that a plastic gasket comes off with it, and also a plastic split ring.  Clean and save them all.  If you can, notice how the plastic split ring is set into the flywheel housing adapter as you will need to know this for reinstall.
  14. You will now see the exposed flywheel and vibration dampener.
  15. There are 6 Allen head bolts that will need removed.  I marked the vibration dampener and its relation to the flywheel for reinstallation. wiki-changingseal5
  16. You will need to make sure the camshaft can’t move in order to loosen the bolts.  We used a crescent wrench on the front of the engine on the camshaft.  Place the crescent wrench over one of the tabs on the crankshaft pulley and wedge it against the water
  17. Once the Allen head bolts are removed, I took a plastic handle and gently pried the vibration dampener off, as it was kind of stuck on.
  18. With the vibration dampener off, you will see the 6 bolts that hold on the flywheel.  We noticed that our flywheel had the 6 bolts, but also a locating pin.  If yours has a locating pin, you don’t need to mark its location, but if it doesn’t mark its location in relation to the shaft, by using a sharpie marker on the small inside hole.  You will notice the flywheel has bolt holes in it.  Using the bolts that we took off the flywheel housing adapter, we put these into the holes in the flywheel to make lifting it easier.  It is one heavy bugger, don’t pinch your fingers.   We spent the better part of two hours to get off those 6 bolts.  Repeated dosing of PB Blaster, use of an impact driver, and then using a spanner with a cheater bar and lots of muscle finally broke them
  19. We just left the flywheel sitting down there by the engine, as it was just too heavy to lift out.  You might want to loop a rope around the bolts you put in the flywheel to help hold it, and have someone hold the rope from above to take some weight off of it.
  20. Once the flywheel is off, you will see the flywheel housing.  You will also see the starter protruding into the housing, and the main shaft with the seal on it.  Our housing had 8 bolts to remove that took another 4 hours, PB Blaster, impact driver and spanner with cheater and lots of muscle to


    Remove the two bolts that hold the starter onto the flywheel housing, just let the starter dangle.  Make sure you look at all the wires going to your starter in case some fall off.  Remove your bolts, and the seal might come right off with the housing, if not you can pull it off with your hands, although ours seemed kind of suctioned on.

  22. Now you can see the engine block and main crankshaft.  Notice the starter just hanging to the
  23. Clean the mating surfaces of the engine block and the flywheel housing well, Use a degreaser on both.  Notice if you have any scoring on the main shaft.  We did.  I took some emery cloth to the scoring just to smooth it out, and make sure there were no burrs.
  24. Now you are ready to install the new seal.  Put some grease around the lip of the new seal where it slides onto the shaft.  BE VERY CAREFULL.  We had to do the job twice because for some reason, the seal either had debris, or something that caused it to deform and we didn’t notice, put everything back together and had an even worse leak, and had to do to the job all over again.  MAKE SURE EVERYTHING IS CLEAN..
  25. Once the seal is on, apply the gasket material as stated in the workshop manual.  Our gasket material was orange, and it doesn’t take a lot to make a good seal.  Don’t over apply it.  Contrary to our manual, the second time we put the seal on first and then the gasket sealant.  I think this is a safer way to go.
  26. Here you can see the new seal on the engine block.  Notice the rubber side faces the flywheel
  27. Now make sure the crescent wrench on the crankshaft pulley is set to lock the crankshaft for tightening.
  28. Now you can install the flywheel housing, and use anti-seize on all the bolts and torque them to the specified amount.
  29. Install the starter back into the flywheel housing.  Install the bolts, but don’t tighten them all the way down, just let the starter hang loose.  This will make it easier to get the flywheel back on.
  30. Make sure the forward portion of the flywheel is clean where it mates up to and sits on the main shaft and seal.
  31. Install the flywheel.  This is a pain as it is so heavy.  It helps a little if someone can hold the weight a little while someone else gets it in position.    Torque the flywheel bolts to specified amount and use anti-seize.
  32. You can now tighten up the starter bolts and fasten it securely.
  33. Install the vibration dampener, tighten bolts to specified torque.
  34. Take the flywheel housing adapter and place the plastic gasket on it, and the plastic split ring.  I used a little silicone to hold the plastic split ring in place, as otherwise it just kept falling off. 
  35. Install the flywheel housing adapter with the plastic split ring in place and the plastic isolator gasket.  Torque bolts to specified amounts. 
  36. Now slide the engine back to the saildrive.  Make sure the saildrive is in neutral.  Slide the engine back to the saildrive.  You may have to adjust the book levels on the boards to make sure it mates up nicely.  You also may have to use the crescent wrench to slightly turn the crankshaft to get it to align with the saildrive.
  37. Once they are mated, but in the bolts that hold the saildrive to the flywheel housing adapter, but don’t tighten. 
  38. Position the engine and lower it a little so you can start the bolts that hold the engine mounts to the support structure.
  39. Once the engine mount bolts are started, and then tighten the saildrive to flywheel housing adapter.
  40. Now you can let all the lines loose and finish bolting the engine down.
  41. Hook up anything else you may have taken off ( Fuel, water or electrical lines)
  42. Make sure all electrical to the starter is reinstalled.
  43. Put on a new engine oil filter and top off the oil.
  44. Check the saildrive oil.
  45. Check the antifreeze
  46. Turn on fuel, raw water and battery switch.
  47. Start you engine, listen to it purr, and have yourself a cold one. – You deserve it.