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Old 09-03-2016, 14:58   #16
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Re: MD2020 raw water pump leak

[QUOTE=Horus;2067608]
Quote:
Originally Posted by belizesailor View Post

The seals on the MD2020 pumps are very easy to replace. They are standard oil seals, readily available from many autoparts stores or seal suppliers. For a few dollars you can buy a handful, so dont waste money on the grossly over priced Volvo seals, they are the same thing. Ditto for the bearings (more challenging to replace successfully in the field...best done in a shop that can press them on).

QUOTE]

The VP seals are NOT standard seals. The seal at the freshwater side must have a Stainless Steel spring in it. You understand if not the spring will be gone within one season!. At the engine side (oil) there you can use a standard seal. Note the side with the spring in sight is the pressure side; so the seals must be mounted with the springs facing the oil/water.
Got specifics to back that up?

Sure they are, I've looked them up based on the manufactures markings on the seal and watched VP provided seal springs rust and fail. Stick a magnet to one a see what happens. Have also had standard automotive seals last just as long as official VP seals. Packing with a little grease helps.

Also, the seals on the raw water side of the MD2020 pump will work just fine with the spring oriented toward the weep slot and thus more protected.

Replacing the spring with an o-ring is a better solution either way.
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Old 09-03-2016, 15:09   #17
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Re: MD2020 raw water pump leak

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Originally Posted by deblen View Post
Is it wise to apply pressurized water from a garden hose? Doesn't that cause hose water to back up in thru the exhaust valves?
Maybe better to insert seacock end of RW hose in a pail of water & let it suck thru the RW pump.
Yes, if you left it like that for a little while without the motor running it could cause some issues (water lock). Ive done it just very briefly to test, but yes the bucket approach is safer.

Surprising how much flow it takes to keep the bucket full even on such a small engine.
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Old 09-03-2016, 15:40   #18
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Re: MD2020 raw water pump leak

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Originally Posted by thunderhoof View Post
I just replaced both seals on my MD2030. Same problem you saw. Easy to replace water side seal. Oil side requires disassembly. Stainless spring nitrile seals easily available online about $7 each. Cross ref VP Part No.
To replace water side seal close water intake, remove two hoses and 4 bolts to dismount pump. Remove cover to access impeller. BTW this can be hardest part because brass screws seem to rot and break when removed. I needed a drill and an Easy Out to remove mine. I switched to socket head SS screws with anti seize.
Then use a short, 90 degree bend tool to push sea from back into impeller area. There is an air space between water and oil sides of pump that the tool will fit in. Clean up shaft with fine emery cloth. I put a small dab of grease on seal center before inserting. Flat side of seal goes in first. A new impeller and paper seal and you are done. Be careful when reseating pump on engine to ensure good oil seal there.
My oil side seal looked new but I replaced it any way. You need a way of removing the drive gear and an arbor press to do this.
Yes, that's a handy trick if you just need to replace a seal fast, like underway. Then deal with a rebuild of the pump later...if the seal is going probably other things need attention too.

The thread below shows the procedure with pics. Other good related discussion too. Also shows replacing the spring with an o-ring. You can carefully extract the spring to use in sizing the o-ring. Ive discovered that the little o-ring for Racor 500 fuel filter housing t-handles work.

Quick Raw Water Pump Sea Water Seal Replacement

Never had much luck cross refing Volvo part numbers. They guard that info pretty closely. But, for replacing seals, anywhere on a motor, all you need is a good set of calipers and most seals are marked with the dimensions anyway. If possible, I just take the seal with me to the supplier.

In the field, which is the usual cruiser place for repairs, Ive had good luck with just carefully tapping the properly supported gear off. A chunk of wood with a hole drilled in it works well for support. I keep a block of wood aboard with a few "jigs" bored in it for that use. Pass the shaft thru a hole, put the nut over the threads to protect them, put a block or wood on top of the nut or use a hard plastic mallet, and give it a few good raps, usually pops right off. Pressing it back on with just the nut works fine.

Also, a home made tool to press the seals back in is very handy. I made mine from PVC pipe. A properly sized socket also works.

Of course, I get the impression that the OP may just have a mechanic deal with it, so this all may be overkill for him, but hopefully useful to others.
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Old 09-03-2016, 16:56   #19
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Re: MD2020 raw water pump leak

the pump is toast by a new one
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Old 09-03-2016, 18:34   #20
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Re: MD2020 raw water pump leak

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Originally Posted by bsurvey View Post
the pump is toast by a new one
Just talked to the mechanic...this was the decision.

He said bearings and seals were bad and it needed to be rebuilt. It's 14 years old and is the original with no rebuilds, only impeller changes. I wouldn't save much, if any, rebuilding over just getting a new pump*.

Thanks for the info and advice though, I learned quite a bit. I'll get a rebuild kit and attempt to rebuild the old one myself as a spare if I ever need it...one of these days, or years, I'd like to be able to deal with more stuff myself. In any case, the cost of the new pump is a fraction of the cost of the other work being done so it's not the end of the world.

*The raw water pump, it turns out, is covered under the 'Critical systems will be professionally maintained' clause which I (not a mechanic) verbally entered in to when we bought the boat as one of the conditions for buying the boat.
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Old 10-03-2016, 05:14   #21
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Re: MD2020 raw water pump leak

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Originally Posted by brianc View Post
Just talked to the mechanic...this was the decision.
...

Thanks for the info and advice though, I learned quite a bit. I'll get a rebuild kit and attempt to rebuild the old one myself as a spare if I ever need it...one of these days, or years, I'd like to be able to deal with more stuff myself. In any case, the cost of the new pump is a fraction of the cost of the other work being done so it's not the end of the world.

...
Do keep the old one and rebuild it yourself. As long as the body is not excessively worn, which is unlikely, its an easy rebuild. You will learn more about your motor and have a spare in the end.

If the shaft isn't badly worn, get new bearings (not from Volvo) and have a shop press them on.

All good stuff if you plan to do any extended cruising. And, if you screw it up, no big loss.
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Old 10-03-2016, 10:03   #22
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Re: MD2020 raw water pump leak

Here is a link to a workshop manual for your engine. It is same engine as Perkins M20.
http://wilfredmacdonald.com/parts/perkins.pdf


Perkins M20 - Removed head and this lovely sight presented me!
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Old 10-03-2016, 22:17   #23
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Re: MD2020 raw water pump leak

If anyone is interested the seal information is:
(4) SKF692671 12 X 24 X 7 Nitrile oil seals.
To cross reference other manufacturers 12 is the ID in mm 24 is the OD and 7 is the width. Specify Stainless seal spring unless you want to do the o_ring trick. I do not agree that reversing the seal to protect the spring is a good idea because the open side of the seal should always be toward the higher pressure side, in this case toward the impeller.
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Old 29-03-2016, 03:39   #24
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Re: MD2020 raw water pump leak

Great post, excellent Contributions from anyone
VoLvo TAMD 31-LA (1997) has a similar pump....

I just changed bearings and seals, but still having leaking....

The O-ring trick is great.... Sure the spring must face the pressure side, water/oil... therefore they should go back to back. BUT on the Volvo drawing they look like both facing upfront...

Am I wrong!?


We all agree that raw pump and oil pump are at the heart of the engine.... well, why Volvo engineers thrived for savings, by combining them into one!? I HATE THIS poor DESIGN (as an engineer, I get really pissed off by this, believe me....)

GOD provided mammals with pairs of tits, but possibly Swedish engineers are fed by a nursing bottle only, so they prefer the all-in-one design!?

Miserable, indeed, on a 400kg engine.

More generally, the impeller concept is totally wrong in this case. It is prone to work under friction. Rubber gets severely bent inducing fatigue and long-cycle stress/failure...end if the engine is not operated routinely, some parts of the impeller get bent for good.
On top, Volvo managed to have "their" impeller 2 millimeters shorter than the standard model, thus forcing for a captive market...

Overall, i'd send those goteborg based engineers go fishing salmon....with bare hands , Beyond the Polar circle
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Old 29-03-2016, 07:36   #25
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Re: MD2020 raw water pump leak

Old pump, still leaking, could be a worn shaft.
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Old 29-03-2016, 16:48   #26
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Re: MD2020 raw water pump leak

to: The Thunderbird
The MD2030 does not combine oil and raw water pump. The "oil side" on the same shaft is the water pump drive gear that is splash lubricated by some part of the oil return path.
I cannot easily tell from the parts breakdown what the seal orientations are. I was going by what I found during disassembly. Each seal open side faced the pressure.
On the idea of using nitrile o-rings to replace the SS springs my comment is that SKF knows more about making seals than I ever will. They probably have a support page where one could send them a query on this subject.
Lastly, (for now): Carefully check the source the oil leak. When I first reinstalled the pump I did not seat it properly on the engine and it leaked at the large o-ring gasket. Do you have an undamaged o-ring at the pump-engine interface? Another possibility is the location and seating of the oil side shaft seal. On my pump it seems the seal is not positively located along the shaft. There is a plastic spacer on the shaft between the two seals and a small o-ring on the water pump side of the spacer. The flat side of the oil side seal should be flush with the engine side of the weep holes behind the water pump.
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