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Old 08-03-2016, 14:30   #1
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MD2020 raw water pump leak

I noticed some water collecting under the engine which used to be completely dry. I'm pretty sure looking at it that it's the water pump">raw water pump. Everything else is completely dry without salt buildup. It's in the yard now so I can't easily run the engine to confirm that it's leaking, or more specifically where it's leaking. The seal was replaced a year ago.

To me, a non-expert, because of the salt pattern, it looks like the seal is leaking rather than the shaft wobbling or other problem, does that make sense from this picture? What's the best way to clean it up before replacing the impeller and seal or is it too late? Any other suggestions?

I tried to attach an image, also insert one using the image insert, and neither seem to be showing up when I'm looking at the post, so here's a direct link to the picture...

Raw water pump picture

Thanks in advance! Brian

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Old 08-03-2016, 14:38   #2
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Re: MD2020 raw water pump leak

By the looks of the corrosion, it may have been leaking a long time. You must check your oil asap, as it is possible that water can get into the oil when a leak is found in the raw water pump. I just pulled mine off today on my perkins 4108. The new pump is over 800 bucks and the rebuild kit is about $300. If it is merely a seal around the impeller housing, that's probably no big deal. Why not take it out, clean it and retighten and see what happens. Next step is probably a rebuild or new pump. I hope it costs less than for my engine.
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Old 08-03-2016, 14:55   #3
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Re: MD2020 raw water pump leak

Quote:
Originally Posted by Paul Annapolis View Post
By the looks of the corrosion, it may have been leaking a long time. You must check your oil asap, as it is possible that water can get into the oil when a leak is found in the raw water pump. I just pulled mine off today on my perkins 4108. The new pump is over 800 bucks and the rebuild kit is about $300. If it is merely a seal around the impeller housing, that's probably no big deal. Why not take it out, clean it and retighten and see what happens. Next step is probably a rebuild or new pump. I hope it costs less than for my engine.
Thanks for the info! I agree that it looks like it's been leaking for a while but I think at most around six months because it looked pretty close to normal last summer. I started noticing a little salt around then but didn't think much of it at the time. My suspicion is that the seal between the impeller and housing wasn't properly installed when it was replaced last year (perhaps facing the wrong direction or was re-used (I don't know, I didn't do the work) and failed prematurely.

I check the oil regularly and it looks fine but it's due to be changed so I'll get an oil test done as well to make sure.

Unfortunately I think the cost for this one is similar to yours, part of the reason I hope I can recover it rather than replacing it!

What would you use to clean it up?
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Old 08-03-2016, 15:54   #4
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Re: MD2020 raw water pump leak

If there is water in the oil--you don't need a test. It will be sludgy, gray or milky and not as viscous as it should be--and you will have a real problem on your hands. You can clean the bronze with bronze wool and some scrubbing --or maybe use some naval jelly (phosphoric acid) but on my pump, and others, it does not actually leak out the cap but from tiny weep holes made for that purpose. Your looks much worse so I hope it works out. I need to take mine apart to more fully understand it but the rebuild kit is about 1/3 of a new pump. My mechanic says they don't seem to work as well--and I trust him but I am going to take my chances here.
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Old 08-03-2016, 16:21   #5
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Re: MD2020 raw water pump leak

Yuk, judging from all the external corrosion, looks like its been leaking at the fitting for the hoses for a long time. Easy fix: clean the nipples that the hoses attach to and replace the hoses. The hose ends are probably compressed and worn making a good seal more difficult.

The MD2020 pumps (actually a Johnson pump, with a Volvo specific flange) have a slot between the salt water seal and the oil seal which is designed to leak if either starts to fail. Water or oil will discharge from here in that case. Extremely unlikely to get water in your oil with this design.

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).

You can run the motor on the hard by just connecting a water hose to the intake hose or even directly to the pump intake nipple. You need good water flow to do this, but you wont be running the engine very long...just long enough to check for a leak at the weep slot. An inspection mirror and flashlight are handy for this.

There is an existing thread on replacing these seals...just search for it.
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Old 08-03-2016, 16:23   #6
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MD2020 raw water pump leak

Just had my son pull the front cover off of a 3208 for a similar issue. We were requested to investigate an oil leak. During the replacement of an oil hose we noticed severe corrosion of the motor mount below the raw water pump.

A fresh water wash down is the best way that I know to remove saltwater. Even in electrical components. Just dry before energizing higher voltage stuff.
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Old 08-03-2016, 16:30   #7
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Re: MD2020 raw water pump leak

Let's hope it's just the hoses as Belize Sailor seems to know a lot about this specific item--so keep us informed--hope it works out.
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Old 08-03-2016, 17:03   #8
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Re: MD2020 raw water pump leak

Quote:
Originally Posted by belizesailor View Post
Yuk, judging from all the external corrosion, looks like its been leaking at the fitting for the hoses for a long time. Easy fix: clean the nipples that the hoses attach to and replace the hoses. The hose ends are probably compressed and worn making a good seal more difficult.

The MD2020 pumps (actually a Johnson pump, with a Volvo specific flange) have a slot between the salt water seal and the oil seal which is designed to leak if either starts to fail. Water or oil will discharge from here in that case. Extremely unlikely to get water in your oil with this design.

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).

You can run the motor on the hard by just connecting a water hose to the intake hose or even directly to the pump intake nipple. You need good water flow to do this, but you wont be running the engine very long...just long enough to check for a leak at the weep slot. An inspection mirror and flashlight are handy for this.

There is an existing thread on replacing these seals...just search for it.
@belizesailor - great info, thanks. Likely then if water is coming from the weep slot that the water seal behind the impeller is failing (there's no hint of oil) but given the dispersion of salt on the surface it looks most likely that the hoses are what is leaking, right? The weep slot is where I can see the shaft? That area actually looks pretty clean. I'm hoping you're right about the hoses, it certainly looks like water could just be running out of the hose connection down over the unit.

@Paul Annapolis - I've seen water in my saildrive gear oil (which is actually why we're in the yard now) and the engine oil looks completely normal. I was advised to replace the pump rather than trying to rebuild (if it turns out it needs to be replaced or rebuilt) but we'll see what happens.

It'll probably be a couple days before I can get to it because the saildrive diaphragm is being replaced and I don't want to get in the way. I'll probably have the mechanic take a look since he's already there to see what he thinks too.

Anyway, thanks for the responses!
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Old 09-03-2016, 06:07   #9
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Re: MD2020 raw water pump leak

Quote:
Originally Posted by brianc View Post
@belizesailor - great info, thanks. Likely then if water is coming from the weep slot that the water seal behind the impeller is failing (there's no hint of oil) but given the dispersion of salt on the surface it looks most likely that the hoses are what is leaking, right? The weep slot is where I can see the shaft? That area actually looks pretty clean. I'm hoping you're right about the hoses, it certainly looks like water could just be running out of the hose connection down over the unit.

...
Yes, the slot is where you can see the shaft and where water/oil will exit if a seal is leaking.

Unlikely you need a new pump, the body and shaft are normally very long lived. Mine are 15 years old and still quite serviceable. However, a spare pump is not a bad idea. I carry a spare and when I notice a pump issue I just swap in the spare and rebuild the other as I have the time.

Looks like to me you had/have a leak at the hose connections, just run it and see.
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Old 09-03-2016, 06:43   #10
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Re: MD2020 raw water pump leak

Failure after only one year would be unusual. I would look at the previous rebuild. The seal orientation is first place, they have a spring that if improperly installed, reversed, would have been exposed to salt water and could have caused the failure of the seal. Other place to look would be scoring of the shaft. If this was not addressed in previous rebuild, it could be the source of your leak. I'm not sure if you can sleeve this shaft, but would seem likely. I would not buy a new pump. Call Depco in FL, they sell the rebuild kits for Johnson pumps. I have a spare shaft I bought from them a year ago, I believe the price was about $50.


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Old 09-03-2016, 07:12   #11
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Re: MD2020 raw water pump leak

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Old 09-03-2016, 09:06   #12
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Re: MD2020 raw water pump leak

[QUOTE=belizesailor;2067117]

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.
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Old 09-03-2016, 12:21   #13
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Re: MD2020 raw water pump leak

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.
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Old 09-03-2016, 12:55   #14
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Re: MD2020 raw water pump leak

Re the stainless/non-stainless springs in the lip seals:

It is common practice to replace the springs with appropriate sized o-rings. All the seal shops that I have dealt with were familiar with this and would do it for the cost of the o-ring, usually less than twenty five cents.

IME, even the allegedly s/s springs will fail in salt water exposure.

Jim
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Old 09-03-2016, 13:49   #15
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Re: MD2020 raw water pump leak

Quote:
Originally Posted by belizesailor View Post
Yuk, judging from all the external corrosion, looks like its been leaking at the fitting for the hoses for a long time. Easy fix: clean the nipples that the hoses attach to and replace the hoses. The hose ends are probably compressed and worn making a good seal more difficult.

The MD2020 pumps (actually a Johnson pump, with a Volvo specific flange) have a slot between the salt water seal and the oil seal which is designed to leak if either starts to fail. Water or oil will discharge from here in that case. Extremely unlikely to get water in your oil with this design.

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).

You can run the motor on the hard by just connecting a water hose to the intake hose or even directly to the pump intake nipple. You need good water flow to do this, but you wont be running the engine very long...just long enough to check for a leak at the weep slot. An inspection mirror and flashlight are handy for this.

There is an existing thread on replacing these seals...just search for it.
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.
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