Oberdorfer Pump Identification

[britinusa]

I had a spare Oberdorfer Pump on the boat when I purchased her, I changed them out and now would like to service the old one but am not certain of the model.

The body casting has the numbers 8928-5P and 0108
The Impeller cover plate has no markings but the body does have an O-ring where the plate attaches with 4 bolts.

I have read Mainesail's article about servicing a similar pump on his site.

Any advice on the model, or how'to ?

Paul

[KWKloeber]

Paul,

If the ports are 1/2" NPT, it is a N(new, o-ring case)202M(marine)-16, or alternately if 3/8" NPT ports, an N202M-15 (parts are the same.)

The obvious wear parts are the
http://c34.org/bbs/index.php/topic,8493.msg59876.html#msg59876

* Cover (reverse it if considerable wear on the inside face from the impeller.)
* Bearing.
* Inner and outer seals.
* Shaft (inspect for wear at bearing and also a groove at the seal location.)
Don't use the cir clip, and coat the shaft under the impeller w/ SuperLube gel (ptfe).

Note  if you replace all parts, and approaches the cost of a new pump.
10% disc to members on parts.

IIRC there's also an article on refurb in the tech notes.

K

[Stu Jackson]

Paul,

101 topics again:

Oberdorfer Pump Rebuild 101 - http://c34.org/bbs/index.php/topic,6766.0.html [Link added to main page of C34 Tech wiki]

That wiki may be the one Ken noted.

[KWKloeber]

Thanks for the link Stu.

Actually mine was to the exploded parts diagram.
Both links, along with the link to the TN article are on the TWiki resource (Engine -> Cooling.)

k

[britinusa]

Thanks Guys!

Ken, the widest part of the threaded ports is about 0.67 so I'm assuming (risky) that's 3/8" NPT according to https://en.wikipedia.org/wiki/National_pipe_thread 0.675" pipe nominal OD for 3/8"NPT

I'll take the shaft & seals out before looking to order parts / get a new pump.

Paul

[KWKloeber]

Ya, I'd say that's a safe ass/u/mption.  What you want to compare at is the pipe thread dia at the "effective" length (i.e., where the "front" of the fitting sits when tightened.)  It's more than the hand-tight (E1) location but probably less than the full wrench-tight (E2) location.

Universal used both 1/2" and 3/8" pumps on its engines, with the split leaning toward 3/8" NPT.  If you are going to do any "work" in that area, I could suggest some belt/suspenders improvements we could guinea pig on you (not positive if they fit in the C34 engine space) but otherwise, I'd just be jaw slappin'.

k

[britinusa]

Successfully manufactured the magic tool. Removed the shaft (easy), removed the two seals (tool=easy)

Spent an hour cleaning up the pump body.

There is an O ring where the plate covers the impeller. I'll Wet-n-Dry the both inside and outside of the cover.

Shaft looks good, I can see where the seals were, but cannot feel them, it's just shiny.

So I believe all I need to get is the two seals, O ring, engine gasket. Not sure if the carbon bearing surface is replaceable or if it needs it.

Paul

[KWKloeber]

P

Yes the bearing is replaceable.  What do you see on the shaft re the bearing location?  Do you have a micrometer?

IIW messing with my pump right now I'd stick a zerk on the body to fill the area between the two seals w/lithium grease.  The sister pump (202M-03/07) has a grease cup (turn once or twice a season) to do that.  Why not the -15/-16 pumps???  They are identical pumps, identical parts, identical bodies; except for the shape of the base that sits on the pump land. Easy peazy, drill and tap a 1/8 npt hole for a zerk fitting.  Viola, belt and suspenders, and another item to tinker with..

K

[britinusa]

Ken, the weep hole is between the two seals, could just pump lithium grease in there.

I have the gear to drill & tap a hole for the zerk fitting.

I could pickup a micrometer in the morning from HF.

Are you suggesting that if I replace the carbon bearing, then I should also replace the shaft?

Is there a Rebuild kit for this pump?



Paul

[KWKloeber]

You're saying tap the weep hole? I suppose that would work. Obviously you don't want a weep, as the grease should be under slight pressure.  Like a trailer Bearing Buddy grease cap.

Before deciding to replace, need facts.  Is the shaft worn any at the bearing?  Is there any slop at all?  Does the shaft pass as easily through the entire length?  Etc

IIRC those parts are only individually because not always is a new shaft and/or bearing needed. 

[KWKloeber]

PS. I orig had a 202M-07 with the grease cup, I believe that pump has no weep hole.

[Stu Jackson]

If the carbon bushing is OK, just leave it, put the new seals in, and call it a day.  No need for anything in between the seals. You WANT that to be clear above the weep hole so any oil or water that gets out you WILL see.  Don't block it with anything.  KISS 

[britinusa]

Thanks guys.

Ken, the reason I asked about the Zerk was that you had said

IIW messing with my pump right now I'd stick a zerk on the body to fill the area between the two seals w/lithium grease.

And the weep holes are between the two seals. But I just re-read you later reply that that pump did not have the weep holes.

Ken & Stu, The shaft glides in and out of the bearing without any restriction, but there is a very slight 'wobble' when attempting to move the shaft perpendicular to the bearing.

Paul

[KWKloeber]

Paul,  Clarification.  The pumps that (IIRC) had no weep, were the M-03/07, not yours.  It's going back too many years or more when I replaced mine (-07, with the grease cup) with the -15 (w/o the grease cup,) so memory is a little sketchy.   

IIRC, the older M-15/16 had a small weep hole (that could be tapped for a zerk to exclude any water getting past the seal.)  Not having an old one to compare, I can't say for sure.  The newer castings I think Ob changed the weeps, so that it may not be able to do what I was going to look at when I next have mine off the engine.  The words I left out were I'd "look at the possibility of..."  It's just one of those things that I do .... consistently look how to improve on an already good situation, using the database of past experience.  I used to trailer sail for many years - the wheel bearings were a constant headache -- always worrying about inspecting and rebuilding them before a long road trip.  To the point of carrying spare setups for each wheel.  I installed Bearing Buddies.  NEVER a drop of water in them; NEVER had to replace a bearing again -- because it was impossible for water to displace the grease.  Did it "work" before, yes.  Was it better to improve on the situation? Yes.  Same on anything else -- in my mind, if there's an improvement to anything to totally exclude the possibility of even a 1/100 chance failure, then I'll evaluate doing it.  It doesn't make it any less "kiss" to eliminate failure point, it makes is more "kiss" in the long run.  There's two schools of industrial management, "If it works, don't break it" (status quo), and "If it works, make it better (i.e., Demming's continuous improvement concept.)

As to yours, Stu is correct... IF THE bearing is ok.  As I said (not having eyes and hands on) it's hard to say whether it needs replacing.  Chances are that the bearing and shaft are "ok", but if not then you can get premature seal wear and you're back to the problem again.  Without a history no the pump, my thought train would be, "Why did PO replace it?"  Are the shaft or bearing worn so that he got fed up with seals failing?  I can't tell that w/o having the pump in my hand.  Even a new pump has a margin between the shaft/bearing, and you'll feel ever so SLIGHT a wobble but it shouldn't be excessive -- if I had it in my hand I could gauge it -- but in that absence, I would check for wear on the shaft and go from there (plus you acquire a new man toy.)  The cost of a new bearing is less than ONE seal, so I'd be tempted to replace it and use the old shaft if it mics up with no wear........ Or to skimp a little, keep with the current bearing and see what happens down the road. YBYD.

Here's the list on wear parts:
Shaft $50
Seal set $48
Carbon bearing $22
o-ring $7
impeller $41


I have not yet seen a pump that leaked oil to the weep, only water.  Tho it's theoretically possible, there's no pressure behind the gear case to "pump" oil out of the pump land.  Oil under atmospheric pressure would have to be forced thru the margin between the bearing/shaft (unlikely) to get to the weep.  Consider also that the rear seal is installed in the direction (p/n facing the water) to keep water from getting out of the pump, not to keep oil in the engine.  Seals are always installed with the p/n facing what you want to prevent going past it.  If there's a pump w/ that failure I'd love to see so that I could see what condition the rear seal and bearing are in.

Cheers
Ken